OBJECTIVE To describe the clinical features, prognosis, and treatment of patients presenting with atypical forms of acute myocardial infarction.

DESIGN Consecutive cases of possible acute myocardial infarction were sought from coronary care registers, biochemistry records, and hospital management systems. Case notes were reviewed and predefined epidemiological and clinical variables were abstracted.

SETTING 20 adjacent hospitals in the former Yorkshire region.

PATIENTS 3684 consecutive cases of possible acute myocardial infarction admitted in a three month period were identified, of whom 2096 had a first episode of confirmed acute myocardial infarction.

RESULTS 20.2% of all patients admitted with an eventual diagnosis of acute myocardial infarction presented with symptoms other than chest pain. Compared with the group presenting with chest pain, these patients were older (76.6v 69.1 years, p < 0.001), were more often women (54.6% v 35.3%, p < 0.001), and were more likely to have a history of heart failure (18.6%v 6.9%, p < 0.001). They had a higher 30 and 365 day mortality (49.2% and 61.0%, respectively) compared with patients presenting with chest pain (17.9% and 26.2%). In a Cox regression analysis the hazard ratio for presentation without chest pain was 1.60 (95% confidence interval 1.30 to 1.97) (p < 0.001) adjusted for age, heart rate, blood pressure, left ventricular impairment, and infarction with ST segment elevation as covariates. Importantly, they were also less likely to receive treatments with a proven ability to improve prognosis.

CONCLUSIONS Atypical presentation of myocardial infarction without chest pain is common and associated with increased mortality. This may result in part from a failure to use beneficial treatment strategies.