Abstract Body (Do not enter title and authors here): Introduction
Echocardiography-derived septal strain patterns can serve as indicators of the progressive left ventricular (LV) remodeling caused by left bundle branch block (LBBB)-induced dyssynchrony.
Research question
What is the prognostic value of these strain patterns in predicting volumetric response and clinical outcome in patients undergoing cardiac resynchronization therapy (CRT)?
Methods
In this prospective multicenter study, CRT candidates from 5 centres received pre-implantation echocardiographic assessments with speckle-tracking strain analysis. Dyssynchrony was quantified through the analysis of septal strain curves, categorizing patients into 5 distinct strain patterns, denoted as Stage-0 through Stage-4 (Fig. 1). Extent of reverse remodeling was determined at 1 year. The pre-defined endpoint was death from any cause.
Results
A total of 267 patients were included (66±11 years, 69% males, 90% LBBB, LV ejection fraction [EF] 30±7%). CRT yielded a progressive reverse remodeling: minimal in Stage-0 patients (ΔLV end-systolic volume (ESV) -9±21ml; ΔLVEF +4±8%) and substantial in Stage-4 patients (ΔLV ESV -85±54ml; ΔLVEF +20±9%) (ANOVA p<0.001 for both) (Fig. 2). Median follow-up was 49 months. Stage-0 patients showed the least favorable outcome (log rank p=0.002), while subsequent stages exhibited progressively more favorable outcome (log rank p=0.045) (Fig. 3). The occurrence of death decreased incrementally according to the strain stages, with corresponding hazard ratios of Stage-1 through -4: 0.61 (95% CI 0.25-1.50), 0.26 (95% CI 0.10-0.68), 0.29 (95% CI 0.11-0.77), and 0.13 (95% CI 0.04-0.51) compared to Stage-0 (all p<0.001). After adjusting for baseline LVEF, ischemic heart disease, and the presence of an ICD, strain staging maintained a significant association with a reduced risk of adverse outcomes (hazard ratio 0.69 (95% CI 0.51-0.92), p<0.001).
Conclusions
Septal strain patterns show a clear association with the extent of reverse remodeling and outcome in CRT-treated patients. The proposed strain staging classification offers valuable insights into the pathophysiology of LBBB-induced LV remodelling and may assist in the identification of candidates who stand to gain the most from CRT implantation.