ECG - BASED LEFT VENTRICULAR ACTIVATION TIME IN PREDICTING RESPONSE TO CARDIAC RESYNCHRONIZATION THERAPY
Introduction: Optimal identification of “responders” among patients referred for cardiac resynchronization therapy (CRT) remains one of unanswered clinical questions. Publications suggested that delayed left ventricular activation time (LVAT) calculated from surface electrocardiography (ECG) may play a crucial role in selection of CRT responders. The purpose of the study was to assess the relationship between baseline LVAT and ECG/ echocardiography (ECHO)/ hemodynamic changes and clinical outcome in patients implanted with CRT.
Methods: The study includes 37 III-IV NYHA class heart failure patients (33M, mean age 68yo) who underwent CRT implantation. In all patients ECG, ECHO and impedance cardiography were recorded pre- and 1 year post CRT implantation (1FU) in order to assess intrinsic QRS duration, ejection fraction (EF) and cardiac output (CO), respectively. The LVAT was measured from ECG in pre-CRT strips and was calculated as a difference of QRS duration minus RV activation time (RVAT- the time (ms) between QRS onset and first notch in any of the 2 adjacent leads, excluding notches in the first 40 ms of the S wave in V1 and V2) for each lead. The longest LVAT in any lead was considered as the final value. “Responders” were defined by 10% increase in EF.
Figure 76.1. Changes in selected parameters transmitted via telemonitoring during 30 days before adverse event in a patient with ICD.
Results: During 1FU 11 (29%) patients died. Those who survived were divided based on ECHO changes into group A “responders” (18 patients - 69%) and group B non-responders (8 patients - 31%). Baseline LVAT did not correlate with pre CRT implantation EF and CO, nor with delta changes in these parameters (pre- vs 1FU). Baseline LVAT did not differ significantly between patients who died and survived (98 ± 22 vs 105± 33 ms, p=NS). Furthermore LVAT was not significantly different between group A and B (99.4±21 vs 95±21 ms, p=NS).
Conclusion: Baseline LVAT did not predict responders in patients with CRT.