# Chest pain & suspected ACS

Obtain an early 12-lead, check medication exclusions, and coordinate a cardiac destination.

Population: Adult / adolescent. Scope: ALS.
Status: published. Source-linked OCEMS summary.
Summary updated: 2026-09-16.
Source checked: 2026-09-16.
Source version: See linked source for document revision and implementation dates..
Canonical page: https://www.ocmedic.com/guides/chest-pain/
Official source: [SO-C-015 — Chest Pain of Suspected Cardiac Origin or Suspected Angina Equivalent Symptoms](https://www.ochealthinfo.com/sites/hca/files/2021-07/SO-C-15%20updated.pdf)

Independent OC Medic summary. Does not replace the complete policy, current system notices, or clinical judgment.

## Key cautions & base contact

- Hold aspirin for allergy, anticoagulant/antiplatelet use, or direct midline mid-back pain raising concern for dissection.
- Do not give nitroglycerin after sildenafil, vardenafil, or tadalafil within 24 hours. Avoid IO in potential CVRC patients because of possible thrombolysis-related bleeding.

## Source documents

- [SO-C-015 — Chest Pain of Suspected Cardiac Origin or Suspected Angina Equivalent Symptoms](https://www.ochealthinfo.com/sites/hca/files/2021-07/SO-C-15%20updated.pdf)

## Recognize & assess

- Suspect an anginal equivalent with unexplained diaphoresis, sudden weakness, dyspnea, anxiety, or atypical chest discomfort. Heartburn-like, pleuritic, or musculoskeletal-sounding pain does not exclude cardiac disease.
- Monitor rhythm and obtain a 12-lead as soon as practical before leaving the scene. A normal/non-STEMI tracing does not rule out acute MI.

## Initial treatment

- If no source contraindication applies, give four 81 mg aspirin tablets (324 mg) or one 325 mg tablet to chew.
- When room-air SpO₂ is below 95%, provide mask oxygen or nasal cannula at 6 L/min as tolerated.
- For discomfort, give nitroglycerin 0.4 mg SL if systolic BP is above 100; repeat about every 3 minutes, up to 3 EMS doses while BP stays above 100. Prior self-doses are not included in that EMS count.

## Persistent pain or nausea

- If 3 nitroglycerin doses fail or nitroglycerin cannot be given, the source permits morphine 5 mg (or 4 mg carpuject) IV, or fentanyl 50 mcg IV. Either may repeat once after about 3 minutes; hold if systolic BP is below 90.
- For nausea/vomiting without known or suspected pregnancy: ondansetron 8 mg ODT or 4 mg IV, with one IV repeat after about 3 minutes if needed.

## Destination & reassessment

- Suspected/identified acute MI requires base contact for a CVRC with an available catheterization lab. Otherwise provide ALS escort to an appropriate ERC.
- Reassess pain, BP, breathing, rhythm, and treatment response. If a patient with a performed 12-lead requests AMA, contact base before leaving the scene.