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Division of Environmental Medicine and Population Sciences, Department of Social and Environmental Medicine, Graduate School of Medicine, Osaka University, Suita, Japan
Division of Environmental Medicine and Population Sciences, Department of Social and Environmental Medicine, Graduate School of Medicine, Osaka University, Suita, Japan
Shigeru Miyagawa, MD, PhD, Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine, 2-2-E1, Yamadaoka, Suita, Osaka 565-0871, Japan.
The study objectives were to determine the incidence, predictors, and clinical impact of ventricular arrhythmias after coronary artery bypass grafting and to evaluate the impact of implantable cardioverter defibrillators on the survival of patients with ventricular arrhythmias.
Methods
We enrolled 498 patients with a left ventricular ejection fraction of 40% or less who underwent coronary artery bypass grafting between 1993 and 2015. Clinical follow-up was completed in 94.0% of patients, with a median follow-up of 58.4 months.
Results
Overall, 212 patients (43%) died, mainly of heart failure (n = 54, 10.8%) or sudden cardiac death (n = 40, 8.0%). The sudden cardiac death rate was highest during the first 6 months, with a monthly rate of 0.37%. Overall, 99 patients (20%) developed postoperative ventricular arrhythmias, and implantable cardioverter defibrillator was implanted in 55 patients. Previous ventricular arrhythmias (hazard ratio, 3.22; 95% confidence interval, 1.98-5.24; P < .001), left ventricular end-systolic dimension (hazard ratio, 1.07; 95% confidence interval, 1.04-1.10; P < .001), and myocardial infarction in the left anterior descending artery territory (hazard ratio, 1.73; 95% confidence interval, 1.10-2.73; P = .02) were independent predictors of postoperative ventricular arrhythmias. Notably, the 5-year survival of patients with ventricular arrhythmias who received an implantable cardioverter defibrillator was significantly higher than that of patients with ventricular arrhythmias who did not receive it (76.1% vs 22.7%, P < .001) and was comparable to that of patients without ventricular arrhythmias (76.1% vs 73.6%, P = .98).
Conclusions
Sudden cardiac death affects a significant proportion of patients with ischemic cardiomyopathy undergoing coronary artery bypass grafting, most frequently within 6 months postoperatively. To prevent sudden cardiac death, earlier implantable cardioverter defibrillator implantation should be indicated for high-risk patients with scars in the left anterior descending artery territory and excessive left ventricular remodeling.
SCD occurs most frequently within 6 months post-CABG in patients with ischemic cardiomyopathy. Whether earlier ICD implantation improves survival remains to be determined.
Patients with prior myocardial infarction in the LAD territory and excessive LV remodeling are more likely to develop postoperative VAs. Further studies are warranted to determine whether earlier ICD implantation prevents SCD after CABG in these patients.
See Commentary on page 176.
Sudden cardiac death (SCD) is a major public health problem worldwide, accounting for approximately half of all cardiovascular deaths.
Ischemic heart disease is the most common underlying substrate associated with SCD, whereas SCD related to ventricular arrhythmias (VAs) remains a significant cause of death in patients with ischemic cardiomyopathy.
Coronary artery bypass grafting (CABG) is the treatment of choice for ischemic cardiomyopathy and may improve ischemia in the damaged myocardium, thereby conferring electrical stability. However, the incidence, timing, and predictors of postoperative VAs after CABG remain largely unknown. In addition, it remains unclear whether postoperative implantation of an implantable cardioverter defibrillator (ICD) improves outcomes after CABG in patients with ischemic cardiomyopathy who develop postoperative VAs.
Therefore, this study aimed to elucidate the incidence, predictors, and clinical impact of post-CABG VAs in patients with ischemic cardiomyopathy. Furthermore, the impact of postoperative ICD implantation on long-term survival was assessed.
Materials and Methods
The baseline characteristics and surgical data of patients were obtained from the surgical database of the Osaka Cardiovascular Surgery Research Group, which is a prospective database. A total of 504 patients with ischemic cardiomyopathy (defined as severely impaired left ventricular [LV] systolic function with an ejection fraction of ≤40%
2022 AHA/ACC/HFSA guideline for the management of heart failure: a report of the American College of Cardiology/American Heart Association Joint Committee on clinical practice guidelines.
) who underwent CABG between 1993 and 2015 were identified. Of these patients, those who underwent ICD implantation before CABG (n = 6) were excluded. Finally, 498 patients were included in the study (Figure E1). The investigation complied with the principles outlined in the Declaration of Helsinki. The study protocol was approved by the Institutional Review Board of the Osaka University Hospital (Number 16105, approved November 2, 2016), and all patients provided informed consent before undergoing the procedures.
Echocardiography
Two-dimensional and Doppler echocardiography was performed by expert echocardiographic examiners preoperatively (baseline), at 1 and 12 months postoperatively, and annually thereafter to evaluate changes in LV function parameters.
Surgical Procedures
The off-pump revascularization technique was favored in high-risk patients and those with contraindications for cardiopulmonary bypass and aortic crossclamping (eg, extensive atherosclerotic disease of the ascending aorta). The on-pump technique was favored when manipulation of the heart was likely to induce hemodynamic instability. The in situ right or left internal thoracic artery was used for bypass to the left anterior descending (LAD) artery when indicated. The use of bilateral internal thoracic arteries was favored in younger patients when anatomically and clinically suitable. The decision to perform concomitant procedures, such as surgical ventricular restoration (SVR) or mitral valve surgery, was generally based on the patient's clinical condition, coronary anatomy, extent of LV remodeling, and mitral regurgitation (MR) grade. However, the final decision was at the discretion of the attending surgeon.
Clinical End Points and Follow-up
The primary end point was all-cause mortality during follow-up, and the secondary end point was postoperative VAs, including ventricular fibrillation, pulseless ventricular tachycardia (VT), sustained VT, and nonsustained VT. The tertiary study end point was the serial change of LV functional parameters. SCD was defined as a sudden unexpected death that was assumed to be due to a cardiac cause.
Clinical follow-up examinations were completed in 468 patients (94.0%) with a median follow-up period of 58.4 months (interquartile range [IQR], 31.5-87.5 months). The cumulative follow-up period was 2624 patient-years.
Statistical Analysis
To elucidate the incidence, predictors, and clinical impact of post-CABG VAs, patients were classified into 2 groups depending on the occurrence of postoperative VAs. Continuous variables were expressed as median with IQR, and categorical variables were expressed as numbers and frequencies (percentage). Comparisons among groups were evaluated using the Mann–Whitney U test for continuous variables and the Fisher exact test or chi-square test for categorical variables, as appropriate.
Survival curves were constructed using the Kaplan–Meier method and compared using the log-rank test. The conditional SCD rates per month for different time intervals were calculated by dividing the total number of SCDs that occurred during each time interval by the number of months for the time interval and the number of patients who survived at the beginning of each time interval. Longitudinal data of LV functional parameters were assessed using a mixed-effects model including factors for group, time, and interaction between group and time. The variance-covariance matrix of the observations in the linear mixed-effects models was assumed to be unstructured. Assessment time points were treated as categorical factors. Univariate and multivariate Cox proportional hazard models were used to assess the predictors of postoperative VAs. Hazard ratios were reported with 95% confidence intervals. Statistical analyses were performed using JMP Pro 15.1.0 (SAS Institute Inc).
Results
Baseline Characteristics and Operative Data
The median age of patients was 68.0 years, and there were 421 men (84.5%) (Table 1). The median LV end-systolic dimension and ejection fraction were 52.0 mm and 30.0%, respectively. Emergency or urgent surgery was performed in 82 patients (16.5%). Concomitant mitral valve surgery, SVR, and mitral valve surgery plus SVR were performed in 165 patients (33.1%), 80 patients (16.1%), and 55 patients (11.0%), respectively.
Table 1Patients' characteristics according to presence of postoperative ventricular arrhythmias
Total (n = 498)
Post-op VAs (-) (n = 399)
Post-op VAs (+) (n = 99)
P value
Demographic characteristics
Age, y
68 [61-73]
68 [61-73]
66 [60-72]
.133
Male
421 (84.5)
333 (83.5)
88 (88.9)
.215
Preoperative IABP
60 (12.0)
43 (10.8)
17 (17.2)
.086
euroSCORE II
6.5 [3.1-13.3]
5.7 [3.0-12.0]
10.2 [5.1-22.3]
<.001
Emergency/urgent surgery
82 (16.5)
64 (16.0)
18 (18.2)
.650
Redo surgery
25 (5.0)
14 (3.5)
11 (11.1)
.004
Medical history
Atrial fibrillation
46 (9.2)
34 (8.5)
12 (12.1)
.331
Previous VAs
60 (12.0)
32 (8.0)
28 (28.3)
<.001
Diabetes
296 (59.4)
247 (61.9)
49 (49.5)
.030
Previous PCI
.057
Single
92 (18.5)
77 (19.3)
15 (15.2)
Multiple
86 (17.3)
61 (15.3)
25 (25.3)
Prior MI
429 (86.1)
339 (85.0)
90 (90.9)
.145
Prior LAD-MI
267 (53.6)
195 (48.9)
69 (69.7)
<.001
On hemodialysis
45 (9.0)
34 (8.5)
11 (11.1)
.434
Peripheral artery disease
73 (14.7)
58 (14.5)
15 (15.2)
.874
Previous stroke
66 (13.3)
50 (12.5)
16 (16.2)
.325
Echocardiographic data
LVEF (%)
30 [25-36]
31 [25-36]
28 [23-35]
.031
LVESD (mm)
52 [47-57]
51 [46-56]
56 [51-60]
<.001
MR grade ≥moderate
202 (40.6)
152 (38.1)
50 (50.5)
.030
Coronary anatomy
Triple-vessel disease
375 (75.3)
305 (76.4)
70 (70.7)
.243
Left main disease
75 (15.1)
57 (14.3)
18 (18.2)
.347
Operation data
ITA use
.420
No ITA
42 (8.4)
31 (7.8)
11 (11.1)
Single ITA
316 (63.5)
252 (63.2)
64 (64.7)
Bilateral ITA
140 (28.1)
116 (29.1)
24 (24.2)
No. of grafted vessels
3 [2-4]
3 [2-4]
3 [2-4]
.073
Concomitant surgeries
<.001
MV surgery
165 (33.1)
130 (32.6)
35 (35.4)
SVR
80 (16.1)
62 (15.5)
18 (18.2)
MV surgery + SVR
55 (11.0)
34 (8.5)
21 (21.2)
Post-op, Postoperative; VA, ventricular arrhythmia; IABP, intra-aortic balloon pump; euroSCORE, European System for Cardiac Operative Risk Evaluation; PCI, percutaneous coronary intervention; MI, myocardial infarction; LAD, left anterior descending; LVEF, left ventricular ejection fraction; LVESD, left ventricular end-systolic dimension; MR, mitral regurgitation; ITA, internal thoracic artery; MV, mitral valve; SVR, surgical ventricular restoration.
During the follow-up, 99 patients (20%) developed postoperative VAs (ventricular fibrillation/pulseless VT, n = 46; sustained VT, n = 27; nonsustained VT, n = 26). There were no differences in age, prevalence of preoperative intra-aortic balloon pump support, left main coronary artery disease, 3-vessel disease, and major comorbidities except for hypertension and diabetes between patients with VAs and those without VAs. However, patients who developed post-CABG VAs were more likely to undergo emergency/urgent and redo surgeries, and present previous VAs, prior myocardial infarction in the LAD system, poorer LV functional parameters, and greater MR severity, thereby higher operative risk as predicted by European System for Cardiac Operative Risk Evaluation II. The frequencies of concomitant mitral valve surgery, SVR, and both procedures were higher in patients who developed postoperative VAs.
Sudden Cardiac Death Rate According to the Time Interval From Coronary Artery Bypass Grafting
The 30-day mortality rate was 3.6%. During a median follow-up period of 58 months, 212 patients died. The main cause of death was heart failure (n = 54, 10.8%), followed by SCD (n = 40, 8.0%) (Figure 1).
Figure 1Causes of overall mortality. GI, Gastrointestinal; MI, myocardial infarction.
Cumulative incidence rates of SCD and other-cause death over the 5-year follow-up period after CABG are shown in Table 2. The 1-, 3-, and 5-year cumulative incidences of SCD after CABG in this series were 3.0%, 5.0%, and 6.4%, respectively. The conditional risk of SCD per month over different time intervals after CABG is shown in Figure 2. The risk of SCD per month was the highest during the first 6 months (0.37%). After 6 months, the risk per month decreased to 0.10% and remained relatively stable thereafter.
Table 2Cumulative number and incidence rate of sudden cardiac death and other-cause deaths at different time after coronary artery bypass grafting
Time after surgery
SCDs
Other-cause deaths
Cumulative deaths, n
Cumulative incidence rate, % (95% CI)
Cumulative deaths, n
Cumulative incidence rate, % (95% CI)
1 month
3
0.6 (0.2-1.8)
14
2.8 (1.7-4.7)
3 months
6
1.2 (0.6-2.6)
26
5.2 (3.6-7.5)
6 months
11
2.2 (1.2-3.9)
35
7.0 (5.1-9.6)
1 year
15
3.0 (1.8-4.9)
46
9.2 (7.0-12.1)
3 years
25
5.0 (3.4-7.3)
91
18.3 (15.1-21.9)
5 years
32
6.4 (4.6-8.9)
112
22.5 (19.0-26.4)
*Eight SCDs and 60 other-cause deaths happened during the follow-up period after 5 years after surgery. SCD, Sudden cardiac death; CI, confidence interval.
Clinical Impact and Predictors of Postoperative Ventricular Arrhythmias
Patients with postoperative VAs had significantly lower 5-year (74% vs 53%) and 10-year (50% vs 27%) survival than those without VAs (P < .001; Figure 3, A).
Figure 3Kaplan–Meier curves for overall survival. Shaded areas represented 95% confidence limits. A, Comparison between the patients who developed postoperative VAs and those who did not. B, Comparison among the patients who did not develop VAs, those who developed VAs and received postoperative ICD implantation, and those who developed VAs but did not receive postoperative ICD implantation. Post-op, Postoperative; VA, ventricular arrhythmia; ICD, implantable cardioverter-defibrillator.
Univariate analysis showed that preoperative intra-aortic balloon pump support, renal dysfunction, prior history of VAs, redo surgery, LV dysfunction, and preoperative MR grade moderate or greater were associated with post-CABG VAs (Table 3). Multivariate analysis revealed that prior VAs, prior myocardial infarction in the LAD territory, redo surgery, and preoperative LV end-systolic dimension were independently associated with an increased risk of postoperative VAs.
Table 3Unadjusted and adjusted hazard ratios of the development of postoperative ventricular arrhythmias
Clinical Impact of Implantable Cardioverter Defibrillator Implantation on Long-Term Survival
Among 99 patients who developed postoperative VAs, 55 received ICD implantation, with a median interval from CABG of 3.9 (IQR, 1.3-33.7) months (Table E1). The overall survival in patients receiving ICD implantation was significantly higher than in those who did not receive it (5-year: 75.6% vs 24.5%, 10-year: 41.7% vs 6.3%, P < .001) and was comparable to that in patients who did not develop postoperative VAs (5-year: 75.6% vs 73.6%, 10-year: 41.7% vs 50.0%, P = .98) (Figure 3, B). Moreover, the significant differences in mortality were shown in early stage after surgery (Table E2).
When we compared survival between patients with VAs who received and did not receive an ICD according to the type of VAs, the clinical benefit concurred by ICD implantation was observed regardless of life-threatening (5-year: 70.0% for ICD protection vs 22.2% for unprotected ICD, P < .001) or hemodynamical stability of post-CABG VAs (5-year: 76.7% vs 37.5%, P < .001) (Figure E2).
Longitudinal Changes in Left Ventricular Function Parameters
Longitudinal echocardiography data demonstrated that at 1 month after CABG, LV end-systolic dimension decreased and ejection fraction improved in both patients with and without post-CABG VAs, with subsequent changes apparently distinctive irrespective of the occurrence of post-CABG VAs (Figure 4). These improvements were sustained for up to 2 years in patients without VAs, whereas those with VAs achieved less improvement, resulting in better LV function parameters in the former group (interaction effect P < .001).
Figure 4Longitudinal changes in (A) LV ejection fraction and (B) LV end-systolic diameter. Post-op, Postoperative; VA, ventricular arrhythmia; LV, left ventricle; EF, ejection fraction; Ds, end-systolic dimension; Pre-op, preoperative; 1M, 1 month; 6M, 6 months; 2Y, 2 years.
When evaluating LV function parameters in patients with post-CABG VAs according to ICD implantation status, the magnitude of change in LV end-systolic dimension was greater in those with an ICD (interaction effect; P = .03), although both groups showed comparable improvement in LV ejection fraction over time (interaction effect P = .80) (Figure E3).
Discussion
The major findings of this study can be summarized as follows: (1) SCD was the second major cause of death in patients with ischemic cardiomyopathy who underwent CABG, with a cumulative incidence of 8%; (2) the monthly risk of SCD was the greatest during the first 3 months, followed by a 3- to 6-month window after surgery and decreased subsequently, remaining nearly constant after the first year; (3) occurrence of postoperative VAs was associated with a lower survival, along with less LV functional recovery; (4) preoperative VAs, prior myocardial infarction in the LAD system, excessive LV remodeling, and redo operation were the independent predictors for post-CABG VAs; (5) the survival in patients with post-CABG VAs who received ICD implantation was significantly higher than that in those who did not receive it and was comparable to that in patients who did not develop postoperative VAs.
In patients with ischemic cardiomyopathy, SCD is one of the main causes of mortality.
Coronary Artery Bypass Graft (CABG) Patch Trial Investigators Prophylactic use of implanted cardiac defibrillators in patients at high risk for ventricular arrhythmias after coronary-artery bypass graft surgery.
The Surgical Treatment for Ischemic Heart Failure trial demonstrated that CABG plus medical therapy reduces SCD rate and heart failure events to a greater degree than medical therapy alone, supporting the protective effect of CABG for life-threatening VAs. The pathophysiological benefit of CABG may be related to a reduction in severe ischemic events, which would reduce the substrate for the development of re-entrant VAs.
However, SCD remained the most frequent cause of mortality in the Surgical Treatment for Ischemic Heart Failure trial, with an incidence of 12.1% for CABG plus medical therapy and 16.4% for medical therapy alone. These findings support the pursuit of identifying how the risk of SCD changes over time and who would be at high risk of life-threatening VAs after CABG. Our data on the greatest monthly risk of SCD during the first 3 months after surgery were consistent with the previous findings from Rao and colleagues,
Sudden cardiac death in patients with ischemic heart failure undergoing coronary artery bypass grafting: results from the STICH Randomized Clinical Trial (surgical treatment for ischemic heart failure).
who reported that 8.5% of patients died of SCD and the highest monthly risk of SCD was between the first and third months in 1411 patients with impaired left ventricular ejection fraction who underwent CABG. Moreover, we found that preoperative VAs, prior myocardial infarction in the LAD territory, preoperative excessive LV remodeling, hypertension, and redo surgery were independent predictors of post-CABG VAs, allowing us to speculate that the greater extent of myocardial scarring might be associated with VAs in our series of patients with chronic coronary artery diseases, most of whom had a history of myocardial infarction before CABG procedure.
Scar extent evaluated by late gadolinium enhancement CMR: a powerful predictor of long term appropriate ICD therapy in patients with coronary artery disease.
Myocardial scar but not ischemia is associated with defibrillator shocks and sudden cardiac death in stable patients with reduced left ventricular ejection fraction.
Our speculation might be supported by a novel finding from the longitudinal echocardiography data, which revealed the association of the presence of postoperative VAs with less LV functional recovery after revascularization. Together, these findings suggest that special attention should be paid to prevent SCD in the early post-CABG period in patients with advanced LV remodeling accompanied by a large extent of myocardial scarring.
Multicenter Automatic Defibrillator Implantation Trial II Investigators Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction.
reported that in patients with a prior myocardial infarction who are at high risk for ventricular tachyarrhythmia, prophylactic ICD therapy leads to improved survival compared with conventional medical therapy. However, the CABG-Patch trial failed to show a beneficial effect of prophylactic ICD implantation at the time of CABG. This finding can be explained by several potential reasons. One potential reason is that ICD implantation at the time of CABG is beneficial only in high-risk patients, because coronary revascularization could improve LV systolic function, decrease the risk of SCD, and eliminate the necessity for ICD implantation.
Coronary Artery Bypass Graft (CABG) Patch Trial Investigators Prophylactic use of implanted cardiac defibrillators in patients at high risk for ventricular arrhythmias after coronary-artery bypass graft surgery.
Second, in the trial, approximately 9% of patients assigned to the defibrillator group had their implanted defibrillators removed mainly because of infection and were not protected thereafter. Finally, patients enrolled in the trial had more episodes of heart failure (42.5%) than those with VAs (19.4%), in whom death was not preventable with ICD implantation. The DINAMIT trial
which were conducted to investigate the impact of ICD implantation in the early stage after myocardial infarction on overall survival, also could not show the superiority of prophylactic ICD implantation. In both studies, ICD implantation increased the cardiac-cause mortality except SCD, although that decreased the rate of SCD. These results might demonstrate that the patients with lethal VAs had lower cardiac function or broader infarction and eventually died of heart failure even if they were saved by ICD shock. Accordingly, the latest guideline recommends that a decision about ICD implantation be reassessed based on postoperative LV functional recovery at 3 months after revascularization.
2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: A report of the American College of Cardiology/American Heart Association task force on clinical practice guidelines and the Heart Rhythm Society.
Another novelty of this study was to demonstrate that the degree of reduction in LV dimension was greater in patients with postoperative VAs who did not receive ICD implantation than in those with VAs who received it. Considering postoperative LV functional recovery, approximately half of the patients (n = 22/44) with postoperative VAs who did not receive ICD implantation were judged to be at low risk of SCD and without indications for ICD implantation for primary prevention. Consequently, 20 of these patients died of SCD. This finding implies that a more detailed stratification of high-risk populations for postoperative VAs might be crucial in addition to the current guidelines based on postoperative LV functional recovery.
Study Limitations
The present study has several limitations that should be acknowledged. First, this study had a retrospective design and a relatively small sample size. Second, the study cohort was heterogeneous. Concomitant surgical procedures, such as surgical ventricular reconstruction and mitral valve surgery, might have also influenced the results, although such concomitant procedures are usually performed in patients with ischemic cardiomyopathy who present with severely impaired clinical status. However, in the multivariate analysis for the predictors of postoperative VAs, concomitant surgeries were not independent factors. Third, information on the preoperative and postoperative use of antiarrhythmic drugs and the catheter-based or surgical ablation treatments, which might have affected the results,
SCD is the second most common cause of mortality in patients with ischemic cardiomyopathy undergoing CABG, affecting approximately 8% of these patients and occurring most frequently within 3 months postoperatively. Patients with prior myocardial infarction in the LAD territory and excessive LV remodeling are more likely to develop postoperative VAs. Further studies are warranted to determine whether earlier ICD implantation prevents SCD after CABG.
The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest.
The authors thank Yasushi Yoshikawa, MD, PhD, Hiroki Hata, MD, PhD, Takayoshi Ueno, MD, PhD, Toru Kuratani, MD, PhD, and Haruhiko Kondoh, MD, PhD, for their contributions to analysis the surgical data; Arudo Hiraoka, MD, PhD, Taichi Sakaguchi, MD, PhD, Hidenori Yoshitaka, MD, PhD, Yukitoshi Shirakawa, MD, PhD, Toshiki Takahashi, MD, PhD, Masayuki Sakaki, MD, PhD, Takafumi Masai, MD, PhD, and Yoshiki Sawa, MD, PhD, for the revision of the manuscript for important intellectual content; and Mariko Yamashita, Chikako Matsuo, and Misa Fujioka for assistance with clinical data collection; and Editage (www.editage.com) for English language editing.
Appendix E1
Table E1Patients' characteristics according to presence of implantable cardioverter defibrillator implantation in patients with postoperative ventricular arrhythmias
Crude
Propensity score matched
Post-op VAs (+) with ICD (n = 55)
Post-op VAs (+) without ICD (n = 44)
P value
Post-op VAs with ICD (n = 22)
Post-op VAs without ICD (n = 22)
P value
Demographic characteristics
Age, y
65 [60-71]
67 [60-75]
.514
67 [62-72]
64 [61-72]
.796
Male
51 (92.7)
37 (84.1)
.209
21 (95.5)
22 (100.0)
1.000
Preoperative IABP
14 (25.5)
3 (6.8)
.017
4 (18.2)
3 (13.6)
1.000
euroSCORE II
11.0 [5.0-24.8]
8.1 [5.5-17.2]
.164
11.2 [6.5-28.5]
7.9 [5.5-16.8]
.398
Emergency/urgent surgery
13 (23.6)
5 (11.4)
.189
6 (27.3)
4 (18.2)
.721
Redo
6 (10.9)
5 (11.4)
1.000
0 (0)
2 (9.1)
.488
Medical history
Atrial fibrillation
6 (10.9)
6 (13.6)
.762
3 (13.6)
3 (13.6)
1.000
Previous VAs
22 (40.0)
6 (13.6)
.006
8 (36.4)
5 (22.7)
.510
Diabetes
25 (45.5)
24 (54.6)
.422
11 (50.0)
10 (45.5)
1.000
Previous PCI
.616
.439
Single
8 (14.6)
7 (15.9)
2 (9.1)
5 (22.7)
Multiple
16 (29.1)
9 (20.5)
6 (27.3)
6 (27.3)
Prior MI
52 (94.6)
39 (88.6)
.461
20 (90.9)
19 (86.4)
1.000
Prior LAD-MI
37 (67.3)
32 (72.7)
.661
13 (59.1)
16 (72.7)
.526
On hemodialysis
4 (7.3)
7 (15.9)
.209
3 (13.6)
3 (13.6)
1.000
Peripheral artery disease
6 (10.9)
9 (20.5)
.260
3 (13.6)
5 (22.7)
.698
Previous stroke
9 (16.4)
7 (15.9)
1.000
3 (13.6)
4 (18.2)
1.000
Echocardiographic data
LVEF (%)
28 [23-34]
29 [22-35]
.868
27 [23-30]
27 [21-36]
.906
LVESD (mm)
56 [52-61]
55 [50-60]
.347
57 [52-61]
56 [50-62]
.672
MR grade ≥moderate
33 (66.0)
17 (38.6)
.044
11 (50.0)
11 (50.0)
1.000
Coronary anatomy
Triple vessels disease
34 (61.8)
36 (81.8)
.045
16 (72.7)
16 (72.7)
1.000
Left main disease
8 (14.6)
10 (22.7)
.309
3 (13.6)
5 (22.7)
.698
Operation data
ITA use
.148
.567
Non-ITA
8 (14.6)
3 (6.8)
1 (4.6)
3 (13.6)
Single ITA
31 (56.4)
33 (75.0)
16 (72.7)
14 (63.6)
Bilateral ITA
16 (29.1)
8 (18.2)
5 (22.7)
5 (22.7)
No. of grafted vessels
3 [2-3]
3 [2-4]
.017
3 [2-4]
3 [2-3]
1.000
Concomitant surgeries
.596
.690
MV surgery
20 (36.4)
15 (34.1)
6 (27.3)
9 (40.9)
SVR
9 (16.4)
9 (20.5)
2 (9.1)
3 (13.6)
MV surgery + SVR
14 (25.5)
7 (15.9)
7 (31.8)
5 (22.7)
Post-op, Postoperative; VA, ventricular arrhythmia; ICD, implantable cardioverter defibrillator; IABP, intra-aortic balloon pump; euroSCORE, European System for Cardiac Operative Risk Evaluation; PCI, percutaneous coronary intervention; MI, myocardial infarction; LAD, left anterior descending; LVEF, left ventricular ejection fraction; LVESD, left ventricular end-systolic dimension; MR, mitral regurgitation; ITA, internal thoracic artery; MV, mitral valve; SVR, surgical ventricular restoration.
Table E2Mortality of patients developing postoperative ventricular arrhythmias by year
Post-op VAs(+) with ICD (n = 55)
Post-op VAs(+) without ICD (n = 45)
P value
30-day mortality
0 (0%)
5 (11.4%)
<.001
1-year mortality
2 (3.6%)
18 (40.9%)
<.001
2-year mortality
4 (7.3%)
21 (47.7%)
<.001
3-year mortality
8 (14.6%)
28 (63.6%)
<.001
4-year mortality
12 (21.8%)
31 (70.5%)
<.001
5-year mortality
13 (23.6%)
33 (75.0%)
<.001
Twelve deaths in patients developing VAs with ICD and 8 deaths in those without ICD occurred during the follow-up period after 5 years after surgery. Post-op, postoperative; VA, ventricular arrhythmia; ICD, implantable cardioverter defibrillator.
Figure E2Kaplan–Meier curves for overall survival of patients who developed postoperative VAs comparing those who received postoperative ICD implantation with those who did not receive postoperative ICD implantation. Shaded areas represented 95% confidence limits. A, Patients who developed symptomatic VAs (ventricular fibrillation and pulseless VT). B, Patients who developed asymptomatic VAs (sustained VT and nonsustained VT). Post-op, Postoperative; VA, ventricular arrhythmias; ICD, implantable cardioverter defibrillator.
Figure E3Comparison of longitudinal changes in (A) LV ejection fraction and (B) LV end-systolic diameter in patients with postoperative VAs between those who received ICD implantation and those who did not receive ICD implantation. Post-op, Postoperative; VA, ventricular arrhythmia; ICD, implantable cardioverter defibrillator; LV, left ventricle; EF, ejection fraction; Ds, end-systolic diameter.
2022 AHA/ACC/HFSA guideline for the management of heart failure: a report of the American College of Cardiology/American Heart Association Joint Committee on clinical practice guidelines.
Sudden cardiac death in patients with ischemic heart failure undergoing coronary artery bypass grafting: results from the STICH Randomized Clinical Trial (surgical treatment for ischemic heart failure).
Scar extent evaluated by late gadolinium enhancement CMR: a powerful predictor of long term appropriate ICD therapy in patients with coronary artery disease.
Myocardial scar but not ischemia is associated with defibrillator shocks and sudden cardiac death in stable patients with reduced left ventricular ejection fraction.
2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: A report of the American College of Cardiology/American Heart Association task force on clinical practice guidelines and the Heart Rhythm Society.
This work was partially supported by the Takeda Science Foundation.
Institutional Review Board of Osaka University Hospital, Number 16105 (approved November 2, 2016). Written informed consent was obtained from each patient for publication of this study.
Sudden cardiac death (SCD) is a well-known complication after coronary revascularization in patients with left ventricular dysfunction. Implantable cardioverter-defibrillator (ICD) therapy is associated with a reduction in the rate of death due to life-threatening ventricular arrhythmia (VA). The SCD rate could be greatest in the early period of revascularization. However, previous studies failed to show survival benefit of prophylactic implantation of ICD at the time of coronary artery bypass grafting (CABG)1 or early after acute myocardial infarction.
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