Safe evolution towards routine off-pump coronary artery bypass: negotiating the learning curve.

Abstract

Off-pump coronary artery bypass (OPCAB) hopes to avoid morbidity associated with cardiopulmonary bypass, improving clinical outcomes. Yet its technical difficulty and unfamiliarity raise concern that adoption of OPCAB might be associated with poorer outcomes during each surgeon's 'learning curve'. We examined trends in patient selection over time as a single surgeon's practice evolved to routine OPCAB. Between 10-1-96 and 12-31-01, 1479 consecutive patients had isolated coronary artery bypass grafting (CABG). Clinical data were gathered prospectively and reviewed retrospectively. Trends in adoption of OPCAB and clinical outcomes were examined. There were 756 OPCAB and 723 CABG/cardiopulmonary bypass patients. The practice evolved from 90% conventional CABG to 93% OPCAB. An abrupt transition coincided with evolution of techniques to expose the obtuse marginal arteries, and improvements in suction-based coronary stabilizers. Mortality was 1.0% for the off-pump group and 2.1% for the on-pump group. Careful patient selection helped maintain acceptable outcomes during the 'learning curve'. Patients with depressed left ventricular ejection fraction, left main disease, and complex three vessel disease were excluded from OPCAB until significant experience (>200 cases) was attained. Presently, all isolated coronary bypass cases are candidates for OPCAB except patients with ischemic ventricular arrhythmias, those in cardiac arrest, and those for whom previous left pneumonectomy or deep pectus excavatum prevent rightward mobilization of heart. Despite a significant learning curve, evolution to routine OPCAB can be achieved while maintaining good patient outcomes. The development of specialized techniques, coronary stabilizers, and apical suction devices allows the application of OPCAB to virtually all coronary bypass patients, as surgeon experience matures.