Effect of pacing chamber and atrioventricular delay on acute systolic function of paced patients with congestive heart failure

Background-Previous studies of pacing therapy for dilated congestive heart failure (CHF) have not established the relative importance of pacing site, AV delay, and patient heterogeneity on outcome. These variables were compar ed by a novel technique that evaluated immediate changes in hemodynamic fun ction during brief periods of atrial-synchronous ventricular pacing. Methods and Results-Twenty-seven CHF patients with severe left ventricular (LV) systolic dysfunction and LV conduction disorder were implanted with en docardial pacing leads in the right atrium and right ventricle (RV) and an epicardial lead on the LV and instrumented with micromanometer catheters in the LV, aorta, and RV. Patients in normal sinus rhythm were stimulated in the RV, LV, or both ventricles simultaneously (BV) at preselected AV delays in a repeating 5-paced/15-nonpaced beat sequence. Maximum LV pressure deri vative (LV+dP/dt) and aortic pulse pressure (PP) changed immediately at pac ing onset, increasing at a patient-specific optimal AV delay in 20 patients with wide surface QRS (180+/-22 ms) and decreasing at short AV delays in 5 patients with narrower QRS (128+/-12 ms) (P<0.0001). Overall,BV and LV pac ing increased LV+dP/dt and PP more than RV pacing (P<0.01), whereas LV paci ng increased LV+dP/dt more than BV pacing (P<0.01), Conclusions-In this population, CHF patients with sufficiently wide surface QRS benefit from atrial-synchronous ventricular pacing, LV stimulation is required for maximum acute benefit, and the maximum benefit at any site occ urs with a patient-specific AV delay.