Right Atrial Pacing Impairs Cardiac Function During Resynchronization Therapy

OBJECTIVES We aimed to compare the hemodynamic effects of right-atrial-paced (DDD) and right-atrialsensed (VDD) biventricular paced rhythm on cardiac resynchronization therapy (CRT). BACKGROUND Cardiac resynchronization therapy improves hemodynamics in patients with severe heart failure and left ventricular (LV) dyssynchrony. However, the impact of active right atrial pacing on resynchronization therapy is unknown. METHODS Seventeen CRT patients were studied 10 months (range: 1 to 46 months) after implantation. At baseline, the programmed atrioventricular delay was optimized by timing LV contraction properly at the end of atrial contraction. In both modes the acute hemodynamic effects were assessed by multiple Doppler echocardiographic parameters. RESULTS Compared to DDD pacing, VDD pacing resulted in much better improvement of intraventricular dyssynchrony assessed by the septal-to-posterior wall motion delay (VDD 106 83 ms vs. DDD 145 95 ms; p 0.001), whereas the interventricular mechanical delay (difference between onset of pulmonary and aortic outflow) did not differ (VDD 20 21 ms vs. DDD 18 17 ms; p NS). Furthermore, VDD pacing significantly prolonged the rate-corrected LV filling period (VDD 458 123 ms vs. DDD 371 94 ms; p 0.0001) and improved the myocardial performance index (VDD 0.60 0.18 vs. DDD 0.71 0.23; p 0.01). CONCLUSIONS Our findings suggest that avoidance of right atrial pacing results in a higher degree of LV resynchronization, in a substantial prolongation of the LV filling period, and in an improved myocardial performance. Thus, the VDD mode seems to be superior to the DDD mode in CRT patients. (J Am Coll Cardiol 2005;45:1482–7) © 2005 by the American College of ublished by Elsevier Inc. doi:10.1016/j.jacc.2005.01.033