Effect of Permanent Right Internal Mammary Artery Occlusion on Extracardiac Coronary Collateral Supply

Plain-language summary

Coronary artery disease and the benefit of bypasses: Despite considerable advances in medicine, cardiovascular diseases remain the number one cause of death globally, primarily consequence of myocardial infarction (MI). Coronary collaterals exert a protective effect by providing an alternative source of blood flow to a myocardial territory potentially affected by an acute coronary occlusion. Coronary collaterals represent pre-existing inter-arterial anastomoses and as such are the natural counter-part of surgically created bypasses. Sufficient coronary collaterals have been shown to confer a significant benefit in terms of overall mortality and cardiovascular events. In this regard, the concept of augmenting coronary collateral function as an alternative treatment strategy to alter the course of CAD, as well as to control symptoms, is attractive. Durable promotion of coronary collateral circulation: Before the advent of coronary artery bypass grafting, permanent augmentation of coronary collateral supply by a single structural modification has already been attempted. Bilateral ligation of the internal mammary arteries (IMA) was performed in CAD patients to alleviate angina pectoris and electrocardiographic (ECG) signs of ischemia. The prevalent in vivo function of natural internal mammary arteries (IMA)-to-coronary artery bypasses and their anti-ischemic effect has been recently demonstrated by the investigators' research group. Levels of collateral function and myocardial ischemia were determined in a prospective, open-label clinical trial of permanent IMA device occlusion. In this study, coronary collateral function, has been shown to be augmented in the presence vs the absence of distal permanent ipsilateral IMA occlusion. These findings have been corroborated by the observed reduction in ischemia in the intracoronary ECG. After this first step, the concept of permanent right IMA occlusion will be now investigated with a randomized, sham-controlled clinical trial.

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