[Effect of the left ventricular pacing site on echocardiographic parameters of ventricular dyssynchrony in patients receiving cardiac resynchronization therapy].

INTRODUCTION AND OBJECTIVES Cardiac resynchronization therapy has been shown to be an option in the treatment of patients with congestive heart failure. The current indication for this treatment is based on clinical and electrocardiographic criteria, although echocardiography has also been shown to be a useful tool for the diagnosis of ventricular dyssynchrony. The aim of this study was to assess left ventricular dyssynchrony by echocardiography and to evaluate the effect of the stimulation site on the magnitude of resynchronization. PATIENTS AND METHOD We studied 25 patients with biventricular stimulation (left ventricular lead located in a lateral position in 13 patients, and in an anterior position in 12). A complete echo-Doppler evaluation, including left ventricular ejection fraction, ventricular diameters and parameters of inter- and intraventricular dyssynchrony, was performed before implantation and 3 months after the procedure, with the device connected and disconnected. RESULTS Left ventricular ejection fraction increased significantly from 23.7 (6.5) to 27.8 (5.5) (P=.007) at 3 months. In the group as a whole, biventricular pacing was associated with a significant decrease in all intraventricular dyssynchrony parameters (septal-to-lateral wall motion delay and septal-to-posterior wall motion delay). This decrease in septal-to-posterior wall motion delay and septal-to-lateral wall motion delay was significantly greater in patients with the electrode implanted in the lateral position (58.1 ms vs 118 ms; P=.02) than with the lead in the anterior position (39.5 ms vs 86.5 ms; P=.04). Three patients, all with the electrode in an anterior location, were considered non-responders. CONCLUSIONS Left lateral free wall stimulation provided significantly better intraventricular resynchronization compared to stimulation at an anterior site. Echocardiography is a useful tool to evaluate changes in intra- and interventricular synchrony related to the pacing site.