Natural History of MYH7-related Dilated Cardiomyopathy

Abstract

Background Variants in MYH7 are responsible for disease in 1-5% 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% females, 35.6±19.2 years) recruited from 29 international centers.

Results At initial evaluation, 106 patients (72.1%) had DCM (LVEF 34.5±11.7%). Median follow-up was 4.5 years (interquartile range: 1.7-8.0) 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. Thirty-six percent of patients with DCM met imaging criteria for LV non-compaction. During follow-up, 28% showed left ventricular reverse remodeling (LVRR). Incidence of adverse cardiac events among patients with DCM at 5 years was 11.6%, with 5 (4.6%) deaths due to end-stage heart failure (ESHF) and 5 patients (4.6%) requiring heart transplantation. The major ventricular arrhythmia (MVA) rate was low (1.0% and 2.1% at 5 years in patients with DCM and in those with LVEF?35%, respectively). ESHF and MVA were significantly lower compared with LMNA-related DCM and similar than in DCM caused by TTN truncating variants.

Conclusions MYH7-related DCM is characterized by early age of onset, high phenotypic expression, low LVRR, and frequent progression to ESHF. Heart failure complications predominate over ventricular arrhythmias, which are rare.