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The effect of the time interval between coronary angiography and on-pump cardiac surgery on risk of postoperative acute kidney injury: A meta-analysis

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Reports of the association between the time interval from coronary angiography (CAG) to cardiac surgery and risk of postoperative acute kidney injury (AKI) are controversial. We attempted to examine this association by conducting a meta-analysis. We searched the Pubmed, MEDLINE, EMBASE, Web of Science databases, and the Cochrane Library from January 1966 to March 2013. A meta-analysis of studies reporting data for 1-day and 3-day time intervals between CAG and cardiac surgery was conducted after evaluation of heterogeneity and publication bias. Study-specific estimates were combined with inverse variance-weighted averages of logarithmic odds ratios (ORs) in fixed-effects models. From 8 studies involving 11542 persons, the pooled OR of AKI associated with an interval of 1 day or less between CAG and surgery was 1.21 (95 % confidence interval (CI), 1.04 to 1.39) relative to an interval of more than 1 day. From 4 studies involving 5420 persons in the cardiopulmonary-bypass subgroup, the pooled OR of AKI associated with an interval of 3 days or less between CAG and surgery was 1.25 (95 % CI, 1.07 to 1.43) relative to an interval of more than 3 days. The adjusted OR of the study in the cardiopulmonary bypass/ deep hypothermic circulatory arrest subgroup was 0.35 (95 % CI, 0.17 to 0.73). A time interval of 1 day or less between CAG and on-pump cardiac surgery was significantly associated with increased risk of AKI. A delay of on-pump cardiac surgery until 24 hours after CAG can potentially decrease postoperative AKI.
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RES E AR C H A R T I C L E Open Access
The effect of the time interval between coronary
angiography and on-pump cardiac surgery on
risk of postoperative acute kidney injury:
a meta-analysis
Yijie Hu, Zhiping Li, Jianming Chen, Cheng Shen, Yi Song and Qianjin Zhong
*
Abstract
Background: Reports of the association between the time interval from coronary angiography (CAG) to cardiac
surgery and risk of postoperative acute kidney injury (AKI) are controversial. We attempted to examine this
association by conducting a meta-analysis.
Methods: We searched the Pubmed, MEDLINE, EMBASE, Web of Science databases, and the Cochrane Library from
January 1966 to March 2013. A meta-analysis of studies reporting data for 1-day and 3-day time intervals between
CAG and cardiac surgery was conducted after evaluation of heterogeneity and publication bias. Study-specific
estimates were combined with inverse variance-weighted averages of logarithmic odds ratios (ORs) in fixed-effects
models.
Results: From 8 studies involving 11542 persons, the pooled OR of AKI associated with an interval of 1 day or less
between CAG and surgery was 1.21 (95% confidence interval (CI), 1.04 to 1.39) relative to an interval of more than
1 day. From 4 studies involving 5420 persons in the cardiopulmonary-bypass subgroup, the pooled OR of AKI
associated with an interval of 3 days or less between CAG and surgery was 1.25 (95% CI, 1.07 to 1.43) relative to an
interval of more than 3 days. The adjusted OR of the study in the cardiopulmonary bypass/ deep hypothermic
circulatory arrest subgroup was 0.35 (95% CI, 0.17 to 0.73).
Conclusions: A time interval of 1 day or less between CAG and on-pump cardiac surgery was significantly
associated with increased risk of AKI. A delay of on-pump cardiac surgery until 24 hours after CAG can potentially
decrease postoperative AKI.
Keywords: Acute kidney injury, Coronary angiography, Cardiac surgery
Background
Postoperative acute kidney injury (AKI) is one of the
most serious and frequent complications of cardiac
surger y. Previous studies have demonstrated that even
small increases in serum cre atinine following cardiac
surgery are independently a ssociated with increased
mortality and longer hospitalization [1-3]. As no
causal therapy f or AKI is currently available, every
efforthastobemadetopreventAKI[4].
Lately it has become common practice to provide
same admission [5] or even one-stage diagnostic coron-
ary angiography (CAG) and surgical services for patients
undergoing cardiovascular surgery. The types of surgeries
mainly include coronary artery bypass grafting (CABG),
aortic surgery, and valve surgery. AKI is reported to occur
in up to 30% of patients after on-pump cardiac surgery
[6,7], while contrast-induced nephropathy after CAG
occurs in up to 10% of patients with normal renal func-
tion and up to 25% of patients with pre-existing renal
impairment [8]. Hence, many studies have dealt with
the question of whether the closely spaced double hit
on renal function increases the risk of postoperative
* Correspondence: zhongqianjin@qq.com
Department of Cardiovascular Surgery, Institute of Surgery Research, Daping
Hospital, Third Military Medical University, No. 10 Changjiang Zhi Road,
Yuzhong District, Chongqing 400042, China
© 2013 Hu et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Hu et al. Journal of Cardiothoracic Surgery 2013, 8:178
http://www.cardiothoracicsurgery.org/content/8/1/178
AKI. Conflicting data have been reported. Some authors
claimed that the risk of AKI after cardiac surgery is not
influenced by the time interval between angiography and
cardiac surgery [9-13]. Conversely, other authors empha-
sized the deleterious effect of performing both procedures
in close succession [14-17].
In view of the limited clarity of the available data, we
conducted a systematic review of the literature and a
meta-analysis of selected studies to evaluate the effect of
the time interval between CAG and cardiac surgery on
risk of postoperative AKI.
Methods
Search strategy
The keywords used to search included the following:
cardiac surgery or CABG or valve surgery or aortic sur-
gery and catheterization or angiography or percutan-
eous coronary intervention and "acute kidney injury or
AKI or renal failure." A computerized search of the
Pubmed, MEDLINE, EMBASE, Web of Science data-
bases, and the Cochrane Library from January 1966 to
March 20 13 was undertaken to identify potentially eli-
gible studies on the basis of the title, abstract, and key-
words; no language limitation was applied. Then, the full
content of each article was examined to decide which
studies met the inclusion and exclusion criteria men-
tioned in the next section. The reference lists from all
studies, narrative reviews, and systematic reviews identi-
fied by electronic searches were manually searched to
identify additional eligible studies. Two authors (Yijie
Hu and Zhiping Li) independently performed the eligi-
bility assessments; if opinion s differed, the differences
were resolved by consensus.
Inclusion and exclusion criteria
Included studies met the following criteria: (1) the study
focused on the risk of AKI and the time interval between
angiography and cardiac surgery; (2) the study was a
randomized controlled trial, case-control, or cohort
study; (3) the study either provided risk estimates with
the odds ratio (OR), and 95% confidence interval (95%
CI), or suffic ient information was available to calculate
the OR and 95% CI.
A study was excluded from the meta-analysis if (1) it
only provided an effect estimate but no means to calcu-
late a 95% CI; (2) it did not provide an accurate defin-
ition of AKI; (3) it did not provide an accurate time
interval; (4) off-pump heart surgery was performed, but
the combined AKI risk due to contrast media and car-
diopulmonary bypass (CPB) could not be evaluated; or
(5) it was a low-quality study. In the case of multiple
studies with the same or overlapping data published by
the same researchers, we selected the most recent study
with the largest number of participants.
Data extraction
For each study, two authors (Yijie Hu and Yi Song)
extracted the following data: the first authors surname,
country the study was conducted in, year reported, study
design, sample size, primary operation, definition of
AKI, effect estimate (95% CI), and adjusted covariates.
If the effect estimate could be acquired from the
searched results of the tabulated literature, they were
extracted carefully from all eligible publications, which
met the inclusion criteria. If data were not directly avail-
able, they were calculated from the published positive
predictive values and/or the negative predictive values
when appropriate. If a study contained unclear or in-
complete information, the reviewers contacted the ori-
ginal authors for verification. Differences in data
extraction were resolved by a third reviewer, referring
back to the original article.
Quality evaluation
We applied the Newcastle-Ottawa scale (NOS) [18] to
evaluate the qualities of the included studies. A star sys-
tem was used to judge the data quality of these studies
on the basis of three broad categories: the selection, the
comparability, and the outcome or exposure of interest.
The stars were summed to compare the quality of a
study in a quantitative fashion. The scores ranged from
0 to 9 stars. Studies with scores of 6 stars or greater
were considered to be of high quality studies. Two re-
viewers (Yijie Hu and Yi Song) independently evaluated
and cross-checked the qualities of the included studies,
and assessed the bias of the studies. An open discussion
was held to confirm the scores of those studies that re-
ceived a different score from each reviewer.
Statistical analysis
For each study, data regarding the incidence of AKI were
used to generate ORs and 95% CI; or the adjusted ORs
and 95% CI were extracted directly. According to time
intervals reported in the literature, two meta-analyses
were conducted: one analysis for interval of 1 day or
less (the <1-day group), and one analysis for interval of
3 days or less ( the <3-day group). Among the studies of
each group, AKI was mainly induced by contrast and
ischemia-reperfusion injury after cardiopulmonary by-
pass, with the exception of the only study that used deep
hypothermic circulatory arrest (DHCA), which we
reported separately. All studies included in the subgroup
analysis are functionally identical, and the effect size in
our meta-analysis differ mainly because of sampling
error. Accordingly the pooled OR estimates were com-
bined by using inverse variance-weighted averages of
logarithmic ORs in a fixed-effe cts model (the Mantel
Haenszel method). Heterogeneity among studies was de-
termined by the chi-square-based Q test and the I
2
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statistics. A P value of less than .05 for the Q test and
an I
2
value of greater than 50% were considered as a
measure of severe heterogeneity. A funnel plot was
constructed to determine if publication bias existed and
to examine differences between the effects in large and
small studies; the studies were also assessed by applying
Eggers weighted regression test. The Eggers test was
also applied to assess less than 6 studies, with a P value
of < 0.05 indicating significant publication bia s among
the included studies. The effects sizes, given as the OR
on a logarithmic scale, were plotted against a measure of
precision expressed as the inverse standard error. All
statistical analyses were performed by using Stata Statis-
tical Software (Version 11.0; StataCorp LP, Texas, USA).
Results
Description of the studies
As outlined in Figure 1, we identified 9 studies for the
meta-analysis, including 5 cohort studies and 4 case-
control studies. Detailed characteristics of the studies
are listed in Table 1. Among the 9 stud ies, 5 studies used
the AKI Network definition of AKI [19], an absolute in-
crease in serum creatinine to 0.3 mg/dL, or a relative
increase of 50% from the baseline value within 48 h
after surgery, or a requirement for postoperative dialysis;
3 studies defined AKI on the basis of the RIFLE (Risk,
Injury, Failure, Loss , End-stage renal disease) criteria
[20] (R stage: plasma creatinine levels 1.5 × baseline;
I stage: plasma creatinine levels 2.0 × baseline); and 1
study defined AKI as a greater tha n 25% rise in serum
creatinine by the third postoperative day or as renal dys-
function that required the initiation of dialysis. Quality
assessment of all studies was performed by using the
NOS method (Table 2). The assessments ranged from a
star rating of 6 to 8 (mean star rating, 7) with a higher
value indicating better methodology.
There were 8 studies of a 1-day time interval between
CAG and cardiac surgery, and 5 studies of a 3-day time
interval.
Meta-analysis of studies reporting data for a 1-day time
interval between CAG and cardiac surgery
Four of the 8 individual studies demonstrated a statisti-
cally significant effect of a 1-day time interval on the
incidence of AKI. Pooled analysis of the 8 studies re-
vealed a significant increase in AKI risk by a factor of
1.21 with a 1-day time interval relative to >1 day
in fixed-effect s models (Figure 2). There was minimal
trial heterogeneity (I
2
= 24.0%, P = 0.238). Assessment
of publication bias by visual examination of the funnel
plot (Figure 3) and by application of Eggers weighted
regression test (P = 0.102) indicated no significant publi-
cation bias.
Meta-analysis of studies reporting data for a 3-day time
interval between CAG and cardiac surgery
The 5 studies of a 3-day time interval exhibite d severe
heterogeneity (I
2
= 86.7%, P < 0.01). After comparing the
basic and clinical characteristics of the 5 studies, we di-
vided them into two subgroups: one (the CPB subgroup)
included 4 studies that did not use deep hypothermic
circulatory arrest (DHCA), which is a significant risk fac-
tor of AKI [23,24]; and the other (the CPB/DHCA sub-
group) included only one study that did use DHCA.
Meta-regression was not further performed due to the
limited number of available studies.
In the CPB subgroup, only 1 of the 4 studies demon-
strated a statistically significant effect of a 3-day time
interval between CAG and cardiac surgery on the inc i-
dence of AKI. Pooled analysis of the 4 studies revealed a
significant increase in AKI risk, by a factor of 1.25, with
a 3-day time interval relative to > 3 days in fixed-effects
models (Figure 4). The 4 studies of this subgroup
exhibited no heterogeneity (I
2
= 0%, P = 0.682). In
addition, Eggers test revealed no e vidence of significant
publication bias (P = 0.295).
The study in the CPB/DHCA subgroup showed no
significant difference in AKI risk between a 3-day time
interval and an interval of more than 3 days, with an ad-
justed OR of 0.35 (95% CI, 0.17-0.73; P = 0.005).
Discussion
This meta-analysis is the first to evaluate the impact of
the time interval between CAG and cardiac surgery on
postoperative AKI incidence. Our results suggest that a
1-day time interval significantly increases postoperative
AKI. This review provides important evidence that may
resolve the ongoing controversy arising from previous
Figure 1 Flow diagram of study selection for the meta-analysis.
AKI = acute kidney injury; CAG = coronary angiography.
Hu et al. Journal of Cardiothoracic Surgery 2013, 8:178 Page 3 of 7
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studies. For instance, Ko et al published a series of 2133
consecutive patients who underwent cardiac surgery but
found no association between the time interval from
angiography to surgery and the incidence of postopera-
tive AKI [9]. Conversely, Ranucci et al recently reported
that surgery on the same day as angiography signifi-
cantly increases the risk of AKI, after risk-adjustment in
a total of 4440 consecutive patients [14]; these results
closely resemble those of the present meta-analysis. The
validity of these results supports the idea that the
Table 1 Main characteristics of 9 included studies
Study Year Country Type of study Sample size Main operation Definition
of AKI
Total AKI
incidence
Adjustment
Ranucci [14] 2013 USA Cohort 4440 CABG A 21.7% Age, EF, MI, congestive heart failure,
previous operation, urgent operation,
creatinine, CPB duration, nadir HCT
Valve Surgery
Ko [9] 2012 USA Cohort 2133 CABG A 32.0% None
AVR
Mcllroy [21] 2012 USA Cohort 644 CABG A 21.9% Age, BMI, CPB duration, procedure
type, N-acetylcysteine administration,
modified EuroSCORE
Valve Surgery
Greason [11] 2012 USA Cohort 642 AVR A 22.7% None
Andersen [10] 2012 USA Case-control 285 Aorta replacement B (R) 31.0% Age, sex, BMI, eGFR, hypertension,
CHF, diabetes, CPB duration, EF,
hemoglobin, aprotinin exposure
CABG
Mehta [22] 2011 USA Case-control 2441 CABG A 17.1% Age, sex, race, BMI, diabetes, CHF, MI,
EF, hypertension, contrast volume and
type, cardiogenic shock, cross-clamp
time, creatinine, hemoglobin
Medalion [17] 2010 Israel Case-control 395 CABG B (R) 13.6% None
Hennessy [16] 2010 USA Cohort 197 Valve Surgery B (I) 6.6% None
CABG
Del Duca [15] 2007 Canada Case-control 649 CABG C 24.0% Age, CPB duration, baseline GFR
Valve Surgery
A: defined by the AKI network: absolute increase of 0.3 mg/dL or a relative increase of 50% in serum creatinine from baseline value within 48 h after surgery,
or a requirement for postoperative dialysis.
B: defined by the Risk, Injury, Failure, Loss, End-stage renal disease (RIFLE) criteria for acute renal failure, which are based on differences betwe en the baseline and
peak postoperative serum creatinine levels (R stage: plasma creatinine level 1.5 × baseline; I stage: plasma creatinine level 2.0 × baseline).
C: defined as a rise in serum creatinine of greater than 25% by the third postoperative day or renal dysfunction that requ ires the initiation of dialysis.
Abbreviations, AKI acute kidney injury, AVR aortic valve replacement, BMI body mass index; CABG coronary artery bypass grafting, CHF congestive heart failure, CPB
cardiopulmonary bypass, DHCA deep hypothermic circulatory arrest, EF ejection fraction, eGFR estimated glomerular filtration rate, GFR glomerular filtration rate,
HCT hematocrit, IMA internal mammary artery, MI myocardial infarction.
Table 2 Assessment of study quality
Study Quality indicators from the Newcastle-Ottawa scale Score
Selection Comparability Exposure/Outcome
1234 5a 5b 6 7 8
Ranucci [14] Yes Yes No Yes No No Yes Yes Yes 6
Ko [9] Yes Yes No Yes No No Yes Yes Yes 6
Mcllroy [21] Yes Yes No Yes Yes Yes Yes Yes Yes 8
Greason [11] Yes No No Yes Yes Yes Yes Yes Yes 7
Andersen [10] Yes Yes No Yes No Yes Yes Yes Yes 7
Mehta [22] Yes Yes No Yes Yes Yes Yes Yes Yes 8
Medalion [17] Yes Yes No Yes Yes No Yes Yes Yes 7
Hennessy [16] Yes No No Yes Yes Yes Yes Yes Yes 7
Del Duca [15] No Yes No No Yes Yes Yes Yes Yes 6
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incidence of postoperative AKI can be contained by lim-
iting the practice of performing cardiac surgery on the
same day as angiography [14].
The 5 studies of a 3-day time interval that were in-
cluded in this meta-analysis exhibited severe heterogen-
eity. After considering the obvious difference of the use
of DHCA, a risk factor of AKI [23,24], we divided the
studies into to two subgroups: the CPB subgroup, in-
cluded 4 studies; and the CPB/DHCA subgroup, only 1.
Once we removed the study that used DHCA, the het-
erogeneity of the CPB subgroup disappeared.
Analysis of the CPB subgroup determined that a time
interval of 3 days or less between CAG and cardiac sur-
gery significantly increases postoperative AKI. This time
interval includes surgeries performed 1, 2, and 3 days
after CAG. Without consideration of the effect of a time
interval of 1 day or less , it is difficult to evaluate the ef-
fect of 2-day and 3-day time intervals on the incidence
of postope rative AKI. In fact, the pooled effect is largely
based on data on the incidence of AKI from 2 studies,
which contributed to more than 90% of the total weight.
In the cohort study by Ko et al, the number of days
Figure 2 Forest plot for time interval, 1-day vs >1 day. The estimated odds ratio (OR) of each individual article corresponds to the middle
of the squares, and the horizontal line gives the 95% confidence interval (CI). The sum of the statistics along with the summary
OR is represented by the middle of the solid diamonds. The heterogeneity test statistic (I statistic) between articles is given below the
summary statistics.
Figure 3 Funnel plot for studies of a 1-day time interval.
Hu et al. Journal of Cardiothoracic Surgery 2013, 8:178 Page 5 of 7
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between CAG and cardiac surgery was not a predictor
of postoperative AKI after the data were adjusted for
confounding factors (OR, 0.99; 95% CI, 0.99 - 1.00; P =
0.41) [9]. In the study by Mehta et al, cardiac surgeries
performed 2 days and 3 days after CAG were not associ-
ated with an increased risk of AKI when compa red with
those performed later (OR, 1.26; 95% CI, 0.94 1.74;
and OR, 1.11; 95% CI, 0.77 1.59) [22]. Accordingly, the
significant association between a time interval of 3 days
or less and increased risk of AKI may have resulted from
inclusion of data from a time interval of 1 day or less,
not from inclusion of data from 2-day or 3-day time
intervals.
The lack of associat ion between CAG on preoperative
days 1 through 3 and increased risk of AKI in the one
study of the CPB/DHCA subgroup seems controversial,
given that the pooled effect of the CPB subgroup did
show a significant association (adjusted OR, 0.35; 95%
CI, 0.17-0.73; P = 0.005) [10]. However, the CPB/DHCA
subgroup had a much more higher incidence of AKI,
about 31% if defined by the RIFLE criteria, while, the
highest incidence of the other studies was only 18% if
defined by the RIFLE criteria, or 32% if defined by the
AKI network criteria [9]. W e interpret this to mean that
DHCA plays an important role in postoperative AKI.
Moreover, the inc reased risk of AKI due to DHCA
would probably dilute the difference between any
CPB/DHCA subgroups containing stud ies that report
data from different time intervals.
Our review has several limitations that must be con-
sidered for accurate interpretation of the reported ef-
fect s. First, this observational meta-analysis was based
on a limited number of cohort and case-control studies
and was short of randomized trials and a large scale of
comprehensive clinical trials. Accordingly, the potential
confounding factors such as age, mellitus diabetes, type
of disease, type or complexity of the operation, bypass
time and the use of DHCA were unequally distributed .
The impact of this bias on the estimated effects
presented in this review is unknown, even after adjust-
ment. To address this issue, the methods we used to se-
lect studies and analyze pooled data were in accordance
with the MOOSE guideline [25] and current recommen-
dations for meta-analysis of observational trials. Add-
itionally, we used a funnel plot analysis and Eggers'
test to exclude publication bias. Secondly, this review
was limited by the use of different definitions of AKI,
although Haase et al reported tha t the incidence of post-
operative AKI in patients with cardiac surgery was simi-
lar when AKI was defined according to either the RIFLE
or the AKI Network classification [26]. We attempted to
mitigate this bias to some extent by adopting OR as the
summary statistic. Lastly, our review did not account for
differences in study quality, since the rating of methodo-
logical qua lity was goo d for all included studies.
Conclusions
The results of this meta-analysis strongly support an as-
sociation between a 1-day time interval from CAG to
cardiac surgery and increased risk of AKI. The similar
association between a day time interval of 3 days or less
and risk of AKI probably resulted from inclusion of data
from an interval of a day or less. We propose that the
delay of cardiac surgery until 24 hours after C AG can
potentially decrease postoperative AKI. In the future it
will be necessary to evaluate the risk of a short time
interval between CAG and cardiac surgery in a random-
ized trial, and clarify the other AKI risk factors in the
setting of a short interval between CAG and cardiac
surgery. This would help to adjust the estimation of
Figure 4 Forest plot for time interval, 3-day vs >3 days, in CPB subgroup. The estimated odds ratio (OR) of each individual article
corresponds to the middle of the squares, and the horizontal line gives the 95% confidence interval (CI).The sum of the statistics along with the
summary OR is represented by the middle of the solid diamonds. The heterogeneity test statistic (I statistic) between articles is given below the
summary statistics.
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appropriate individual risk and to optimize the flow of
treatment in patients who require diagnostic preopera-
tive coronary angiography.
Abbreviations
CAG: Coronary angiography; AKI: Acute kidney injury; ORs: Odds ratios;
CI: Confidence interval; CABG: Coronary artery bypass grafting;
CPB: Cardiopulmonary bypass; DHCA: Deep hypothermic circulatory arrest.
Competing interests
The authors declare that they have no competing interests.
Authors contributions
ZQ and HY designed the study. HY and LZ carried out studies searching and
performed the eligibility assessments. HY and SY evaluated the qualities of
the included studies and carried out data extracting. ZQ, CJ, LZ and SC
analyzed and interpreted the data. HY drafted the manuscript. ZQ, LZ, CJ and
SC made critical revision of the manuscript for important intellectual content.
All authors read and approved the final manuscript.
Acknowledgements
We thank Yao Zhang, associated professor of Department of Epidemiology,
Clinic Epidemiology Center, Third Military Medical University, for help on
statistical analysis.
Received: 18 June 2013 Accepted: 1 August 2013
Published: 3 August 2013
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Cardiothoracic Surgery 2013 8:178.
Hu et al. Journal of Cardiothoracic Surgery 2013, 8:178 Page 7 of 7
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... Acute kidney injury is reported to occur in up to 30% of patients after cardiac surgery with CPB, whereas CIN after CAG has been reported to occur in 10% of patients with normal renal function but in 25% of patients with pre-existing renal failure [31]. Contrast-induced AKI is defined as the onset of acute renal failure within 2-7 days after administration of iodinated CM (most common-ly after CAG and percutaneous coronary intervention), and it is one of the leading causes of acute renal failure during hospital stay [32]. ...
... Among the criteria that can be modified for the development of AKI, the time elapsed between CAG and CABG is an important risk factor [31]. The reason for this is that the contrast agents used in CAG and stress of CABG (double hit) may cause postoperative AKI in these patients [28]. ...
Article
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Aim: The aim of the article was to study the role of the time between cardiac catheterization and cardiac surgery in the development of early postoperative acute kidney injury in patients who underwent isolated coronary artery bypass grafting was investigated. Material and methods: A total of 1196 patients (832 males, 364 females; mean age 60.8 ±8.2 years; range: 32-74 years) operated between November 2006 and June 2014 at the same centre and by the same team for isolated coronary artery bypass grafting with cardiopulmonary bypass, whose preoperative serum creatinine level was < 1.5 mg/dl, were enrolled in the study. Patients were divided into group 1 - with acute kidney injury in the early postoperative period (n = 207) and group 2 - without (n = 989). Univariate analyses were done to determine significant clinical factors, and subsequent multiple logistic regression analysis was performed to determine independent predictors of acute kidney injury. Results: A total of 207 (17.3%) patients developed acute kidney injury during 72 h postoperatively. Regarding the time interval between coronary angiography and coronary artery bypass grafting, there was a statistically highly significant difference between the patients with and without acute kidney injury (7.8 and 11.9 days, respectively; p = 0.0001). Postoperative C-reactive protein (p = 0.0001) and erythrocyte sedimentation rate (p = 0.0001) were significantly increased in group 1. Multivariate logistic regression analysis revealed the time between cardiac catheterization and surgery (p = 0.0001), increased postoperative C-reactive protein (p = 0.007 and p = 0.0001, respectively), and erythrocyte sedimentation rate (p = 0.0001) as independent predictors of early postoperative acute kidney injury in patients undergone isolated coronary artery bypass grafting. Conclusions: If patients to be operated on are stable from a cardiac aspect, limitation of surgery in the early period following catheterization results in reduction of the incidence of postoperative acute kidney injury.
... Nevertheless, concerns persist in the surgical setting owing to the physiological insult of surgery potentially predisposing patients to the risk of contrast media, acting as a second hit that leads to AKI 17 . Concerns regarding the risk of contrast-induced nephropathy can have a significant impact on the patient care pathway, based on recommendations to undergo additional tests, withhold medications, enact protocols for periprocedural volume expansion, consider restricting use of contrast media 18 , or potentially delay interventions 19 . ...
... Several mechanisms for how iodinated contrast might cause AKI have been proposed 31 . The multiple-hit hypothesis suggests that contrast-induced nephropathy may be more likely to occur in the presence of pre-existing renal insults, such postoperative physiological stress or postoperative complications 11,17,19 . To test the latter hypothesis, a subgroup analysis was conducted with stratification according to whether patients developed major complications. ...
... In patients undergoing elective surgery, creatinine should be at the lowest individual value within a year before cardiac surgery [35••] and surgery delayed 24-72 h after iodine contrast administration [44,45]. ...
Article
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Purpose of review: Recommendations about shared decision-making and guidelines on preoperative evaluation of patients undergoing non-cardiac surgery are abundant, but respective recommendations for cardiac surgery are sparse. We provide an overview of available evidence. Recent findings: While there currently is no consensus statement on the preoperative anesthetic evaluation and shared decision-making for the adult patient undergoing cardiac surgery, evidence pertaining to specific organ systems is available. Summary: We provide a comprehensive review of available evidence pertaining to preoperative assessment and shared decision-making for patients undergoing cardiac surgery and recommend a thorough preoperative workup in this vulnerable population.
Chapter
Acute kidney injury (AKI) remains a frequent and serious complication of surgical procedures and critical illness that is consistently associated with worse outcomes and increased long-term morbidity and mortality. Much work has gone into finding kidney protective measures with disappointingly few therapeutic options available to prevent or to treat AKI. Research has defined some effective kidney protective practices and the purpose of this chapter is to help the clinician to differentiate better clinical practices that are either ineffective, detrimental, or protective to the kidney. The chapter will first provide an introduction to kidney physiology with particular focus on areas that make it vulnerable to injury. The chapter will then shift focus to diagnosis of kidney injury including definitions and early biomarkers that can help risk stratify patients. Then, specific mechanisms of postoperative and critical illness-associated kidney injury will be outlined. The rest of the chapter will review evidence from renal-protective research studies pertinent to the preoperative, intraoperative, and postoperative periods. After reading this chapter, the clinician should have a more robust framework for adoption (mostly avoidance) of renal protective practices (stratified based on level of evidence available) to guide their clinical practice.
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Background: Recently, there has been an interest in the temporal relationship between contrast exposure (CM) and cardiac surgery suggesting that a "double hit" on the kidney function in close succession increases the risk of acute kidney injury (AKI) after cardiac surgery. However, data from young children is limited. The purpose of this study was to retrospectively evaluate the effects of preoperative CM exposure on postoperative AKI in infant and young children patients and to further analyze the influence of exposure time interval. Methods: Patients (age ≤ 3 years) who underwent diagnostic imaging within 14 days before on-pump cardiac surgery between 1 May 2017 and 31 May 2018 in Fuwai Hospital, Beijing, were analyzed. Kidney outcome was assessed according to Kidney Disease: Improving Global Outcomes creatinine-based criteria. Results: One thousand four hundred pediatric patients (192 CM and 1,248 non-CM) were identified. Postoperative AKI occurred in 57 (29.7%) of the 192 patients who were exposed to CM. Following propensity score adjustment, no difference in risk for AKI was observed between the CM and non-CM groups (RR 1.142, 95% CI 0.916-1.424; P = 0.264). Multivariable logistic regression of the CM group indicated that independent predictors of postoperative AKI were lower weight, lower preoperative creatinine level, and longer CPB duration. Time interval between CM exposure and on-pump cardiac surgery was not significantly associated with increased risk of AKI (OR 0.853, 95% CI 0.265~2.747; P = 0.790). Conclusions: For pediatric patients who are soon to undergo on-pump cardiac procedures, there appears to be no need to hesitate in performing the diagnostic imaging investigations requiring CM, or delay CPB after CM exposure. These patients may benefit from increased diagnostic utility without increasing their risk of postoperative AKI.
Article
Objectives: Cardiac surgery and contrast media are both related to acute kidney injury. We investigated whether undergoing coronary computed tomography angiography, which uses less contrast medium, before on-pump cardiac surgery could reduce the risk of postoperative acute kidney injury compared to coronary angiography. Methods: In this retrospective study, 745 and 171 patients underwent coronary angiography and coronary computed tomography angiography, respectively, within 30 days before on-pump cardiac surgery. Postoperative acute kidney injury was defined according to Kidney Disease Improving Global Outcomes Definition and Staging criteria. Results: Age, hypertension, cardiopulmonary bypass time, and performing cardiac surgery within 24 h of preoperative angiography (odds ratio: 1.507, 95% confidence interval: 1.111‒2.045, P = 0.008) independently predicted postoperative acute kidney injury on multivariable analysis. After propensity score matching, the acute kidney injury incidence in coronary angiography and computed tomography angiography groups was 43% and 46%, respectively (P = 0.65), and the groups had similar intensive care unit stay (2 days vs. 2 days, P = 0.209), postoperative hospital stay (11 days vs. 12 days, P = 0.084), postoperative continuous renal replacement therapy use (0.6% vs 1.9%, P = 0.314), and in-hospital mortality (0 vs. 1.3%, P = 0.156). In-hospital outcomes were similar among patients who underwent preoperative coronary angiography or computed tomography angiography within 24 h before cardiac surgery. Conclusion: Although coronary computed tomography angiography uses less contrast medium, it does not reduce the risk of postoperative acute kidney injury or improve in-hospital outcomes compared to coronary angiography.
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This chapter presents the spectrum of adult cardiac surgical disease that is encountered in most cardiac surgical practices. It presents the pathophysiology, indications for surgery, specific preoperative considerations, and surgical options for various diseases. The chapter includes coronary artery disease (CAD), left ventricular aneurysm, ventricular septal rupture, aortic stenosis, aortic regurgitation, mitral stenosis, mitral regurgitation, tricuspid valve disease, and infective endocarditis. It also includes hypertrophic obstructive cardiomyopathy, aortic dissections, thoracic aortic aneurysms, atrial fibrillation, advanced heart failure, pericardial disease, and congenital heart disease. CAD results from the progressive blockage of the coronary arteries by atherothrombotic disease. Primary prevention of cardiovascular disease entails control of modifiable risk factors. Occlusion of a major coronary artery may produce extensive transmural necrosis, which converts muscle into thin scar tissue. This results in formation of a left ventricular aneurysm which exhibits dyskinesia during ventricular systole.
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Perioperative renal dysfunction is a major determinant of both operative and long‐term mortality following cardiac surgery. Therefore, it is essential to identify patients at high risk for developing postoperative acute kidney injury who may benefit from specific interventions aimed at optimizing renal function. Use of Swan‐Ganz monitoring (and its correlation with echocardiographic findings) is helpful in providing a scientific basis for fluid management after surgery, especially in patients with significant right or left ventricular dysfunction or after very complex operations with long durations of CPB, although it may not be necessary in low‐risk patients. Various forms of renal replacement therapy can be used to remove excessive fluid and solute to improve electrolyte balance and remove other nitrogenous waste products. A low cardiac output state causing tissue hypoperfusion is usually the primary cause of metabolic (lactic) acidosis in the cardiac surgery patient.
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When a patient is considered a potential candidate for cardiac surgery, a comprehensive evaluation of their overall medical condition and comorbidities is essential. This includes a detailed history and physical examination, which may identify cardiac and noncardiac problems that may need to be addressed perioperatively to minimize postoperative morbidity. This chapter discusses general preoperative considerations and preparation of the patient for surgery. The Society of Thoracic Surgeons (STS) operative risk calculator provides a reliable computerized assessment of mortality for most types of cardiac surgical procedures and also quantitates the risk of important postoperative morbidities, such as re‐exploration for bleeding, stroke, prolonged ventilation, and renal failure. A history of heavy alcohol abuse identifies potential problems with intraoperative bleeding and postoperative hepatic dysfunction, agitation, and alcohol withdrawal. An important element of the preoperative preparation for cardiac surgery is an assessment of the patient's surgical risk.
Chapter
Acute kidney injury (AKI) is a common and serious complication of cardiac surgery. The spectrum of cardiac surgery-associated AKI (CS-AKI) ranges from transient loss of renal reserve, through AKI, to long-term irreversible renal failure requiring renal replacement therapy (RRT). Notably, CS-AKI is also associated with numerous complications including: short and long-term mortality; development and progression of chronic kidney disease (CKD); extended hospital and intensive care unit (ICU) lengths of stay; and hospital readmission (Brown et al. Ann Thorac Surg 97(1):111–117, 2014; Pickering et al. Am J Kidney Dis 65(2):283–293, 2015; Xu et al. Medicine 94(45):e2025, 2015; Hu et al. J Cardiothorac Vasc Anesth 30(1):82–89, 2016). Thus, a review of avoidable CS-AKI sources, and interventions that preserve or promote recovery of renal function is highly pertinent to care of cardiac surgical patients.
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Because of the pressure for timely, informed decisions in public health and clinical practice and the explosion of information in the scientific literature, research results must be synthesized. Meta-analyses are increasingly used to address this problem, and they often evaluate observational studies. A workshop was held in Atlanta, Ga, in April 1997, to examine the reporting of meta-analyses of observational studies and to make recommendations to aid authors, reviewers, editors, and readers. Twenty-seven participants were selected by a steering committee, based on expertise in clinical practice, trials, statistics, epidemiology, social sciences, and biomedical editing. Deliberations of the workshop were open to other interested scientists. Funding for this activity was provided by the Centers for Disease Control and Prevention. We conducted a systematic review of the published literature on the conduct and reporting of meta-analyses in observational studies using MEDLINE, Educational Research Information Center (ERIC), PsycLIT, and the Current Index to Statistics. We also examined reference lists of the 32 studies retrieved and contacted experts in the field. Participants were assigned to small-group discussions on the subjects of bias, searching and abstracting, heterogeneity, study categorization, and statistical methods. From the material presented at the workshop, the authors developed a checklist summarizing recommendations for reporting meta-analyses of observational studies. The checklist and supporting evidence were circulated to all conference attendees and additional experts. All suggestions for revisions were addressed. The proposed checklist contains specifications for reporting of meta-analyses of observational studies in epidemiology, including background, search strategy, methods, results, discussion, and conclusion. Use of the checklist should improve the usefulness of meta-analyses for authors, reviewers, editors, readers, and decision makers. An evaluation plan is suggested and research areas are explored.
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Cardiac surgery and coronary angiography are both associated with risk of acute kidney injury (AKI). We hypothesized that the risk of post-operative AKI increases when coronary angiogram and cardiac surgery are performed in close succession, without sufficient time for recovery from the adverse effects of intravenous contrast. We included 2133 consecutive patients who underwent cardiac surgery at the Minneapolis Veterans Administration Medical Center from 2004 to 2010. Acute kidney injury was defined by the AKI network and the risk, injury, failure, loss, end-stage (RIFLE) criteria. Patients were 66 ± 10 years old. Mean pre-operative creatinine and estimated glomerular filtration rate were 1.1 ± 0.4 mg/dL and 75 ± 22 mL/min/1.73 m(2), respectively. Cardiac surgery was performed 14 days (range 0-235) after coronary angiography. Acute kidney injury occurred in 680 (32%) patients per AKI network, 390 (18%) patients per RIFLE risk, and 111 (5%) patients per RIFLE injury criteria. Age, body mass index, diabetes mellitus, New York Heart Association class III/IV, cardiopulmonary bypass time, and impaired pre-operative renal function were independent predictors of AKI. However, time between coronary angiogram and cardiac surgery was not a predictor (P = 0.41). AKI occurred in 35% of 433 patients operated within 3 days of coronary angiogram vs. 31% of 1700 patients operated after 3 days (P = 0.17). Results were the same in patients with impaired pre-operative renal function and those with contrast-induced nephropathy. Risk of AKI after cardiac surgery is not influenced by the time between coronary angiogram and cardiac surgery. These results do not support the notion of delaying cardiac surgery for the sole purpose of renal recovery after coronary angiogram.
Article
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There is limited data about the influence of timing of cardiac surgery in relation to diagnostic angiography and/or the impact of the amount of contrast media used during angiography on the occurance of acute renal failure (ARF). Therefore, in the present study the effect of the time interval between diagnostic angiography and cardiac surgery and also the amount of contrast media used during the diagnostic procedure on the incidence of ARF after cardiac surgery was investigated. Data of 1177 patients who underwent different types of cardiac surgeries after cardiac catheterization were prospectively examined. The influence of time interval between cardiac catheterization and surgery as well as the amount of contrast agent on postoperative ARF were assessed using multivariable logistic regression. The patients who progressed to ARF were more likely to have received a higher dose of contrast agent compared to the mean dose. However, the time interval between cardiac surgery and last catheterization was not significantly different between the patients with and without ARF (p = 0.05). Overall, postoperative peak creatinine was highest on day 0, then decreased and remained significantly unchanged after this period. Overall prevalence of acute renal failure during follow-up period had a changeable trend and had the highest rates in days 1 (53.57%) and 6 (52.17%) after surgery. Combined coronary bypass and valve surgery were the strongest predictor of postoperative ARF (OR: 4.976, CI = 1.613-15.355 and p = 0.002), followed by intra-aortic balloon pump insertion (OR: 6.890, CI = 1.482-32.032 and p = 0.009) and usage of higher doses of contrast media agent (OR: 1.446, CI = 1.033-2.025 and p = 0.031). Minimizing the amount of contrast agent has a potential role in reducing the incidence of postoperative ARF in patients undergoing cardiac surgery, but delaying cardiac surgery after exposure to these agents might not have this protective effect.
Article
Background: N-Acetylcysteine, theophylline, and other agents have shown inconsistent results in reducing contrast-induced nephropathy. Purpose: To determine the effect of these agents on preventing nephropathy. Data Sources: Relevant randomized, controlled trials were identified by computerized searches in MEDLINE (from 1966 through 3 November 2006), EMBASE (1980 through November 2006), PubMed, Web of Knowledge (Current Contents Connect, Web of Science, BIOSIS Previews, and ISI Proceedings for the latest 5 years), and the Cochrane Library databases (up to November 2006). Databases were searched for studies in English, Spanish, French, Italian, and German. Study Selection: Randomized, controlled trials that administered N-acetylcysteine, theophylline, fenoldopam, dopamine, iloprost, statin, furosemide, or mannitol to a treatment group; used intravenous iodinated contrast; defined contrast-induced nephropathy explicitly; and reported sufficient data to construct a 2 x 2 table of the primary effect measure. Data Extraction: Abstracted information included patient characteristics, type of contrast media and dose, periprocedural hydration, definition of contrast-induced nephropathy, and prophylactic agent dose and route. Data Synthesis: In the 41 studies included, N-acetylcysteine (relative risk, 0.62 [95% Cl, 0.44 to 0.88]) and theophylline (relative risk, 0.49 [Cl, 0.23 to 1.06]) reduced the risk for contrast-induced nephropathy more than saline alone, whereas furosemide increased it (relative risk, 3.27 [Cl, 1.48 to 7.26]). The remaining agents did not significantly affect risk. Significant subgroup heterogeneity was present only for N-acetylcysteine. No publication bias was discerned. Limitations: All trials evaluated the surrogate end point of contrast-induced nephropathy as the primary outcome. The lack of a statistically significant renoprotective effect of theophylline may result from insufficient data or study heterogeneity. True study quality remains uncertain. Conclusion: N-Acetylcysteine is more renoprotective than hydration alone. Theophylline may also reduce risk for contrast-induced nephropathy, although the detected association was not significant. Our data support the administration of N-acetylcysteine prophylaxis, particularly in high-risk patients, given its low cost, availability, and few side effects.
Article
Background: Contrast media used for coronary angiography may result in a contrast-induced nephropathy. Acute kidney injury (AKI) is a common complication of cardiac surgery. It has been hypothesized that cardiac surgery in close succession to coronary angiography may increase the risk of postoperative AKI. However, data from the existing literature are conflicting. The aim of this study is to investigate the risk of AKI in patients undergoing angiography and cardiac surgery on the same day, and to assess the efficacy of a policy limiting this practice. Methods: A total of 4,440 consecutive patients receiving coronary angiography and cardiac surgery at our institution were retrospectively analyzed. The AKI was defined as stage 1 or stage 2-3 according to the existing classification. Predictive models for AKI stage 1, stage 2-3, and any AKI were built, including various risk factors and the occurrence of surgery on the same day of angiography. Results: Surgery on the day of angiography was an independent risk factor for AKI stage 2-3 (odds ratio 1.58, 95% confidence interval 1.04 to 2.40). An institutional policy limiting the practice of surgery on the same day of angiography (years 2009 to 2012) resulted in a significant (p = 0.001) 30% decrease of AKI stage 1 and 42% decrease of any AKI with respect to patients operated in the years 2003 to 2008. Conclusions: Acute kidney injury after cardiac surgery is a multifactorial event; surgery on the same day of angiography significantly increases the risk of AKI, and limiting this practice results in a containment of the postoperative AKI incidence.
Article
The authors sought to evaluate the association between the time interval from contrast administration to cardiac surgery and postoperative acute kidney injury (AKI). A retrospective observational study over a 1-year period. A US academic medical institution. Six hundred forty-four adult patients undergoing nonemergent cardiac surgery. No interventions were performed as part of the study. AKI was defined as an increase in serum creatinine by ≥0.3 mg/dL or ≥50% above baseline within the first 2 postoperative days or the commencement of renal replacement therapy within the same period. Using a contrast-to-surgery time interval >7 days as the baseline, multivariable logistic regression analysis determined the association between a contrast-to-surgery time interval ≤1 day or 2 to 7 days and postoperative AKI adjusting for potential confounding variables. The incidence of AKI within the study cohort was 21.9%. After adjusting for other covariates, there was no association between the contrast-to-surgery time and AKI (odds ratio [OR] ≤1 day = 0.93; 95% confidence interval [CI], 0.52-1.66; p = 0.81; OR = 2-7 days = 1.28; 95% CI, 0.78-2.11; p = 0.34). In an appropriately selected population, cardiac surgery can be performed within 1 day of cardiovascular catheterization and contrast administration without an increase in the incidence of postoperative AKI. Recommendations to delay cardiac surgery for a specified period after contrast administration to reduce the risk of postoperative AKI are premature. Additional evidence is required before making recommendations on optimal surgical timing after contrast exposure.
Article
Some prior studies have suggested that the time to cardiac surgery after cardiac catheterization is inversely related to postoperative acute kidney injury (AKI). However, these studies, because of the small number of patients, were unable to adequately account for patient case-mix and included both those undergoing elective surgery and those undergoing urgent surgery. We examined data on 2441 consecutive patients undergoing elective coronary artery bypass surgery (CABG) after cardiac catheterization. The association of post-CABG AKI (defined as increase in post-CABG serum creatinine ≥ 50% above baseline or the need for new dialysis) and time between cardiac catheterization and CABG was evaluated using multivariable logistic regression modeling. AKI occurred in 17.1% of CABG patients. The risk of AKI was highest in patients in whom CABG was performed ≤ 1 day after cardiac catheterization (adjusted mean rates [95% CI]: 24.0% [18.0%, 30.9%], 18.4% [14.8%, 22.5%], 17.3% [13.3%, 21.9%], 16.4% [12.6%, 20.8%], and 15.8% [13.7%, 18.0%] for days ≤ 1, 2, 3, 4, and ≥ 5, respectively; P=0.019 for test of trend). Post-CABG AKI was associated with increased risk of long-term death (hazard ratio 1.268, 95% CI 1.093, 1.471). The risk of post-CABG AKI was inversely and modestly related to the time between cardiac catheterization and CABG, with the highest incidence in those operated ≤ 1 day after cardiac catheterization despite their lower risk profile. Whether delaying elective CABG >24 hours of exposure to contrast agents (when feasible) has the potential for decreasing post-CABG AKI remains to be evaluated in future studies.
Article
Cardiac catheterization shortly before coronary artery bypass grafting or valve surgery has been associated with increased postoperative acute kidney injury. The relationship between catheterization timing and acute kidney injury after proximal aortic surgery remains unknown. Between August 2005 and February 2011, a total of 285 consecutive patients underwent cardiac catheterization before elective proximal aortic surgery with cardiopulmonary bypass at a single institution. The association between timing of catheterization and postoperative acute kidney injury (defined as postoperative increase in serum creatinine ≥ 50% of baseline) was assessed using logistic regression analysis. Of 285 patients, 152 (53%) underwent catheterization on preoperative days 1 to 3 and 133 (47%) underwent catheterization on preoperative day 4 or before. Acute kidney injury occurred in 88 (31%) patients, 3 (1.1%) requiring dialysis. Acute kidney injury occurred in 37 (24%) patients catheterized on preoperative days 1 to 3, and 51 (38%) patients catheterized on preoperative day 4 or before. Catheterization on preoperative days 1 to 3 was not associated with an increased risk of acute kidney injury relative to catheterization on preoperative day 4 or before (unadjusted odds ratio, 0.52; 95% confidence interval, 0.31-0.86; P = .01; adjusted odds ratio, 0.35; 95% confidence interval, 0.17-0.73; P = .005). Cardiac catheterization within 1 to 3 days of elective proximal aortic surgery appears safe and should be considered acceptable practice for patients at low risk of acute kidney injury.