The Clinical Impact of Imaging Surveillance and Clinic Visit Frequency after Acute Aortic Dissection

Abstract

Background Guidelines recommend frequent follow-up after acute aortic dissection (AAD), but optimal rates of follow-up are not clear.
Methods We examined rates of imaging and clinic visits in 267 individuals surviving AAD during recommended intervals (≤1, > 1–3, > 3–6, > 6–12 months, then annually), frequency of adverse imaging findings, and the relationship between follow-up and mortality.
Results Type A and B AAD were noted in 46 and 54% of patients, respectively. Mean follow-up was 54.7 ± 13.3 months, with 52 deaths. Adverse imaging findings peaked at 6 to 12 months (5.6%), but rarely resulted in an intervention (3.4% peak at 6–12 months). Compared with those with less frequent imaging, patients with imaging for 33 to 66% of intervals (p = 0.22) or ≥66% of intervals (p = 0.77) had similar adjusted survival. In comparison to patients with fewer clinic visits, those with visits in 33 to 66% of intervals experienced lower adjusted mortality (hazards ratio: 0.47, 95% confidence interval: 0.23–0.97, p = 0.04), with no difference seen in those with ≥66% (vs. < 33%) interval visits (p = 0.47). Imaging at 6 to 12 months (vs. none) was associated with decreased adjusted mortality (hazards ratio: 0.50, 95% confidence interval: 0.27–0.91, p = 0.02), while imaging during other intervals, or clinic visits during any specific intervals, was not associated with a difference in mortality (p > 0.05 for each).
Conclusions Adverse imaging findings following AAD are common, but rarely require prompt intervention. Patients with the lowest and highest rates of clinic visits experienced increased mortality. While the overall rate of surveillance imaging did not correlate with mortality, adverse imaging findings and related interventions peaked at 6 to 12 months after AAD, and imaging during this time was associated with improved survival.

Full text

The Clinical Impact of Imaging Surveillance and Clinic
Visit Frequency after Acute Aortic Dissection
Ashish Chaddha, MD1Kim A. Eagle, MD1Himanshu J. Patel, MD2G. Michael Deeb, MD2
Bo Yang, MD2Kevin M. Harris, MD3Alan C. Braverman, MD4Stuart Hutchison, MD5
Arturo Evangelista, MD6Rossella Fattori, MD7James B. Froehlich, MD1Christoph A. Nienaber, MD8
Eric M. Isselbacher, MD9Dan G. Montgomery, BS1Eva Kline-Rogers, NP1Elise Woznicki, BS1
Troy M. LaBounty, MD1
1Department of Medicine, University of Michigan, Ann Arbor, Michigan
2Department of Surger y,Univer sity of Michigan, Ann Arbor, Michigan
3Department of Medicine, Minneapolis Heart Institute, Minneapolis,
Minnesota
4Department of Medicine, Washington University, St. Louis, Missouri
5Department Medicine, University of Calgary, Calgary, Canada
6Department of Medicine, Hospital General Universitari Vall
d’Hebron,Barcelona,Spain
7Department of Medicine, University Hospital S. Orsola, Bologna, Italy
8Department of Medicine, University of Rostock, Rostock, Germany
9Massachusetts General Hospital, Harvard Medical School, Boston,
Massachusetts
AORTA 2019;7:75–83.
Address for correspondence Troy LaBounty, MD, Department of
Medicine, University of Michigan, 1500 E. Medical Center Dr.,
SPC 5853, Ann Arbor, MI 48109 (e-mail: labt@med.umich.edu).
Keywords
►aortic diseases
►aorta
►diagnostic imaging
Abstract Background Guidelines recommend frequent follow-up after acute aortic dissection
(AAD), but optimal rates of follow-up are not clear.
Methods We examined rates of imaging and clinic visits in 267 individuals surviving AAD
during recommended intervals (1, >1–3, >3–6, >6–12 months, then annually), fre-
quency of adverse imaging findings, and the relationship between follow-up and mortality.
Results Type A and B AAD were noted in 46 and 54% of patients, respectively. Mean
follow-up was 54.7 13.3 months, with 52 deaths. Adverse imaging findings peaked
at 6 to 12 months (5.6%), but rarely resulted in an intervention (3.4% peak at 6–12
months). Compared with those with less frequent imaging, patients with imaging for
33 to 66% of intervals (p¼0.22) or 66% of intervals (p¼0.77) had similar adjusted
survival. In comparison to patients with fewer clinic visits, those with visits in 33 to 66%
of intervals experienced lower adjusted mortality (hazards ratio: 0.47, 95% confidence
interval: 0.23–0.97, p¼0.04),withnodifferenceseeninthosewith66% (vs. <33%)
interval visits (p¼0.47). Imaging at 6 to 12 months (vs. none) was associated with
decreased adjusted mortality (hazards ratio: 0.50, 95% confidence interval: 0.27–0.91,
p¼0.02), while imaging during other intervals, or clinic visits during any specific
intervals, was not associated with a difference in mortality (p>0.05 for each).
Conclusions Adverse imaging findings following AAD are common, but rarely require
prompt intervention. Patients with the lowest and highest rates of clinic visits experienced
increased mortality. While the overall rate of surveillance imaging did not correlate with
mortality, adverse imaging findings and related interventions peaked at 6 to 12 months
after AAD, and imaging during this time was associated with improved survival.
received
August 18, 2017
accepted after revision
March 5, 2019
DOI https://doi.org/
10.1055/s-0039-1692187.
ISSN 2325-4637.
Copyright © 2019 by Thieme Medical
Publishers, Inc., 333 Seventh Avenue,
New York, NY 10001, USA.
Tel: +1(212) 584-4662.
THIEME
Original Research Article 75
Published online: 15.10.2019

Introduction
Patients surviving acute aortic dissection (AAD) have a
significant risk of morbidity and mortality following dis-
charge.1,2 Long-term management of these patients includes
follow-up clinic visits for assessment of symptoms, blood
pressure control, smoking cessation, and lifestyle modifica-
tions, as well as surveillance imaging to identify anatomic
changes in the aorta. Both A merican and European consensus
guidelines recommend surveillance imaging of the postdis-
section aorta at intervals of 1, 3, 6, and 12 months, and then
annually in patients with stable findings. European guide-
lines also endorse regular outpatient visits at these same
intervals by the physicians specialized in managing patients
with aortic dissection.3,4 These guidelines are largely based
on expert opinion, and there is a lack of data establishing the
need and clinical utility of such frequent follow-up. We
examined patterns of clinic visit and imaging follow-up after
discharge for AAD, and evaluated the prevalence and clinical
impact of adverse imaging findings. We hypothesized that
low rates of follow-up after discharge for AAD may be
associated with increased mortality.
Materials and Methods
This retrospective study examined consecutive adult indivi-
duals presenting with AAD at a major enrolling site in the
International Registry of Acute Aortic Dissection. Thedetails of
this registry have previously been described in detail.5–7All
patients were enrolled between January 1, 1996 and Novem-
ber 1, 2011. Type A AAD was defined as any nontraumatic
dissection involving the ascending aorta and presenting
within 14 days of symptom onset. Type B AAD was defined
as any nontraumatic dissection involving the descending aorta
and presenting within 14 days of symptom onset. Patients
were identified either prospectively at presentation or retro-
spectively via discharge diagnoses, imaging, and surgical
databases. Diagnosis was based on imaging or surgical visua-
lization. A total of 92 of 267 patients (34%) experienced AAD
prior the publication of guidelines endorsing imaging and
clinic visit follow-ups at intervals of 1, 3, 6, and 12 months,
then annually. This study was approved by the Institutional
Review Board with a waiver of informed consent.
For this study, inclusion criteria included adult patients
presenting with AAD who survived to discharge (n¼425). We
excluded individualswho lived >500 milesfrom the enrolling
site (n¼23) as they would be less likely to have follow-up at
the index hospital. All clinical records were carefully reviewed
for any indication that patients had partial imaging or specia-
lized clinic visits at other sites, and all patients with partial
follow-up at other sites were also excluded (n¼11). Finally,
we excluded those without at least one imaging test and one
follow-up clinic visit after discharge (n¼124), resulting in a
total of 267 patients for the study.
A standardized baseline form was used to record clinical
variables, which included information on patient demo-
graphics, history, clinical presentations, aortic imaging find-
ings, management, and patient outcomes. All-cause mortality
was assessed using the Social Security Death Index and using
the electronic medical record based on its query of state and
federal death records. Supplemental review of the electronic
medical record was used to determine patterns of imaging
surveillance and clinic visit follow-up, and records were
reviewed to determine blood pressure, rates of tobacco cessa-
tion, and adverse imaging findings. Clinic visitswere limited to
specialized follow-up with a cardiothoracic surgeon, vascular
surgeon, cardiovascular physician, or other physician specia-
lized in aortic dissection as recommended per guidelines.4
Imaging follow-up included transesophageal echocardiogra-
phy (TEE), computed tomographic (CT) angiography, and/or
magnetic resonance angiography (MRA). Adverse imaging
findings were defined as any adverse imaging finding on the
clinical reports, and included new dissection, false lumen
enlargement, new aneurysm or increased aortic dilatation,
new endograft leak, new intramural hematoma, new pseu-
doaneurysm, newpenetrating ulcer expansion,new dilation of
branch artery, new partial thrombosis of the false lumen, or
other aortic or related change on imaging. In all cases, images
were directly compared with the prior study as well as earlier
studies to assess for any interval change using multiplanar
reformats as appropriate, and all patients had index studies
available for comparison. Increased false lumen enlargement
and aortic dilatation were based on any increase 1mmin
size compared with the prior studies on direct side-by-side
comparison; differences in measurements that were consid-
ered within measurement error by the radiologist were not
counted as adverse imaging findings (in all cases, these did not
exceed 1 mm difference from the prior study). Imaging find-
ings that prompted interventional procedures were defined as
an adverse imaging finding that was documented in the
medical record to prompt open surgery of the aorta or
endovascular aorta repair.
Comparisons in mean blood pressure were performed
between individuals with <33%, 33 to 66%, and >66% clinic
visit follow-up, using the mean of all available blood pressu re
results following discharge and at expected intervals listed
below. Rates of tobacco use were compared between index
admission and the date of last follow-up.
All imaging studies were interpreted by nonblinded,
experienced, and specialized clinical readers. CT and MR A
studies were interpreted by board-certified fellowship-
trained cardiothoracic radiologists, and TEE studies were
interpreted by cardiologists with dedicated fellowship train-
ing in echocardiography and level III certification for echo-
cardiography. All readers had at least several years of
experience interpreting studies with aortic pathology
including aortic dissection.
We examined rates of adherence to guidelines for imaging
and clinic visit follow-up at defined intervals of 1, >1to
3, >3to6,>6 to 12, >12 to 24, >24 to 36, >36 to 48,
and >48 to 60 months. Analyses for imaging sur veillance
and clinic visit follow-up were performed separately, with
patients censored after their last imaging test or clinic visit
follow-up for each analysis, as we could not exclude the
possibility that patients may have had imaging and clinic
visits at other sites after that time.
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The Clinical Impact of Imaging Surveillance and Clinic Visit Frequency after Acute Aortic Dissection Chaddha et al.76

Patients were divided into three groups based on percen-
tage of imaging or clinic visits obser ved within their available
follow-up data (<33, 33–66, or >66%), with all analyses
done separately for imaging and clinic visits, respectively.
Comparisons between these three groups were performed
using chi-square tests and t-tests for categorical and contin-
uous variables, respectively.
Kaplan–Meier analysis and log-rank tests were used to
determine whether different rates of imaging surveillance or
clinic visits were associated with differences in survival after
discharge. After univariate analysis to identify variables
related to mortality, candidate variables were selected with
p-values less than 0.20 to introduce to a multivariable analysis.
Cox proportional hazards analysis was performed using a
backward stepwise method to determine the independent
relationship between follow-up groups and mortality. Con-
sidered variables included age >65 years, Type B versus Type
A aortic dissection, gender, comorbidities such as hyperten-
sion, atherosclerosis, aortic aneurysm, bicuspid aortic valve,
iatrogenic dissection, prior coronary angiography, coronary
artery disease, heart failure, chronic renal disease, aortic
insufficiency, ischemic spinal cord injury, cerebrovascular
accident, electrocardiographic findings such as low voltage
and prior Q waves, chest X-ray findings such as aortic calcifica-
tion and pleural effusion, and presenting symptoms such as
anterior chest pain, leg pain, and syncope. A p-value of <0.05
was considered statistically significant. IBM SPSS Statistics
Version 22.0 (IBM Corp., Armonk, NY) was used for analysis.
Results
The study group included 267 individuals. Patient demo-
graphics, past medical history, dissection type, and dissec-
tion management are provided in ►Tables 1 and 2,andare
stratified by <33%, 33 to 66%, and >66% follow-up. Surgery
or endovascular repair were performed in 80 (99/123) and
40% (57/144) of individuals with Type A and Type B AAD,
respectively, prior to discharge. Inpatient events, including
stroke or transient ischemic attack, myocardial infarction or
ischemia, and acute renal failure, were not different between
groups (p>0.10 for each).
Patients were followed for a maximum of 5 years after
initial discharge. Mean follow-up was 54.7 13.3 months
overall, and there were 52 deaths. In the subgroup with Type
AAAD(n¼123), mean follow-up was 57.7 7.9 months
with 13 deaths, while in the subgroup with Type B AAD
(n¼144), mean follow-up was 52.2 16.1 months with 39
deaths.
►Figure 1 demonstrates the observed frequency of ima-
ging surveillance and clinic visit follow-up for each time
interval. CT was utilized in 94.5% of cases, magnetic reso-
nance imaging (MRI) in 4.6% of cases, and TEE alone in 1.0% of
cases. ►Table 3 provides the incidence of adverse imaging
findings among the proportion of patients with imaging
performed at each recommended interval, peaking between
6 and 12 months. Of these adverse findings, CT identified all
but three cases, with the remainder reported by MRI. There
were a total of 13 interventional procedures or surgeries
prompted by adverse imaging findings during the period of
follow-up (►Table 4). Rates of adverse imaging findings that
resulted in a procedure or surger ywere low, with the highest
rate observed between 6 and 12 months after discharge
(►Fig. 2). ►Tables 5 and 6provide the number of imaging
studies and clinic visits for patients in each of the three
groups.
In the subgroup of patients with imaging performed in at
least 4 of the 8 recommended intervals (n¼126), adverse
imaging findings were observed in 2.8% (2/72) at 1 to
3 months, 14.0% (9/64) at 3 to 6 months, 27.0% (27/100) at
6to12months,18.4%(19/103)at12to24months,17.0%(16/
94) at 24 to 36 months, 9.8% (9/92) at 36 to 48 months, and
14.1% (10/71) at 48 to 60 months.
In patients stratified by <33%,33to66%,or >66% com-
pletion of interval imaging surveillance tests (►Fig. 3A)and
follow-up clinic visits (►Fig. 3B), significant differences in
unadjusted all-cause mortality were observed between
groups for completion of recommended follow-up clinic
visits (p¼0.007) but not for completion of recommended
imaging surveillance tests (p¼0.10).
Compared with those with <33% of imaging tests, multi-
variate analysis observed that patients with more frequent
imaging did not have a difference in survival (►Table 7). In
comparison to those wit h <33% of clinic visits , patients with
33 to 66% of clinic visits had lower mortality on multivariable
analysis, although no difference was seen in those with
>66% of clinic visits (►Table 8).
Patients with any imaging between 6 and 12 months (vs.
none) had lower mortality (p<0.001) on unadjusted ana-
lysis (►Fig. 3C), while imaging at other time intervals was
not associated with a difference in mortality (p>0.05 for
each). The presence versus absence of clinic visits at specific
time intervals was not associated with any difference in
mortality (p>0.05 for each). On multivariable analysis,
imaging at 6 to 12 months was associated with improved
survival (hazards ratio: 0.50, 95% confidence interval: 0.27–
0.91, p¼0.02; c-statistic: 0.66). There were no significant
differences in clinical characteristics between patients with
and without adverse imaging findings, including the pre-
sence of Marfan syndrome, prior aortic aneurysm, prior
aortic dissection, elevated systolic blood pressure, or ele-
vated diastolic blood pressure (p>0.05 for each), which may
be due to lack of statistical power.
Postdischarge blood pressure values were available for
93% (249/267) of patients. Between patients with <33%, 33
to 66%, and >66% clinic follow-up, there were no dif ferences
in mean systolic (131.9 26.8 vs. 132.14 17.3 vs.
127.9 15.2 mm Hg, p¼0.30) or diastolic (71.6 14.6
vs. 71.0 11.2 vs. 71.6 8.3 mm Hg, p¼0.92) blood pres-
sure between groups. In patients with known baseline
tobacco status (n¼204), no difference in smoking between
index hospitalization and follow-up was observed in those
with <33% clinic visit follow-up (43% [21/49] vs. 35% [17/
49], p¼0.41), while a significant reduction in smoking was
observed in those with 33 to 66% of clinic visits (37% [34/92]
vs. 21% [19/92], p¼0.01) and >66% of clinic visits (32% [20/
63] vs. 16% [10/63], p¼0.04).
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The Clinical Impact of Imaging Surveillance and Clinic Visit Frequency after Acute Aortic Dissection Chaddha et al. 77

Discussion
This study observes a wide range in the rate of surveillance
imaging and clinic visit follow-up. Further, while adverse
imaging findings were not uncommon, they rarely resulted
in surgical or interventional procedures. Patients with inter-
mediate rates of follow-up clinic visits after AAD had lower
rates of mortality than patients with lower or higher rates of
clinic visits. And finally, while the overall rate of surveillance
imaging after AAD was not associated with mortality, ima-
ging at 6 to 12 months was associated with improved
survival. When coupled with o ur observation of peak adverse
imaging findings and peak interventions for adverse imaging
findings during this same interval, these results suggest that
imaging between 6 and 12 months following discharge for
AAD may represent an especially important period for
surveillance imaging.
Existing guidelines endorse frequent follow-up, and
recommend four clinic visits and surveillance imaging3,4
studies in the first year, with annual follow-up thereafter
Table 1 Patient characteristics stratified by proportion of interval surveillance imaging performed after acute aortic dissection
Variables Overall n¼267 <33%, n¼80 (30%) 33–66%, n¼86 (32%) >66%, n¼101 (38%) p-Value
Demographics:
Age (y) 59.9 14.3 62.2 15.1 58.0 14.0 59.8 13.7 0.16
Female gender 91 (34%) 28 (35%) 33 (38%) 30 (30%) 0.45
Caucasian (vs. other) 202 (77%) 54 (68%) 64 (76%) 84 (86%) 0.02
Distance to home (miles) 70.9 61.4 74.5 76.0 72.0 49.4 67.3 58.0 0.73
Past medical history:
Marfan syndrome 17 (7%) 2 (3%) 4 (5%) 11 (11%) 0.07
Hypertension 202 (76%) 63 (80%) 69 (80%) 70 (70%) 0.18
Aortic aneurysm 37 (14%) 8 (10%) 12 (14%) 17 (17%) 0.45
Coronary artery disease 81 (31%) 23 (30%) 28 (33%) 30 (30%) 0.88
Bicuspid aortic valve 10 (4%) 2 (3%) 4 (5%) 4 (4%) 0.79
Prioraorticdissection 21(8%) 3(4%) 6(7%) 12(12%) 0.14
Mitral valve disease 9 (6%) 3 (7%) 3 (8%) 3 (5%) 0.83
Diabetes 19 (7%) 9 (12%) 4 (5%) 6 (6%) 0.22
Current smoking 76 (36%) 24 (39%) 25 (40%) 27 (31%) 0.45
Cocaine abuse 13 (5%) 4 (5%) 6 (7%) 3 (3%) 0.46
Renal insufficiency 7(5%) 4(9%) 2(5%) 1(2%) 0.23
PCI 11(5%) 4(5%) 4(5%) 3(3%) 0.93
Aortic valve disease 29 (11%) 7 (9%) 11 (13%) 11 (11%) 0.74
Emphysema 24 (17%) 7 (16%) 8 (21%) 9 (15%) 0.70
CABG 19 (7%) 6 (8%) 5 (6%) 8 (8%) 0.86
Dissection type:
Type A 123 (46%) 30 (38%) 46 (54%) 47 (47%) 0.12
Type B 144 (54%) 50 (63%) 40 (47%) 54 (54%)
Dissection management:
Surgery 116 (43%) 28 (35%) 43 (50%) 45 (45%) 0.14
Endovascular repair 40 (15%) 14 (18%) 10 (12%) 16 (16%) 0.54
Medical management 97 (36%) 34 (43%) 28 (33%) 35 (35%) 0.37
Chronic medical therapy:
ARB 9(7%) 2(5%) 3(8%) 4(7%) 0.91
ACE-I 98 (38%) 28 (35%) 33 (40%) 37 (37%) 0.85
Beta-blocker 254 (96%) 76 (96%) 83 (97%) 95 (96%) 0.98
Calcium channel blocker 131 (50%) 39 (49%) 45 (54%) 47 (48%) 0.71
Statin 21 (26%) 3 (14%) 9 (41%) 9 (24%) 0.14
Diuretic 64 (46%) 18 (43%) 18 (49%) 28 (46%) 0.88
Abbreviations: ACE-I, angiotensin-conver ting enz yme inhibitor; ARB, angiotensin-receptor blocker; CABG, coronary artery bypass graf t; PCI,
percutaneous coronary intervention.
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The Clinical Impact of Imaging Surveillance and Clinic Visit Frequency after Acute Aortic Dissection Chaddha et al.78

in stable patients. Our results suggest that clinical practice is
not entirely consistent with guidelines, although about a
third of our cohort experienced A AD prior to their publica-
tion,4limiting our ability to determine adherence to guide-
line recommendations. The present results likely
overestimate the actual rate of follow-up, as the study
censored patients at the time of their last clinic visit or
imaging follow-up for the respective analyses. This was done
to reduce the possibility of underestimating follow-up, as
this study did not have permission to contact patients
directly to determine which patients may have moved or
transferred their postdissection care to other centers.
Furthermore, it is likely that patterns of follow-up may be
lower at outside centers specializing in aortic disease.
Table 2 Patient characteristics stratified by proportion of interval follow-up clinic visits after acute aortic dissection
Variables Overall
(n¼267)
<33%, n¼75
(28%)
33–66%, n¼115
(43%)
>66%, n¼77
(29%)
p-Value
Demographics:
Age (y) 59.9 14.3 61.4 16.0 58.8 13.6 60.2 13.5 0.46
Female gender 91 (34%) 28 (37%) 38 (33%) 25 (33%) 0.78
Caucasian (vs. other) 202 (77%) 55 (74%) 82 (73%) 65 (87%) 0.07
Distance to home (miles) 70.9 61.3 79.8 71.5 71.0 61.5 62.3 48.9 0.22
Past medical history:
Marfan syndrome 17 (6%) 0 (0%) 12 (10%) 5 (7%) 0.02
Hypertension 202 (76%) 58 (78%) 90 (79%) 54 (70%) 0.33
Aortic aneurysm 37 (14%) 11 (15%) 16 (14%) 10 (13%) 0.94
Coronary artery disease 81 (31%) 22 (31%) 40 (35%) 19 (25%) 0.34
Bicuspid aortic valve 10 (4%) 3 (4%) 5 (5%) 2 (3%) 0.79
Prior aortic dissection 21 (8%) 3 (4%) 12 (11%) 6 (8%) 0.30
Mitral valve disease 9 (6%) 1 (2%) 6 (10%) 2 (5%) 0.34
Diabetes 19 (7%) 7 (10%) 7 (6%) 5 (7%) 0.66
Current smoking 76 (36%) 26 (46%) 30 (33%) 20 (32%) 0.39
Cocaine abuse 13 (5%) 7 (10%) 4 (4%) 2 (3%) 0.11
Renal insufficiency 7 (5%) 2 (5%) 4 (7%) 1 (3%) 0.89
PCI 11 (5%) 6 (9%) 4 (4%) 1 (1%) 0.19
Aortic valve disease 29 (11%) 7 (10%) 14 (12%) 8 (11%) 0.84
Emphysema 24 (17%) 7 (16%) 10 (16%) 7 (19%) 0.92
CABG 19 (7%) 5 (7%) 9 (8%) 5 (7%) 0.93
Dissection type:
Type A 123 (46%) 29 (39%) 60 (60%) 34 (34%) 0.17
Type B 144 (54%) 46 (61%) 58 (48%) 43 (56%)
Dissection management:
Surgery 116 (43%) 23 (31%) 56 (49%) 37 (48%) 0.03
Endovascular repair 40 (15%) 10 (13%) 17 (15%) 13 (17%) 0.83
Medical management 97 (36%) 37 (49%) 37 (32%) 23 (30%) 0.02
Chronic medical therapy:
ARB 9 (7%) 1 (2%) 5 (8%) 3 (9%) 0.46
ACE-I 98 (38%) 26 (35%) 43 (38%) 29 (40%) 0.85
Beta-blocker 254 (96%) 70 (95%) 112 (97%) 72 (96%) 0.61
Calcium channel blocker 131 (50%) 35 (47%) 57 (50%) 39 (52%) 0.84
Statin 21 (26%) 6 (29%) 9 (23%) 6 (29%) 0.85
Diuretic 64 (46%) 18 (43%) 31 (51%) 15 (41%) 0.56
Abbreviations: ACE-I, angiotensin-conver ting enz yme inhibitor; ARB, angiotensin-receptor blocker; CABG, coronary artery bypass graf t; PCI,
percutaneous coronary intervention.
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The Clinical Impact of Imaging Surveillance and Clinic Visit Frequency after Acute Aortic Dissection Chaddha et al. 79

Frequent imaging is associated with increased costs, and
in the case of CT may expose patients to potential risks such
as ionizing radiation and contrast-induced nephropathy.
These must be weighed against the likelihood of adverse
imaging findings that al ter management. This study obser ves
that adverse imaging findings are not uncommon, with the
bulk of these demonstrating an increase in aortic size,
greater false lumen size, and new partial thrombosis of a
false lumen. While these findings may convey prognostic
significance, they rarely resulted in changes in patient man-
agement in this study, suggesting that the clinical benefitof
frequent imaging may be small in a general cohort of
individuals following AAD.
Our observation of a potential survival benefit related to
imaging between 6 and 12 months after discharge makes
sense given the increased rate of adverse imaging findings
and associated interventions that we observed during this
interval. These findi ngss uggest that this may be an especial ly
important period for surveillance imaging, although we may
be underpowered to detect dif ferences in morta lity related to
imaging during other inter vals. In contrast, there was a lack
of survival benefit based on the overall frequency of imaging
surveillance. This suggests that we could consider a reduced
frequency of overall imaging surveillance in some patients
following AAD, with a possible targeted approach for ima-
ging during potentially higher-risk intervals. Future research
to identify populations and time intervals at higher risk is
needed to determine the optimal frequency and timing of
imaging surveillance. While we did not identify clinical
characteristics that predicted adverse imaging findings,
this may be due to a lack of statistical power.
While frequent clinic visit follow-up with physicians
specializing in post-AAD management may not necessarily
correlate with the small risks inherent in imaging, it may also
be associated with increased cost, and often requires sig-
nificant patient travel due to the relatively small number of
Fig. 1 Frequency of aortic imaging follow-up (A) and clinic visits (B) at each recommended interval. The bars represent the number of patients
with clinic visit and imaging follow-up for each in terval, among the patients with available follow-up. As patients are censored from the study, the
number of patients with available follow-up decreases.
Table 3 Frequency of new adverse imaging findings at each interval
Imaging interval (mo)
Adverse imaging findings >1–3,
n¼134
>3–6,
n¼111
>6–12,
n¼147
>12–24,
n¼139
>24–36,
n¼111
>36–48,
n¼98
>48–60,
n¼74
Increased false lumen size 47 3 3 1
New partial thrombosis of false lumen 1 4 6 2 1 1 
Aortic dilatation or new aneurysm 1 9 25 20 16 7 8
New endograft leak 2
New dissection 11
Intramural hematoma 1
Pseudoaneurysm 1   1
Penetrating ulcer expansion 2   
New dissection expansion
into branch vessel

Other cardiovascular finding 1 111
Note: The total number of adverse findings is provided in ►Fig. 2.
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The Clinical Impact of Imaging Surveillance and Clinic Visit Frequency after Acute Aortic Dissection Chaddha et al.80

centers that specialize in post-AAD management. This study
observed that patients with interm ediate rates of clinic visits
had the lowest adjusted mortality, suggesting a potential
survival benefit related to regular follow-up in specialized
clinics. Patients with higher rates of clinic visits had greater
mortality, which could relate to unmeasured variables that
may convey higher risk and prompt more frequent clinic
follow-up. The higher mortality observed in patients with
low rates of follow-up suggest a potential survival benefitof
more frequent follow-up in specialized clinics, and suggest
those with infrequent follow-up may be at higher risk. It is
also possible that patients in the low follow-up group are
noncompliant, and thus may be noncompliant with recom-
mendations for other cardiac risk factors as well increasing
the risk of mortality. Alternatively, patients with frequent
Table 4 Procedures performed following adverse imaging findings
Case number Initial dissection type Adverse imaging findings Treatment
1B NewTypeAAAD Surgicalreplacement
2 A Enlarging arch and descending aorta Surgical replacement
3 A Enlarging descending aorta Endovascular repair
4 A Enlarging proximal descending aorta Surgical replacement
5 A New occlusion of common carotid from false lumen Surgical bypass
6B Enlargingarch Surgicalreplacement
7 B Enlarging arch and descending aorta Surgical replacement
8 B Enlarging descending aorta Surgical replacement
9 B Enlarging descending aorta Surgical replacement
10 B Enlarging ascending aorta and arch Surgical replacement
11 B Enlarging abdominal aneurysm Surgical replacement
12 B Enlarging descending aorta Surgical replacement
13 B Enlarging descending aorta Surgical replacement
Abbreviation: AAD, acute aortic dissection.
Note: Since the patients were enrolled between 1996 and 2011, treatment approaches may not be consistent with contemporary practice.
Fig. 2 Frequenc y of adverse findings on imaging at each interval. The
bars represent the number of imaging studies with adverse findings
for each interval and the number of adverse imaging findings that are
documented to prompt interventional procedures.
Table 5 Surveillance imaging at each follow-up time interval
Follow-up
time
interval
(mo)
<33%,
n¼80
(30%)
33–66%,
n¼86
(32%)
>66%,
n¼101
(38%)
p-Value
1 19 (23.8%) 30 (24.8%) 23 (35.9%) 0.192
>1–3 29 (36.3%) 69 (57.0%) 36 (57.1%) 0.008
>3–6 22 (27.5%) 49 (41.2%) 40 (64.5%) <0.001
>6–12 20 (25.0%) 72 (61%) 55 (91.7%) <0.001
>12–24 9 (12.3%) 77 (67.5%) 53 (94.6%) <0.001
>24–36 6 (9.1%) 54 (50.0%) 51 (94.4%) <0.001
>36–48 3 (5.4%) 51 (52.0%) 44 (97.8%) <0.001
>48–60 2 (4.1%) 36 (38.7%) 36 (92.3%) <0.001
Table 6 Follow-up clinic visits at each time interval
Follow-up
time
interval
(mo)
<33%,
n¼75
(28%)
33–66%,
n¼155
(43%)
>66%,
n¼77
(29%)
p-Value
1 30 (43.5%) 67 (55.4%) 56 (74.7%) 0.001
>1–3 38 (55.1%) 83 (68.6%) 60 (81.1%) 0.004
>3–6 16(23.2) 75(62.5) 53(73.6) <0.001
>6–12 9 (13.0%) 63 (53.4%) 58 (81.7%) <0.001
>12–24 3 (4.7%) 55 (49.5%) 61 (89.7%) <0.001
>24–36 1 (1.8%) 30 (28.0%) 60 (92.3%) <0.001
>36–48 0 33 (33.7%) 46 (90.2%) <0.001
>48–60 1 (2.4%) 25 (27.2%) 34 (72.3%) <0.001
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The Clinical Impact of Imaging Surveillance and Clinic Visit Frequency after Acute Aortic Dissection Chaddha et al. 81

follow-up may have higher risk features prompting more
frequent follow-up. We observed no differences in blood
pressure control between groups, which may represent
adequate treatment by both the specialists and primary
care providers for these individuals. While decreased
tobacco smoking was observed in patients with increased
clinic visit follow-up, this could also be due to more moti-
vated patients who may have been more likely to return to
clinic.
There are several limitations of this observational study.
This was limited to review of the electronic medical record and
the Social Security Death Index, and we could not directly
contact patients to more completely establish follow-up. We
acknowledge a potential selection bias due to exclusion of
patients who may have been followed at other centers and
undergone imaging elsewhere. To mitigate this limitation, we
excluded patients who lived more than 500 miles away from
our academic medical center, and censored patients at the
time of the last clinic visit or imaging follow-up, which would
be expected to overestimate follow-up. Further, there were
univariate differences between groups stratified by rates of
follow-up, and there may be unmeasured variables that we
cannot account for. While we performed multivariable analy-
sis to account for biases present on univariable analyses (such
as differences in follow-up for patients with Marfansyndrome,
prior cocaine use, and treated with medical management), we
cannot exclude the possibility of incomplete multivariable
adjustment and residual bias. Also, we limited follow-up to
5 years to have a more contemporary cohort, and we therefore
cannot assess the effect of longer follow-up on events, and
would miss delayed adverse events. Finally, we evaluated
patients over a significant time interval to obtain an adequate
sample size; there have been significant changes in practice
patterns and recommendations during this time, which may
be incompletely captured in our data.
Another limitation is that adverse imaging changes, such as
false lumen enlargement or increased aortic dilatation, were
based on any increase in size compared with the prior studies
unless the radiologist felt this was within measurement error
(in all cases within 1 mm from the prior study); while we
considered the use of thresholds, the retrospective nature of
this study with the use of clinical reports, and the lack of
definitive thresholds, limit the utility of such an approach. We
therefore decided to err on the side of including any potential
adverse imaging findings and included any increase in size as
an adverse event. Finally, this represents the experience of a
single academic medical center. While this site is the largest
enrollment site in the International Registry of Aortic Dissec-
tion, its experience may differ from other sites.
Conclusions
We observed a wide range in the rate of specialized clinic
visits and imaging surveillance following A AD that often did
not match the frequency suggested in guidelines. While
adverse imaging findings were not uncommon, they rarely
resulted in management changes. We observed that patients
with intermediate rates of clinic visits had lower mortality
Fig. 3 (A–C)Kaplan–Meier curves for all-cause mortality in patients with acute aortic dissection stratified by frequency of imaging (A), clinic
visit follow-up (B), and imaging between 6 and 12 months (C). The number at risk is provided below each image. For p-values, please refer the
“Results”section.
Table 7 Adjusted all-cause mortality in patients with acute
aortic dissection stratified by frequency of surveillance imaging
Imaging frequency HR 95% CI p-Value
Imaging <33% 1.0 (baseline) 
Imaging 33–66% 0.66 0.34–1.28 0.22
Imaging >66% 1.11 0.56–2.17 0.77
Abbreviations: CI, confidence interval; HR, hazards radio.
Note: c-Statistic ¼0.67.
Table 8 Adjusted all-cause mortality in patients with acute
aortic dissection stratified by frequency of follow-up clinic visits
Clinic visit frequency HR 95% CI p-Value
Clinic visit <33% 1.0 (baseline) 
Clinic visit 33–66% 0.47 0.23–0.97 0.04
Clinic visit >66% 1.26 0.67–2.38 0.47
Abbreviations: CI, confidence interval; HR, hazards radio.
Note: c-Statistic ¼0.73.
AORTA Vol. 7 No. 3/2019
The Clinical Impact of Imaging Surveillance and Clinic Visit Frequency after Acute Aortic Dissection Chaddha et al.82

than those with lower or higher rates. Further, while the
overall rate of surveillance imaging after AAD did not appear
to impact mortality, imaging at 6 to 12 months was asso-
ciated with improved mortality, which corresponds to peak
rates in adverse imaging findings and associated interven-
tions. These findings may improve our ability to optimize the
frequency and timing of specialized clinic visits and surveil-
lance imaging following AAD. Future prospective research
comparing guideline-based follow-up to less frequent fol-
low-up could be considered in patients at lower risk of
complications.
Funding
None.
Conflict of Interest
Dr. Eagle reports grants from Gore, grants from Terumo,
and grants from Medtronic, outside the submitted work.
All other authors declare no conflict of interest related to
this article.
Acknowledgments
None.
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