Microvascular Dysfunction in Nonischemic Cardiomyopathy: Insights From CMR Assessment of Coronary Flow Reserve

Inclusion Criteria: * Men or women aged 18 years or older Cardiomyopathy patients * Patients presenting for CMR with the clinical diagnosis of hypertrophic cardiomyopathy based on left ventricular wall thickness of at least ≥15 mm in the absence of any other cardiac or systemic cause of hypertrophy * Patients presenting for CMR with the clinical diagnosis of idiopathic dilated cardiomyopathy based upon left ventricular ejection fraction ≤40%, LV end-diastolic diameter ≥55 mm or left ventricular end-systolic diameter ≤45 mm, and the absence of coronary stenoses on angiography. Control patients * Patients presenting for CMR without evidence of obstructive coronary artery disease either by coronary angiography or stress testing. Exclusion Criteria: * Decompensated heart failure or hemodynamic instability * Prior coronary revascularization (PCI or CABG) or myocardial infarction (as evidenced by previously elevated CPK-MB or troponin levels) * Accelerating angina or unstable angina * Inability to physically tolerate MRI or implanted objects that are MRI incompatible * Inability to provide written informed consent obtained at time of study enrollment. * Severe claustrophobia * Advanced heart block or sinus node dysfunction * Hypersensitivity or allergic reaction to regadenoson or adenosine * Hypotension * Active bronchospasm or history of hospitalization due to bronchospasm * History of seizures * Recent cerebrovascular accident * Use of dipyridamole within the last 5 days *…