Optimal depolarization sequence for cardiac resynchronization therapy patients

Electrical ventricular dyssynchrony is a hallmark of intraventricular conduction disease in heart failure with reduced ejection fraction. Although cardiac resynchronization therapy (CRT) is effective, a proportion of patients with electrical dyssynchrony evidenced by an electrocardiogram (ECG) remain non-responders. Besides the QRS duration, visualization and quantification of the depolarization sequence could contribute to improving CRT response. The study aimed to evaluate the CineECG-derived mean temporo-spatial isochrone trajectory of depolarization in CRT patients.

Among the adult cohort of 121 patients who underwent CRT implantation, there were 93 (33% female) responders and 28 (7% female) non-responders. ECGs recorded before and immediately after CRT implantation were collected and analysed using the CineECG modality with a generic heart/torso model. The CineECG-derived path directions were computed for the QRS on anteroposterior, interventricular, and apicobasal axes within the cardiac anatomy. Spatial depolarization characteristics were tested for the association with left ventricle reverse-remodelling at 6-month follow-up. The pre-implantation depolarization sequence was predominantly from the right to the left ventricle, and after the CRT implant, it has been transformed into an apicobasal direction. In multivariate logistic regression, the pre-implant QRS duration, apicobasal depolarization gradient, and CRT-induced QRS shortening independently predicted CRT response. The Akaike information criterion indicated that combining all three yielded the strongest predictive model.

CineECG-derived depolarization gradients, which reflect ventricular activation sequence, changed significantly after CRT, and the pre-implantation apicobasal gradient independently predicted echocardiographic outcome, with a less pronounced gradient associated with better haemodynamic response.