Impact of pump status and conduit choice in coronary artery bypass: A 15-year follow-up study in 1412 propensity-matched patients

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.

Differences in long-term survival outcomes after coronary artery bypass grafting using single vs multiple arterial grafts: a meta-analysis with reconstructed time-to-event data and subgroup analyses

OBJECTIVE

We reviewed the available literature on patients with coronary artery disease undergoing isolated coronary artery bypass grafting (CABG) with either single (SAG) or multiple arterial grafting (MAG).

METHODS

Original research studies that evaluated the long-term survival of MAG versus SAG were identified, from 1995 to 2022. The median overall survival (OS) and event-free OS were the primary endpoints. Comparison of median OS between the right internal mammary artery (RIMA) and radial artery (RA) as a second arterial conduit was the secondary endpoint. Subgroup analyses were performed regarding patients older than 70 years, with diabetes mellitus, and females. A sensitivity analysis was performed with the leave-one-out method.

RESULTS

Forty-four studies were included in the qualitative and thirty-nine in the quantitative synthesis. After pooling data from 180 to 459 patients, the MAG group demonstrated a higher OS (HR, 0.589; 95% CI, 0.58-0.60; p < 0.0001) and event-free OS compared with the SAG group (HR, 0.828; 95% CI, 0.80-0.86; p < 0.0001). In addition, RITA was associated with superior OS compared with RA as a second arterial conduit (HR, 0.936; 95% CI, 0.89-0.98; p = 0.009). MAG was also superior to SAG in patients over 70 years, females, and patients with diabetes mellitus. Sensitivity analysis demonstrated a small-size study effect on the female subgroup analysis.

CONCLUSION

The present meta-analysis indicates that MAG is associated with enhanced survival outcomes compared to SAG for patients undergoing isolated CABG.

Robustness of the Comparative Observational Evidence Supporting Class I and II Cardiac Surgery Procedures

Background

Current cardiac surgery guidelines give Class I and II recommendations to valve‐sparing root replacement over the Bentall procedure, mitral valve (MV) repair over replacement, and multiple arterial grafting with bilateral internal thoracic artery based on observational evidence. We evaluated the robustness of the observational studies supporting these recommendations using the E value, an index of unmeasured confounding.

Methods and Results

Observational studies cited in the guidelines and in the 3 largest meta‐analyses comparing the procedures were evaluated for statistically significant effect measures. Two E values were calculated: 1 for the effect‐size estimate and 1 for the lower limit of the 95% CI. Thirty‐one observational studies were identified, and E values were computed for 75 effect estimates. The observed effect estimates for improved clinical outcomes with valve‐sparing root replacement versus the Bentall procedure, MV repair versus replacement, and grafting with bilateral internal thoracic artery versus single internal thoracic artery could be explained by an unmeasured confounder that was associated with both the treatment and outcome by a risk ratio of more than 16.77, 4.32, and 3.14, respectively. For MV repair versus replacement and grafting with bilateral internal thoracic artery versus single internal thoracic artery, the average E values were lower than the effect sizes of the other measured confounders in 33.3% and 60.9% of the studies, respectively. For valve‐sparing root replacement versus the Bentall procedure, no study reported effect sizes for associations of other covariates with outcomes.

Conclusions

The E values for observational evidence supporting the use of valve‐sparing root replacement, MV repair, and grafting with bilateral internal thoracic artery over the Bentall procedure, MV replacement, and grafting with single internal thoracic artery are relatively low. This suggests that small‐to‐moderate unmeasured confounding could explain most of the observed associations for these procedures.

Radial Artery Versus Right Internal Thoracic Artery Versus Saphenous Vein as the Second Conduit for Coronary Artery Bypass Surgery: A Network Meta-Analysis of Clinical Outcomes

Background

There remains uncertainty regarding the second‐best conduit after the internal thoracic artery in coronary artery bypass grafting. Few studies directly compared the clinical results of the radial artery (RA), right internal thoracic artery (RITA), and saphenous vein (SV). No network meta‐analysis has compared these 3 strategies.

Methods and Results

MEDLINE and EMBASE were searched for adjusted observational studies and randomized controlled trials comparing the RA, SV, and/or RITA as the second conduit for coronary artery bypass grafting. The primary end point was all‐cause long‐term mortality. Secondary end points were operative mortality, perioperative stroke, perioperative myocardial infarction, and deep sternal wound infection (DSWI). Pairwise and network meta‐analyses were performed. A total of 149 902 patients (4 randomized, 31 observational studies) were included (RA, 16 201, SV, 112 018, RITA, 21 683). At NMA, the use of SV was associated with higher long‐term mortality compared with the RA (incidence rate ratio, 1.23; 95% CI, 1.12–1.34) and RITA (incidence rate ratio, 1.26; 95% CI, 1.17–1.35). The risk of DSWI for SV was similar to RA but lower than RITA (odds ratio, 0.71; 95% CI, 0.55–0.91). There were no differences for any outcome between RITA and RA, although DSWI trended higher with RITA (odds ratio, 1.39; 95% CI, 0.92–2.1). The risk of DSWI in bilateral internal thoracic artery studies was higher when the skeletonization technique was not used.

Conclusions

The use of the RA or the RITA is associated with a similar and statistically significant long‐term clinical benefit compared with the SV. There are no differences in operative risk or complications between the 2 arterial conduits, but DSWI remains a concern with bilateral ITA when skeletonization is not used.

Disagreement Between Randomized and Observational Evidence on the Use of Bilateral Internal Thoracic Artery Grafting: A Meta-Analytic Approach

Background

The ART (Arterial Revascularization Trial) showed no difference in survival at 10 years between patients assigned to the single versus bilateral internal thoracic artery grafting strategies. This finding is in contrast with the results of most observational studies, where the use of 2 internal thoracic arteries has been associated with improved survival.

Methods and Results

We selected propensity‐matched studies from the most comprehensive observational meta‐analysis on the long‐term outcomes of patients receiving 1 versus 2 internal thoracic arteries. Individual participant survival data from each study and the ART were reconstructed using an iterative algorithm that was applied to solve the Kaplan‐Meier equations. The reconstructed individual participant survival data were aggregated to obtain combined survival curves and Cox regression hazard ratios with 95% CIs. Individual participant survival data were obtained from 14 matched observational studies (24 123 patients) and the ART. The 10‐year survival of the control group of ART was significantly higher than that of the matched observational studies (hazard ratio, 0.86; 95% CI, 0.80–0.93). The 10‐year survival of the experimental group of ART was significantly lower than that of the bilateral internal thoracic artery group of the observational studies (hazard ratio, 1.11; 95% CI, 1.03–1.20).

Conclusions

Both the improved outcome of the control arm and the lower beneficial effect of the intervention had played a role in the difference between observational evidence and ART.

Use Rate and Outcome in Bilateral Internal Thoracic Artery Grafting: Insights From a Systematic Review and Meta-Analysis

Background

This meta‐analysis was designed to assess whether center experience affects the short‐ and long‐term results and the relative benefits of bilateral internal thoracic artery grafting (BITA) for coronary artery bypass grafting.

Methods and Results

MEDLINE and EMBASE were searched to identify all articles reporting the outcome of BITA in patients undergoing coronary artery bypass grafting. The BITA center experience was gauged according to the percentage use of BITA in the institutional overall coronary artery bypass grafting population (%BITA). The primary outcome was long‐term all‐cause mortality. Secondary outcomes were operative mortality, perioperative myocardial infarction, perioperative stroke, deep sternal wound infections (DSWIs), and major postoperative adverse event. The rates of the primary and secondary outcomes were calculated after adjusting for %BITA. Primary and secondary outcomes were also compared between the BITA and the single internal thoracic artery arms in the adjusted studies. Meta‐regression was used to evaluate the effect of %BITA on the primary and secondary outcomes. Thirty‐four studies (27 894 patients undergoing BITA) were included. In the pooled analysis, the incidence rate for long‐term mortality was 2.83% (95% confidence interval, 2.21%–3.61%). %BITA was significantly and inversely associated with long‐term mortality and the rate of DSWI. In the pairwise comparison, %BITA was significantly and inversely associated with the risk of long‐term mortality and DSWI in the group undergoing BITA.

Conclusions

BITA series with higher %BITA report significantly lower long‐term mortality and DSWI rate as well as higher long‐term survival advantage and lower relative risk of DSWI in their BITA cohort. These findings suggest that a specific volume‐outcome relationship exists for BITA grafting.

Unmeasured Confounders in Observational Studies Comparing Bilateral Versus Single Internal Thoracic Artery for Coronary Artery Bypass Grafting: A Meta-Analysis

Background

Observational studies suggest a survival advantage with bilateral single internal thoracic artery (BITA) versus single internal thoracic artery grafting for coronary surgery, whereas this conclusion is not supported by randomized trials. We hypothesized that this inconsistency is attributed to unmeasured confounders intrinsic to observational studies. To test our hypothesis, we performed a meta‐analysis of the observational literature comparing BITA and single internal thoracic artery, deriving incident rate ratio for mortality at end of follow‐up and at 1 year. We postulated that BITA would not affect 1‐year survival based on the natural history of coronary artery bypass occlusion, so that a difference between groups at 1 year could not be attributed to the intervention.

Methods and Results

We searched MEDLINE and Pubmed to identify all observational studies comparing the outcome of BITA versus single internal thoracic artery. One‐year and long‐term mortality for BITA and single internal thoracic artery were compared in the propensity‐score–matched (PSM) series, that is, the form of observational evidence less prone to confounders. Thirty‐eight observational studies (174 205 total patients) were selected for final comparison. In the 12 propensity‐score–matched series (34 019 patients), the mortality reduction for BITA was similar at 1 year and at the end of follow‐up (incident rate ratio, 0.70; 95% confidence interval, 0.60–0.82 versus 0.77; 95% confidence interval, 0.70–0.85; P for subgroup difference=0.43).

Conclusions

Unmeasured confounders, rather than biological superiority, may explain the survival advantage of BITA in observational series.

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.

Bilateral internal mammary artery Y construct with multiple sequential grafting improves survival compared to bilateral internal mammary artery with additional vein grafts: 10-year experience at 2 different institutions†

OBJECTIVES

Utilization of bilateral internal mammary arteries (BIMAs) has been shown to improve long-term outcomes in patients undergoing coronary artery bypass grafting. To achieve complete revascularization, BIMAs may be used as either sole conduits for revascularization through a Y-graft configuration (BIMA-Y) or deployed with additional grafts used in conjunction with BIMAs. The purpose of this study was to compare the long-term outcomes of two institutions that predominantly used either the BIMA-Y configuration or BIMA plus additional grafts to achieve optimal revascularization.

METHODS

From 1 January 2000 to 31 December 2010, 436 patients were revascularized using a non-sequential BIMA grafting at one institution (Group A), with veins being used for additional targets. At the second institution (Group B), 771 patients were revascularized using a BIMA-Y graft for all distal targets. Kaplan–Meier analysis was used to compare unadjusted survival between the groups. Cox proportional hazards regression modelling was used to provide an adjusted comparison of survival between the groups.

RESULTS

There was no statistically significant difference between the average number of anastomotic sites used in Group A and Group B (A = 4.0 ± 0.7 vs B = 4.0 ± 0.7; P = 0.24). Group A did not have a significantly greater in-hospital mortality (0.7% vs 1.0% P = 0.39), stroke (0.5% vs 0.8% P = 0.40), deep sternal wound infection (0.0% vs 0.6% P = 0.11) or reoperation for bleeding (1.6% vs 0.6% P = 0.10) than Group B. Cox proportional hazards analyses demonstrated that at 14 years, Group B had a significantly improved survival compared to Group A (Group B = 88% vs Group A = 81%) with an overall reduction in mortality (adjusted hazard ratio 0.780, 95% confidence interval 0.448–0.849; P = 0.043).

CONCLUSION

Utilization of the BIMA-Y configuration was associated with improved survival when compared to BIMA grafting with additional vein grafts. Further studies are necessary to evaluate the efficacy of BIMA-Y grafting against other means of providing complete arterial revascularization.

Current outcomes of off-pump coronary artery bypass grafting: evidence from real world practice

Coronary artery bypass grafting (CABG) can be performed conventionally using cardiopulmonary bypass (CPB) and aortic clamping or on a beating heart (BH) without the use of CPB, the so-called off-pump CABG. Some surgeons, who are proponents of off-pump CABG, preferentially use this technique for the majority of operations, whereas others use it only in certain situations which warrant avoidance of CPB. Ever since the conception of off-pump CABG, the never-ending debate about which technique of CABG is safe and efficacious continues to date. Several randomized controlled trials (RCTs) have been conducted that have either favored on-pump CABG or have failed to show a significant difference in outcomes between the two techniques. However, these RCTs have been fraught with claims that they do not represent the majority of patients undergoing CABG in real world practice. Therefore, assessment of the benefits and drawbacks of each technique through observational and registry studies would be more representative of patients encountered in daily practice. The present review examines various retrospective studies and meta-analyses of observational studies that compare the early and long-term outcomes of off- and on-pump CABG, which assesses their safety and efficacy. Additionally, their outcomes in older patients, females, and those with diabetes mellitus, renal dysfunction, presence of ascending aortic disease, and/or acute coronary syndrome (ACS) have also been discussed separately. The general consensus is that early results of off-pump CABG are comparable to or in some cases better than on-pump CABG. However, on-pump CABG provides a survival benefit in the long term according to a majority of publications in literature.

Off-pump coronary artery bypass: past, present and future of a controversial technology

PURPOSE OF REVIEW

This review will examine the current role of off-pump coronary artery bypass (OPCAB) surgery compared with on-pump coronary artery bypass (ONCAB) surgery for the revascularization of ischemic myocardium.

RECENT FINDINGS

Recent studies have confirmed earlier findings that OPCAB is associated with less grafts per patient and less complete revascularization, and increased incidence of recurrent angina and need for repeat revascularization procedures, and more frequent rehospitalization for cardiac-related issues. OPCAB does not prevent postoperative renal dysfunction and is associated with worse long-term outcomes. Hospital costs are not reduced and are increased in those OPCAB patients who require intraoperative conversion to ONCAB procedures; however, when multiple arterial grafts are used and a complete revascularization is performed, OPCAB outcomes are equivalent to those of ONCAB procedures.

SUMMARY

OPCAB should only be performed by surgeons experienced in this technique in patients in whom a complete revascularization can be achieved; preferably with multiple arterial grafts.

Complete myocardial revascularization using only bilateral internal thoracic arteries provides a low-risk and durable 10-year clinical outcome

OBJECTIVES

Bilateral internal thoracic artery (BITA) bypass provides long-term survival benefits over strategies that use single internal mammary arteries during coronary artery bypass grafting (CABG). However, the rate of adoption of this strategy remains very low. Moreover, optimal BITA configuration and the use of cardiopulmonary bypass still remain a matter of debate. We investigated the long-term results of a coronary revascularization strategy, utilising exclusively BITA-Y composite grafts using off-pump platform and sequential anastomoses.

METHODS

From March 2000 to November 2010, all isolated CABGs (n = 2057 patients) were performed using an off-pump platform. Of these, 1240 patients had three-vessel coronary disease (60.3%), with severe coronary disease defined as >70% stenosis and three-vessel disease defined as the presence of 3 vessels with >70% stenosis, of which 784 (63.2%) were treated with two internal thoracic artery grafts in a composite fashion with a no-touch technique avoiding any manipulation of the ascending aorta. The primary end-point was the long-term survival and freedom from major adverse cerebral and cardiovascular events (MACCEs). The follow-up was completed using the annual anniversary method.

RESULTS

The mean number of anastomoses per patient was 4.0. Hospital mortality occurred in 8 patients (1%). Ninety-day stroke, myocardial infarction and repeat revascularization rates were respectively 0.7, 0.6 and 0.3%. The mean follow-up was 6.6 ± 3.2 years and was obtained for 99% of the patients. The 5- and 10-year survival rates were 93.1 ± 1.6 and 83.8 ± 3.2%, respectively. Freedom from major adverse cardiac and cardiovascular event (MACCE) at 5 and 10 years was: cardiovascular event: 98.7 ± 1.6 and 96.1 ± 1.7%, documented ischaemia: 90.5 ± 2 and 80.2 ± 3.8%, revascularization: 94.0 ± 1.5 and 89.7 ± 2.5%, infarction: 98.1 ± 0.8 and 96.0 ± 1.6%. The patency of left and right internal thoracic artery in a BITA-Y configuration was 91.1 and 88.8% at 5 ± 3 years, respectively.

CONCLUSION

Performance of an exclusive composite BITA off-pump revascularization strategy optimal and sustained long-term protection from MACCE.

Improving quality and outcomes of coronary artery bypass grafting procedures

The evolution in the approach, clinical care and outcomes of ischemic heart disease, has been dramatic over the past decade. Optimizing medical therapy initially and throughout the care delivery process has been transformative. The addition of new physiologic data to the traditional anatomic framework for diagnosis and therapy of more extensive stable ischemic heart disease (SIHD) enables quality and outcomes improvements in this patient population overall and in the patient subsets of acute coronary syndrome and SIHD. In patients undergoing coronary artery bypass grafting (CABG), these developments have changed the objective goal of surgical revascularization over this time interval. This review discusses the opportunities for quality and outcomes improvement in CABG, in the context of SIHD overall.