Long-term survival after off-pump versus on-pump coronary artery bypass graft surgery. Does completeness of revascularization play a role?

Abstract

Background: We sought to compare the incidence of incomplete revascularization (IR) and long-term survival (up to 20years) after off-pump (OPCAB) versus on-pump (ONCAB) coronary artery bypass in a high OPCAB volume centre where OPCAB was introduced in 1996 and has become the preferred strategy over the years.

Methods and results: From 1996 to 2015 a total of 7,427 OPCAB and 7128 ONCAB procedures were performed at Bristol Heart Institute, United Kingdom. We obtained 5423 propensity matched pairs for final comparison. Mixed effect Cox model accounting for clustering due to different surgeon was used to investigate the treatment effect on mortality.

Results: OPCAB was associated with higher rate of incomplete revascularization 13.3% versus 6.7%; P<0.0001). Mean follow-up time was 7.8±4.6year [max 17.3]. At 12years OPCAB was associated with a marginal but significant +3% increase in overall mortality (67.4%[95%CI 65.8-69.1] vs 64.4%[95%CI 62.7-66.2]; stratified log-rank P=0.03). When compared to ONCAB with complete revascularization, OPCAB with IR (HR 1.74;95%CI 1.53-1.99; P<0.001) and ONCAB with IR (HR 1.29; 95%CI 1.06-1.57; P=0.01) but not OPCAB with complete revascularization (HR 1.02;95%CI 0.94-1.11; P=0.63) were associated with increased risk of late mortality.

Conclusion: Despite completeness of revascularization was achieved in the majority of OPCAB cases, OPCAB remained associated with a significantly higher rate of incomplete revascularization. This translated into a marginal but significant reduction in late survival rates after OPCAB when compared to ONCAB.

Keywords: Incomplete revascularization; Long-term survival; Off-pump coronary artery bypass grafting.