Internal mammary artery grafting. Clinical results, patency rates, and long-term survival in 833 patients.

This report reviews 833 patients who underwent internal mammary artery grafting alone or with vein grafts between 1968 and 1981. Use of the internal mammary artery was indicated in young or middle-aged patients with the following characteristics: a significant lesion of the proximal left anterior descending artery or its diagonal branch alone (70.1%) or combined with diffuse atherosclerosis (19.9%) or a small caliber (3.4%); absent or unsuitable veins for grafting (5.5%); atherosclerosis or an aneurysm of the ascending aorta (0.6%); and failure of previous vein grafts (0.5%). The left anterior descending artery system was grafted by the left internal mammary artery in 53.2%, and the arterial graft was complimented by vein grafts in 2.6%. In 45.2% of the patients, grafts of the left anterior descending artery by the left internal mammary artery were supplemented by vein grafts to the right coronary artery (23.8%), to the circumflex artery (15.2%), or to both (6.2%). The overall operative mortality was 2.2%. It rose to 16.7% with associated cardiac procedures and to 18.5% in patients who were in New York Heart Association Class IV. If these two high-risk categories of patients are excluded, the perioperative death rate in the remaining 750 was only 0.4%. Of the 815 patients who survived the perioperative period (mean 53.1 months follow-up), 63.1% were relieved of angina and 83.4% were in Class I or II of the New York Heart Association, as compared to 27.4% before the operation. At cardiac recatheterization (mean 18.9 months), 87.9% of the internal mammary artery grafts and 63.3% of the vein grafts were patent (p less than 0.05). The cumulative actuarial 10 year survival rate was 88.6% +/- 1.3%.