Mitral regurgitation in patients with hypertrophic cardiomyopathy: a case series.

Background: Mitral regurgitation (MR) is a frequent occurrence in hypertrophic cardiomyopathy (HCM), often explained by valvular or sub-valvular abnormalities as part of a broad HCM phenotype spectrum. Case summary: In this case series, we present two HCM cases diagnosed with systolic anterior motion of the anterior mitral valve (MV) leaflet and left ventricular outflow tract (LVOT) obstruction. Both cases had abnormal sub-valvular abnormalities that led to deterioration of LVOT obstruction and MR. The series highlights the need for close collaboration within a multidisciplinary team, with a special emphasis on the need for a personalized treatment strategy when considering septal reduction therapy and/or MV surgery. Discussion: Mitral regurgitation is linked to adverse cardiac outcomes, often contributing towards symptoms, poor functional capacity, hospitalization, and advanced therapies. Complex and interlinked biomechanical factors lead to MR, often co-existing with LVOT obstruction. Multimodality imaging with echocardiography (transthoracic and transoesophageal) and cardiac magnetic resonance imaging plays a key role in determining the aetiology of MR in HCM. This case series highlights the role of this comprehensive assessment, paving the way for a personalized treatment pathway for patients.