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