Abstract
Accumulating evidence suggests that individuals with sarcomeric hypertrophic cardiomyopathy (HCM) carrying MYH7 mutations may have a worse prognosis than MYBPC3 mutation carriers. Myocardial deformation analysis is superior to standard echocardiography in detecting subtle myocardial dysfunction and scar formation, but studies evaluating the association with HCM genotype are scarce. We therefore aimed to compare myocardial strain parameters between MYBPC3 and MYH7 mutation carriers with proven HCM. Participants of the prospective Graz HCM Registry carrying at least one causative mutation in MYBPC3 (n = 39) or MYH7 (n = 18) were enrolled. MYBPC3 mutation carriers were older, predominantly male and more often treated with an implantable cardioverter-defibrillator (39% vs. 0%; p = 0.002). Using analyses of covariance, there were no significant differences between MYBPC3 and MYH7 mutation carriers with regard to left ventricular global longitudinal strain (estimated marginal means ± standard deviation: −16.9 ± 0.6% vs. −17.3 ± 0.9%; p = 0.807) and right ventricular 6-segments endocardial strain (−24.3 ± 1.0% vs. 26.3 ± 1.5%; p = 0.285). Our study suggests, that myocardial deformation analysis may not be helpful in concluding on the underlying HCM genotype, and vice versa.
Highlights
Sarcomeric hypertrophic cardiomyopathy (HCM) is a heritable cardiac disease affecting 1 in 200 to 500 people
The Graz HCM Registry is a prospective cohort study launched in February 2019 and includes all patients aged over 18 years who are admitted to the HCM outpatient clinic of the Department of Cardiology of the Medical University of Graz, and provide written informed consent for participation
Patients carrying a MYBPC3 mutation had a lower estimated glomerular filtration rate and were more often treated with a loop diuretic (21% vs. 0%; p = 0.038)
Summary
Sarcomeric hypertrophic cardiomyopathy (HCM) is a heritable cardiac disease affecting 1 in 200 to 500 people. Pathogenic or likely pathogenic variants in sarcomere protein encoding genes can be identified in 40–60% of adolescents and adults affected by HCM. MYH7 and MYBPC3 mutations affect the thick filament of the sarcomere [8], but via differing pathways. Regarding MYH7, more than 95% of known disease causing variants are missense mutations leading to integration of altered myosin into the sarcomere [10]. Most MYBPC3 mutations lead to diminished levels of cMyBPC in the sarcomere resulting in haploinsufficiency [11]. Mutations in both genes cause hyperdynamic contraction and poor relaxation of the myocardium [11]. Previous studies failed in the majority to demonstrate phenotypic differences between MYBPC3 and MYH7 mutation carriers
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