Clinical Efficacy of Permanent Internal Mammary Artery Occlusion in Stable Coronary Artery Disease

Plain-language summary

Cardiovascular diseases remain the number one cause of death globally, primarily consequence of myocardial infarction. Although widely used in stable coronary artery disease (CAD), percutaneous coronary intervention (PCI) has not been shown to reduce the incidence of myocardial infarction or death. In contrast, coronary artery bypass grafting (CABG) significantly reduces rates of death and myocardial infarction compared to PCI, but at a higher rate of stroke. Similarly, 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. While a multitude of interventions has been shown to be effective in collateral growth promotion, so far, the effect of current interventions is only temporary, and therefore, repeated application is necessary to sustain the level of collaterals. 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. Coronary functional changes observed in response to permanent distal IMA occlusion have so far, not been related to clinical outcome parameters. Therefore, a controlled, randomized, double-blind comparison of clinical efficacy between a group of patients receiving permanent IMA occlusion vs. a sham-procedure will be consequently performed. Since single antianginal agents have been demonstrated to increase exercise time in comparison to placebo, an improvement of the physical performance due to the increased blood flow by the permanent distal IMA occlusion is expected.

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