P153 - EXAMINING THE ASSOCIATION BETWEEN SERIOUS ARRHYTHMIA AND INCREASED 30-DAY MORTALITY IN PATIENTS WITH FULMINANT MYOCARDITIS ON VENO-ARTERIAL EXTRACORPOREAL MEMBRANE OXYGEN

Background: Fulminant myocarditis (FM) could lead to fatal outcomes. To improve survival, patients are offered mechanical support devices, such as veno-arterial extracorporeal membrane oxygen (VA-ECMO). One serious complication of FM is arrhythmia, including tachycardia and bradycardia, which occurs as a result of cardiac inflammation and dysfunction. The prognostic impact of severe arrhythmia is uncertain. Therefore, this study’s objective is to evaluate whether the occurrence of serious arrhythmia in FM patients on VA-ECMO is associated with increased 30-day mortality.

METHODS AND RESULTS: This is a multicentre retrospective study including patients with FM on VA-ECMO. Serious arrhythmias prior to or during VA-ECMO support included ventricular tachycardia (VT), ventricular fibrillation (VF), and third-degree atrioventricular block (3AVB). We used Wilcoxon Rank Sum test for continuous variables and Chi-Square test for categorical variables to compare baseline characteristics between patients with and without arrhythmias. We performed multivariable logistic regression and reported odds ratio and 95% CI to test the association between arrhythmias and 30-day mortality and other complications

Among 340 FM patients; median age was 44 (25th-75th percentile 37-55) with 48% males. Overall 30-day mortality was 37% (125 patients) and 120 (35%) of patients had arrhythmia. Patients with arrhythmia experienced higher frequency of cardiac arrest pre-VA-ECMO (44% vs 29% in those with no arrhythmia, OR 1.90, 95%-CI 1.20-3.01) and had higher troponin levels (median 17,500, 5,203-42,730 vs 5,897, 870-24,847 in those with no arrhythmia, p< 0.001). Among patient groups, those who died at 30 days post-VA-ECMO included: 52 patients (43%) with arrhythmia and 73 patients (33%) with no arrhythmia (OR 1.54, 95%-CI 0.98-2.43); 23 patients (46%) with VT and 102 patients (35%) without VT (OR 1.57, 95%-CI 0.86-2.88); 10 patients (48%) with VF and 115 patients (36%) with no VF (OR 1.61, 95%-CI 0.67-3.91); 97 patients (36%) with 3AVB and 28 patients (40%) with no 3AVB (OR 1.19, 95%-CI 0.694-2.04). By multivariable analysis adjusting for age, sex, troponin, and cardiac arrest, the presence of arrhythmia was not associated with increased 30-day mortality (OR 1.18, 95%-CI 0.62-2.25).

Conclusion: Patients with FM requiring VA-ECMO experiencing arrhythmias had higher risk features with increased frequency of cardiac arrest and troponins. Our study showed a non-statistically significant 10% increase in absolute 30-day mortality, after adjusting for confounding. These findings provide important prognostic information and may help inform physicians of how to treat patients so that optimal outcomes are achieved. We plan to submit to the American Heart Association in June 2025.