Effect of left ventricular endocardial activation pattern on echocardiographic and clinical response to cardiac resynchronization therapy

Abstract

To explore the left ventricular (LV) electrical activation pattern in heart failure (HF) and its implication to cardiac resynchronization therapy (CRT). Observational study at the University Teaching Hospital. 23 optimally treated patients with HF with New York Heart Association class III, QRS duration >120 ms and LV ejection fraction <35%. The LV endocardial activation pattern and total activation time (Tat) was determined by non-contact mapping and the LV mechanical dys-synchrony was determined by standard deviation (Ts-SD) and maximal difference (Ts-diff) of time to peak systolic contraction (Ts) among 12 LV segments using tissue Doppler imaging before receiving CRT. Correlation between electrical and mechanical dys-synchrony; volumetric responder to CRT at 3 months; HF hospitalisation or death by Kaplan-Meier analysis. Homogenous (type I, n = 8) and presence of conduction block (type II, n = 15) patterns were identified. Significant correlation between Tat and Ts-SD/Ts-diff was noted only in type II (r = 0.73/0.56, p = 0.002/0.03). Ts-SD and Ts-diff in type II were significantly longer than type I. 12 patients in type II and 2 in type I were CRT responders (p = 0.01). After 487 (447) days, patients with type II pattern had significantly lower risk of HF hospitalisation or death than those with type I (log rank chi(2) = 5.25; p = 0.02). Patients with type II LV endocardial activation pattern had a more favourable echocardiographic and clinical response to CRT than those with type I pattern.