Long-Term Impact of Cardiac Resynchronization Therapy by Left Ventricular Septal Pacing

Abstract

Background: Left bundle branch area pacing (LBBAP) is considered to be an alternative modality to deliver cardiac resynchronization therapy (CRT). However, left bundle branch pacing and left ventricular septal pacing (LVSP) are characterized as left bundle branch area pacing. The long-term effect of only LVSP in patients with a CRT indication is still unknown.

Methods: Consecutive patients who met the CRT indication were retrospectively included. LVSP was determined during the procedure. New York Heart Association functional class, NT-proBNP (N-terminal pro-B-type natriuretic peptide), and echocardiographic and pacing parameters were assessed at implant and follow-up visit.

Results: A total of 40 consecutive patients with successful LVSP were included for analysis with a mean follow-up period of 29.4±16.2 months. The QRS complex in lead V₁ during LVSP featured a QS pattern (52.5%), Qr/qR pattern (30%), or rsR pattern (17.5%). LVSP significantly shortened QRS duration (from baseline 172.5±16.8 to 135.3±19.8 ms, P<0.001) with V₆ R-wave peak time of 96.4±9.6 ms. Left ventricular ejection fraction mproved from 26.7±7.4% at baseline to 38.8±16.1% (P<0.001) and a decrease in the LV end-diastolic diameter (67.9±9.8 versus 59.7±10.4 mm; P<0.001) during the follow-up. Echocardiographic response and superresponse were observed in 52.5% and 22.5% of patients, respectively. New York Heart Association functional class improved from 2.7±0.4 at baseline to 1.9±0.6 (P<0.01) and NT-proBNP concentration decreased significantly (4544±975 versus 2353±1225 pg/mL; P<0.001). No procedure-related complications occurred during the implantation procedure.

Conclusions: LVSP is clinically feasible and safe in patients undergoing CRT. LVSP appears to be an alternative CRT pacing strategy with suboptimal ventricular resynchronization.

Keywords: biventricular pacing; cardiac resynchronization therapy; left bundle branch area pacing; left bundle branch pacing; left ventricular septal pacing.