Long-term Prognosis Following Hospitalization for Acute Myocarditis - a Matched Nationwide Cohort Study

The aim of this study was to examine the long-term risk of heart failure (HF) and all-cause mortality, in patients discharged alive following hospitalization for myocarditis. . Prognosis in patients with apparently uncomplicated myocarditis is in general perceived as good, but data on long-term outcomes are sparse. From nationwide Danish registries we included patients without prior cardiac disease, discharged alive with a first-time diagnosis of myocarditis 1996-2016. Patients were matched 1:10 by age- and sex, with controls from the general population. Risk of HF hospitalization and death in cases and controls was compared by use of adjusted Cox regression analyses. . We identified 1557 patients with a first-time diagnosis of myocarditis, 72% men, median age 39 years. Patients with myocarditis had more hypertension, diabetes, and cancer, and received more pharmacotherapy prior to hospitalization compared to matched controls. During a mean follow-up of 8.5 years, the event rate of HF hospitalization was 8.7 vs. 2.2 per 1000 patient-years (py) in cases and controls; HR 4.59 (95% CI; 3.58-5.88) and for all-cause mortality, event rate 21.9 vs 11.2 per 1000 py; HR 2.10 (95% CI; 1.82-2.43). Among 784 patients with no events or HF medication one year after diagnosis, risk of HF hospitalization (HR 2.15; 95% CI; 1.18-3.92), and all-cause mortality (HR 1.62; 95% CI; 1.21-2.16) remained elevated compared to matched controls. . Myocarditis in younger patients without prior cardiac disease was associated with a long-term excess risk of HF hospitalization, and death, even in patients free of events and HF medication 1 year after discharge.HighlightsMyocarditis ranges from chest discomfort to severe heart failure.In most patients, left ventricular ejection fraction recovers but the long-term adverse cardiac risk is unknown.Patients with myocarditis and no prior cardiac disease were at higher risk of death and heart failureRoutine follow-up may be warranted following an episode of acute myocarditis.