Objective To explore the left ventricular (LV) electrical activation pattern in heart failure (HF) and its implication to cardiac resynchronization therapy (CRT).
Design Observational study
Setting University Teaching Hospital
Patients 23 optimally treated HF patients with New York Heart Association class III, QRS duration >120ms and LV ejection fraction <35%.
Interventions The LV endocardial activation pattern and total activation time (Tat) was determined by non-contact mapping and the LV mechanical dyssynchrony 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.
Main outcome measures Correlation between electrical and mechanical dyssynchrony; volumetric responder to CRT at 3 months; HF hospitalization or death by Kaplan Meier analysis
Results 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 (80%) in Type II and 2 (25%) in Type I were CRT responders (p=0.01). After 487 ± 447 days, patients with Type II pattern had significantly lower risk of HF hospitalization or death than those with Type I (Log rank GBP q2= 5.25; p=0.02).
Conclusion Patients with Type II LV endocardial activation pattern had a more favorable echocardiographic and clinical response to CRT than those with Type I pattern.
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