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

Background. While internal mammary artery (IMA) use predicts improved survi val after coronary bypass grafting (CABG), it remains unknown whether patie nts 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 1991 (n = 227) were examined retrospectively. Results. Patients receiving an IMA graft (yesIMA, n = 135) and patients rec eiving only saphenous vein grafts (nonIMA, n = 92) were not different in th eir 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 o peration, be younger, and have a greater body surface, Morbidity was not di fferent 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 de monstrated that use of an IMA graft improved survival, while recent myocard ial infarction, diabetes, earlier year of operation, and lower ejection fra ction diminished longterm survival. The relative risk of IMA grafting was 0 .570. Conclusions. Within the limits of a retrospective analysis, patients in a m odern era of cardiac operation, who undergo combined AVR-CABG, do not suffe r increased morbidity from lMA use, and may realize a survival benefit from use of the IMA as a conduit for bypass of the LAD coronary artery. (C) 200 0 by The Society of Thoracic Surgeons.