[End of the millennium - end of the single mammary artery graft? Two internal mammary arteries - standard for the next millennium? Early clinical results and analysis of risk factors in 1487 patients with bilateral internal mammary artery bypass]
OBJECTIVE: CABG with bilateral IMA grafts (BIMA) can improve long-term results in cardiac morbidity and mortality. An enhanced incidence of bleeding and wound complications compared to patients with single IMA (SIMA) remains a matter of debate. The aim of the study was to compare the operative outcomes of patients who had undergone CABG with BIMA and SIMA in situ grafts, especially to identify patient-related risk factors, such as obesity, diabetes mellitus and age above 70 years. METHODS: Out of a total of 5144 patients operated on between January 1996 and September 1999, patients with isolated CABG (n = 3671) with BIMA or SIMA were analyzed retrospectively. In the BIMA group, the patients' (n = 1478) mean age was 64.0 years; mean EF was 62.1%. In the SIMA group (n = 2184), mean age was 65.4 years and mean EF was 60.6% (n.s.). In the BIMA group, the right IMA was led anterior of the aorta to the LAD, the left IMA to the lateral wall. In the SIMA group, the LAD was revascularized with the left IMA. Additional bypasses were performed with vein grafts. RESULTS: The 30-day mortality was 1.6% in the BIMA group, 1.7% in the SIMA group in patients under 70 years, and 4.1% (BIMA) and 4.0% (SIMA) in patients over 70 years (p = n.s.). A significantly higher blood loss was observed in the BIMA group (BIMA 979 +/- 708 ml; SIMA 790 +/- 575 ml; p < 0.05). The rethoracotomy rate due to bleeding was significantly higher in patients with BIMA (4.1%) compared to those with SIMA (2.5%; p < 0.05). In patients with a body mass index (BMI) of less than 27, no significant difference could be found (SIMA 2.8%, BIMA 3.4%; p = n.s.). Patients with a BMI > 27 showed a significantly higher rethoractomy rate (SIMA 2.2%; BIMA 4.9%). A higher incidence of sternal instabilities could be observed in the BIMA group (4.2%; p < 0.05). Diabetes mellitus could not be identified as an independent risk factor for sternal complications (SIMA 2.9%; BIMA 5.0%; p = n.s.). CONCLUSION: CABG using both IMAs can be performed in nearly all patients as a routine method with good clinical results and low mortality. Bleeding in the BIMA group within 48 h was increased. BMI > 27 could be identified as a risk factor for sternal complications, but not diabetes mellitus or age over 70 years.