Prevalence, clinical characteristics, and mortality among patients with myocardial infarction presenting without chest pain

Context Although chest pain is widely considered a key symptom in the diagn osis of myocardial infarction (MI), not all patients with MI present with c hest pain. The extent to which this phenomenon occurs is largely unknown. Objectives To determine the frequency with which patients with MI present w ithout chest pain and to examine their subsequent management and outcome. Design Prospective observational study. Setting and Patients A total of 434 877 patients with confirmed MI enrolled June 1994 to March 1998 in the National Registry of Myocardial Infarction 2, which includes 1674 hospitals in the United States. Main Outcome Measures Prevalence of presentation without chest pain; clinic al characteristics, treatment, and mortality among MI patients without ches t pain vs those with chest pain, Results Of all patients diagnosed as having MI, 142 445 (33%) did not have chest pain on presentation to the hospital. This group of MI patients was, on average, 7 years older than those with chest pain (74.2 vs 66.9 years), with a higher proportion of women (49.0% vs 38.0%) and patients with diabet es mellitus (32.6% vs 25.4%) or prior heart failure (26.4% vs 12.3%). Also, MI patients without chest pain had a longer delay before hospital presenta tion (mean, 7.9 vs 5.3 hours), were less likely to be diagnosed as having c onfirmed MI at the time of admission (22.2% vs 50.3%), and were less likely to receive thrombolysis or primary angioplasty (25.3% vs 74.0%), aspirin ( 60.4% vs 84.5%), beta-blockers (28.0% vs 48.0%), or heparin (53.4% vs 83.2% ). Myocardial infarction patients without chest pain had a 23.3% in-hospita l mortality rate compared with 9.3% among patients with chest pain (adjuste d odds ratio for mortality, 2.21 [95% confidence interval, 2.17-2.26]). Conclusions Our results suggest that patients without chest pain on present ation represent a large segment of the MI population and are at increased r isk for delays in seeking medical attention, less aggressive treatments, an d in-hospital mortality.