Abstract 8: Dynamic ECG Changes in Wearable Cardioverter-Defibrillator Patients Predict Sudden Cardiac Arrest

Abstract

Purpose: Sudden cardiac arrest (SCA) prediction continues to be an active area of investigation. The wearable cardioverter defibrillator (WCD) records ECG periodically. The objective of this study was to study the predictive value of dynamic ECG changes occurring between baseline (Base), one week prior to SCA (1WK), and immediately prior to shock (pre-S) for ventricular tachyarrhythmias VT/VF Methods: 100 sequential patients (pts) who were prescribed a WCD for bridge to ICD or recovery, and who were shocked for VT/VF between November 2009 and June 2011 were retrospectively analyzed. ECG’s were examined for dynamic changes in heart rate (HR), QRSd, QRS amplitude, QTc, PVCs, rhythm, and NSVT to see if they were predictive of impending shock. Individual manual measurements were collected at Base, 1WK, and pre-S. Only pts wearing the WCD ≥1 week were included for analysis. Results: Pts (68% male, age 59 ± 16 years, mean LVEF 23±7.5%) had dynamic increases in mean HR and PVC burden from Baseline to 1WK to pre-S (p≤0.0001)(Table 1). Interestingly, changes in traditional measures such as QTc or QRSd or amplitude did not predict shock. Conclusions: The WCD provides a unique opportunity to monitor ECG patterns in at-risk pts prior to defibrillation. A dynamic increase in HR and ventricular ectopy changes prior to VT/VF could indicate a shift of sympathetic-vagal balance towards sympathetic predominance and reduced vagal modulation.