Differences in symptom presentation and hospital mortality according to type of acute myocardial infarction.

BACKGROUND: Chest pain/discomfort (CP) is the hallmark symptom of acute myocardial infarction (MI), but some patients with MI present without CP. We hypothesized that MI type (ST-segment elevation MI [STEMI] or non-STEMI [NSTEMI]) may be associated with the presence or absence of CP.

METHODS: We investigated the association between CP at presentation and MI type, hospital care, and mortality among 1,143,513 patients with MI in the National Registry of Myocardial Infarction (NRMI) from 1994 to 2006.

RESULTS: Overall, 43.6% of patients with NSTEMI and 27.1% of patients with STEMI presented without CP. For both MI type, patients without CP were older, were more frequently female, had more diabetes or history of heart failure, were more likely to delay hospital arrival, and were less likely to receive evidence-based medical therapies and invasive cardiac procedures. Multivariable analysis indicated that NSTEMI (vs STEMI) was the strongest predictor of atypical symptoms (adjusted odds ratio [95% CI], 1.93 [1.91-1.95]). Within the 4 CP/MI type categories, hospital mortality was highest for no CP/STEMI (27.8%), followed by no CP/NSTEMI (15.3%) and CP/STEMI (9.6%), and was lowest for CP/NSTEMI (5.4%). The adjusted odds ratio of mortality was 1.38 (1.35-1.41) for no CP (vs CP) in the STEMI group and 1.31 (1.28-1.34) in the NSTEMI group.

CONCLUSIONS: Hospitalized patients with NSTEMI were nearly 2-fold more likely to present without CP than patients with STEMI. Patients with MI without CP were less quickly diagnosed and treated and had higher adjusted odds of hospital mortality, regardless of whether they had ST-segment elevation.