The Relationship between Coronary Artery Movement Type andStenosis Severity with Acute Myocardial Infarction.

INTRODUCTION The severity of coronary artery stenosis which leads to myocardial infarction (MI) has been a matter of controversy. Historical data are in favor of mild luminal stenosis (<50% diameter stenosis) while recent studies suggest hemodynamically-significant coronary stenosis as the main substrate for subsequent MI. Also, mechanical stress resulted from coronary artery movement (CAM) may be responsible for plaques rupture. In this study, we evaluated the severity of plaques leading to MI and common CAM patterns in the involved coronary segments. METHODS In a cross-sectional descriptive-analytical study, on patients with acute ST-segment myocardial infarction (STEMI) undergoing coronary angiography, the relationship between coronary artery movement type and stenosis severity with acute MI was evaluated. Lesions with stenosis diameter greater than 50 percent were defined as moderate and those equal or higher than 70% were defined as severe stenosis. Three different patterns of coronary artery motion including compression, bending and displacement types were evaluated in segments with culprit lesion. RESULTS One hundred and sixty two patients were enrolled. Ninety patients (55.6%) were male and 72 (44.4%) were female. Mean age of the patients was 60.56±13.43 years. In terms of Infarct related lesions (IRLs), 86% of the cases had at least moderate stenosis and in 67%, severe stenosis was present. More than 50% stenosis was found in all patients with anterior STEMI involving LAD. Among three types of coronary motion patterns, compression pattern was significantly higher in LAD (P<0.001), RCA (P<0.001), Diagonal artery (P<0.001) and OM branch (P=0.044), but not in proper LCX (P=0.307). CONCLUSION Most of the lesions leading to myocardial infarction have a diameter stenosis of at least 50% and mainly are located in the coronary segments with compression movement pattern.