Personalized cardiac resynchronization therapy guided by real-time electrocardiographic imaging for non-left bundle branch block patients

Abstract

Abstract Background Heart failure patients with non-left bundle branch block (non-LBBB) QRS pattern have limited response rate to biventricular pacing (BVP). Objective A personalized cardiac resynchronization therapy (CRT) implantation approach guided by real-time electrocardiographic imaging (ECGi) was studied. Methods Twenty patients with left ventricular ejection fraction (LVEF) ≤35%, QRS duration ≥120ms and non-LBBB (13 right bundle branch block and 7 intraventricular conduction delay) were recruited. During CRT implantation, right atrial, right ventricular, coronary sinus, His-bundle and/or Left-bundle leads were inserted. The total activation time (TAT) with different pacing combinations were measured real-time during implantation by ECGi. The configuration producing shortest TAT would be chosen. Clinical response was defined as ≥1 New York Heart Association (NYHA) class improvement. Echocardiographic response was defined as LV end systolic volume reduction ≥15% and/or LVEF improvement ≥10% at 6-months. Results After ECGi guided CRT implantation, LVEF improved from 26±6% to 34±11% (both p<0.01) and NYHA class improved from 3.0±0.5 to 2.0±0.6 (p<0.01). Both clinical and echocardiographic response rates were 70%. ECGi approach resulted in better acute electrical resynchronization over BVP as measured by TAT reduction (40% vs 14%, p<0.01). Percentage of TAT reduction was found to be a strong predicator for echocardiographic response (AUC for ROC curve 0.91, 95% CI 0.78 – 1.00). A strong positive correlation between percentage TAT reduction and percentage LVEF improvement (Pearson R 0.70, p=0.001) was found. Conclusions ECGi guided CRT implantation in non-LBBB patients generates superior acute electrical resynchronization compared with BVP and is associated with favorable clinical and echocardiographic outcomes.