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CLINICAL STATEMENTS AND GUIDELINES

Circulation. 2025;151:e771–e862. DOI: 10.1161/CIR.0000000000001309 April 1, 2025 e783

1 B-NR 2 In patients with suspected ACS in whom the

initial ECG is nondiagnostic, serial 12-lead ECGs should be performed to detect potential ischemic changes, especially when clinical suspicion of ACS is high, symptoms are persistent, or clinical condition deteriorates.*3

1 B-NR 3 In patients with suspected ACS, cTn should be

measured as soon as possible, preferably using a high-sensitivity cTn (hs-cTn) assay.*4–7

1 B-NR 4 In patients with suspected ACS with an initial

hs-cTn or cTn that is nondiagnostic, the recommended time intervals for repeat measurements after the initial sample collection (time zero) are 1 to 2 hours for hs-cTn and 3 to 6 hours for conventional cTn assays.*8–12

*Adapted from the “2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain.”13

Synopsis Chest pain is the second most common presenting complaint to EDs in the United States and has a wide array of potential causes, including ACS.14 Although most patients with chest pain will not have an ultimate diagnosis of ACS, a missed ACS event has significant implications for the patient’s morbidity and mortality. Patients presenting with signs or symptoms of ACS should undergo a history and physical examination, have timely electrocardiographic acquisition and interpretation (Table 3), and assessment of cardiac troponin, because these tests are central to the diagnosis of MI15 and will guide patient management (Figure 3). A thorough description of the evaluation of patients with suspected ACS is provided in the “2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/ SCMR Guideline for the Evaluation and Diagnosis of Chest Pain.”13 Initial medical treatment should begin immediately for patients with presumed ACS. Urgent echocardiography, which may include an initial point-of-care ultrasound by trained clinicians, is indicated for patients with cardiogenic shock, hemodynamic instability, or for suspected mechanical complications. For patients with suspected STEMI, rapid reperfusion is critical after diagnosis, and further diagnostic testing should not delay cardiac catheterization or fibrinolytic therapy unless it would immediately change patient management. For patients who warrant additional testing to confirm a diagnosis of ACS, selection of the method of assessment may encompass several factors, including clinical history, electrocardiographic findings, cardiac biomarkers, patient preference, and patient exercise capacity. The use of evidence-based clinical decision pathways (CDPs) has been shown to improve outcomes and direct appropriate use of resources.13 CDPs reduce unnecessary testing in 21% to 43% of patients while maintaining a high negative predictive value for major adverse cardiovascular events (MACE).16–19 Recommendation-specific Supportive Text

1 A focused history and rapid evaluation are criti-

cal in the assessment of a patient with suspected ACS.13 Early recognition and initiation of therapy for ACS improves outcomes.2,20 Rapid electrocardiographic acquisition and interpretation is required for identification of STEMI (Table 3). In patients with NSTE-ACS, the ECG may be normal or demonstrate transient ST-segment elevation (a high-risk finding), ST-segment depression, T-wave inversions, or nonspecific changes. Of note, ST-segment depression in the anteroseptal leads (V1-V3) could indicate an evolving posterior STEMI and therefore should be managed with a high index of suspicion with a posterior lead ECG if warranted (Table 3).21 Overall, timely acquisition of an ECG is imperative in patients with a goal to obtain and interpret an ECG by a trained clinician within 10 minutes of presentation.1

2 An initial nondiagnostic 12-lead ECG does not “rule

out” or exclude ACS. Electrocardiographic abnormalities may be dynamic. A nondiagnostic ECG should be compared to prior ECGs, and a repeat ECG should be obtained during the ED course to assess for evolving changes.3 Right-sided leads should be obtained in patients with a concern for inferior STEMI to evaluate for right ventricular involvement.22 Assessment for posterior STEMI with an ECG is described in Table 3. The timing of repeat ECGs should be guided by the patient’s symptoms, especially recurrent chest pain, and any change in clinical condition.15 In NCDR ACTION (National Cardiovascular Data Registry and Acute Coronary Treatment and Intervention Outcomes Network), 11% of patients ultimately diagnosed with STEMI had an initial ECG that was nondiagnostic, and 72.4% of those patients had a follow-up ECG diagnostic of STEMI within 90 minutes of their initial ECG.3

3 cTn is the biomarker of choice for assessing patients

for possible cardiac injury, with hs-cTn assays being preferred. cTn is central to the diagnosis of AMI.15 Given its high sensitivity and specificity for myocardial injury, cTn (I or T) should be utilized to detect or exclude myocardial injury.7 In the setting of electrocardiographic evidence of STEMI, reperfusion therapy should not be delayed pending biomarker results. A cTn concentration >99th percentile upper reference limit (a value unique to each assay) is an indicator of myocardial injury.15,23,24 hs-cTn assays are preferred over conventional cTn assays because the sensitivity and negative predictive values of hs-cTn are greater.4,15 In addition, the time interval from chest pain onset to detection of hs-cTn is shorter with hs-cTn compared with conventional cTn assays, leading to more rapid “rule in” or “rule out” of ischemia.25

4 AMI is characterized by a rising and/or falling pattern

of cTn values with at least 1 value above the 99th

Recommendations for Initial In-Hospital Assessment of Patients With Confirmed or Suspected ACS (Continued ) COR LOE Recommendations

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