Prognostic Impact of Cardiac Diastolic Function and Coronary Microvascular Function

Cardiac diastolic dysfunction refers to a condition in which abnormalities in mechanical function are present during diastole and is an independent predictor of mortality, even in patients with preserved left ventricular (LV) systolic function. Clinical manifestations of cardiac diastolic dysfunction are also variable, from asymptomatic subclinical heart failure to heart failure with preserved ejection fraction, angina or exercise intolerance without significant epicardial coronary artery disease, or end-stage heart failure. Although its pathophysiology remains incompletely understood, findings from clinical and pre-clinical studies have suggested systemic endothelial dysfunction, oxidative stress, and coronary microvascular dysfunction (CMD) could be important pathophysiologic mechanisms for cardiac diastolic dysfunction. In this regard, recent studies evaluated non-invasively measured coronary flow reserve (CFR) from positron emission tomography (PET), cardiac magnetic resonance imaging (MRI), or Doppler echocardiography, and presented the association of depressed global CFR with cardiac diastolic dysfunction and higher risk of clinical events. The presence of CMD can be also evaluated by invasive physiologic assessment using both CFR and index of microcirculatory resistance (IMR). Previous studies presented CMD could be one of the major causes of angina without significant epicardial coronary artery disease and an independent predictor of adverse clinical events in patients with stable ischemic heart disease, acute myocardial infarction (MI), or myocardial disease. Nevertheless, there has been limited study which evaluated the association between cardiac diastolic dysfunction and CMD using invasive physiologic indices and their prognostic implications, especially in non-MI patients without significant coronary artery stenosis. Therefore, the current study was designed the current DIAST-CMD registry to evaluate 3 important clinical questions as to whether: (1) cardiac diastolic dysfunction is significantly associated with the presence of CMD; 2) both cardiac diastolic dysfunction and CMD are significantly associated with long-term cardiovascular death; and 3) integration of both disease entities would have incremental prognostic stratification in non-MI patients without significant epicardial coronary artery disease.