Same MYH7 gene mutation but different phenotypes of cardiomyopathy in one family.

Abstract

A 51-year-female presented to our hospital for repeated syncope. Eighteen years before, she had been diagnosed with hypertrophic obstructive cardiomyopathy and discharged after alcohol septal ablation with symptoms relieved. Family history revealed the patient's mother and her older brother had died suddenly at the age of 40 years of unidentified reason. Blood test was negative except for N-terminal pro-brain natriuretic peptide (NT-proBNP) 636 pg/mL and troponin T 35.4 ng/L. Echocardiography revealed asymmetric left ventricular hypertrophy with the interventricular septum (IVS) of 19 mm (Figure 1A) and left ventricular posterior wall (LVPW) of 12 mm, along with left atrial enlargement, normal systolic function (left ventricular ejection fraction: 57%) and Grade II diastolic dysfunction (transmitral E/A ratio 0.5). Cardiac magnetic resonance (CMR) showed multiple patchy late gadolinium enhancement (LGE) in the IVS (Figure 1B). Implantable cardioverter defibrillator was implanted for sudden cardiac death prevention. Family screening reported her asymptomatic daughter to have similar asymmetric and extreme LV hypertrophy (IVS 20 mm) with no left ventricular outflow tract obstruction on echocardiography and patchy LGE in the same area on CMR. However, the patient's younger brother, who suffered recurrent cerebral infarction with atrial fibrillation and recently admitted due to exertional shortness of breath, developed different abnormalities on echocardiography. Both atria were remarkably enlarged, exceeding his ventricles (Figure 1C). LV systolic function was preserved (left ventricular ejection fraction: 54%) while E/A ratio (>2) and E/e0 ratio (>15) was prominently increased, suggesting a typical restrictive filling pattern. Unlike the proband's, his left ventricular wall was only mildly thickened (IVS 12 mm and LVPW 12 mm) on echocardiography while CMR revealed no obvious thickening but diffuse patchy LGE in the left ventricular walls (Figure 1D). Based on these findings, his final diagnosis was restrictive cardiomyopathy.