USE OF THE INTERNAL MAMMARY ARTERY GRAFT IN NORTHERN NEW-ENGLAND

Background There is evidence that patients who receive an internal mam mary artery graft (IMA) during coronary artery bypass surgery have inc reased long-term survival. However, an IMA is not used in all patients . Methods and Results We studied the use of IMA grafts among 7944 pati ents undergoing initial, isolated coronary artery bypass surgery in Ma ine, New Hampshire, and Vermont from 1992 to 1995. Overall, the IMA gr aft was used in 82% of patients; of these, 97.2% had left IMA grafts. The use of the IMA graft varied considerably by patient and disease fa ctors. Women received an IMA graft significantly less often (76% versu s 85% in men, P<.01). Older patients (greater than or equal to 75 year s) were less likely to receive an IMA graft (67% versus 86%, P<.001). Smaller BSA was also associated with lower rates of IMA grafts in both sexes, however, men and women with BSA <1.8 m(2) received an IMA graf t at about the same rate. In general, more sick and more urgent patien ts had lower rates of IMA use. Patients with left ventricular ejection fraction <40% received an IMA less often than those with an ejection fraction greater than or equal to 60% (77% versus 85%, P<.01). Patient s with a greater number of diseased coronary vessels received an IMA m ore often (one, 78%; two, 82%; three, 85%). IMA use varied significant ly by priority of surgery, with elective patients receiving an IMA 88% of the time, urgent 83%, and emergent 51% (P-trend<.01). The use of t he IMA graft varied from 42% to 95% among individual surgeons. Surgeon s were consistent in their patterns of IMA graft use for specific risk groups. All surgeons had lower rates of IMA use among older patients, lower rates of IMA among women, and lower rates of IMA use among emer gent or urgent patients. However, ''low-use'' surgeons had consistentl y lower rates of use within these patient groups. The overall rate of IMA graft use increased from 76% in 1992 to 86% in 1995 (P-trend<.001) . Ih IA graft use increased in all five centers and in all patient sub groups. The largest increases in use were seen among women (from 69% t o 83%), among patients older than 75 years (from 55% to 75%), and in e mergent patients (from 40% to 72%). Conclusions This regional prospect ive study of IMA graft use in initial coronary artery bypass surgery d escribes substantial variability in patient groups receiving an IMA as well as increasing IMA graft use over time. It also suggests that the practice patterns of surgeons are an important determinant of IMA use . These data indicate that even more patients could benefit from the u se of this technique.