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Prognosis of Coronary Microvascular Disease Identified by CMR
Quick Takes
- Low myocardial perfusion reserve index on CMR is a marker of coronary microvascular disease in the absence of epicardial CAD.
- A low myocardial perfusion reserve index on CMR is associated with increased adverse events.
Study Questions:
What is the prognostic impact of coronary microvascular disease (CMD) identified by stress cardiac magnetic resonance (CMR)?
Methods:
This retrospective study evaluated patients from three sites with chest pain but no epicardial coronary artery disease (CAD) or myocardial disease undergoing stress perfusion CMR. The myocardial perfusion reserve index (MPRI) on CMR was compared to the rate of adverse events including mortality, acute coronary syndrome, epicardial CAD development, heart failure hospitalization, and stroke.
Results:
There were 281 patients studied (mean age 59 years, 50% male), and the mean MPRI was 1.56 ± 0.33. Over a median follow-up of 5.5 years, adverse events were observed in 15.6% of patients. A MPRI threshold of ≤1.47 was determined to be the optimal cutoff value to predict adverse events, and patients with a MPRI ≤1.47 experienced more adverse events (hazard ratio [HR], 3.1; 95% confidence interval [CI], 1.6-6.3; p = 0.001) compared to those with higher values. After adjusting for age and hypertension, MPRI was independently associated with adverse events (HR, 0.10; 95% CI, 0.03-0.34; p < 0.001).
Conclusions:
A low MPRI on CMR is associated with increased adverse events in patients with chest pain and no epicardial CAD.
Perspective:
A substantial proportion of patients with chest pain lack obstructive epicardial CAD, and some of these patients have evidence of CMD, which may be due to impaired flow reserve of coronary arterioles or stress-induced microvascular spasm, which can result in a lack of dilatation to maintain normal perfusion of the myocardium. While MPRI on CMR has been reported to have good accuracy to identify CMD, the prognostic value of the MPRI on CMR has not been established. This study suggests that a low MPRI on CMR has prognostic value and can identify patients at increased risk of adverse events. These findings suggest this may be a promising approach to evaluate patients with suspected CMD, although future prospective studies are needed to better assess the prognostic value of these measurements as well as the effects of treatment based on these findings.
Clinical Topics: Acute Coronary Syndromes, Cardiovascular Care Team, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Stable Ischemic Heart Disease, Atherosclerotic Disease (CAD/PAD), Acute Heart Failure, Magnetic Resonance Imaging, Nuclear Imaging, Chronic Angina
Keywords: Acute Coronary Syndrome, Chest Pain, Coronary Artery Disease, Diagnostic Imaging, Heart Failure, Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy, Microvascular Angina, Myocardial Ischemia, Myocardium, Perfusion, Perfusion Imaging, Stroke
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