Study population
The inclusion criteria were as follows: New York Heart Association functional class II to III, LV ejection fraction (LVEF) of 35% or less, prolonged QRS width (≥150 ms), and sinus rhythm with intact atrioventricular (AV) conduction (PR interval ≤ 250 ms). The exclusion criteria were persistent or permanent atrial fibrillation, recent (within 40 days) myocardial infarction, cardiac surgery, or coronary revascularization within three months or scheduled within the following 12 months, intravenous inotropic support within 30 days, and planned heart transplantation within the next 12 months. We prospectively enrolled 32 consecutive patients fulfilling the current class I/IIa indications for the implantation of a CRT device.13