Six-month echocardiographic follow-up of left bundle branch optimized cardiac resynchronization therapy (LOT-CRT) versus traditional CRT

Abstract Background Traditional cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) may be less effective in patients with nonspecific intraventricular conduction delay (NIVCD). Left bundle branch area pacing (LBBAP) combined with LV coronary venous lead pacing (i.e., LOT-CRT), may be more effective in these patients. Purpose We aimed to assess the six-month echocardiographic response of LOT-CRT in those with left bundle branch block (LBBB) versus IVCD and compare the response to a contemporary propensity-matched BVP cohort. Methods Patients undergoing conventional CRT indications were enrolled. Echocardiographic parameters, including absolute % change in LV ejection fraction (LVEF) and relative % change in LV end-systolic volume (LVESV), were assessed prior to implantation and 6 months postoperatively. The BVP cohort was from an independent (contemporary) study of CRT indicated patients, selected according to 1:1 propensity score matching. The propensity model was a logistic regression that included age, sex, ischemic cardiomyopathy, QRS duration, conduction disease, and LVESV as predictors. For the LOT-CRT patients, conduction system pacing (CSP) capture type was adjudicated, and patients were further divided into "successful LOT-CRT" (i.e. LBBAP capture subtype) and "DOT-CRT" (i.e. deep septal capture subtype; no terminal r/R’ in V1). Results Baseline demographics of LOT-CRT cohort (N=34) were (mean); age 64 y, female 38%, NIVCD 47%, LBBB 53%, ICM 21%, QRSd 175ms and LVEF 27.6%. LOT-CRT patients had a larger absolute increase in LVEF (16.1% vs 4.9%; p<0.01) and a larger percent change in LVESV (-43.5% vs -19.5%, p<0.01) compared to the matched BVP patients (see Figure top green lines). Sub-classification into LBBB or NIVCD showed no differences in either LVEF or LVESV change for the LOT-CRT cohort, while the BVP cohort showed significantly lower LVEF response in NIVCD patients (see Figure). Among the LOT-CRT patients, no statistically significant difference was found between those with "successful LOT-CRT" (N=18) and "DOT-CRT" (N=15) in LVEF change (13.5% vs 20.7%; p=0.13) or LVESV change (-42.6% vs -46.2%; p=0.67). Moreover, multivariate analysis of LVEF and LVESV improvement in response to LOT-CRT showed no significant effects within the different conduction disease types (p=0.90 and p=0.75, respectively) or CSP capture types (p=0.74 and p=0.33, respectively). Conclusions Compared to a matched historical BVP cohort, LOT-CRT patients showed a significantly larger improvement in LVEF and in LVESV after 6 months in both LBBB and IVCD patients suggesting that placement of an LBBAP lead rather than a traditional RV lead may augment response in CRT patients. In this analysis, the presence of a terminal r/R’ in V1-ECG in LOT-CRT recipients was not a prerequisite for the larger echocardiographic response observed.BVP vs LOT-CRT response in LBBB or NIVCD