Accelerated Diagnostic Protocol May Identify Patients With Chest Pain at Low Risk of Major Cardiac Events

DynaMed Weekly Update - Volume 6, Issue 13

Most patients visiting emergency departments with symptoms consistent with acute coronary syndrome are likely to have less serious conditions, but current diagnostic protocols are costly and lengthy and tend to require hospital admission. The Asia-Pacific Evaluation of Chest Pain Trial (ASPECT) evaluated a 2-hour accelerated diagnostic protocol to rule out acute coronary syndrome in a cohort of 3,582 patients with chest pain presenting to emergency departments in 9 countries. Patients were evaluated by Thrombolysis in Myocardial Infarction (TIMI) score, electrocardiogram and a point-of-care triple biomarker panel at presentation and again at 2 hours. The TIMI score is comprised of 7 factors with 1 point given for each: age > 65 years, presence of at least 3 coronary artery disease risk factors (family history, hypertension, diabetes, hypercholesterolemia, current smoker), prior coronary stenosis > 50%, ST-segment deviation on electrocardiogram at presentation, at least 2 anginal events in prior 24 hours, use of aspirin in prior 7 days, and elevated serum cardiac markers (creatine kinase MB or cardiac troponin) (JAMA 2000 Aug 16;284(7):835). The biomarker panel included troponin, creatine kinase MB (also part of the TIMI score) and myoglobin.

Patients were classified as having low-risk for major cardiac events if they had all 3 of the following: TIMI score = 0, no evidence of ischemic changes on the electrocardiogram, and normal values for all biomarkers at 0 and 2 hours after arrival. Major cardiac events included death, cardiac arrest, emergency revascularization, cardiogenic shock, acute myocardial infarction, and ventricular arrhythmia or high-degree atrioventricular block needing intervention.

Major cardiac event occurred in 11.8% of patients overall. A total of 370 patients were classified as low-risk, with 3 patients suffering major events in analysis of 352 patients who were followed for 30 days (18 patients were lost to follow-up, though they were reported to have had no in-hospital major cardiac events). For identifying low-risk patients, the accelerated protocol had 99.3% sensitivity and 99.1% negative predictive value (level 2 [mid-level] evidence). Specificity was 11% and positive predictive value was 12.9%. Of the individual components of the protocol, TIMI score = 0 had the highest sensitivity (96.7%) (Lancet 2011 Mar 26;377(9771):1077).

For more information, see the Chest pain topic in DynaMed.

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