Cardiac Magnetic Resonance Myocardial Perfusion Reserve Index Is Reduced in Women With Coronary Microvascular Dysfunction

Background— Women with signs and symptoms of ischemia and no obstructive coronary artery disease often have coronary microvascular dysfunction (CMD), diagnosed by invasive coronary reactivity testing (CRT). Although traditional noninvasive stress imaging is often normal in CMD, cardiac MRI may be able to detect CMD in this population. Methods and Results— Vasodilator stress cardiac MRI was performed in 118 women with suspected CMD who had undergone CRT and 21 asymptomatic reference subjects. Semi-quantitative evaluation of the first-pass perfusion images was completed to determine myocardial perfusion reserve index (MPRI). The relationship between CRT findings and MPRI was examined by Pearson correlations, logistic regression, and sensitivity/specificity. Symptomatic women had lower mean pharmacological stress MPRI compared with reference subjects (1.71±0.43 versus 2.23±0.37; P <0.0001). Lower MPRI was predictive of ≥1 abnormal CRT variables (odds ratio =0.78 0.70, 0.88, P <0.0001, c-statistic 0.78 0.68, 0.88). An MPRI threshold of 1.84 predicted CRT abnormality with sensitivity 73% and specificity 74%. Conclusions— Noninvasive cardiac MRI MPRI can detect CMD defined by invasive CRT. Further work is aimed to optimize the noninvasive identification and management of CMD patients. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00832702.