Abstract 12433: Cardiac Sympathetic Nerve Activity Predicts Ventricular Tachyarrhythmia After Implantable Cardioverter Defibrillator Implantation

Introduction: In patients with implantable cardioverter defibrillators (ICDs), increased sympathetic tone is associated with sudden death. Hypothesis: We assumed that cardiac sympathetic nerve activity (CSNA)is associated with Ventricular arrhythmia(VT). Methods: To evaluate whether CSNA estimated by the heart to mediastinum ratio (H/M) of I-123 MIBG imaging can predict the occurrence of VT after ICD implantation, 56 consecutive patients (43 males/13 females, 61±13 y.o.) who received ICD implantation were enrolled. The endpoint was defined as the occurrence of VT that required antitachycardia pacing (ATP) and/or shock therapy by the device. Receiver-operating characteristic curve analysis was used to obtain the cut-off value of the delayed H/M ratio required to predict VT. The patients were divided into two groups based on this cut-off value: a higher H/M (≥1.92) group (H-H/M, n=31), and a lower H/M (<1.92) group (L-H/M, n=25). The average follow-up was 10.7 ± 6.4 months. Results: One or more VT episodes occurred in 11 patients (ATP:4, shocks:7). The VT event rate in the L-H/M group was significant higher than that in the H-H/M group (40% (10/25) vs. 3.2% (1/31), p=0.0013). The Kaplan-Meier VT event-free curve showed a worse outcome in the L-H/M group than in the H-H/M group (p=0.00044 by the log-rank test, Fig.1). Conclusions: CSNA estimated by the H/M ratio of I-123 MIBG imaging might predict the occurrence of VT after ICD implantation.