Does This Patient With Chest Pain Have Acute Coronary Syndrome?
Clinical question: What is the accuracy of the initial history, physical examination, electrocardiogram (EKG), and cardiac risk scores for diagnosing acute coronary syndrome (ACS)?
What was already known: More than 8 million patients in the US present to the emergency room with acute chest pain, but fewer than 10% of these patients are diagnosed with ACS and around 2.2% of patients with ACS are missed and mistakenly discharged, a miss rate that is higher than that desired by most physicians (1%).
Methods: This is a systematic review of 58 high-quality studies that calculated the sensitivity, specificity, and likelihood ratio of the history, physical examination, EKG findings, and clinical prediction tools (that incorporated these three elements in addition to troponin levels) for diagnosis of ACS. ACS was defined as a final hospital diagnosis of ACS or the occurrence of a cardiovascular event within 6 weeks. This review excluded studies that incorporated serial troponin or EKGs, used high-sensitivity troponin measurements, or exclusively enrolled low-risk or high-risk patients.
Results/implications: The elements most suggestive of ACS included prior abnormal stress tests, peripheral artery disease, radiation of pain into both arms, ST-segment depression and any evidence of ischemia on EKG. Incorporating all elements of the initial history, physical exam, and EKG findings yielded better accuracy than any element alone, yet these elements could not confirm or exclude ACS. The best diagnostic tests were clinical prediction tools that incorporate these elements with initial cardiac troponin measurement, specifically the HEART and TIMI risk scores for high- and low-risk patients, and the HFA/CSANZ for low-intermediate risk patients.
Bottom line: In patients presenting with acute chest pain, use of cardiac risk scores that incorporate history, physical exam findings, and EKG with cardiac troponin levels yields better diagnostic accuracy than using any of these elements individually.