Functional Myocardial Ischemia in Ischemia with no Obstructive Coronary Artery Disease

Ischemia in the absence of obstructive coronary artery disease (INOCA) is prevalent in women, and constitutes a major risk factor for life-altering adverse cardiovascular events, including myocardial infarction, stroke, and new onset heart failure—especially heart failure with preserved ejection fraction (HFpEF). Annual mortality rates for women with ischemic heart disease are ten-fold higher than mortality from breast cancer, and the annual cost to the US health care system to care for women with angina/effort intolerance exceeds $162 billion. Despite these alarming statistics, etiology and treatment remain elusive. Sex-specific research initiatives, have established Coronary Microvascular Dysfunction (CMD) as a cardinal feature of ischemic heart disease in women. Dysregulation of coronary microvessels may therefore be mechanistically linked to functional myocardial ischemia, and therefore an important source of diastolic dysfunction.

This study therefore sought to establish the relationship between functional myocardial ischemia and diastolic dysfunction in women with INOCA.

Women with INOCA and healthy age-, sex-, and BMI-matched controls underwent comprehensive cardiac magnetic resonance imaging at rest and during cardiovascular stress (i.e. isometric handgrip exercise). Left ventricular (LV) diastolic function (primary endpoint) was measured by diastolic strain rate. Coronary microvascular dysfunction was assessed by the myocardial perfusion reserve index.