The association between paced left ventricular activation time and cardiac reverse remodeling in heart failure patients with left bundle branch block

Introduction: The association between paced LVAT and cardiac structure and function at baseline, as well as whether longer LVAT is associated with worse cardiac reverse remodeling in patients with heart failure (HF) and left bundle branch block (LBBB) has not been well investigated. The purpose of this study is to investigate the association between paced LVAT and baseline echocardiographic parameters and cardiac reverse remodeling at follow-up. Methods: Patients with HF and LBBB receiving successful left bundle branch pacing (LBBP) from June 2018 to April 2023 were enrolled and grouped based on paced LVAT. NT-proBNP and echocardiographic parameters were recorded during routine follow-up. The relationships between paced LVAT and echocardiographic parameters at baseline and follow-up were analyzed. Results: Eighty-three patients were enrolled (48 males, aged 65 +/- 9.8, mean LVEF 32.1 +/- 7.5%, mean LVEDD 63.0 +/- 8.5 mm, median NT-proBNP 1057[513-3158] pg/mL). The paced QRSd was significantly decreased (177 +/- 17.9 vs. 134 +/- 18.5, p < .001) and median paced LVAT was 80[72-88] ms. After a median follow-up of 12[9-29] months, LVEF increased to 52.1 +/- 11.2%, LVEDD decreased to 52.6 +/- 8.8 mm, and NT-proBNP decreased to 215[73-532]pg/mL. Patients were grouped based on paced LVAT: LVAT < 80 ms (n = 39); 80 <= LVAT < 90 ms (n = 24); LVAT >= 90 ms (n = 20). Patients with longer LVAT had larger LVEDD and lower LVEF (LVEDDbaseline: p < .001; LVEFbaseline: p = .001). The difference in LVEF6M was statistically significant among groups (p < .001) and patients with longer LVAT had lower LVEF6M, while the difference in LVEF1Y was not seen (p = .090). There was no significant correlation between Delta LVEF6M-baseline, Delta LVEF1Y-6M and LVAT respectively (Delta LVEF6M-baseline: p = .261, r = -.126; Delta LVEF1Y-6M: p = .085, r = .218). Conclusion: Long paced LVAT was associated with worse echocardiographic parameters at baseline, but did not affect the cardiac reverse remodeling in patients with HF and LBBB. Those with longer LVAT required longer time to recover.