ECG as a risk stratification tool in patients with wearable cardioverter-defibrillator

Background: The wearable cardioverter defibrillator (WCD) is increasingly used in patients at elevated risk for ventricular arrhythmias but not fulfilling the indications for an implantable cardioverter defibrillator (ICD). Cur-rently, there is an insufficient risk prediction of fatal arrhythmias in patients at risk. In this study, we assessed the prognostic role of baseline electrocardiogram (ECG) in WCD patients.Methods: WCD patients from diverse clinical institutions in Germany (n = 227) were retrospectively enrolled and investigated for the incidences of death or ventricular arrhythmias during WCD wearing. In addition, the widely accepted ECG predictors of adverse outcome were analyzed in patients with arrhythmic events.Results: Life-threatening arrhythmias occurred in 22 (9.7 %) patients, mostly in subjects with ischemic heart dis-ease (15 of 22). There was no difference in baseline left ventricular ejection fraction (LVEF) in subjects with and without arrhythmic events (31.3 +/- 7.9 % vs. 32.6 +/- 8.3 %; p = 0,24). Patients with arrhythmia exhibited signif-icantly longer QRS duration (109.5 +/- 23.1 ms vs. 100.6 +/- 22.3 ms, p = 0,04), Tpeak-Tend (Tp-e) (103.1 +/- 15.6 ms vs. 93.2 +/- 19.2 ms, p = 0,01) and QTc (475.0 +/- 60.0 ms vs. 429.6 +/- 59.4 ms, p < 0,001) intervals. In contrast, no significant differences were found for incidences of fragmented QRS (27.3 % vs. 24 %, p = 0.79) and inverted/ biphasic T-waves (16.6 % vs. 22.7 %, p = 0,55). In multivariate regression analysis both Tp-e (HR 1.03; 95 % CI 1.001-1.057; p = 0.02) and QTc (HR 1.02; 95 % CI 1.006-1.026; p < 0.001) were identified as independent pre-dictors of ventricular arrhythmias. After WCD use, the prophylactic ICD was indicated in 76 patients (33 %) with uneventful clinical course but per-sistent LVEF <= 35 %. The ECG analysis in these subjects did not reveal any relevant changes in arrhythmogenesis markers. Conclusions: ECG repolarization markers Tp-e and QTc are associated with malignant arrhythmias in WCD pa-tients and may be used -in addition to other established risk markers -to identify appropriate patients for ICD implantation.(c) 2022 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.