BACKGROUND Variants in myosin heavy chain 7 (MYH7) are responsible for disease in 1% to 5% of patients with dilated cardiomyopathy (DCM); however, the clinical characteristics and natural history of MYH7-related DCM are poorly described.
OBJECTIVES We sought to determine the phenotype and prognosis of MYH7-related DCM. We also evaluated the influence of variant location on phenotypic expression.
METHODS We studied clinical data from 147 individuals with DCM-causing MYH7 variants (47.6% female; 35.6 +/- 19.2 years) recruited from 29 international centers.
RESULTS At initial evaluation, 106 (72.1%) patients had DCM (left ventricular ejection fraction: 34.5% +/- 11.7%). Median follow-up was 4.5 years (IQR: 1.7-8.0 years), and 23.7% of carriers who were initially phenotype-negative developed DCM. Phenotypic expression by 40 and 60 years was 46% and 88%, respectively, with 18 patients (16%) first diagnosed at <18 years of age. Thirty-six percent of patients with DCM met imaging criteria for LV noncompaction. During follow-up, 28% showed left ventricular reverse remodeling. Incidence of adverse cardiac events among patients with DCM at 5 years was 11.6%, with 5 (4.6%) deaths caused by end-stage heart failure (ESHF) and 5 patients (4.6%) requiring heart transplantation. The major ventricular arrhythmia rate was low (1.0% and 2.1% at 5 years in patients with DCM and in those with LVEF of <= 35%, respectively). ESHF and major ventricular arrhythmia were significantly lower compared with LMNA-related DCM and similar to DCM caused by TTN truncating variants.
CONCLUSIONS MYH7-related DCM is characterized by early age of onset, high phenotypic expression, low left ventricular reverse remodeling, and frequent progression to ESHF. Heart failure complications predominate over ventricular arrhythmias, which are rare.This study has been funded by Instituto de Salud Carlos III (ISCIII) through the projects PI18/0004, PI20/0320, and PT17/0015/0043 (cofunded by European Regional Development Fund/European Social Fund “A way to make Europe”/“Investing in your future”). The Centro Nacional de Investigaciones Cardiovasculares (CNIC) is supported by the ISCIII, MCIN, the Pro-CNIC Foundation, and the Severo Ochoa Centers of Excellence program (CEX2020-001041-S). The Hospital Universitario Puerta de Hierro, the Hospital Sant Joan de Déu, and the Hospital Universitario Virgen de la Arrixaca are members of the European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart. Dr de Frutos receives grant support from ISCIII (CM20/00101). Genetic examinations of Polish patients were funded with DETECTIN-HF grant from the ERA-CVD framework, NCBiR. Dr Baas has received funding from CVON2020B005 DOUBLE-DOSE, Dutch Heart Foundation (Dekker 2015T041). Dr Fatkin has received funding from Victor Chang Cardiac Research Institute and NSW Health. Dr Lopes is funded by an MRC UK Clinical Academic Research Partnership award (MR/T005181/1). Dr Meder has received funding from the Deutsches Zentrum für Herz-Kreislauf-Forschung (German Center for Cardiovascular Research) and Informatics for Life (Klaus Tschira Foundation). Dr Kubanek has received grant support from the Ministry of Health, Czech Republic (NV19-08-00122) and IPO (Institute for Clinical and Experimental Medicine–IKEM, IN 00023001)
