Electromechanical correlates at the atrio-ventricular (AV) level remain poorly investigated in patients with dyssynchronised systolic heart failure (HF). The aim of the present study was to assess the exact prevalence and the electrical determinants of AV mechanical dyssynchrony in the left heart, in this patient population.

Prospective observational study of 49 HF patients with stable sinus rhythm and wide QRS complex (mean: 160±19ms), all scheduled for CRT device implantation. 12% were in NYHA class II, 85% in NYHA class III. Mean PR intervall was 200±40ms, mean LV ejection fraction = 26±5%. Left AV dyssynchrony (LAVD) was definited as LV filling time (LVFT) <40% RR interval on transmitral flow at doppler-echocardiography. PR interval, P wave duration, P'R interval (interval between P wave termination of and QRS onset), QRS duration and QRS morphology (type of bundle branch block) were investigated as possible predictors of LAVD. Correlations between LVFT and ECG intervals were assessed by linear regression.

LAVD was present in 13 patients (26,5). P wave duration, PR interval and QRS morphology had no predictive value for LAVD. In contrast, a significant correlation was observed between LVFT and P'R interval (P<0,005) and QRS duration (p=0,001).

Evidence of resting LAVD is observed in 26,5% patients with a CRT guideline indication. QRS duration and the P'R interval but not the PR interval are significant determinants of LAVD. These data may be of practical importance for optimal programming of CRT devices.