Internal mammary artery grafting: is this a benign procedure?

2,784 patients had a primary coronary artery reconstruction, between 1977 and 1987. From 1984, one internal mammary artery (IMA) and later both IMAs were used as the grafts of choice, supplemented where necessary with a saphenous vein graft (SVG). As a result, 1,681 patients had SVG, 726 had a single internal mammary artery graft (SIMA), while 377 patients had a bilateral internal mammary artery reconstruction (BIMA). Comparison of the pre-operative data showed that patients who had a SIMA were similar to those who had a SVG except that they were older, had a more stable presentation and they had a higher incidence of myocardial infarction. Patients who had a BIMA reconstruction were younger, more frequently male, presented with more stable symptoms, and had better left ventricular function than patients who had a SVG alone. Despite these favourable findings, the incidence of peri-operative myocardial infarction was higher in the BIMA group, compared with the SVG group. The change from SVG grafting to SIMA grafting was also associated with a higher incidence of post-operative bleeding. The surgical mortality was similar in all 3 groups. These findings suggest that the change to IMA grafting is associated with a slightly increased morbidity and perhaps this operation should be performed on selected patients rather than used routinely.