Introduction: Regional myocardial contraction heterogeneity with activation delay (AD) is observed by echocardiography among patients with heart failure (HF). It is never been investigated whether there is an association of regional AD among HF patients having narrow QRS and long-term outcomes in a prospectively followed population.
Hypothesis: AD by tissue-Doppler cross correlation analysis (CCA) is related to long-term outcome in Echocardiography Guided Cardiac Resynchronization Therapy (Echo-CRT) trial patients not receiving CRT.
Methods: In Echo-CRT trial HF patients with narrow QRS (<130ms) having moderate to severe symptoms despite optimized medical therapy were included and randomized to CRT-On or CRT-Off in 1:1 fashion. At baseline, CCA could be performed on 404 of the 405 patients originally included randomized to CRT-Off. The primary composite outcome of the study was death or hospitalization due to HF and secondary outcome was hospitalization due to HF.
Results: Restricted cubic spline curve (figure) showed that patients with increased dyssynchrony by CCA had poorer primary outcome. A cut-off of 90ms was determined from the figure. Among the 404 patients, 293 (73%) had lesser AD (< 90ms) by CCA and 111 (27%) had longer AD (≥ 90ms) by CCA. There were no significant difference of baseline characteristics among the two groups. For the primary composite outcome, presence of longer AD (≥ 90ms) by CCA at baseline was associated with poorer prognosis with borderline significance (adjusted HR 1.52, 95% CI 0.99-2.34, p=0.054). However, for the secondary outcome, presence of longer AD (≥ 90ms) by CCA was significantly associated with increased risk of HF hospitalization (adjusted HR 1.60, 95% CI 1.01-2.53, p=0.04).
Conclusions: Assessment of AD by CCA in HF patients with narrow QRS duration can be of prognostic significance.