Prognosis of acute myocarditis beyond hospitalization: Results of a long-term prospective study

To assess long-term outcomes of acute myocarditis (AM).

Prospective, single-center observational study including patients admitted with AM between 2007 and 2022, followed at a tertiary cardiology center. Follow-up (FUP) included annual clinical evaluations, treadmill testing, Holter and echocardiography. Statistical analysis was performed using chi-square test and Cox regression.

We included 158 patients, 12.7% female, with a mean age of 32±12 years. Most presented with chest pain (94.3%). Severe complications, including cardiogenic shock or arrhythmic storm, occurred in 3.6%. Upon admission, the mean left ventricle ejection fraction (LVEF) was 57%. Out of the 140 patients who underwent cardiac magnetic resonance imaging (CMR), myocardial oedema and late gadolinium enhancement (LGE) were present in 47.8% and 88.5%, respectively. During a mean FUP time of 6±4.3 years, 13.3% patients were readmitted, 80.9% of them due to recurrent myocarditis. Only one patient with LVEF <50% at admission did not recover at FUP. No patients exhibited significant arrhythmias during Holter monitoring or treadmill stress tests. Six patients died at FUP. Three patients had experienced fulminant myocarditis (FM) at index admission; two of them died due to CV causes. There was a statistically significant association between death and fulminant presentation during index admission (p<0.001).

AM in adults typically followed a benign course with favorable short- and long-term outcomes. In contrast, a small but significant subset with FM had a markedly poorer prognosis, with severe recurrences frequently proving fatal. Clinical presentation was the sole determinant of prognosis, prompting consideration of whether patients with milder cases truly require extended FUP.