When a patient presents with chest pain, what initial test should be performed to rule out acute coronary syndrome?

In the evaluation of a patient presenting with chest pain, the initial test to rule out acute coronary syndrome is a 12-lead ECG (electrocardiogram). This test is crucial because it provides immediate information about the electrical activity of the heart and can help identify abnormalities such as ST elevation or depression, which are indicative of myocardial ischemia or infarction.

The 12-lead ECG is the standard first-line diagnostic tool in emergency settings for patients with chest pain because it is fast, non-invasive, and can quickly identify life-threatening arrhythmias or ST elevation myocardial infarctions (STEMIs). Having this information early in the assessment allows for timely interventions that are critical for improving patient outcomes.

Other tests, while important, are not initially prioritized for ruling out acute coronary syndrome. For instance, cardiac enzymes help in diagnosing myocardial injury but become positive only after a few hours post-infarction. Chest X-rays might be helpful for identifying other causes of chest pain, like pulmonary issues, but do not directly assess cardiac status. CT Angiography is used for vascular assessment, such as coronary artery disease, but is not typically the first test performed in an acute setting due to time constraints and resource intensity.