Effects of Cardiac Resynchronization Therapy on Ventricular Electrical Remodeling in Patients With Heart Failure

Cardiac resynchronization therapy (CRT) reverses structural remodeling of the left ventricle. We investigated whether CRT reverses left-ventricular electrical remodeling. Eighty patients were enrolled and implanted with CRT-devices. Echocardiography and electrocardiography data were obtained from each patient prior to implantation and two years after implantation. At two years after implantation, the patients were classified into a responder group and a non-responder group based on echocardiography. Over the next 2 years, 75 patients completed follow-up, and 5 patients had died. Echocardiography results showed that 23 patients could be classified as non-responders and 52 as responders. Larger numbers of non-responders were diagnosed with either ischemic cardiomyopathy (ICM) or nonspecific intraventricular conduction delay (NICD). The intrinsic QRS duration was not changed in responders, patients with dilated cardiomyopathy, or in the patient categories of male and female. However, the intrinsic QRS duration was significantly prolonged in non-responders and patients with ischemic cardiomyopathy (P = 0.041). The mean left ventricular end-diastolic diameter in the responder group was significantly decreased by CRT (P < 0.05), while there was no significant change in intrinsic QRS duration. While CRT does not reduce the intrinsic QRS duration, it can delay negative ventricular electrical remodeling. Continuous CRT is necessary.