MR imaging in hypertrophic cardiomyopathy: From magnet to bedside

Hypertrophic cardiomyopathy (HCM), the most common genetically transmitted cardiac disorder, has been the focus of extensive research over the past 50 years. HCM is a multifaceted disease with highly heterogeneous genetic background, phenotypic expression, clinical presentation, and long-term outcome. Though most patients have an indolent course with a life expectancy comparable to that of the general population, early diagnosis and accurate risk profiling are essential to identify the sizeable subset at increased risk of sudden cardiac death or disease progression and heart failure–related complications, requiring aggressive management options. Imaging has a central role in the diagnosis and prognostic assessment of HCM patients, as well as screening of potentially affected family members. In this context, magnetic resonance (MR) imaging has recently emerged as an ideal complement to transthoracic echocardiography. Its multiparametric approach, fusing spatial, contrast, and temporal resolution, provides the clinician with detailed characterization of the HCM phenotype and assessment of its functional consequences including causes and site of dynamic obstruction, presence and extent of myocardial perfusion abnormalities, and fibrosis. Moreover, MR is key in differentiating HCM from “phenocopies”—that is, hearts with similar morphology but profoundly different etiology, such as amyloid or Anderson-Fabry disease. Long term, the incremental information provided by MR is relevant to planning of septal reduction therapies, identification of the early stages of end-stage progression, and stratification of arrhythmic risk. The aim of this review is to depict the increasingly important role of MR imaging in relation to the complexity of HCM, highlighting its role in clinical decision making.