Fig. 1

The UCG and ECG of the proband and his daughter. a The UCG before the CRT-D implantation. Severe myocardial hypertrophy and left ventricle outflow tract obstruction with the gradient of 124 mmHg. b The LVOT obstruction was greatly relieved and the gradient dropped to 27 mmHg after 1 week of the CRT-D implantation. c 12 Lead ECG in 2013 showed atrial fibrillation with slow ventricular rates. J waves could be seen in leads I, II, aVL, aVF, and V4–V6, with the amplitudes ranging from 0.2 to 0.4 mV. Covex-shaped ST segment elevation could be seen in lateral leads V4–V6. The QTc averaged 356 ms in V5 and V6 leads. d The ECG of the sustained ventricular tachycardia. e The UCG of the daughter showed left ventricle hypertrophy and mild LVOT obstructions. f The ECG of the daughter showed abnormal Q waves in leads V1–V3, but we didn’t find any ER waves