Efficacy of the internal mammary artery in combined aortic valve replacement-coronary artery bypass grafting

BACKGROUND: While internal mammary artery (IMA) use predicts improved survival after coronary bypass grafting (CABG), it remains unknown whether patients undergoing concomitant aortic valve replacement (AVR) realize a similar benefit. METHODS: All patients at a single teaching institution, undergoing combined AVR-CABG, which included a graft to the left anterior descending coronary artery (LAD) from 1984 to 1994 (n = 227) were examined retrospectively. RESULTS: Patients receiving an IMA graft (yesIMA, n = 135) and patients receiving only saphenous vein grafts (nonIMA, n = 92) were not different in their presenting symptoms, or in their incidence of preoperative risk factors. The patients with IMA were more likely to be male, have a later year of operation, be younger, and have a greater body surface. Morbidity was not different between groups. IMA use did not affect 30-day mortality. Long-term actuarial survival was greater in the group with IMA (63% +/- 7% vs 42% +/- 6% at 5 years, p < 0.01). A multivariate Cox proportional hazards model demonstrated that use of an IMA graft improved survival, while recent myocardial infarction, diabetes, earlier year of operation, and lower ejection fraction diminished long-term survival. The relative risk of IMA grafting was 0.570. CONCLUSIONS: Within the limits of a retrospective analysis, patients in a modern era of cardiac operation, who undergo combined AVR-CABG, do not suffer increased morbidity from IMA use, and may realize a survival benefit from use of the IMA as a conduit for bypass of the LAD coronary artery.