Accessory and solitary main papillary muscle hypertrophy resulting in dynamic mid-left ventricular obstruction: Contribution of multimodality imaging in highlighting of dynamic and structural abnormalities.

Solitary main and/or accessory papillary muscle (PM) hypertrophy may be an uncommon type of hypertrophic cardiomyopathy that does not meet all the usual criteria. The dynamic intraventricular obstruction related to this PM hypertrophy can be deleterious with an important clinical impact on patients. The mechanisms of such obstruction attracted a lot of attention in order to propose an appropriate treatment. We report a case of a 36-year-old man presenting with a chief complaint of progressively worsening exertional dyspnea. He had demonstrated labile systolic murmur for more than 3 years. Rest echocardiography revealed coexistence of a solitary main PM hypertrophy and additional accessory PM with no left ventricular outflow tract or mid ventricle obstructions. The patient underwent exercise stress echocardiography unmasking severe mid-ventricle obstruction (peak systolic gradient at exercise of 100 mmHg). There was no obvious parietal hypertrophy elsewhere. Cardiac magnetic resonance imaging provided us with anatomical arguments that could explain the dynamic process of obstruction. In fact, multimodality imaging has a determinant role in the screening of spatial configuration and structural abnormalities of PMs in order to avoid the misinterpreting of some atypical presentations of hypertrophic cardiomyopathy. <Learning objective: Solitary main and/or accessory papillary muscle (PM) hypertrophy is an uncommon type of hypertrophic cardiomyopathy: hypertrophy concerns only the PM and spares the other parietal left ventricle segments. Multimodality imaging has a crucial role in the characterization of PM morphology and their incrimination in the pathological process of dynamic obstruction. Surgical treatment depends on the concerned PM, its extent to the mitral leaflet or the septum, or both, and the severity of hypertrophy.>.