Right bundle branch block and long-term mortality in patients with acute congestive heart failure

Article (PDF Available)inJournal of Internal Medicine 260(5):421-8 · December 2006with60 Reads
DOI: 10.1111/j.1365-2796.2006.01703.x · Source: PubMed
Abstract
Risk stratification in acute congestive heart failure (ACHF) is poorly defined. The aim of the present study was to assess the impact of right bundle brunch block (RBBB) on long-term mortality in patients presenting with ACHF. The initial 12-lead electrocardiogram was analysed for RBBB in 192 consecutive patients presenting with ACHF to the emergency department. The primary endpoint was all-cause mortality during 720-day follow-up. This study included an elderly cohort (mean age 74 years) of ACHF patients. RBBB was present in 27 patients (14%). Age, sex, B-type natriuretic peptide levels and initial management were similar in patients with RBBB when compared with patients without RBBB. However, patients with RBBB more often had pulmonary comorbidity. A total of 84 patients died during follow-up. Kaplan-Meier analysis revealed that mortality at 720 days was significantly higher in patients with RBBB when compared with patients without RBBB (63% vs. 39%, P = 0.004). In Cox proportional hazard analysis, RBBB was associated with a two-fold increase in mortality (hazard ratio 2.18, 95% CI 1.26-3.66; P = 0.003). This association persisted after adjustment for age and comorbidity. RBBB is a powerful predictor of mortality in patients with ACHF. Early identification of this high-risk group may help to offer tailored treatment in order to improve outcome.
Right bundle branch block and long-term mortality in
patients with acute congestive heart failure
C. MUELLER, K. LAULE-KILIAN, T. KLIMA, T. BREIDTHARDT, W. HOCHHOLZER,
A. P. PERRUCHOUD & M. CHRIST
From the Department of Internal Medicine, University Hospital Basel, Basel, Switzerland
Abstract. Mueller C, Laule-Kilian K, Klima T,
Breidthardt T, Hochholzer W, Perruchoud AP,
Christ M (University Hospital Basel, Basel,
Switzerland). Right bundle branch block and long-
term mortality in patients with acute congestive
heart failure. J Intern Med 2006; 260: 421–428.
Objectives. Risk stratification in acute congestive
heart failure (ACHF) is poorly defined. The aim of
the present study was to assess the impact of right
bundle brunch block (RBBB) on long-term mortality
in patients presenting with ACHF.
Methods and results. The initial 12-lead
electrocardiogram was analysed for RBBB in 192
consecutive patients presenting with ACHF to the
emergency department. The primary endpoint was
all-cause mortality during 720-day follow-up. This
study included an elderly cohort (mean age
74 years) of ACHF patients. RBBB was present in
27 patients (14%). Age, sex, B-type natriuretic
peptide levels and initial management were similar
in patients with RBBB when compared with patients
without RBBB. However, patients with RBBB more
often had pulmonary comorbidity. A total of 84
patients died during follow-up. Kaplan–Meier
analysis revealed that mortality at 720 days was
significantly higher in patients with RBBB when
compared with patients without RBBB (63% vs.
39%, P ¼ 0.004). In Cox proportional hazard
analysis, RBBB was associated with a two-fold
increase in mortality (hazard ratio 2.18, 95% CI
1.26–3.66; P ¼ 0.003). This association persisted
after adjustment for age and comorbidity.
Conclusions. RBBB is a powerful predictor of
mortality in patients with ACHF. Early
identification of this high-risk group may help to
offer tailored treatment in order to improve
outcome.
Keywords: acute heart failure, electrocardiogram,
mortality, right bundle branch block.
Introduction
The epidemic of heart failure (HF) is a major public
health problem. HF is the most frequent cause of
hospitalizations in patients more than 65 years of
age and these hospitalizations contribute signifi-
cantly to the enormous cost of the disease [1, 2]. In
contrast to chronic HF, risk stratification and initial
management is poorly validated in patients present-
ing with acute congestive heart failure (ACHF).
Hence, current American College of Cardiology/
American Heart Association (ACC/AHA) and Euro-
pean Society for Cardiology (ESC) initiatives call for
more research targeting ACHF [1, 2].
The electrocardiogram (ECG) has been a corner-
stone in clinical medicine for more than six decades.
In contrast to current belief, additional diagnostic
and prognostic applications continue to emerge each
year [3, 4]. Twelve-lead ECG is an important tool in
the diagnosis of ACHF, particularly in the identifi-
cation of the cause of acute decompensation inclu-
ding tachyarrhythmia and myocardial infarction [1,
2]. It is unknown, whether electrocardiography also
provides prognostic information in patients with
ACHF. This would be very attractive, as electrocar-
diography is routinely performed, easy, safe and
inexpensive. Whilst no data are available for ACHF,
a large retrospective cohort study including patients
Journal of Internal Medicine 2006; 260: 421–428 doi:10.1111/j.1365-2796.2006.01703.x
2006 Blackwell Publishing Ltd
421
with acute myocardial infarction reported that
patients with right bundle brunch block (RBBB)
had an increased risk of in-hospital death compared
with patients with no BBB. RBBB seemed to predict
in-hospital death at least as powerful as left bundle
brunch block (LBBB) [5].
We hypothesized that RBBB may be a marker of
pulmonary artery hypertension and/or right ven-
tricular dysfunction [6] and may therefore be
associated with increased mortality in patients with
ACHF.
Methods
Setting and study population
This study specifically evaluated the prognostic
utility of RBBB in patients with ACHF enrolled in
the B-type natriuretic peptide for Acute Shortness of
Breath Evaluation (BASEL) study [7]. The BASEL
study was a prospective study conducted in the
emergency department (ED) of the University Hos-
pital Basel, Switzerland. The study was carried out
according to the principles of the Declaration of
Helsinki and approved by our local ethical commit-
tee. Written informed consent was obtained from all
participating patients. A total of 452 patients were
enrolled in the BASEL study, and 217 patients were
diagnosed as ACHF according to current guidelines
[1, 2]. The final discharge diagnosis of ACHF was
based on clinical presentation and standard inves-
tigations, and adjudicated by an internal medicine
specialist not involved in the ED care on the basis of
all available medical records pertaining to the
individual patient, including the response to therapy
and autopsy data in those patients dying in-hospital.
B-type natriuretic peptide (BNP) levels were meas-
ured and available for the final discharge diagnosis
in 50% of patients. We excluded patients in whom
the presence of RBBB could not be determined due to
ventricular pacing, ventricular tachycardia, or miss-
ing ECG. Overall, 192 patients (88.5%) qualified for
the current study.
ECG, RBBB and LBBB
At the time of presentation to the ED, resting 12-lead
ECG was recorded at a paper speed of 25 mm s
)1
.
The ECGs were interpreted by a core laboratory that
classified the presence of RBBB and LBBB using
standard criteria [8]. The core laboratory physician
scoring the ECGs had no information regarding
patient baseline characteristics or outcome.
Right bundle brunch block was defined by a QRS
duration (QRSd) 120 ms, in association with the
presence of rsR¢, or rSR¢ complexes in V
1
or V
2
,
delayed onset of the intrinsicoid deflection in V
1
and
V
2
more than 50 ms, and wide, slurred S waves in
leads I, V
5
, and V
6
. The ST-T-wave vectors are
opposite in direction to the major QRS vector [8].
Left bundle brunch block was defined by a
QRSd 120 ms, delayed onset of the intrinsicoid
deflection in leads I, V
5
,V
6
> 50 ms, the presence of
a broad monophasic, often notched R-wave in leads
I, V
5
and V
6
, with rS or QS complexes in lead V
1
and
V
2
, and ST-T-wave vectors opposite in direction to
the major QRS vector [8].
End-point and statistical analysis
All-cause mortality was the primary end-point of
this study. Patients were contacted 6, 12 and
24 months after the initial presentation by tele-
phone interview performed by a single trained
researcher. In addition, referring physicians were
contacted. The administrative databases of the
respective hometowns were assessed to ascertain
the vital status of those patients who could not be
contacted by telephone. All information derived
from contingent hospital readmission records or
provided by the referring physician or by the
outpatient clinic was reviewed and entered into
the computer database. The statistical analyses were
performed using the SPSS/PC (version 13.0; SPSS
Inc., Chicago, IL, USA) software package. Com-
parisons were made using the t-test, Mann–Whitney
U-test, Fisher’s exact test and chi-square test as
appropriate. All hypothesis testing was two-tailed.
The Kaplan–Meier method was used to analyse and
compare survival in patients with or without RBBB.
Cox proportional hazard analysis was used to
identify predictors of death in univariate and multi-
variable analysis. Together with RBBB, all baseline,
demographic, clinical and laboratory variables rou-
tinely available in the ED were entered in a
univariate Cox regression analysis. Variables asso-
ciated with long-term mortality in univariate ana-
lysis (P < 0.05) were entered into the multivariable
models. To closely reflect clinical practice, three
multivariate models were constructed. Model 1
2006 Blackwell Publishing Ltd Journal of Internal Medicine 260: 421–428
422 C. MUELLER et al.
adjusted for age and coronary artery disease
(the well-established risk markers in HF patients).
Model 2 adjusted for age, and all variables from
patient history/comorbidity significantly associated
with mortality in univariate analyses. Model 3
adjusted for all variables from history/comorbidity,
vital signs, physical examination, laboratory tests
routinely available in the ED, and discharge
medication significantly associated with mortality
in univariate analyses.
Results
This study included an elderly cohort (mean age
74 years) of ACHF patients. Nearly half of patients
were women, and comorbidity including pulmonary
disease was extensive (Table 1). RBBB was present
in 27 patients (14%) and LBBB in 32 patients (17%).
Baseline demographic, clinical, and laboratory char-
acteristics including BNP levels and left ventricular
ejection fraction (LVEF) were very similar in patients
with RBBB when compared with patients without
RBBB. In the BNP group, in those with RBBB no
patient had a BNP < 100 pg mL
)1
and 64% had a
BNP > 500 pg mL
)1
. In those without RBBB, 5%
had a BNP < 100 pg mL
)1
and 66% had a
BNP > 500 pg mL
)1
(P ¼ NS). Differences amongst
groups were restricted to a higher incidence of
pulmonary disease, tachypnea, and wheezing in
patients with RBBB. In addition, concomitant left
axis deviation with left anterior fascicular block was
more frequent in patients with RBBB when com-
pared with patients without RBBB (37% vs. 8%,
P < 0.001). Initial management including hospita-
lization rate and admission to intensive care were
similar amongst groups. Discharge medication was
comparable in both groups with the exception of
calcium channel blockers, which were prescribed
more often to patients with RBBB (33% vs. 13%,
P ¼ 0.009). This difference was already present on
admission.
A total of 84 patients (44%) died during follow-
up. Median duration of follow-up until patient death
or last contact was 686 days. No patient was lost to
follow-up within the first 12 months. Kaplan–Meier
analysis (Fig. 1) revealed that mortality at 720 days
was significantly higher in patients with RBBB when
compared with patients without RBBB (63% vs.
39%, P ¼ 0.004). In Cox proportional hazard
analysis, RBBB was associated with a two-fold
increase in mortality (hazard ratio 2.18, 95% CI
1.26–3.66; P ¼ 0.003). As shown in Table 2, this
association persisted after multivariable adjustment
in several models. After adjusting for age, history/
comorbidity, physical examination, vital signs,
laboratory tests routinely available in the ED, and
discharge medication, the predictive value of RBBB
was no longer statistically significant (P ¼ 0.090).
In patients with RBBB, concomitant left ventricular
systolic dysfunction (LVEF < 50%) did not further
impact on the risk of death (P ¼ 0.8).
In contrast to the findings regarding RBBB,
mortality at 720 days was similar in patients with
LBBB when compared with patients without LBBB
(Fig. 2).
Discussion
In patients presenting with ACHF to the ED, the
ECG offers unique diagnostic and prognostic infor-
mation. The major finding of this analysis was that
RBBB but not LBBB is a powerful predictor of
long-term mortality in unselected consecutive
patients. This finding has important clinical impli-
cations. First, patients with ACHF have a very high
mortality rate. Despite this, there are little data
regarding long-term outcome of patients with ACHF
[1, 2]. Therefore, risk stratification in patients with
ACHF is by far less well validated than in patients
with chronic HF. Secondly, RBBB can easily be
assessed from the 12-lead ECG immediately on
presentation. Thirdly, rapid initiation of intensive
care and several specific therapeutic interventions
possibly including levosimendan [9] or selective
PDE5 inhibition [10] may particularly benefit high
risk patients identified by RBBB [1, 2]. Fourthly, as
the presence of RBBB not only increased 30-day
mortality but also long-term mortality, patients
with RBBB may benefit from more intense follow-up
[1, 2]. Of note, the incidence of RBBB in ACHF was
twice the incidence observed in patients with
moderate to severe chronic HF [6].
This study complements and extends previous
studies on the impact of RBBB in other patient
settings. Go et al. [5] examined patients with acute
myocardial infarction and found that patients with
RBBB had an increased risk of in-hospital death
when compared with patients without BBB. RBBB
seemed to predict in-hospital death at least as
powerful as LBBB. Wong et al. [11] confirmed this
2006 Blackwell Publishing Ltd Journal of Internal Medicine 260: 421–428
RBBB AND MORTALITY IN ACUTE HEART FAILURE 423
Table 1 Patient characteristics
All patients (n ¼ 192) RBBB (n ¼ 27) No RBBB (n ¼ 165) P value
Age (years) 74 ± 11 76 ± 11 74 ± 11 0.480
Female sex 86 (45) 9 (33) 77 (47) 0.197
History
Coronary artery disease 135 (70) 20 (74) 115 (70) 0.644
Arterial hypertension 125 (65) 18 (67) 107 (65) 0.854
COPD 43 (22) 9 (33) 34 (21) 0.141
Asthma 4 (2) 0 4 (2) 1.000
Previous pneumonia 23 (12) 6 (22) 17 (10) 0.077
Previous pulmonary embolism 6 (3) 2 (7) 4 (2) 0.200
Other pulmonary or pleural disease
a
14 (7) 5 (19) 9 (6) 0.031
Any pulmonary disease 77 (40) 16 (59) 61 (37) 0.028
Diabetes mellitus 65 (34) 12 (44) 53 (32) 0.210
Chronic kidney disease 75 (39) 12 (44) 63 (38) 0.536
Symptoms
Paroxysmal nocturnal dyspnoea 93 (48) 15 (56) 78 (47) 0.425
Nycturia 77 (40) 15 (56) 62 (38) 0.077
Weight gain 32 (17) 7 (26) 25 (15) 0.164
Vital status
Systolic blood pressure (mmHg) 148 ± 32 149 ± 26 148 ± 33 0.853
Diastolic blood pressure (mmHg) 88 ± 22 86 ± 21 89 ± 22 0.498
Heart rate (per min) 98 ± 62 90 ± 17 100 ± 27 0.091
Temperature (C) 37.2 ± 0.9 37.3 ± 1.0 37.2 ± 0.9 0.796
Signs
Tachypnoea (>20 per min) 87 (45) 17 (63) 70 (42) 0.047
Elevated JVP 41 (21) 6 (22) 35 (21) 0.905
Hepatojugular reflux 30 (16) 5 (19) 25 (15) 0.655
Rales 117 (61) 16 (59) 101 (61) 0.835
Wheezing 26 (14) 7 (26) 19 (12) 0.042
Hyper-resonant percussion 13 (7) 3 (11) 10 (6) 0.399
Lower-extremity oedema 86 (45) 11 (41) 75 (46) 0.648
Laboratory tests
Creatinine clearance (mL min
)1
/1.73 m
2
) 54 ± 29 51 ± 26 55 ± 29 0.545
Haemoglobin (g dL
)1
) 12.9 ± 2.4 12.4 ± 2.3 13.0 ± 2.4 0.201
Serum albumin (g L
)1
) 33 ± 6 32 ± 5 33 ± 6 0.461
Troponin I (lgL
)1
) 0.5 (0.3–2.4) 1.0 (0.3–6.3) 0.5 (0.3–2.3) 0.380
B-type natriuretic peptide (pg mL
)1
) 840 (355–1300) 847 (210–1300) 840 (372–1300) 0.545
Left ventricular ejection fraction (%)
b
40 (30–55) 40 (22–60) 40 (30–53) 0.810
Medication at admission
ACE-inhibitor or angiotensin receptor blocker 92 (47) 16 (57) 76 (45) 0.221
Beta-blocker 71 (36) 9 (32) 62 (37) 0.658
Diuretics 125 (63) 19 (68) 106 (62) 0.576
Nitroglycerin 40 (20) 8 (29) 32 (19) 0.234
Digoxin 27 (14) 7 (25) 20 (12) 0.059
Calcium channel blocker 31 (16) 9 (32) 22 (13) 0.010
Aspirin 89 (45) 15 (54) 74 (44) 0.322
Anticoagulation 58 (29) 13 (46) 45 (27) 0.032
Oral steroids 18 (9) 7 (25) 11 (7) 0.002
Inhaled bronchodilators 18 (9) 5 (18) 13 (8) 0.145
Medication at discharge
c
ACE-inhibitor or angiotensin receptor blocker 143 (79) 20 (83) 123 (78) 0.756
Beta-blocker 113 (62) 14 (58) 99 (63) 0.656
Diuretic 158 (87) 23 (96) 135 (86) 0.177
Nitroglycerin 66 (37) 8 (33) 58 (37) 0.732
Digoxin 19 (11) 3 (13) 16 (10) 0.722
Calcium channel blocker 28 (16) 8 (33) 20 (13) 0.009
Aspirin 89 (49) 13 (54) 76 (48) 0.599
Anticoagulation 90 (50) 12 (50) 78 (50) 0.977
2006 Blackwell Publishing Ltd Journal of Internal Medicine 260: 421–428
424 C. MUELLER et al.
observation by showing that RBBB accompanying
anterior acute myocardial infarction is an
independent predictor of 30-day mortality [12,
13]. Similar findings were reported in patients
referred for symptom-limited nuclear exercise test-
ing. Complete RBBB and LBBB were independent
predictors of all-cause mortality risk even after
adjustment for exercise capacity, nuclear perfusion
defects, and other risk factors [1]. Together with
these reports, our data strongly contradict the
dogma that RBBB heralds a much more favourable
cardiovascular prognosis than LBBB [14]. Instead,
our data highlight the fact that the prognostic
impact of RBBB depends on the clinical setting in
which it is recorded.
Why does RBBB predict mortality in ACHF?
By its observational design, our study can only
partly elucidate the links between RBBB and mor-
tality. RBBB may result from various disorders
affecting the right heart including pulmonary
comorbidity. RBBB indicates structural changes
in the right ventricle and may highlight that
pulmonary hypertension and/or right ventricular
Table 1 Continued
All patients (n ¼ 192) RBBB (n ¼ 27) No RBBB (n ¼ 165) P value
Oral steroids 15 (8) 3 (13) 12 (8) 0.425
Inhaled bronchodilators 28 (16) 5 (21) 23 (15) 0.543
Outcome
Hospitalization 171 (89) 26 (96) 145 (88) 0.194
Intensive care admission 53 (28) 8 (30) 45 (27) 0.800
Time to discharge (days) 11 (5–19) 14 (7–19) 10 (4–20) 0.313
30-day mortality (%) 24 (13) 7 (26) 17 (10) 0.023
720-day mortality (%) 63.3 ± 9.4 38.6 ± 3.8 0.004
Data are presented as mean ± SD, median (IQR), or number of patients (%). The P-value is given for the comparison of patients with RBBB
versus patients without RBBB. COPD, chronic obstructive pulmonary disease; JVP, jugular venous pressure.
a
Including interstitial lung
disease, pneumothorax, and pleural effusion.
b
Determined in 131 patients during hospitalization.
c
Amongst survivors (n ¼ 181) at hospital
discharge.
0 180 360 540 720
Days
0.0
0.2
0.4
0.6
0.8
1.0
Survival
No RBBB
RBBB
P = 0.0041 by log-rank
Fig. 1 Survival rates in patients with right bundle branch block
(RBBB) when compared with patients without RBBB.
Table 2 Univariate and multivariate analysis of right bundle
brunch block (RBBB) as a predictor of all-cause mortality
Univariate P 0.003
HR (95% CI) 2.18 (1.26–3.66)
Model 1
a
Multivariate P 0.012
HR (95% CI) 1.96 (1.16–3.31)
Model 2
b
Multivariate P 0.041
HR (95% CI) 1.82 (1.03–3.24)
Model 3
c
Multivariate P 0.090
HR (95% CI) 1.79 (0.91–3.51)
HR, hazard ratio.
a
Adjusting for age, and coronary artery disease
(CAD).
b
Adjusting for age and patient history/comorbidity. Inde-
pendent variables in the final model included age, CAD, arterial
hypertension, and other pulmonary or pleural disease.
c
Adjusting
for age, history/comorbidity, physical examination, vital signs,
laboratory tests routinely available in the ED, and discharge
medication. Independent variables in the final model included age
(HR 1.05, P ¼ 0.001), arterial hypertension (HR 0.53, P ¼
0.027), and oral steroids as discharge medication (HR 3.28, P ¼
0.003).
2006 Blackwell Publishing Ltd Journal of Internal Medicine 260: 421–428
RBBB AND MORTALITY IN ACUTE HEART FAILURE 425
dysfunction has complicated the clinical course of
the primarily left heart disease resulting in ACHF. In
this regard, ACHF seems to have some pathophys-
iological details in common with acute anterior
myocardial infarction [11, 13]. Both are disorders
primarily involving the left ventricle where secon-
dary pulmonary hypertension due to severe left
ventricular dysfunction or confounding right ven-
tricular disease may impact on outcome. Supporting
this concept and data from Wong et al. [11], a large
cohort study demonstrated that RBBB increased in-
hospital and 1-year mortality rates in patients with
acute anterior myocardial infarction [15]. Moreover,
recent studies have shown that right ventricular
systolic function as quantified by either echocardi-
ography or right heart catheterization is an
independent predictor of death in patients with
chronic HF [4, 16–18]. In ACHF, RBBB may result
from right ventricular pressure overload induced by
the combination of passive transduction of increased
left atrial pressure and hypoxia-triggered increase in
pulmonary vascular resistance [1, 2]. Therefore,
selective PDE5 inhibition might be a potential thera-
peutic strategy in ACHF patients with RBBB [10].
Obviously, further clinical studies are necessary to
test this hypothesis. Concomitant left axis devi-
ation with left anterior fascicular block was more
frequent in patients with RBBB when compared with
patients without RBBB. This finding is supported by
previous studies and suggests the concept of ven-
tricular dyssynchrony as reason for worse outcome
[19–21]. Moreover, detailed investigations of the
impact of RBBB on ventricular interdependence
seem warranted [22].
How to detect right ventricular dysfunction in ACHF
Obviously, echocardiography and right heart cath-
eterization provide more detailed information
regarding right ventricular dysfunction than the
ECG. However, logistic and practical considerations
limit the use of echocardiography and right heart
catheterization in patients presenting with ACHF to
the ED. Respiratory distress, tachypnoea, inability to
maintain the supine position are major limitations
on the patient side. In addition, echocardiography
and right heart catheterization require expertise and
devices often not available on a 24-h basis in the ED.
In contrast, the ECG is simple, inexpensive, readily
available in an ED, and can be interpreted with high
accuracy by emergency or internal medicine spe-
cialists working in the ED.
Why does LBBB not predict mortality in ACHF?
Left bundle brunch block indicates structural chan-
ges in the left ventricle and has consistently been
shown to be a powerful predictor of cardiovascular
disease and mortality in the general population [11,
12, 23]. In patients with acute myocardial infarc-
tion, LBBB identifies a high-risk group with
increased comorbidity, less likely to receive therapy,
and increased risk for in-hospital death [12]. More-
over, LBBB seems to be a predictor of mortality in
stable outpatients with chronic HF [24]. Therefore,
at first glance it is surprising that LBBB does not
predict mortality in ACHF. The following considera-
tion may explain this observation. By definition, the
vast majority of patients with ACHF do have
advanced cardiac disease involving the left ventricle
that is severe enough to cause ACHF. Therefore,
LBBB as an indicator of left ventricular disease does
not provide additional prognostic information in a
cohort of patients with severe left ventricular disease
resulting in ACHF.
Our analysis has three particular strengths.
First, it included a large contemporary cohort of
0 180 360 540 720
Days
0.0
0.2
0.4
0.6
0.8
1.0
Survival
LBBB
No LBBB
P = 0.9313 by log-rank
Fig. 2 Survival rates in patients with left bundle branch block
(LBBB) when compared with patients without LBBB.
2006 Blackwell Publishing Ltd Journal of Internal Medicine 260: 421–428
426 C. MUELLER et al.
consecutive patients. Secondly, the study population
was highly representative of the elderly population
of patients with ACHF in clinical practice [1, 2].
Thirdly, it is one of the first studies of patients with
ACHF providing long-term follow-up data [2, 9].
Study limitations
Potential limitations of the present study merit
consideration. First, this was a post-hoc analysis of
a randomized controlled trial. However, as the
BASEL study recruited consecutive patients, we are
not aware of any bias potentially confounding our
results. Secondly, echocardiography was performed
during hospitalization in two-thirds of patients.
However as common in clinical routine, this assess-
ment did not include standardized measurement of
right ventricular ejection fraction. Additional studies
seem warranted to evaluate whether measurement
of right ventricular ejection fraction provides addi-
tional prognostic information to that obtained by the
simple identification of RBBB in the ECG of patients
with ACHF. Thirdly, the onset of RBBB as well as
potential disappearance during follow-up was
unknown in our cohort. Systematic ECG follow-up
might reveal whether patients have improved out-
come once RBBB disappears.
Conclusions
Right bundle brunch block is a powerful predictor of
mortality in patients with ACHF. Attention to this
easy accessible parameter may improve patient
management.
Conflict of interest statement
No conflict of interest was declared.
Acknowledgements
This study was supported by research grants from
the Swiss National Science Foundation, the Swiss
Heart Foundation, the Novartis Foundation, and the
Krokus Foundation.
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428 C. MUELLER et al.
    • "It may be explained by the fact that LV plays the essential role in global heart function and therefore the asynchrony of contraction of LV myofibers during LBBB may affect pump function more than RBBB does. However, the RBBB was also a powerful predictor of mortality in patients with acute congestive heart failure (ACHF) (Mueller et al 2006). Early identification of this high-risk group may help to offer tailored treatment in order to improve the outcome. "
    [Show abstract] [Hide abstract] ABSTRACT: Asynchronous electrical activation, induced by bundle branch block (BBB), can cause reduced ventricular function. However, the effects of BBB on the mechanical function of heart are difficult to assess experimentally. Many heart models have been developed to investigate cardiac properties during BBB but have mainly focused on the electrophysiological properties. To date, the mechanical function of BBB has not been well investigated. Based on a three-dimensional electromechanical canine heart model, the mechanical properties of complete left and right bundle branch block (LBBB and RBBB) were simulated. The anatomical model as well as the fiber orientations of a dog heart was reconstructed from magnetic resonance imaging (MRI) and diffusion tensor MRI (DT-MRI). Using the solutions of reaction-diffusion equations and with a strategy of parallel computation, the asynchronous excitation propagation and intraventricular conduction in BBB was simulated. The mechanics of myocardial tissues were computed with time-, sarcomere length-dependent uniaxial active stress initiated at the time of depolarization. The quantification of mechanical intra- and interventricular asynchrony of BBB was then investigated using the finite-element method with an eight-node isoparametric element. The simulation results show that (1) there exists inter- and intraventricular systolic dyssynchrony during BBB; (2) RBBB may have more mechanical synchrony and better systolic function of the left ventricle (LV) than LBBB; (3) the ventricles always move toward the early-activated ventricle; and (4) the septum experiences higher stress than left and right ventricular free walls in BBB. The simulation results validate clinical and experimental recordings of heart deformation and provide regional quantitative estimates of ventricular wall strain and stress. The present work suggests that an electromechanical heart model, incorporating real geometry and fiber orientations, may be helpful for better understanding of the mechanical implications of congestive heart failure (CHF) caused by BBB.
    Full-text · Article · Feb 2009
  • [Show abstract] [Hide abstract] ABSTRACT: Hospitalization for heart failure is associated with high postdischarge mortality and morbidity. The predictive value of the QRS duration during admission for heart failure has not been well studied. To investigate the predictive value of the QRS duration in patients hospitalized for heart failure with reduced left ventricular ejection fraction (LVEF). Retrospective, post hoc analysis from the Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study With Tolvaptan (EVEREST), an event-driven, randomized, double-blind, placebo-controlled study in patients hospitalized for heart failure and having an LVEF of 40% or less. A total of 4133 patients were enrolled at 359 North American, South American, and European sites between October 7, 2003, and February 3, 2006. After excluding 1029 patients with a pacemaker, implantable cardioverter-defibrillator, or both at enrollment and 142 patients without a reported baseline QRS duration, 2962 patients were included in the analysis: 1641 had a normal QRS duration (< 120 ms) and 1321 had a prolonged QRS duration (> or = 120 ms). Dual primary end points were all-cause mortality and the composite of cardiovascular death or hospitalization for heart failure. During a median follow-up of 9.9 months, all-cause mortality was 18.7% for patients with a normal baseline QRS duration and 28.1% for patients with a prolonged baseline QRS duration (hazard ratio [HR], 1.61; 95% confidence interval [CI], 1.38-1.87). The composite of cardiovascular death or hospitalization for heart failure was 32.4% for patients with a baseline QRS duration less than 120 ms and 41.6% for patients with a baseline QRS duration of 120 ms or greater (HR, 1.40; 95% CI, 1.24-1.58). The increased risk associated with prolonged QRS duration was confirmed after adjusting for multiple variables for all-cause mortality (HR, 1.24; 95% CI, 1.02-1.50) and the composite of cardiovascular death or hospitalization for heart failure (HR, 1.28; 95% CI, 1.10-1.49). Only 105 patients (3.6%) who presented with a prolonged baseline QRS duration had a normal QRS duration on their last inpatient electrocardiogram. A prolonged QRS duration appears common in patients with reduced LVEF who are hospitalized for heart failure and is an independent predictor of high postdischarge morbidity and mortality.
    Full-text · Article · Jun 2008
  • [Show abstract] [Hide abstract] ABSTRACT: A widened QRS interval is associated with increased mortality in patients with heart failure (HF). However, the prognostic significance of the type of bundle branch block (BBB) pattern in these patients is unclear. The data of 4,102 patients with HF hospitalized during a prospective national survey were analyzed to investigate the association between BBB type and 1-year mortality in 3,737 patients without pacemakers. Right BBB (RBBB) was present in 381 patients (10.2%) and left BBB (LBBB) in 504 patients (13.5%). RBBB and LBBB were associated with increased 1-year mortality on univariate analysis (odds ratio [OR] 1.44, 95% confidence interval [CI] 1.15 to 1.81, and OR 1.20, 95% CI 0.97 to 1.47, respectively). In patients with systolic HF, after adjusting for multiple risk factors, only RBBB was found to be an independent predictor of mortality (RBBB vs no BBB OR 1.62, 95% CI 1.12 to 2.33, and RBBB vs LBBB OR 1.71, 95% CI 1.09 to 2.69). This correlation was stronger in patients with lower left ventricular ejection fractions and was also maintained in patients without acute myocardial infarctions. Analyzing the data for all patients with HF, there was a trend for increased mortality in the RBBB group only (adjusted OR 1.21, 95% CI 0.94 to 1.56). LBBB was not related to mortality in patients with either systolic HF or preserved ejection fractions. In conclusion, RBBB rather than LBBB is an independent predictor of mortality in hospitalized patients with systolic HF. This prognostic marker could be used for risk stratification and the selection of treatment.
    Article · Jun 2008
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