Abstract 13460: Echocardiographic Atrioventricular Delay Optimization during Exercise Improves Cardiac Function in Cardiac Resynchronization Therapy Patients
Background: Atrioventricular (AV) intervals for cardiac resynchronization therapy (CRT) patients are typically optimized at rest. There is limited data on the impact of heart rate change (HR) on AV intervals and cardiac output (CO). The aim of this study was to derive an empiric AV/HR equation capable of predicting optimal AV intervals with changing HR.
Methods: We analyzed 185 EKGs from 56 patients free of structural heart disease and with negative stress test results to obtain HR and corresponding AV intervals for the control group. AV intervals were then serially programmed in 37 study group patients at rest and during exercise-induced (supine-pedaling) HR increases, averaging 20 (N=32) and 40 (N=26) beats per minute (bpm), for comparison. Echo-Doppler images were acquired at each interval and HR. The CO from left ventricular out flow (LVOT) was used as reference for optimization.
Results: Groups consisted of the control group (n=56, 34 male, mean age 53yrs ± 12yrs) and the study group (n=37, 21 male, mean age 57yrs ± 19yrs). The correlation of AV vs. HR was P-R = -0.84 × HR + 231 (r = 0.804, p<0.001) in the control group and AV = -1.60 × HR + 240 (r = 0.799, p<0.001) in the study group (Figure). Optimized intervals in the study group led to an increased CO at rest (4.8±0.9 L vs. preset 3.9±0.8 L), at 20 bpm increased HR (6.2±1.2 L vs. preset 5.2±1.1 L) and at 40 bpm increased HR (6.7±1.7 L vs 5.7±1.3 L) (p<0.001).
Conclusions: CRT with optimal AV delays can be predicted by an empiric equation derived from the correlation between AV delay and HR in heart failure patients. This study suggests the need for devices to alter AV delays based on HR.
- © 2010 by American Heart Association, Inc.