Clinical characteristics and outcomes of patients with myocarditis mimicking ST-segment elevation myocardial infarction

Acute myocarditis mimicking ST-segment elevation myocardial infarction (STEMI) is highly deceptive for an accurate diagnosis, and a systematic study is lacking with regard to the clinical features and prognosis of this distinct clinical entity.Patients with suspected STEMI and eventually diagnosed with myocarditis by cardiac magnetic resonance (CMR) from January 2012 to April 2016 at Fuwai Hospital were identified by reviewing medical records and electronic databases. Follow-up was conducted by clinical visits and phone contacts in a median duration of 17 months.A total of 18 patients were included in the study, with 17 males and 1 female. They were relatively young, and their mean age was 30.8 years. 94.4% of the patients had a high prevalence of infectious prodrome, and inflammatory biomarkers were notably elevated in all patients. Late gadolinium enhancement on CMR was detected in 13 patients. Three patients underwent fulminant course, and left ventricular ejection fraction (LVEF) <45% on admission occurred in 3 patients. The median LVEF improved from 59% on admission to 65% at discharge (P <.001), and none developed cardiac insufficiency, heart transplantation, or death during a median follow-up of 17 months.Myocarditis mimicking STEMI is featured by young age and an existence of flu-like prodrome. CMR benefits the differential diagnosis of this unique clinical entity. Notably, patients with myocarditis mimicking STEMI had a favorable prognosis, and establishing an accurate diagnosis is crucial to avoid unreasonable treatments for them.