Materials and Methods:
This is a prospective, single center, observational study conducted in our institute from march 2019 to march 2020 after getting approval from the institutional ethical committee. Patients provided written informed consent regarding LBBP as a non-standard approach. All patients aged between 80-89 years who were planned for permanent pacemaker implantation for symptomatic bradyarrhythmia and those with left bundle branch with low left ventricular ejection fraction (LVEF) requiring cardiac resynchronization therapy (CRT) were included in the study. Patients who refused for the therapy were excluded.
Intracardiac electrograms along with 12 lead electrocardiography (ECG) were continuously recorded (Workmate Claris, Abbott, Plymouth, MN). The procedure was done as described by Huang et al4 using C315 sheath and 3830 SelectSecuretm lead (Medtronic, Minneapolis, MN). In brief, the pacing lead was placed deep inside the septum at a site 1-1.5cm below the His bundle (fig 1A). LB capture was confirmed by presence of right bundle branch delay pattern (qR in lead V1) along with any one of the following criteria (a) presence of LB potential (b) Non-selective to selective LB capture during unipolar threshold measurement (fig 1B) (c) short and constant peak left ventricular activation time (pLVAT) <80ms. (d) programmed stimulation from the pacing lead to show change in QRS morphology, duration and axis
Patients baseline characteristics and indications for pacing were documented. ECG, electrophysiological and pacing parameters were recorded. LVEF was measured by modified simpson’s method. Follow up was done in device clinic at the end of 15 days, one month and subsequently every 2 months.