ST-segment elevation myocardial infarction (STEMI) often presents acutely at the Emergency Department (ED). Although chest pain is a classical symptom, a significant proportion of patients do not present with chest pain. The impact of a non-chest pain (NCP) presentation on ED processes-of-care and outcomes is not fully understood. We utilised a national registry to characterise predictors, processes-of-care, and outcomes of NCP STEMI presentations. Retrospective data for all STEMI cases occurring between 2010 and 2012 were analysed from the Singapore Myocardial Infarction Registry. Cases of inpatient onset, inter-facility transfers, and out-of-hospital cardiac arrests were excluded. Univariable analysis of demographic, clinical, processes-of-care, and outcome variables was conducted. Multivariable logistic regression ascertained independent predictors of a NCP presentation and 28-day mortality. Of 4667 STEMI cases, 12.9% presented without chest pain. Patients with NCP presentation were older (median, years = 74 vs. 58; p < 0.001), more likely to be female (39.1% vs. 15.7%; p < 0.001), of the Chinese race (72.5% vs. 62.7%; p < 0.001), and with diabetes (48.6% vs. 36.7%; p < 0.001). These patients were more likely to present with syncope (6.0% vs. 1.9%; p < 0.001) or epigastric pain (10.6% vs. 4.9%; p < 0.001). Patients with NCP presentation were less likely to receive percutaneous coronary intervention (27.0% vs. 75.6%; p < 0.001), had longer door-to-balloon time (median, minutes = 83 vs. 63; p < 0.001), and experienced greater mortality at 28 days (31.2% vs. 4.5%; p < 0.001). On multivariable logistic regression, independent predictors of a NCP presentation included age (adjusted odds ratio [aOR] = 1.05, 95% confidence interval [CI] 1.04-1.07), diabetes (aOR = 1.76, 95% CI 1.40-2.19), BMI (aOR = 0.93, 95% CI 0.91-0.96), and dyslipidemia (aOR = 0.73, 95% CI 0.58-0.91). Absence of chest pain was an independent predictor for 28-day mortality (aOR = 3.46, 95% CI 2.64-4.52). Patients who presented with a NCP STEMI had a distinct clinical profile and experienced poorer outcomes. Routine triage ECG could be considered for patients with high-risk factors and non-classical symptoms.
Keywords: Acute myocardial infarction; Atypical presentation; Chest pain; Door to balloon; Painless; ST-elevation myocardial infarction.