Mechano-energetic efficiency in patients with hypertrophic cardiomyopathy with and without sarcomeric mutations

Abstract

Abstract Background Hypertrophic Cardiomyopathy (HCM) is mainly caused by sarcomeric mutations. In about 40% of cases the causal mutation is unknown. Myocardial mechano-energetic efficiency per unit of left ventricular (LV) mass (MEEi) is an echocardiographic parameter of LV pump performance. Sarcomeric mutations may affect energy efficiency. Purpose We investigated the effects of the presence of sarcomeric mutations on MEEi in patients with HCM. Methods We included 49 genetically screened HCM patients (50±10 years, 27% women) with LV ejection fraction >50%, LV maximal wall thickness >14 mm and no moderate to severe mitral regurgitation. MEEi was calculated as the ratio between stroke volume and heart rate, normalized by LV mass. Echo-LV mass was calculated as LV epicardial minus LV endocardial volumes in 4 and 2 chamber views multiplied by 1.05, a method validated with nuclear magnetic resonance. Results 27 HCM patients carried a sarcomeric mutation (HCM-Sarc; 55%). As shown in the table, patients with and without sarcomeric mutations (HCM-Sarc vs HCM-NoSarc) had similar LV ejection fraction, heart rate, LV mass and LV outflow tract gradient. HCM-Sarc showed early age at diagnosis, higher frequency of HCM family history and significantly reduced MEEi as compared with HCM-NoSarc. Presence of sarcomeric mutation could be predicted by younger age, lower MEEi and by family history of HCM (overall p<0.05). Conclusions In a population of HCM patients, the presence of a sarcomeric mutation is the only determinant of reduced the LV pump performance as estimated by MEEi. MEEi may be used as an imaging biomarker in sarcomeric mutation carriers. Funding Acknowledgement Type of funding sources: None.