Clinical efficacy of permanent internal mammary artery occlusion in chronic coronary artery disease: a double-blind, randomized, sham-controlled trial

Abstract

Abstract Introduction Natural internal mammary artery (IMA) bypasses to the coronary circulation have been shown to act as extracardiac sources of myocardial blood supply, which has been found augmented by right IMA device occlusion. The goal of this randomized, sham-controlled trial was to test the efficacy of permanent right or left IMA device occlusion on symptoms of chronic coronary artery disease (CAD), on coronary artery occlusive blood supply, as well as on myocardial ischemia. Methods This was a prospective superiority trial in 100 patients with chronic CAD randomly allocated (1:1) to IMA permanent vascular device occlusion (verum group) or to IMA sham intervention (placebo group). The primary study endpoint was the change in treadmill exercise time (DET in seconds, s) during 6 weeks of follow-up after trial intervention. Secondary study endpoints were the changes in simultaneously obtained collateral flow index (CFI), and angina pectoris during a 1-minute proximal balloon occlusion of the coronary artery of interest. CFI is the ratio between simultaneous mean coronary occlusive divided by mean aortic pressure both subtracted by central venous pressure. Results In the verum and placebo group, exercise time changed from 398±176s to from 421±198s in the verum group (p=0.1745), and from 426±162s to 430±166s in the placebo group (p=0.55); DET was +23±116s and +4±120s, respectively (p=0.44). CFI change during follow-up was +0.022±0.061 in the verum and -0.039±0.072 in the placebo group (p<0.0001). Angina pectoris at follow-up during the coronary balloon occlusion for CFI measurement had decreased or disappeared in 20/48 patients of the verum group, and in 10/47 patients of the placebo group (p=0.0336). Conclusion Permanent IMA device occlusion tends to augment treadmill exercise time in response to heightened coronary artery occlusive blood supply, the fact of which is reflected by mitigated signs of myocardial ischemia.