Bietenbeck M, et al. - Using global myocardial perfusion reserve (MPR), quantitative myocardial first-pass perfusion (1P) cardiovascular magnetic resonance (CMR) was compared with coronary sinus flow (CSF) measurements at rest and during maximal vasodilatation for determining coronary microvascular dysfunction in patients suffering from dilative or hypertrophic cardiomyopathy (DCM/HCM). Findings suggested that in both HCM and DCM patients, the presence of microvascular disease can be non-invasively and quickly detected by velocity-encoded (VENC)-based CSF-MPR measurements during routine stress perfusion CMR. VENC-based CSF-MPR seemed particularly useful in DCM patients with thinned ventricular walls compared to conventional 1P-myocardial perfusion imaging.