Table 1 List of prospectively collected historical variables.

Demographics

• Age (years)

• Date of emergency visit (d/m/y)

• Gender (male/female)

• Arrival by ambulance

Cardiac medications

• Aspirin

• Clopidogrel

• Other anticoagulants (warfarin, aspirin/dipyridamole)

• Beta blockers

• Calcium channel blockers

• Nitroglycerin (or other nitrates)

• Angiotensin converting enzyme inhibitors

• Cholesterol-lowering drugs

Cardiac risk factors

• Hypertension

• Diabetes Mellitus

• Hypercholesterolemia

• Renal insufficiency

• Family history of cardiac disease

• Smoking history

Cardiac history

• Acute myocardial infarction

• Cardiac arrest

• Peripheral vascular disease

• Angina

• Ventricular tachycardia

• Known coronary artery disease

• Atrial fibrillation

• Congestive heart failure

• Stroke or transient ischemic attack

Chest pain characteristics

• Duration and time of onset of longest episode (days, hours, minutes; a.m., p.m.)

• Was the pain present on arrival to the ED?

• Is the pain worse with exertion?

• Is the pain similar to previously diagnosed ischemia?

• Has there been 2 or more episodes of pain in the last 24 hours?

• Where on the chest is the pain located?

• Does the pain radiate?

• Is the pain worse with movement or position?

• The physician's overall assessment of the pain (typical or atypical)

• Has the pain completely resolved?

• Is the pain present at rest?

• Is the pain pleuritic (sharp, worse with deep breathing)?

• Has there been a change in the usual pattern of angina within the last 24 hours?

• Did the pain recur during the ED visit?

• How would you describe the pain?

• Is the pain associated with nausea, vomiting, or diaphoresis?