Risk-adjusted analysis of long-term outcomes after on- versus off-pump coronary artery bypass grafting

Abstract

Objectives: Recent data suggested that off-pump coronary artery bypass (OPCAB) may carry a higher risk for mortality in the long term when compared to on-pump coronary artery bypass (ONCAB). We, therefore, compared long-term survival and morbidity in patients undergoing ONCAB versus OPCAB in a large single-centre cohort.

Methods: A total of 8981 patients undergoing isolated elective/urgent coronary artery bypass grafting between January 2009 and December 2019 were analysed. Patients were stratified into 2 groups (OPCAB n = 6649/ONCAB n = 2332). The primary end point was all-cause mortality. Secondary endpoints included repeat revascularization, stroke and myocardial infarction. To adjust for potential selection bias, 1:1 nearest neighbour propensity score (PS) matching was performed resulting in 1857 matched pairs. Moreover, sensitivity analysis was applied in the entire study cohort using multivariable- and PS-adjusted Cox regression analysis.

Results: In the PS-matched cohort, 10-year mortality was similar between study groups [OPCAB 36.4% vs ONCAB 35.8%: hazard ratio (HR) 0.99, 95% confidence interval (CI) 0.87-1.12; P = 0.84]. While 10-year outcomes of secondary endpoints did not differ significantly, risk of stroke (OPCAB 1.50% vs ONCAB 2.8%: HR 0.51, 95% CI 0.32-0.83; P = 0.006) and mortality (OPCAB 3.1% vs ONCAB 4.8%: HR 0.65, 95% CI 0.47-0.91; P = 0.011) at 1 year was lower in the OPCAB group. In the multivariable- and the PS-adjusted model, mortality at 10 years was not significantly different (OPCAB 34.1% vs ONCAB 35.7%: HR 0.97, 95% CI 0.87-1.08; P = 0.59 and HR 1.01, 95% CI 0.90-1.13; P = 0.91, respectively).

Conclusions: Data do not provide evidence that elective/urgent OPCAB is associated with significantly higher risks of mortality, repeat revascularization, or myocardial infarction during late follow-up when compared to ONCAB. Patients undergoing OPCAB may benefit from reduced risks of stroke and mortality within the first year postoperatively.

Keywords: Coronary artery bypass grafting; Coronary artery disease; Myocardial revascularization; Off-pump coronary artery bypass grafting; Off-pump surgery.

Figure 1:

Study flow diagram. CABG: coronary artery bypass grafting; MIDCAB: minimally invasive direct coronary artery bypass grafting.

Figure 2:

Cumulative event rate of overall mortality (A), stroke (B), myocardial infarction (C) and repeat revascularization (D). Solid line, on-pump group; dotted line, off-pump group.

Figure 3:

Hazard ratios for mortality in off-pump surgery compared with on-pump surgery according to various subgroups. NYHA: New York Heart Association.

Figure 4:

Revascularization ratio by study group.