Abstract
Background Recent studies have demonstrated that response to cardiac resynchronization therapy (CRT) is related to the presence of left ventricular (LV) dyssynchrony before implantation. A cutoff-value for LV dyssynchrony of 65 ms has been proposed, but this value has not been tested in prospective cohorts. Methods Two hundred and twenty consecutive patients (172 male, 60% ischemic cardiomyopathy) undergoing CRT were included. Clinical and echocardiographic parameters were assessed at baseline and after 6 months of CRT. Clinical improvement was defined as an improvement in 1 or more NYHA class and increase ≥ 25% in walking distance. Echocardiographic response was defined as a decrease in LV end-systolic volume ≥ 15%. LV dyssynchrony was assessed with tissue Doppler imaging (TDI) and calculated as the maximum time delay between the peak systolic velocities of 4 opposing basal walls. Results At 6 months follow-up, 143 patients (65%) showed clinical response to CRT. Responders and non-responders had comparable baseline characteristics, except for more LV dyssynchrony (93 ± 49 ms vs. 57 ± 43 ms), longer QRS duration (159 ± 31 ms vs. 142 ± 30 ms), larger LV volumes and lower LV ejection fraction (24 ± 7% vs. 26 ± 7%, all p < 0.05) in responders. Multivariate analyses showed that LV dyssynchrony was the only independent predictor for clinical response to CRT (Table ). LV dyssynchrony of ≥ 65 ms predicted clinical response to CRT with a sensitivity of 90% and a specificity of 74%. Furthermore, LV dyssynchrony of ≥ 65 ms predicted echocardiographic response at 6 months with a sensitivity of 76% and a specificity of 64%. Conclusion LV dyssynchrony ≥ 65 ms, as assessed with TDI, is a strong predictor of clinical and echocardiographic response to CRT in patients with moderate to severe heart failure. Multivariate analysis predicting clinical response to CRT
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