Characteristics and outcomes of patients with acute coronary syndrome who present with atypical symptoms: a systematic review, pooled analysis and meta-analysis.

How frequent and whether outcomes are worse for patients with atypical presentation in acute coronary syndrome (ACS) across the literature is not known. We conducted a systematic review of the literature on patients with ACS or acute myocardial infarction who reported whether their symptoms were atypical or typical. We determined the proportion of patients with atypical or no chest pain and used meta-analysis to evaluate predictors of atypical presentation and mortality associated with atypical presentation. A total of 43 studies were included with 1 691 401 patients (mean age: 65.4 years, 63.8% male). The proportion of patients with atypical presentation ranged from 4.6 to 74.2% while for those with no chest pain it ranged from 1.4 to 35.5%. Atypical presentation occurred in 11.6% of patients (28 studies) and no chest pain occurred in 33.6% of patients (16 studies). The three strongest factors associated with increased odds of atypical presentation or no chest pain presentation were non-ST-elevation myocardial infarction [odds ratio (OR): 2.38, 95% confidence interval (CI): 1.55-3.64], greater Killip class (OR: 2.22, 95% CI: 1.84-2.67), and prior heart failure (OR: 1.79, 95% CI: 1.76-1.82). There is a two-fold increase in odds of mortality with atypical or no chest pain presentation in ACS compared with the typical presentation (OR: 2.07, 95% CI: 1.71-2.50, I2  = 99%). Atypical presentation occurs in approximately 1 in 10 patients with ACS but can be as high as 1 in 3 in some populations. Patients who present atypically are at two-fold increased risk of mortality.