12-Lead ECG and STEMI on the NREMT Paramedic Exam

Acquire, transmit, interpret: where the Paramedic line falls

The National EMS Scope of Practice Model 2019 splits the 12-lead into two skills. Acquiring and transmitting a 12-lead ECG starts at the EMT level. Interpreting it is listed for paramedics only. For the National Registry Paramedic Certification Examination, that means an item can hand you a described 12-lead and ask what you do next, without anyone else reading it first.

The 12-lead sits in Cardiology & Resuscitation (10–14% of the Paramedic exam), and a chest-pain scenario can also test Clinical Judgment steps such as taking action or communicating with the receiving hospital. These are the Paramedic test plan's domains; the EMT exam uses a different blueprint.

This page follows the 2025 ACC/AHA/ACEP/NAEMSP/SCAI guideline for acute coronary syndromes (ACS), published in February 2025. Lead groupings and STEMI criteria are not taught here; learn them from your program and use your system's criteria. Your protocols and medical director decide real care.

The 2025 prehospital ACS pathway in five decisions

That same model has EMS obtain the prehospital ECG, activate the lab from the field, and transport to the nearest PCI center when possible. Destination decisions follow the regional STEMI system, transport times and the patient's immediate needs; PCI capability matters, rather than choosing solely by distance.

Oxygen, aspirin, and nitrates: each number with its condition

Oxygen. Supplemental oxygen may benefit patients who present with hypoxia, defined in the guideline as SpO2 below 90%. Randomized trials have shown no cardiovascular benefit from routine oxygen in patients with known or suspected acute myocardial infarction whose saturation is 90% or higher. In a stem, a saturation of 90% or higher points away from routine oxygen.

Aspirin. The guideline calls for a loading dose of 162 to 325 mg in patients with ACS who have no absolute contraindication, as soon as possible on presentation. It should be nonenteric-coated and chewed when possible, for faster onset.

Nitrates and PDE-5 inhibitors. The guideline's table says to avoid nitrates or nitroglycerin within 12 hours of avanafil, 24 hours of sildenafil or vardenafil, and 48 hours of tadalafil. Ask about these drugs by name when you take the medication history.

The aspirin range appears here exactly as the guideline prints it. Any other medication amount, and whether a given drug is in your formulary, comes from your protocols and medical director. The pharmacology guide puts these decisions next to the other guideline-backed medication rules.

A STEMI decision, worked step by step

The patient is fictional. A 64-year-old man has had heavy jaw and left-arm discomfort for 40 minutes. His room-air SpO2 is 96%. When asked about medications by name, he says he took tadalafil the evening before. Your 12-lead reading meets your system's STEMI criteria.

1. ECG: done early, as the guideline asks, and read in the field.
2. Oxygen: his saturation is above 90%, so routine oxygen adds no proven benefit.
3. Aspirin: chewed, nonenteric-coated, if he has no absolute contraindication and your protocol includes it.
4. Nitrates: tadalafil within the past 48 hours puts nitrates off the table for this call.
5. Activation and destination: notify and activate the PCI-capable center from the field, and transport there under your regional plan, with the 90-minute first-contact-to-device goal in mind.
6. Reassess en route: repeat the assessment and watch for rhythm changes; if he arrests, the cardiac arrest guide takes over.

Notice how many of the decisions are refusals: no routine oxygen, no nitrates, PCI-center transport under the regional plan. In a single-answer item, the more active-sounding option is not always the right one.

The free set's 12-lead item is a post-scene Clinical Judgment case that weighs a nearer non-PCI emergency department against a PCI-capable center. After working the steps above, test the STEMI field-activation item in a mixed NREMT Paramedic set →.

After ROSC, obtain the 12-lead early

The 2025 AHA guidelines recommend a 12-lead ECG for adults after return of spontaneous circulation (COR 1). Pair that with decision 5 in the table: a comatose patient after ROSC whose ECG shows STEMI should preferentially go to a primary PCI center. Obtain it early while supporting oxygenation, ventilation and circulation. Once those immediate needs are addressed, a post-ROSC question may test the link between ECG findings and destination.

What to learn from your program for the 12-lead

Your program's text and instructors cover what this page leaves out: lead groupings, STEMI criteria and their mimics, and how your monitor transmits. The National Registry says exam items are referenced to industry-standard source materials, so learn the criteria your program teaches from those references. For rhythm strips and shock decisions, see the ECG rhythm guide.