Off-pump Coronary Bypass Surgery in Patients with Low Ejection Fraction: Is There a Long-Term Survival Advantage?

10-Year Mortality of Off-Pump Versus On-Pump Coronary Artery Bypass Grafting: An Updated Systematic Review, Meta-Analysis, and Meta-Regression

The longstanding debate on off-pump coronary artery bypass grafting (OPCAB) versus on-pump coronary artery bypass grafting (ONCAB) has primarily focused on short-term and mid-term outcomes, with limited attention to long-term survival. This study aims to address this gap by providing an updated analysis of 10-year mortality rates after OPCAB versus ONCAB. We have conducted a systematic review and meta-analysis, incorporating 22 studies comprising 69,449 patients. The primary end point was all-cause mortality at 10 years. Meta-regression analysis explored sources of heterogeneity. The meta-analysis revealed no significant difference in long-term all-cause mortality between OPCAB and ONCAB (hazard ratio 1.000, 95% confidence interval 0.92 to 1.08, p = 0.95). Although substantial heterogeneity existed across studies, meta-regression identified older age as a significant factor favoring OPCAB. However, patient characteristics like gender, co-morbidities, and graft numbers did not significantly influence the choice of surgical technique. In conclusion, this study challenges historical concerns regarding OPCAB's quality of revascularization and long-term survival demonstrating comparable outcomes to ONCAB in well-selected patients when performed by experienced surgeons. The results emphasize the importance of surgeon proficiency and advocate for recognizing surgical revascularization as a subspecialty.

Cardiac magnetic resonance imaging for myocardial viability assessment: Optimizing surgical revascularization in ischemic heart disease

BACKGROUND

Patients with poor ejection fraction undergoing coronary artery bypass grafting carry higher operative risk and have poor long-term survival. Cardiac magnetic resonance is a useful modality to assess viability which can identify patients likely to benefit most from revascularization. In this study, we aimed to assess the outcome in patients selected for surgical revascularization by cardiac magnetic resonance imaging and identify predictors associated with poor outcomes.

METHODS

The study included patients with severely impaired left ventricular function but with at least six viable segments. Patients requiring emergency surgery, undergoing combined procedures, or where cardiopulmonary bypass was required were excluded. Cardiac magnetic resonance was carried out both preoperatively and at six months postoperatively by the same radiologist in all cases. Late gadolinium enhancement was used for the evaluation of myocardial viability.

RESULTS

Amongst a total of 493 segments studied, there were 89 (18.1%) non-viable, 117 (23.7%) hibernating and 287 (58.2%) viable segments. At six months, the number of non-viable segments changed from 89 (18.1%) to 97 (19.7%), with an increase in viable segments from 287 (58.2%) to 374 (75.8%) and a corresponding reduction of hibernating segments from 117 (23.7%) to 22 (4.5%). There was improvement in ejection fraction from 28 ± 5.54 to 37 ± 5.86 (p < 0.0001) in the entire cohort at six months. Overall mortality was 1 (3.2%). Preoperative left ventricular end-systolic volume had the strongest negative correlation with post-operative ejection fraction.

CONCLUSION

Cardiac magnetic resonance aided revascularization is associated with low mortality. Preoperative left ventricular end-systolic volume is an important determinant of postoperative ejection fraction.

Robotic Off-Pump Totally Endoscopic Coronary Artery Bypass in Patients With Low Ejection Fraction

Objective: Robotic totally endoscopic coronary bypass (R-TECAB) has been shown to be a safe and effective technique with excellent outcomes. The aim of this study is to assess the feasibility of R-TECAB in patients with low left ventricular ejection fraction (LVEF) and to report our midterm outcomes with up to 7-year follow-up. Methods: All patients undergoing R-TECAB at our institution between July 2013 and July 2020 were retrospectively reviewed. A total of 100 patients were identified with low LVEF defined as ≤40%. The preoperative characteristics, perioperative and postoperative outcomes, as well as the midterm results were reviewed. Results: The mean LVEF was 31%, and 62% of all patients had preexisting congestive heart failure. Of the cohort, 59% had 3-vessel disease and 6% underwent previous cardiac surgery. Multivessel TECAB was performed in 54%. Hybrid coronary revascularization occurred in 36 individuals. Two patients required cardiopulmonary bypass, and 35% were extubated in the operating room. No sternotomy conversions were required. One patient underwent reoperation for bleeding. No perioperative stroke, myocardial infarction, or mortality occurred. The left internal mammary artery graft patency was 97% at a mean of 1.6 months in the staged hybrid percutaneous coronary intervention group. At midterm follow-up the cardiac-related mortality was 5%. Heart transplant or left ventricular assist device was required in 4 patients, and 1 patient experienced a myocardial infarction. Freedom from major adverse cardiac events was 89%. Conclusions: Off-pump TECAB can be successfully performed in patients with low LVEF in the setting of an experienced and dedicated robotic cardiac surgery team. Our data demonstrate the feasibility of the technique with excellent perioperative and midterm outcomes.

Meta-Analysis Comparing ≥10-Year Mortality of Off-Pump Versus On-Pump Coronary Artery Bypass Grafting

Off-pump coronary artery bypass grafting (CABG) is suggested to be associated with an increase in long-term (≥5-year) all-cause mortality. To determine whether off-pump CABG is associated with an increase in very long-term (≥10-year) all-cause mortality, we performed a meta-analysis of propensity-score matched observational comparative studies of off-pump versus on-pump CABG. MEDLINE and EMBASE were searched through May 2017. A hazard ratio of follow-up (including early) all-cause mortality for off-pump versus on-pump CABG was extracted from each individual study. Study-specific estimates were combined using inverse variance-weighted averages of logarithmic hazard ratios in the random-effects model. Of 164 potentially relevant studies, our search identified 16 propensity-score matched observational comparative studies of off-pump versus on-pump CABG with ≥10-year follow-up enrolling a total of 82,316 patients. A pooled analysis of all the 16 studies demonstrated that off-pump CABG was significantly associated with an increase in all-cause mortality (hazard ratio 1.07, 95% confidence interval 1.03 to 1.12, p for effect = 0.0008; p for heterogeneity = 0.30, I² = 12%). In a sensitivity analysis, exclusion of any single hazard ratio from the analysis (leave-one-out meta-analysis) did not substantively alter the overall result. There was no evidence of a significant publication bias. In conclusion, off-pump CABG is associated with an increase in very long-term (≥10 years) all-cause mortality compared with on-pump CABG.

Coronary bypass in left ventricular dysfunction and differential cardiac recovery

Background

We aimed to examine the efficacy of surgical revascularization with respect to improvement in ventricular function and survival in patients with ischemic cardiomyopathy and poor left ventricular function.

Methods

We retrospectively analyzed the data of 429 patients (median age 64.6 years, 81.1% male) with ejection fractions <40% undergoing isolated primary coronary artery bypass grafting from 2000 to 2016. Techniques included on-pump cardioplegic arrest ( n = 312), off-pump ( n = 75), and on-pump beating heart ( n = 42). Propensity matching was performed to compare the cardioplegic arrest group ( n = 114) with the combined off-pump and beating heart groups ( n = 114).

Results

Postoperatively, ejection fraction increased by 10.1% ± 13.1% (from 31.4% ± 7.1% to 41.6% ± 13.6%; p < 0.001) and mitral regurgitation grade improved ( p < 0.001) but right ventricular function on echocardiographic assessment worsened over time ( p = 0.04). No difference in ejection fraction improvement was seen in the time periods <1 (9.8% ± 11.2%), 1–5 (11.6% ± 14.5%), and >5 (8.8% ± 14.2%) years ( p = 0.442). Following propensity matching, there was no significant difference between the combined off-pump/beating heart and cardioplegic arrest groups with respect to survival or postoperative complications.

Conclusions

Patients with moderate to severe left ventricular dysfunction experience long-term improvement in left ventricular ejection fraction after coronary artery bypass. However, right ventricular function often continues to decline, contributing to persistent or worsening heart failure symptoms and late mortality. No difference in survival was seen between the 2 techniques.

Does off-pump coronary artery bypass surgery have a beneficial effect on mortality in patients with left ventricular dysfunction?

A best evidence topic was written according to a structured protocol. The question addressed was whether off-pump coronary artery bypass surgery (OPCAB) offered any beneficial effect on mortality when compared with on-pump coronary artery bypass surgery (ONCAB) in patients with left ventricular dysfunction (LVD). A total of 491 papers were found using the reported searches of which 17 represented the best evidence. The authors, date, journal, study type, outcome measures and results are tabulated. The 17 studies (only containing patients with LVD) comprised of one prospective randomized trial, one meta-analysis and 15 retrospective studies. The prospective trial associated the OPCAB technique with significantly lower in-hospital mortality. By comprising of seven studies and 1512 patients, the meta-analysis showed no significant difference in terms of operative mortality. Of the retrospective studies, all 15 compared short-term mortality (<30-day) of which four showed significantly lower mortality in the OPCAB group. Nine of the studies compared mid-term mortality (30 days to 5 years) with no significant difference detected and three of the studies compared long-term mortality (>5 years) with no significant difference detected. We conclude that there is limited evidence to associate the OPCAB technique with improved short-term mortality. The majority of the studies suffered from significant limitations such as containing data from operations carried out prior to the year 2000, a period when off-pump surgery was in its infancy. They frequently contained major differences in baseline characteristics with no specific inclusion/exclusion criteria, description of handling of patients converted from off-pump to bypass or reporting of myocardial viability and concomitant mitral regurgitation. Nine studies reported completeness of revascularization of which eight associated the OPCAB group with a poorer degree of revascularization making comparisons less valid. The lack of high-quality data indicates that prospective randomized trials are needed. The CRISP Trial ('Coronary artery grafting in high-risk patients randomized to off-pump or on-pump surgery') has recently been halted due to recruitment difficulties. The CORONARY ('Coronary artery bypass surgery off- or on-pump revascularization study') trial is a large international multicentre randomized study that is recruiting well and is likely to provide valuable information in the near future.

Long-Term Survival after Minimal Invasive Direct Coronary Artery Bypass (MIDCAB) Surgery in Patients with Low Ejection Fraction

Objective

The long-term survival after minimal invasive direct coronary artery bypass (MIDCAB) surgery to any coronary territory in patients with ejection fraction of ≤30% was investigated for the first time in literature.

Methods

Seventy-three patients with primary MIDCAB and 89 patients with reoperative MIDCAB were studied including preoperative risk factors, operative details, early postoperative complications, and survival up to 10 years postoperatively.

Results

Despite the high-risk profile of the patients, the MIDCAB approach for targeted revascularization resulted in excellent short-term results. Ventricular arrhythmia contributed to four of six early deaths. Survival at 5 years postoperatively was 62.5% for primary MIDCAB and 43.2% for reoperative MIDCAB and at 10 years was 36.9% and 29.5%, respectively. Functionally complete vascularization correlates with significantly better long-term survival particularly in primary MIDCAB procedures.

Conclusions

MIDCAB is a valuable option for targeted revascularization in high-risk patients with low ejection fraction and reoperation.