Imaging phenotype vs genotype in nonhypertrophic heritable cardiomyopathies: dilated cardiomyopathy andarrhythmogenic right ventricular cardiomyopathy.

Advances in cardiovascular imaging increasingly afford unique insights into heritable myocardial disease. Because the clinical presentation of genetic cardiomyopathies may range from nonspecific symptoms to sudden cardiac death, an accurate diagnosis has implications for individual patients as well as related family members. The initial consideration of genetic cardiomyopathy may occur in the imaging laboratory, where one must recognize the patient with arrhythmogenic right ventricular cardiomyopathy (ARVC) among the many with ventricular arrhythmias referred to define the myocardial substrate. Accurate diagnosis of the patient presenting with dyspnea and palpitations whose first-degree relatives have lamin A/C (LMNA) cardiomyopathy may warrant genetic testing plus imaging of diastolic function and myocardial fibrosis. Because advances in cardiac imaging afford the detection of subclinical structural and functional changes, the imaging specialist must be attuned to the signatures of specific genetic disorders. With the increased availability of both advanced imaging and genotyping techniques, this review seeks to provide cardiovascular imaging specialists and clinicians with the contemporary information needed for more precise diagnosis of heritable myocardial disease. A companion article in this series covers imaging phenotype and genotype considerations in hypertrophic cardiomyopathy. This review details the clinical features, imaging phenotypes, and current genetic understanding for 2 of the most common nonhypertrophic cardiomyopathy conditions that prompt myocardial imaging: dilated cardiomyopathy (DCM) and ARVC. Although all imaging modalities are considered herein, considerable focus is given to cardiac magnetic resonance (CMR), with its unique capabilities for myocardial tissue characterization.