Confirmed LBB capture conferred 7.4-fold higher odds of super-response, with super-responders showing greater LV activation time reductions (mean difference 15.2 ms; P=0.015).
Case-Control (n=20)
Does confirmed left bundle branch capture during LBBAP improve electrical resynchronization and predict super-response in patients with nonischemic cardiomyopathy?
In patients with non-ischemic cardiomyopathy, super-response to LBBAP is driven by superior electrical resynchronization, with confirmed left bundle branch capture strongly predicting optimal clinical outcomes.
Effect estimate: Mean difference 15.2 ms (95% CI 3.4-27.1)
p-value: p=0.015
BACKGROUND: Left bundle branch area pacing (LBBAP) is an emerging alternative to biventricular pacing for cardiac resynchronization therapy (CRT), but variability in response remains poorly understood. OBJECTIVE: This study aimed to assess differences in cardiac activation between super-responders and partial responders to LBBAP and identify electrophysiological predictors of response using noninvasive electrocardiographic imaging. METHODS: Patients with nonischemic cardiomyopathy and left bundle branch (LBB) block (QRS >130 ms) who underwent LBBAP were enrolled. 10 super-responders (≥20% improvement in left ventricular LV ejection fraction) and 10 partial responders (<10% improvement) were matched 1: 1. electrocardiographic imaging (CardioInsight, Medtronic) was performed during intrinsic rhythm (CRT-off) and during unipolar pacing (CRT-on) at 2 V and 0. 4 ms. Changes in biventricular total activation time, LV activation time (LVtat), and ventricular electrical uncoupling were assessed. RESULTS: Compared with partial responders, super-responders exhibited significantly greater reductions in LVtat (mean difference 15. 2 ms; 95% confidence interval 3. 4-27. 1; P =. 015) and biventricular total activation time (29. 0 interquartile range IQR 22. 0-39. 8 vs 16. 5 IQR 3. 0-27. 0 ms; P =. 045), alongside superior ventricular electrical uncoupling improvement (55. 7% IQR 39. 0-67. 0 vs 5. 8% IQR -18. 0 to 35. 5; P =. 014). Confirmed LBB capture was associated with substantially greater reduction in LVtat than LV septal capture (33. 2 ± 10. 4 ms vs 13. 1 ± 9. 9 ms; P <. 001) ; consequently, an LVtat reduction of ≥26. 86% predicted LBB capture with high accuracy (area under the curve 0. 96; 83% sensitivity; 100% specificity). Confirmed LBB capture conferred 7. 4-fold higher odds of super-response in Bayesian regression. CONCLUSION: Super-response to CRT via LBBAP was associated with greater reductions in ventricular dyssynchrony. The presence of definitive LBB capture emerged as a strong predictor of super-response, emphasizing the mechanistic relevance of conduction system engagement for optimizing CRT outcomes.
Shroff et al. (Sun,) conducted a case-control in Non-ischemic cardiomyopathy with left bundle branch block (n=20). Left bundle branch area pacing (LBBAP) vs. Partial responders was evaluated on Reduction in left ventricular activation time (LVtat) (Mean difference 15.2 ms, 95% CI 3.4-27.1, p=0.015). Confirmed LBB capture conferred 7.4-fold higher odds of super-response, with super-responders showing greater LV activation time reductions (mean difference 15.2 ms; P=0.015).