Isolated Papillary Muscle (PM) hypertrophy is characterized by an asymmetric hypertrophy of one PM without hypertrophy

Isolated Papillary Muscle (PM) hypertrophy has been supposed to be a phenotypic variant of hypertrophic cardiomyopathy. Whether this finding may explain an electrocardiographic pattern of left ventricular hypertrophy has to be demonstrated. A cardiac magnetic resonance imaging may add additional crucial information. Our case was a 26-year-old asymptomatic male cyclist who underwent routine sport medicine screening. His cousin had suddenly died during a bicycle race at 40 years of age, and autopsy had revealed a hypertrophic cardiomyopathy. Screening revealed an electrocardiographic pattern of left ventricular hypertrophy. A multimodal imaging examination was also performed and the only abnormal finding was a hypertrophic anterolateral PM and cardiac magnetic resonance imaging showed fibrotic substitution of its head. An otherwise unexplained electrocardiographic pattern of left ventricular hypertrophy can be justified by an isolated PM hypertrophy. Cardiac magnetic resonance imaging is crucial for precise ventricular wall and papillary thickness measurement. In the presence of an isolated PM hypertrophy, postgadolinium T1 mapping can demonstrate the presence of abnormal tissue and probably fibrosis of the papillary head, which can confirm the presence of a strictly localized form of hypertrophic cardiomyopathy. *Corresponding author: Alberto Cresti, Cardiological Department, Misericordia Hospital, via Senese 58100 Grosseto, Italy. Fax: +39-0564485830, E-mail: [email protected]