Abstract Sun501: Incidence of Malignant Arrhythmias During and After Targeted Temperature Management

Introduction: Malignant arrhythmias (MA), including ventricular tachycardia and ventricular fibrillation, represent potentially significant complications in patients undergoing therapeutic interventions. The impact of targeted temperature management (TTM) on the incidence, severity, and outcomes of malignant arrhythmias remains contested. It’s important to note the heterogeneous definitions of arrhythmia used in various studies, sometimes to also include bradycardias. Hypothesis: We hypothesize that malignant arrhythmias are rare events after resuscitation from out-of-hospital cardiac arrest. Aims: We aim to calculate the incidence of malignant arrhythmias in patients enrolled in the ICECAP (Influence of Cooling duration on Efficacy in Cardiac Arrest Patients) targeted temperature management trial. Methods: We included all patients enrolled in the ICECAP trial through March 20, 2025. Malignant arrhythmias were identified by extracting case report forms of serious adverse-events (SAEs) that were coded as “malignant cardiac arrhythmia”. Per the trial manual of procedures, malignant arrhythmias were defined as any arrhythmia that requires termination with chest compressions, pacing, defibrillation or electrical cardioversion. SAE forms were reviewed by an investigator and the worst type of arrhythmia, outcome (resolved, resolved with sequelae, continuing, continuing at time of death, unknown) and time from cardiac arrest/911 call were extracted. The incidence of malignant arrhythmias was calculated. The site investigator’s assessment as to whether the MA was associated with treatment (TTM) was extracted. Results: 62 malignant arrhythmias in 60 unique patients were reported out of 1100 patients. 13 were either clear errors or pulseless electrical activity. Of the remaining 49 cases, 19 (39%) were ventricular fibrillation, 15 (31%) ventricular tachycardia, 6 (12%) bradycardia, 4 (8%) asystole, 3 (6%) supraventricular tachycardia and 2 (4%) were atrial fibrillation. 24 (49%) were resolved, 5 (10%) resolved with sequelae, 1 (2%) was continuing at end of study, 19 (39%) were continuing at time of death. 48 (98%) were noted to be unrelated or unlikely to be related to the intervention by the site investigator. Conclusions: Malignant arrhythmias are generally rare events for patients being cared for after cardiac arrest. While studies have reported an increased incidence of overall arrhythmias with targeted temperature management, we show a low rate of malignant arrhythmias.