What Causes Myocardial Infarction in Women Without Obstructive Coronary Artery Disease?

Abstract

Women experience higher mortality rates and more adverse outcomes after acute myocardial infarction (AMI) than men, despite less obstructive coronary artery disease (CAD) and plaque burden with similar plaque responses to intensive risk factor modification.1 Furthermore, nonobstructive CAD by angiography appears to be emerging as a predictor of mortality in women, but not among men.2 These puzzling findings illustrate our incomplete understanding of sex-specific differences in pathophysiological mechanisms of AMI and ischemic heart disease in general. A better understanding of the mechanisms would lead the way for improvement in attempts to optimize ischemic heart disease management among women. Article see p1414 In the current issue, Reynolds and colleagues3 provide new data to help advance our understanding in this area by using intravascular ultrasound (IVUS) and cardiac magnetic resonance imaging (CMR) to investigate women with AMI in the absence of obstructive CAD. They provide the first evidence for plaque disruption and myocardial tissue characteristics among women with confirmed AMI and normal or only minimally abnormal coronary angiograms. To help interpret their novel findings, it seems appropriate to briefly review what we know in this area. Although sex-related results were lacking, autopsy studies from past decades securely linked severe atherosclerotic CAD and intracoronary thrombosis with AMI leading to death. More recent and detailed studies of women and men dying with AMI added disrupted plaque as the culprit for the acute thrombotic event. Overall, the majority had plaque rupture; a third had erosion; and a few percent had calcified nodules contributing to the thrombi.4 Interestingly, plaque erosion was identified as the cause of death in about one third of women, whereas in men, erosion was only about half as frequent as the cause of death. More important, erosion was observed as the cause of acute coronary thrombi in …