Outcomes of the left bundle branch area pacing as a first-line therapy for cardiac resynchronization therapy. Single center experience

Cardiac resynchronization therapy (CRT) is a well-proven non-surgical treatment option in patients with symptomatic congestive heart failure with left ventricular ejection fraction (LVEF) ≤35% and left bundle branch block (LBBB). Left bundle branch area pacing (LBBAP) is novel and promising pacing modality which may lead to better clinical and echocardiographic response for resynchronization therapy. According to latest guidelines, biventricular CRT still the first-line therapy in patients with heart failure and LBBB. We present outcomes from the Central Asian single-center registry in LBBAP as first-line option for cardiac resynchronization therapy.

Inclusion criteria: QRS duration more than 150 ms, LVEF<35%, symptomatic heart failure with NYHA II-III class despite 3-months guideline-directed medical therapy and LBBB. We collected baseline data including previous medical history, baseline ECG and TTE characteristics, pacing parameters, procedural outcomes. Mean follow-up 9,2±3,8 months with monitoring of 12-lead ECG and TTE with device telemetry. In patients with suboptimal criteria of left bundle branch area pacing or partial correction of conduction disorder, additional coronary sinus lead implantation was performed to obtain left bundle branch area pacing optimized CRT (LOT-CRT).

Total 84 patients underwent CRT implantation utilizing LBBAP. 16 (19%) patients crossovered to LOT-CRT. Mean age 61,5±11,38 years. 38 (45%) had ischemic genesis of heart failure. Mean procedure time 120,8±40,1 min and mean fluoroscopy duration was 23,4±15,2 min. LVEF increased from 27,6±5,8% to 40,25±7,2%. LV end-diastolic volume decreased from baseline 205,95±65,14ml to 147,61±52,3ml. LV end-systolic volume decreased from baseline 149,8±56,8ml to 90,7±42,2ml. Fusion between LBBAP and native conduction with recruitment of RBB resulted in significant narrowing of QRS from 172,2±29,3 ms to 118,9±10,6 ms. LBBAP showed pacing threshold of 0,75 V±0,4, mean R-wave amplitude 12,5±5,4 mV and unipolar pacing impedance 645±185 Ohm. Super-response was defined as improvement of LV EF >45%, and this condition was observed in 18 cases (21%). 13 (21%) patients were defined as non-responders (7 patients) and non-progressors (6 patients). Most of this patients had ischemic cardiomyopathy (9 patients), and severe dilatation of LV (LV EDV more than 230 ml).

CRT utilizing left bundle branch area pacing may be used as a first line option in patients with heart failure and LBBB with high success rate and favorable echocardiographic outcomes. Patients with ischemic CMP tends to have less improvement in structural remodeling, however in this cohort of patients additional CS lead with sequential conduction system pacing and epicardial LV pacing resulting in better electrical resynchronization. Further investigations required to define the role of conduction system pacing as a first line modality in lieu pf conventional biventricular pacing.  

LBB-CRT and LOT-CRT in LAO30 view