Background: The evaluation of patients with acute chest pain remains challenging, as it implies the risk of fatal misdiagnosis. It is well recognized that typical angina does not specifically identify patients at high risk. We investigated the predictive value of characteristics atypical for myocardial ischemia for exclusion of acute or subacute coronary events, focusing on patients' symptoms, medical history and risk factors.
Methods: We prospectively studied 1288 consecutive patients presenting with acute chest pain at a non-trauma emergency department. Patients' symptoms, history and risk factors were evaluated using seven predefined criteria and assigned as typical or atypical for ischemic coronary chest pain. Positive predictive value (PPV) and 95% confidence intervals (95% CI) were calculated to predict or exclude acute myocardial infarction (AMI) and major adverse cardiac events (MACE: cardiovascular death, percutaneous coronary interventions, bypass surgery, or myocardial infarction) within six months.
Results: AMI occurred in 168 patients (13%), and 6-months MACE (including AMI) overall in 240 patients (19%). Presence of four or more criteria typical for myocardial ischemia was associated with a PPV of 0.21 (0.17 to 0.25) for predicting AMI and 0.30 (0.25 to 0.35) for 6-months MACE. Presence of four or more criteria atypical for coronary ischemia was associated with a PPV of 0.94 (0.91 to 0.96) for excluding AMI and 0.93 (0.90 to 0.96) for excluding 6-months MACE. In 165 of 476 patients under 40 years of age (35%), four or more atypical criteria excluded AMI and 6-months MACE with PPVs of 0.98 (0.96 to 1.0).
Conclusion: Evaluation of criteria atypical for myocardial ischemia with acute chest pain may help to identify candidates for early discharge, whereas typical characteristics have very little diagnostic value.