Background: Pulsed-wave tissue Doppler imaging (TDI) was shown to predict short-term left ventricular functional recovery after cardiac resynchronization therapy (CRT). However, few data are available regarding the baseline cardiac asynchrony and clinical outcome after CRT. Therefore, we aimed to investigate the prognostic value of pre-CRT cardiac asynchrony on clinical outcome after CRT.
Methods: The study population consisted of 48 consecutive patients with moderate to severe heart failure and a wide QRS complex undergoing implantation of biventricular pacemaker. Cardiac asynchrony was assessed at pulsed-wave TDI from measurements of regional electromechanical coupling times in basal segments of both ventricles (Sum asynchrony). Clinical end-points were cardiac mortality and hospitalization for worsening heart failure.
Results: During a follow-up period of 970+/-319 days, clinical end-point (9 deaths, 15 hospitalizations) occurred in 24 patients (clinical nonresponders). At baseline, responders showed higher asynchrony than nonresponders (153+/-57 ms vs. 103+/-58 ms, p<0.01). Sum asynchrony of >98 ms showed the highest accuracy (AUC=0.80, sensitivity 92%, specificity 67%) to identify responders. In contrast, baseline NYHA class, conventional echo-Doppler indices and QRS complex duration were similar in both groups. Eight end-point events (3 deaths) occurred in 30 patients with significant Sum asynchrony (>98 ms) as compared to 16 events (6 deaths) in 18 patients with smaller Sum asynchrony (27% vs. 89%; HR 0.14; 95% CI 0.04 to 0.46; p<0.001). Favorable clinical outcome was associated with larger left ventricular functional recovery at 2 years follow-up (p<0.001).
Conclusions: TDI-derived index of baseline intra- and interventricular asynchrony appears to predict long-term clinical outcome after CRT.