Bilateral internal mammary artery grafting reverses the negative influence of gender on outcomes of coronary artery bypass grafting surgery.

OBJECTIVES Coronary artery bypass grafting (CABG) has historically demonstrated higher hospital mortality in women compared with men. The influence of gender on long-term outcomes has not been clearly defined. METHODS A retrospective analysis of 4584 consecutive CABG patients was conducted: 3647 men (1761 single internal mammary artery, [SIMA]; 1886 bilateral IMA, [BIMA]) and 937 women (608 SIMA and 329 BIMA). Propensity-score analysis and optimal matching algorithms were used to create matched groups for baseline risk factors between men and women (SIMA: 602 men and 602 women; BIMA: 328 men and 328 women). Cross-sectional follow-up (6 weeks to 32.1 years; mean 12.8 years) was 96.7% complete. RESULTS Hospital mortality was higher in unmatched female vs male patients (SIMA 36/608; 5.9 vs 72/1761; 4.1%; BIMA 11/329; 3.3 vs 47/1886; 2.5%; P = 0.010). However, in the matched groups the increased hospital mortality for females approached statistical significance in the SIMA but not in the BIMA patients. (SIMA male 21/602, 3.5%; female 35/602, 5.8%; P = 0.055; BIMA male 12/328; 3.7%; female 11/328; 3.4%; P = 0.832). When propensity matched for baseline variables, the female SIMA patients experienced prolonged survival compared with their male counterparts. (male vs female, 20-year survival 17.0 ± 2.0 vs 26.4 ± 2.3%; median 10.4 vs 11.4; P = 0.043.) However, long-term survival between the matched male and the female BIMA patients was comparable (male vs female, 20-year survival 31.3 ± 3.6 vs 30.1 ± 3.6%; median 13.7 vs 13.7; P = 0.790). CONCLUSIONS When liberally applied, BIMA grafting ameliorates both the increased perioperative mortality in female patients and the reduced long-term survival of male patients, effectively reversing the negative influence of gender on both short- and long-term outcomes of CABG surgery.