Comparison between single and double internal mammary artery grafts: results over ten years

In view of the superior patency of the internal mammary artery (IMA), grafting of this vessel to the left anterior descending artery is advantageous in terms of survival and quality of life; the benefits of using both the mammary arteries remain unproved.

Among the patients operated upon during the period 1988-1990, we randomly selected 150 patients in whom one IMA (group 1) was grafted and 150 patients in whom both IMAs (group 2) were grafted. The survival and event free curves of these two groups of patients were designed using the Kaplan-Mayer method; the log-rank test was used to assess the statistical difference between the curves and to determine whether, in the long term, benefits were superior in patients in whom both IMAs were grafted.

Patients in group 1 were older (p = 0.002). In this group there were more patients with diabetes (p = 0.004) and with peripheral vascular disease (p = 0.047). There were more female patients in group 2 (p < 0.02) and more coronary vessels were grafted (p = 0.03). Follow-up was complete (100%) and equivalent in duration for both groups (109 +/- 30 months for group 1 and 110 +/- 33 months for group 2, p = NS). The survival rate at 10 years was equal for both groups (82.5 +/- 3.4% for group 2 vs 82.9 +/- 3.2% for group 1, p = NS) and so was the freedom from cardiac death. The provocative test for myocardial ischemia was more frequently positive in group 1 than in group 2 (21 vs 10 cases, p = 0.054). Freedom from new myocardial infarction (p = NS), angina recurrence (p = NS) and reoperation (p = NS) was equally distributed during follow-up. Group 2 patients more frequently necessitated coronary angioplasty but the difference was not significant (p = 0.17). Survival free from angina recurrence, new myocardial infarction, coronary angioplasty and reoperation was more frequent in group 2 (respectively 74.6 +/- 3.8 vs 70.7 +/- 4.1%) but the difference was not statistically significant (p = NS).

After 12 years of follow-up, patients submitted to grafting of a single IMA more frequently presented with inducible myocardial ischemia, but neither survival nor the quality of life were superior in the patients in whom both IMAs were grafted.