Optimal Atrio-Ventricular Delay in CRT Patients Can Be Approximated from Surface ECG P-Wave Duration

Abstract

Cardiac Resynchronization Therapy (CRT) is an established treatment for systolic heart failure with ventricular conduction delays. Optimization of the programmed atrio-ventricular delay (AV) may result in better CRT outcomes. Previous studies have shown positive correlation between inter-atrial conduction time (IACT) and optimal AV. We hypothesized that P-wave duration can be used as a surrogate for IACT and, hence, for AV optimization. During CRT device implant (n=33) we measured IACT as the interval from right atrial pacing or sensing to the left atrial activation observed in the electrogram obtained from an electrophysiology catheter inserted in the coronary sinus. P-wave duration (PWd) was measured from 12-lead surface ECG. Within 3 weeks after the implant patients underwent echocardiographic optimization of the sensed (SAV) and paced (PAV) delays using mitral inflow method. Echo-optimal SAV and PAV were 129±19 (range: 100-180 ms) ms and 175±24 ms (range: 130-230 ms) respectively and correlated with PWd and IACT (Table). Paced PWd correlated with IACT better (R=0.84, p<0.0001) than sensed PWd (R=0.54, p=0.001) possibly due to the delay between P-wave onset and atrial sensing. Compared to nominal programming (SAV=100 ms, PAV=130 in Medtronic devices), adjusting AVs using the regression equations for PWd durations would have reduced the proportion of suboptimally programmed patients (>30 ms away from echo-optimal AV) from 39% to 10% during atrial sensing and from 58% to 9% during atrial pacing. Surface ECG P-wave duration is a reasonable surrogate of inter-atrial conduction time and may be used for AV delay adjustment in CRT patients.Tabled 1Correlation With Echo-Optimal AV Delays During Atrial Sensing and PacingParameter (x)Average value (ms)Correlation, RRegression equation, AV = a*x+bp-valueSensed IACT110 ± 240.760.73*x + 52 ms<0.00001Sensed PWd141 ± 220.600.64*x + 43 ms0.0003Paced IACT148 ± 320.750.58*x + 90 ms<0.0001Paced PWd165 ± 320.660.50*x + 93 ms<0.0001 Open table in a new tab