"Burned-Out" Hypertrophic Cardiomyopathy: Overlap on Cardiac MRI With Other Nonischemic Cardiomyopathies

"Burned-out" or end-stage hypertrophic cardiomyopathy (HCM) refers to HCM with a reduced left ventricular ejection fraction (LVEF) of ≤50%. It is an uncommon initial presentation of HCM, and imaging, including cardiac magnetic resonance imaging (CMR), is essential for diagnosis.

A 66-year-old man presented to clinic with dyspnea while in atrial fibrillation. His LVEF 7 months prior was normal, and he had no history of heart failure. He had a strong family history of HCM, heart failure, and sudden cardiac death. CMR showed a dilated and globally hypokinetic left ventricle with a reduced LVEF of 37% and extensive late gadolinium enhancement in a nonischemic pattern. Genetic testing was positive for a mutation in MYH7.

This case is of particular interest, as CMR findings were not consistent with classic HCM, showing reduced LVEF and only mildly hypertrophied myocardium. The CMR features overlapped with other nonischemic cardiomyopathies, and a definitive diagnosis was able to be made only after genetic testing and a detailed family history.

The CMR findings in burned-out HCM can overlap with other nonischemic cardiomyopathies, including arrhythmogenic cardiomyopathy, cardiac sarcoidosis, chronic myocarditis, dilated nonischemic cardiomyopathy, and infiltrative cardiomyopathies such as cardiac amyloidosis. This case highlights the importance of CMR in combination with family history and genetic testing to diagnose burned-out HCM.