Utility and Validation of Corrected Left Ventricular Filling Time for Determining the Optimal AV Delay in Patients Receiving Cardiac Resynchronization Therapy

摘要

Background: Optimizing the atrio-ventricular delay (AVD) is important for increasing the left ventricular (LV) preload in patients receiving cardiac resynchronization therapy (CRT). The optimal AVD may be considered an AVD in which the maximum LV filling time (LVFT) is obtained. However, it is unclear whether or not the optimal AVD determined by Ritter's method (AVD-Ritter) is identical to the AVD in which the maximum LVFT is obtained. The aim of this study was to clarify this point.Methods: In 17 patients who received CRT, the optimal AVD was determined by Ritter's method and the FT method. Eleven (65%) patients had 1° AV block. We measured the LVFT and R-R time when the AVD was prolonged by 20 ms increments from 80 ms to 180 ms. In the FT method, the optimal AVD (AVD-FT) was defined as the AVD in which the corrected LVFT (LVFTc) was maximally prolonged. The AVD-Ritter and AVD-FT were both determined during atrial pacing (Ap) and sensing (As). The LVFTc at each optimal AVD was also measured and compared.Results: During As, the AVD-Ritter (114 ± 20 ms) showed a marginally significant difference when compared to the AVD-FT (95 ± 18 ms; p = 0.053). However, during Ap, the AVD-Ritter (138 ± 32 ms) was significantly longer than the AVD-ET (113 ± 20 ms; p = 0.017). The LVFTc with the AVD-Ritter was shorter than the AVD-FT (As: 538 ± 40 vs. 557 ± 34 [ms], p = 0.002; Ap: 532 ± 37 vs. 563 ± 33 [ms], p = 0.023). These results were comparable with those obtained in the 11 patients with 1° AV block.Conclusions: The AVD-Ritter during Ap may become shorter than that for the AVD-FT because of the latency in patients receiving CRT. The FT method might be better than the AVD-Ritter method to optimize the AVD in those patients.