Key result
Postimplant QRS duration >160 ms linked to ~7.2-fold higher odds of symptomatic CRT response.
Why the study?
QRS duration and axis as predictors of response to cardiac resynchronization therapy in chronic heart failure with reduced LVEF were evaluated to reduce non-responder rates.
Cohort (n=42)
No
Odds Ratio: 7.2 (95% CI 1.24–41.94)
p-value: p=0.038
Postimplantation QRS >160 ms was associated with symptomatic CRT response; hypothesis-generating for QRS axis, needs prospective validation before practice change.
BACKGROUND: The aim of the study was to evaluate QRS duration and axis as predictors of response to cardiac resynchronization therapy (CRT) in order to reduce the proportion of non-responders. METHODS: Retrospective single-center study including 42 CRT recipients, with left bundle branch block (LBBB), left ventricular ejection fraction (LVEF) < 40%, in New York Heart Association (NYHA) class ≥ II. Response to CRT was declared as NYHA class improvement ≥ 1 (symptomatic) and LVEF improvement by ≥ 10% (echocardiographic) > 6 months post implantation. RESULTS: Symptomatic responders had longer pre- (172.3 ± 17.9 vs. 159.0 ± 18.3 ms; p = 0.027) and postimplantation (157.2 ± 24.1 vs. 136.7 ± 23.2 ms; p = 0.009) QRS duration. Preimplantation QRS < 150 ms predicted poor response (odds ratio [OR] for response vs. lack of response 0.04; 95% confidence interval [CI] 0.001-0.74). Predictors of symptomatic response included: postimplantation QRS > 160 ms (OR 7.2; 95% CI 1.24-41.94), longer QRS duration before (OR for a 1 ms increase 1.04, 95% CI 1.00-1.08) and post implantation (OR for a 1 ms increase 1.04; 95% CI 1.01-1.07). Area under the curve (AUC) for pre- and postimplantation QRS duration was 0.672 (95% CI 0.51-0.84) and 0.727 (95% CI 0.57-0.89), respectively, with cut-off points of 178.5 ms and 157 ms. For post implantation QRS axis, AUC was 0.689 (95% CI 0.53-0.85), with cut-off points of -60.5° or -38.5°. Preimplantation QRS axis was the only predictor of echocardiographic response (OR 0.98; 95% CI 0.96-1.00), with AUC of 0.693 (95% CI 0.54-0.85) and a threshold of -36°. CONCLUSIONS: Marked pre- and postimplantation QRS prolongation and preimplantation negative QRS axis deviation are moderate predictors of response to CRT.
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Fabiszak et al. (2013) conducted a cohort in Chronic heart failure with reduced left ventricular ejection fraction and left bundle branch block (n=42). Postimplantation QRS duration > 160 ms vs. Postimplantation QRS duration ≤ 160 ms was evaluated on Symptomatic response to CRT (NYHA class improvement ≥ 1) (OR 7.2, 95% CI 1.24-41.94, p=0.038). Postimplantation QRS duration >160 ms strongly predicted symptomatic response to cardiac resynchronization therapy (OR 7.2), while negative preimplantation QRS axis predicted echocardiographic response.
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