Myocardial Bridging is Significantly Related to Myocardial Infarction with Non-Obstructive Coronary Artery Disease

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Myocardial infarction with non obstructive coronary arteries (MINOCA) is a complex working diagnosis including coronary and non-coronary causes, like spontaneous coronary dissection, coronary thrombosis or embolism, myocarditis and cardiomyopathy. The prevalence of MINOCA is increasing, but the underlying etiology remains undetermined in more than 10% of cases. Hypotheses on the potential contributing role of myocardial bridge (MB) in takotsubo cardiomyopathy and coronary artery spasm (CAS) have been raised. We aim to investigate the relationship between MB and MINOCA. An observational retrospective study was conducted on 15,036 patients who had been referred for coronary angiography and who fulfilled the Definition of Myocardial Infarction. The study population was divided into STEMI and Non-STEMI patients, from which we defined two main groups: the MINOCA group and the coronary artery disease (CAD) group. The prevalence of MB was calculated in each group ( Fig. 1 ). The distribution of angiographic MB among the groups was significantly greater in the MINOCA group (2.9% vs. 0.8%, P < 0.001). MINOCA accounted for 14.5% of spontaneous myocardial infarctions, and the clinical presentation was frequently NSTEMI rather than STEMI (84.3% vs. 15.7%, P < 0.001). Adjusted multivariate analyses showed a positive association between MB and MINOCA [OR = 3.28, 95% CI (2.34; 4.61) P < 0.001]. Cardiovascular risk factors were less common in the MINOCA population, which was younger and more often female. The main finding of the present study was that MB is an independent predictor for MINOCA, increasing the corresponding risk by threefold. Because MB prevalence differed significantly between the controls (CAD group) and in the MINOCA group, which was positively correlated to MB, it seems likely that MB would be a potential cause of MINOCA. Future prospective studies are necessary to highlight the physiologic significance of MB in some MINOCA patients.