Echocardiographic response to cardiac resynchronization therapy was greatest in patients with LBBB and QRS duration ≥150 ms (12 ± 12% change in ejection fraction) compared to other groups (p<0.0001).
Cohort (n=496)
No
Does QRS morphology and duration predict echocardiographic response and survival in patients receiving cardiac resynchronization therapy?
In patients receiving CRT, baseline QRS morphology (presence of LBBB) is a more important determinant of echocardiographic response than QRS duration.
p-value: p=< 0.0001
OBJECTIVES: The goal of this study was to examine the relative impact of QRS morphology and duration in echocardiographic responses to cardiac resynchronization therapy (CRT) and clinical outcomes. BACKGROUND: At least one-third of all patients treated with CRT fail to derive benefit. Patients without left bundle branch block (LBBB) or patients with smaller QRS duration (QRSd) respond less or not at all to CRT. METHODS: We retrospectively assessed baseline characteristics, clinical and echocardiographic response, and outcomes of all patients who received CRT at our institution between December 2003 and July 2007. Patients were stratified into 4 groups according to their baseline QRS morphology and QRSd. RESULTS: A total of 496 patients were included in the study; 216 (43.5%) had LBBB and a QRSd ≥150 ms, 85 (17.1%) had LBBB and QRSd <150 ms, 92 (18.5%) had non-LBBB and a QRSd ≥150 ms, and 103 (20.8%) had non-LBBB and QRSd <150 ms. Echocardiographic response (change in ejection fraction) was better in patients with LBBB and QRSd ≥150 ms (12 ± 12%) than in those with LBBB and QRSd <150 ms (8 ± 10%), non-LBBB and QRSd ≥150 ms (5 ± 9%), and non-LBBB and QRSd <150 ms (3 ± 11%) (p < 0.0001). In a multivariate stepwise model with change in ejection fraction as the dependent variable, the presented classification was the most important independent variable (p = 0.0003). Long-term survival was better in LBBB patients with QRSd ≥150 ms (p = 0.02), but this difference was not significant after adjustment for other baseline characteristics (p = 0.15). CONCLUSIONS: QRS morphology is a more important baseline electrocardiographic determinant of CRT response than QRSd.
“The key findings of this study can be summarized as follows: 1) non-LBBB, as the baseline ECG morphology before CRT implantation, is much more prevalent in real-world practice than in randomized clinical trials; 2) echocardiographic and clinical response to CRT is determined by baseline QRS morphology in the first place and to a lesser degree by QRSd; 3) event-free survival (from death, heart transplantation, or LVAD) is better in CRT-treated patients with baseline LBBB and QRS ≥150 ms. However, this difference is not significant after adjusting for other baseline characteristics.”
Dupont et al. (2012) conducted a cohort in Heart failure requiring cardiac resynchronization therapy (n=496). Left bundle branch block (LBBB) and QRS duration ≥150 ms vs. Other QRS morphology and duration combinations was evaluated on Echocardiographic response (change in ejection fraction) (p=< 0.0001). Echocardiographic response to cardiac resynchronization therapy was greatest in patients with LBBB and QRS duration ≥150 ms (12 ± 12% change in ejection fraction) compared to other groups (p<0.0001).
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