Predictors of long-term adverse course in acute myocarditis: a multicentre cohort study

Large-scale studies assessing the risk of chronic active myocarditis (CAM) and chronic heart failure (CHF) following acute myocarditis are limited.

This multicentre (seven hospitals) retrospective cohort study included patients diagnosed with acute myocarditis from April 2013 to January 2024. We employed logistic regression and Cox regression to develop models predicting the risk of CAM as primary outcome and CHF as second outcome, respectively. This study included 483 patients with acute myocarditis proven by cardiac magnetic resonance imaging or endomyocardial biopsy. The predictive model for CAM incorporated continuous renal replacement therapy, extracorporeal membrane oxygenation, lactate dehydrogenase, cardiac troponin I (cTnI), left atrial diameter, and duration of hospitalization, achieving an area under the curve (AUC) of 0.881 [95% confidence interval (CI), 0.829-0.934] with clinical applicability confirmed by decision curve analysis (DCA). The model for predicting CHF included cardiopulmonary resuscitation or defibrillation, C-reactive protein, lactate dehydrogenase, alanine aminotransferase, creatine kinase MB isoenzyme, cTnI, and left ventricular end-diastolic diameter, yielding an AUC of 0.872 (95% CI, 0.788-0.925) with clinical utility supported by DCA. Internal and external validation results were consistent with development cohort. Restricted cubic spline analysis revealed that the risks of CAM and CHF significantly increased only when cTnI exceeded 10 000 pg/mL. Notably, CAM significantly increased the risk of subsequent CHF development with a hazard ratio 9.43 (95% CI, 5.55-16.02; P < 0.001).

This study developed two predictive models that exhibited strong performance in discrimination, accuracy, and clinical applicability. A cTnI level of 10 000 pg/mL can serve as a threshold for predicting CAM and CHF. Furthermore, patients with CAM had a significantly higher risk of progressing to CHF in later stages.