ACC Guidelines: The Appetizer (STEMI Equivalents and Troponins)

Acute chest pain evaluation starts with the ECG, and dynamic ischemic changes can outweigh any biomarker shortcut. The 2022 ACC chest pain pathway centers on high-sensitivity troponin I, rapid rule-out only in the right patient, and recognition of STEMI equivalents that should not wait.

STEMI Equivalents and ECG Triage

• Initial ECG priority: The ECG is the first test in suspected ACS, with a 10-minute target from arrival, and an ischemic tracing takes the patient out of any rapid biomarker-only pathway.
• Dynamic ECG change: Improving or worsening ST-T abnormalities remain concerning for ischemia; even normalization in the ED can represent transient occlusion. We get into why that pattern matters in the episode.
• Named STEMI equivalents: Posterior STEMI, de Winter pattern, hyperacute T waves, and Sgarbossa or modified Sgarbossa findings should trigger the same urgency as classic ST-elevation.
• Other high-risk patterns: Wellens pattern, ST elevation in aVR with multilead ST depression, and diffuse ST depression or T-wave inversion signal dangerous proximal or multivessel disease.
• Prehospital ECG value: EMS ECGs can be enough to activate the cath lab before arrival, especially when they show ischemic changes that later evolve or transiently normalize.

High-Sensitivity Troponin and Risk Pathways

• Assay-specific rule out: Aggressive rapid rule-out pathways apply to hs-cTnI assays, not conventional troponin T or I, so knowing your hospital assay is a patient-safety issue.
• Rapid rule-out criteria: A single very low hs-cTnI can support ACS rule-out only when symptoms have been present at least 3 hours and the ECG is non-ischemic.
• Rapid rule-in triggers: An ischemic ECG or hs-cTnI above the 99th percentile is enough to move the patient into an ACS rule-in lane rather than continued low-risk screening.
• Delta troponin significance: A normal repeat hs-cTnI does not end the workup if the delta is abnormal, because change over time can matter as much as the absolute number. We walk through that nuance in the chapter.
• HEART score role: HEART remains one of the best predictors of MACE and still supports shared decision-making, even after a patient is ruled out for ACS by a troponin pathway.
• Type I versus II MI: Type I and Type II MI can produce similar biomarker patterns, but the distinction changes downstream therapy, especially decisions about antithrombotics and cath lab urgency.

References:

1. Writing Committee, et al. 2022 ACC Expert Consensus Decision Pathway on the Evaluation and Disposition of Acute Chest Pain in the Emergency Department: A Report of the American College of Cardiology Solution Set Oversight Committee. J Am Coll Cardiol. 2022;80(20):1925-1960. PMID:36241466
2. https://www.acc.org/latest-in-cardiology/ten-points-to-remember/2022/10/10/23/15/2022-acc-expert-consensus-on-chest-pain
3. Amsterdam EA, et al. 2014 AHA/ACC Guideline for the Management of Patients with Non-ST-Elevation Acute Coronary Syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines [published correction appears in J Am Coll Cardiol. 2014 Dec 23;64(24):2713-4. Dosage error in article text]. J Am Coll Cardiol. 2014;64(24):e139-e228. PMID: 25260718