The Postoperative S Wave in Lead V₅ and/or V₆ Predicts Better Clinical Outcomes in Heart Failure Patients With Left...

S wave in lead V_5/6 has been reported as a marker indicated for successful left bundle branch (LBB) capture. This study aimed to evaluate the value of the S wave in lead V_5/6 in predicting the long-term clinical outcomes in heart failure (HF) patients treated with left bundle area pacing (LBBAP).

Consecutive HF patients receiving LBBAP were prospectively enrolled and followed at least 2 years. ECG were analyzed to identify the S wave in lead V_5/6. The composite end point was all-cause mortality, HF hospitalization, and malignant ventricular arrhythmias. Non-response to LBBAP delivered cardiac resynchronization therapy (CRT) was defined as left ventricular ejection fraction improvement <5% at 6 months after implantation.

A total of 57 patients were included with the mean age of 59.90 ± 12.57 years and 39 (68.42%) males. S wave in V_5/6 was observed in 38 patients. During a mean follow up of 29.84 ± 12.51 months, Kaplan-Meier curves showed a 77.8% reduction in risk of composite end point for V_5/6 with S (HR 0.222; 95% CI 0.065, 0.756; log-rank, p = 0.0069). Multivariate Cox regression analysis revealed that V_5/6 with S was associated with a lower risk of the composite end point by 69.0% (adjusted HR 0.31; 95% CI 0.09, 1.05; p = 0.041). The non-response rate of LBBAP was 22.58% in V_5/6 with S and 58.82% in V_5/6 without S (p = 0.012).

S wave in lead V₅ and/or V₆ after LBBAP predicts better clinical outcomes, and has a better response rate of LBBAP for CRT in HF patients.