Incidence and predictors of major arrhythmic events after acute myocarditis complicated by ventricular arrhythmias: A systematic review and meta-analysis.

BACKGROUND

Acute myocarditis (AM) complicated by ventricular arrhythmias (VAs) carries an uncertain risk of VA recurrence after discharge. Predictors are poorly defined, complicating risk stratification and implantable cardioverter-defibrillator (ICD) decision making.

OBJECTIVE

This study aimed to assess recurrence rates and identify predictors of major arrhythmic events (MAEs) after AM complicated by sustained VA.

METHODS

This systematic review and meta-analysis was registered in PROSPERO (CRD420250594422). PubMed, Web of Science, and Cochrane Library were searched up to December 2024 for studies reporting postdischarge VA recurrence in patients with AM complicated by VA in the acute phase. Unpublished data were obtained from study authors to restrict analysis to sustained ventricular tachycardia and ventricular fibrillation. The primary outcome was MAE at follow-up (documented sustained VA, appropriate ICD therapy, or sudden cardiac death). Pooled recurrence rates and predictors were assessed using random-effects models.

RESULTS

8 observational studies (n = 355) were analyzed. MAE occurred in 46.4% (95% confidence interval, 38.1-54.9; I2 = 50.0) during a mean pooled follow-up of 3.8 years (95% confidence interval, 2.7-5.1). Neither demographic factors (age and sex), comorbidities, cardiovascular risk factors, nor ICD implantation before discharge was associated with MAE at follow-up. Reduced left ventricular ejection fraction and the presence or localization of late gadolinium enhancement on cardiac magnetic resonance were also not predictive.

CONCLUSION

MAE recurrences after AM affect nearly half of patients with sustained VA during the acute phase. No consistent predictors emerged. These findings are consistent with the European Society of Cardiology guidelines and call for refined risk stratification from large, multicenter cohorts with standardized criteria.