Determinants of mid-term response to left bundle branch pacing in heart failure patients with left bundle branch block.

Abstract

Background: Response to left bundle branch pacing (LBBP) varies in patients with left bundle branch block (LBBB). We aimed to investigate whether clinical response to LBBP was associated with ventricular electricity, volume and myocardial glucose uptake in non-ischæmic cardiomyopathy (NICM) patients with LBBB.

Methods: Consecutive NICM patients who received LBBP with successful LBBB correction were prospectively enrolled. Electrocardiography QRS duration (QRSd) and echocardiographic left ventricular (LV) volume were measured. Myocardial glucose uptake was accessed by ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography. The standardized uptake value (SUV) and target to background ratio (TBR) of ¹⁸F-FDG uptake were analyzed.

Results: After 6 months of LBBP, twenty-four patients responded to LBBP (LV end-systolic volume reduction (ΔLVESV%): 31.7±18.7%) and twelve did not (ΔLVESV%: 1.9±1.3%) though comparable QRSd reduction (ΔQRSd) by LBBP were observed (ΔQRSd by 55.57±16.93ms in the response group vs 57.40 ±17.69ms in the non-response group, p=0.780). While the univariate logistic regression model identified risk factors (baseline QRSd, R-wave peak time, LV end-diastolic volume (LVEDV), LVESV, TBRmean-septum, SUVmax-septum, p<0.05) for non-responders, only LVEDV (OR 1.32 (1.18-1.48, p=0.025) and TBRmean-septum (OR 0.85 (0.783-0.931, p=0.005) were predictors of non-responders in the multivariate logistic regression model.

Conclusions: LBBP significantly shortened QRSd in NICM patients with LBBB, however, 6-month clinical response to LBBP varied with 33% non-responders. Larger LVEDV and more depressed glucose uptake were associated with higher odds of LBBP non-responders than the electrical variables of QRSd and ΔQRSd. Besides ventricular electrical desynchrony, volume and myocardial metabolism should be considered for choice of pacing therapy (Public registration: ChiCTR2300070954).