Preliminary ECHO-LBBp study: correlation of typical LBBB mechanical activation pattern by 2D strain echocardiography with acute GWE improvement in patients receiving LBBp or CRT
G Leventopoulos, E Papastavrou, M Bozika, N Fragakis, E Kallergis, V Vassilikos, D Tsiachris, E Repasos, S Nikolidakis, M Agelaki, D Leftheriotis, A Perperis, I Koniari, R Koros, P DavlourosAbstract
Background
A typical left bundle branch block (LBBB) mechanical activation pattern on two-dimensional strain echocardiography (2DSE) is associated with better response to cardiac resynchronization therapy (CRT) than an atypical pattern. We evaluated the acute change in global work efficiency (ΔGWE) after conventional biventricular CRT versus left bundle branch pacing (LBBp), and whether the baseline 2DSE pattern (typical vs atypical LBBB mechanics) influences this effect.
Methods
In this preliminary multicenter study (NCT06689111), adults with HFrEF (LVEF <35%, LBBB) and a CRT indication underwent either conventional BiV-CRT or LBBp per clinical decision. 2DSE was performed pre-implant and 24–48 hours post-implant to derive myocardial work indices. ΔGWE was calculated as the change from baseline to post-implant. Before implantation, patients were classified as having a typical or atypical LBBB mechanical activation pattern on 2DSE using published criteria (absence of any criterion defined an atypical pattern). Continuous variables were compared with t-test or Mann–Whitney U as appropriate; categorical variables with χ² or Fisher’s exact test. A multivariable linear regression evaluated ΔGWE with factors for pacing modality, LBBB pattern, their interaction, and prespecified covariates (age, sex, ischemic cardiomyopathy, atrial fibrillation, chronic kidney disease, prior MI).
Results
A total of 64 patients were enrolled; 6 underwent in-procedure crossover to LOT-CRT, leaving 58 patients in the per-protocol analysis (30 CRT, 28 LBBp). Baseline characteristics were similar (Table 1); no periprocedural complications occured. Overall, the acute ΔGWE was similar between CRT and LBBp (6.7±6.7% vs 5.7±5.7%, p=0.54). However, patients with a typical LBBB pattern had significantly greater ΔGWE than those with an atypical pattern in both pacing groups: in CRT (8.7±6.7% vs 3.1±5.2%, p=0.03) and in LBBp (8.2±5.5% vs 2.5±4.5%, p=0.007). Cross-technique comparisons stratified by pattern were not significant (CRT-typical vs LBBp-typical, p=0.81; CRT-atypical vs LBBp-atypical, p=0.77; Figure 1). Fluoroscopy time was significantly lower with LBBp than CRT (580.9 ± 465.3 vs 1303.9 ± 917.9 s; p<0.001; Figure 2). Total procedural time did not differ (6535.6 ± 2254.2 vs 6761.5 ± 1877.3 s; p=0.684; Figure 3). Neither pacing modality nor 2DSE pattern was associated with the magnitude of ΔGWE in univariate analyses. In multivariable regression (model R²=0.19, p=0.19), no independent predictor of ΔGWE was identified: pacing mode (p=0.32), LBBB pattern (p=0.93), and their interaction (p=0.88) were all non-significant.
Conclusion
LBBp achieved a similar acute improvement in GWE to conventional CRT, and baseline mechanical activation pattern (typical vs atypical LBBB) did not significantly modify this effect. These preliminary findings support LBBp as a physiological alternative to CRT; confirmation in larger cohorts with longitudinal follow-up is needed.