To evaluate the likelihood of and patient features associated with acute myocardial infarction (AMI) versus acute myocarditis in different population segments.
Nationwide, multihospital observational retrospective registry study of 9.6 years in Finland.
All consecutive patients aged =18 years hospitalised with a primary diagnosis of AMI (n=89 399) or acute myocarditis (n=2131) in 22 hospitals with a coronary catheterisation laboratory.
Likelihood of AMI versus acute myocarditis and associated patient features.
Men were over-represented in patients with AMI (59.8%) and in patients with acute myocarditis (76.1%). Age distributions of AMI and acute myocarditis were opposite as a majority of patients with myocarditis were aged 18-29 years, while the number of patients with AMI increased gradually up to 80 years of age. Patients aged 18-29 years were more likely to have acute myocarditis as the cause of hospitalisation (relative risk (RR)=11.4; 95% CI 7.6 to 16.1 for myocarditis, p