Determination of sensed and paced atrial‐ventricular delay in cardiac resynchronization therapy

Abstract

BackgroundOptimization of atrial‐ventricular delay (AVD) during atrial sensing (SAVD) and pacing (PAVD) provides the most effective cardiac resynchronization therapy (CRT). We demonstrate a novel electrocardiographic methodology for quantifying electrical synchrony and optimizing SAVD/PAVD.MethodsWe studied 40 CRT patients with LV activation delay. Atrial‐sensed to RV‐sensed (As‐RVs) and atrial‐paced to RV‐sensed (Ap‐RVs) intervals were measured from intracardiac electrograms (IEGM). LV‐only pacing was performed over a range of SAVD/PAVD settings. Electrical dyssynchrony (cardiac resynchronization index; CRI) was measured at each setting using a multilead ECG system placed over the anterior and posterior torso. Biventricular pacing, which included multiple interventricular delays, was also conducted in a subset of 10 patients.ResultsWhen paced LV‐only, peak CRI was similar (93 ± 5% vs. 92 ± 5%) during atrial sensing or pacing but optimal PAVD was 61 ± 31 ms greater than optimal SAVD. The difference between As‐RVs and Ap‐RVs intervals on IEGMs (62 ± 31 ms) was nearly identical. The slope of the correlation line (0.98) and the correlation coefficient r (0.99) comparing the 2 methods of assessing SAVD‐PAVD offset were nearly 1 and the y‐intercept (0.63 ms) was near 0. During simultaneous biventricular (BiV) pacing at short AVD, SAVD and PAVD programming did not affect CRI, but CRI was significantly (p < .05) lower during atrial sensing at long AVD.ConclusionsA novel methodology for measuring electrical dyssynchrony was used to determine electrically optimal SAVD/PAVD during LV‐only pacing. When BiV pacing, shorter AVDs produce better electrical synchrony.