JACC March 3 , 2004 ABSTRACTS-Cardiac Arrhythmias 131 A Cardiac Arrhythm ias

Background: Biventricular pacing (CRT) has been shown to improve symptoms and exercise capacity in patients with heart failure and a wide QRS complex. Criteria for patient selection and lead positioning are essential for achieving clinical benefit. Methods and Results: Twenty-eight patients (20 males, 66±11 years) with ischemic and nonischemic cardiomyopathy and NYHA class III to IV heart failure and QRS duration >140 ms receiving CRT were assessed before and after pacing. Tissue Doppler echocardiography was performed using a 4-basal, 4-mid segmental model (4-and 2-chamber) to assess the time to peak systolic velocity (TS), and the time to peak myocardial displacement (TPMD). The septal posterior wall delay (SPWD) was measured by M-mode at the base in the parasternal long axis view. Tissue synchrony index (TSI) was used to show the ventricular segmental contraction delay. Patients with LBBB exhibited 3 different patterns of delay by TSI including delay involving the apical septal (n=5), the basal and mid inferior (n=4) and the basal lateral wall (n=16). Patients with RBBB demonstrated delay involving the septum (n=3). The standard deviation of time to TS and TPMD between segments was used as an index of synchronization. There was significant improvement of TSI after pacing.