Abstract: A case of dilated cardiomyopathy complicated with complete left bundle branch block was reported. After admission, the patient was treated with cardiotonic, dilatation, diuresis, inhibition of myocardial remodeling, improvement of myocardial metabolism and so on. The patient was with recurrent ventricular fibrillation during hospitalization and poor heart function, and the patient's symptoms improved significantly after CRT-D (cardiac resynchronization therapy-defibrillator) implantation. Followed up for nearly 2 years, echocardiography showed that left ventricular end diastolic dimension reduced from 70mm to 42 mm, left atrium dimension reduced from 34 mm to 30 mm, and left ventricular ejection fraction increased from 0.35 to 0.62. The patient was generally in good condition and no restrictions on daily activities, which was the CRT-D hyperreactivity. The reason for this patient's hyperreactivity might be that CRT-D has corrected the progressive enlargement of the heart caused by conduction block.

Key words: cardiomyopathy, dilated, complete left bundle branch block, CRT-D, hyperreactivity