The utility of the initial electrocardiogram in predicting acute coronary events in current cocaine users with chest pain in the emergency department.

Introduction: Chest pain suggestive of myocardial ischemia or infarction is a common emergency department complaint and a subset of these is associated with cocaine use. It can be difficult to triage patients with chest pain while using cocaine.

Objective: To assess the reliability of the initial electrocardiogram (ECG) done in the emergency department in current cocaine users suspected of acute coronary syndrome (ACS) in predicting a true event.

Methods: A total of 218 charts of current cocaine users who presented with chest pain judged as possibly cardiac in nature with an initial ECG from September 2003 to August 2007 were reviewed. Initial ECG was classified into: (1) Category A (inverted T waves in two or more contiguous leads and/or characteristic ST segment elevation or depression indicative of an ischemic event possibly acute); (2) Category B (other ischemic changes but without any ST or T abnormalities such as Q wave, or bundle branch block); or (3) Category C (normal tracing, non-specific ST segment or T wave alterations).

Results: Eighteen of 218 (8.3%) were confirmed to have ACS. Ten of 18 confirmed ACS patients were among the 70 cases with ECG classified as Category A. One hundred and one of 218 were Category C ECGs: five of these had ACS (three of the five had significant cardiac history) and 96 did not, consistent with 95% negative predictive value. Patients with Category A ECG characteristics were three times at risk to have ACS compared with a Category C ECG.

Conclusion: The initial ECG with a good clinical history can be used effectively to triage patients presenting with chest pain and current use of cocaine in the emergency department.