Purpose or Case Report: Cardiomyopathy is rare in children but associated with significant morbidity and mortality when symptomatic. It also comprises a large proportion of cardiac MR imaging referrals in typical pediatric radiology practice. The purpose of this educational exhibit is to review the major types of cardiomyopathy in children, focusing on cardiac MRI.
Methods & Materials: Background information (prevalence, demographics) is discussed. An approach to imaging and cardiac MRI protocols are offered. The major types of cardiomyopathy are detailed, including dilated, hypertrophic, restrictive, and unclassified. Within these categories, disorders discussed include myocarditis, Duchenne muscular dystrophy, and anthracycline toxicity (dilated); hypertrophic cardiomyopathy (HCM); Fabry disease (restrictive); and arrhythmogenic right ventricular cardiomyopathy (ARVC), left ventricular non-compaction (LVNC), and Friedreich's ataxia (unclassified). MRI as well as clinical features of each entity are highlighted.
Results: Most cardiomyopathies in children are dilated. Within this group, myocarditis followed by neuromuscular disease is the most common identifiable cause. HCM is the second-most common type in children but comprises a disproportionate number of cardiac MRI referrals; the role for MRI in this disorder is well established, including assessment of wall thickness, systolic anterior motion of the mitral valve (SAM), left ventricular outflow tract obstruction, and fibrosis. Restrictive disease is rare. Within the unclassified category, ARVC and LVNC have well-defined cardiac MR criteria. Common to many cardiomyopathies is subepicardial to mid-myocardial abnormal late gadolinium enhancement (LGE) with an inferolateral predominance and variable systolic dysfunction. Quantitative imaging findings that assist in diagnosis inclide the Lake Louise criteria for myocarditis, wall thickness cutoffs for HCM, the 2010 Revised Task Force Criteria for ARVC, and the non-compacted to compacted (NC/C) ratio for LVNC. While increasingly detected in asymptomatic children with strong family history, cardiomyopathy when symptomatic commonly progresses to cardiac transplant or death.
Conclusions: Cardiomyopathies in children are uncommon and heterogeneous disorders, often with a genetic basis. MRI allows earlier detection compared to other modalities, offering important prognostic information and facilitating prompt initiation of cardioprotective medications. Future directions include targeted imaging markers and personalized therapies.