A Case Report of Asymmetry of Systolic Anterior Motion of the Mitral Valve, a Not Widely Well-Known but Practically Important Echocardiographic Presentation in Hypertrophic Cardiomyopathy

Systolic anterior motion (SAM) of the mitral valve is well known as a typical feature of hypertrophic cardiomyopathy with left ventricular outflow tract (LVOT) obstruction.1,2 A variety of patterns of SAM have been shown in some previous reports.3, 4, 5, 6, 7, 8 However, there have been very few reports that focused on the asymmetry or laterality of SAM.9,10 Here we report a patient with hypertrophic obstructive cardiomyopathy (HOCM) who showed SAM unevenly on the medial side of the anterior mitral leaflet. The existence of asymmetry of SAM should be carefully examined because this phenomenon may cause underestimation of the LVOT pressure gradient (PG) obtained from standard planes in an apical five-chamber or long-axis view. To measure LVOT PG more precisely, anatomic localization of SAM can provide important information because it is necessary to scan the optimal plane in which SAM exists predominantly.