Cardiology
STEMI — the essentials
ST-elevation myocardial infarction (STEMI) is total occlusion of a coronary artery causing transmural ischemia — "time is muscle." The nursing priority is to compress ischemic time: obtain and read a 12-lead ECG within 10 minutes, place the patient on a monitor with the defibrillator ready, and give aspirin, antiplatelet/anticoagulant and analgesia per order while protecting against dysrhythmia and bleeding.
Recognize it (red flags)
- Ischemic chest pain >20 min, not relieved by rest, with diaphoresis, nausea, or a sense of doom
- Atypical/anginal-equivalent presentations — dyspnea, fatigue, jaw/back pain, near-syncope — in women, older adults, and people with diabetes
- New ST-segment elevation in 2 or more contiguous leads with reciprocal ST depression; new LBBB with ischemic symptoms is a STEMI-equivalent
- Acute coronary occlusion can exist WITHOUT classic ST elevation — escalate De Winter, Wellens, or posterior MI patterns too
- Pulseless VT/VF, cardiogenic shock, or acute pulmonary edema = immediate code/escalation
Key numbers
- Door-to-ECG
- 12-lead within 10 minutes of arrival
- ST elevation (limb leads)
- >=1 mm in 2+ contiguous leads, at the J-point
- ST elevation (V2-V3)
- >=2 mm men >=40 y, >=2.5 mm men <40 y, >=1.5 mm women
- FMC-to-device (PCI center)
- <=90 min
- FMC-to-device (transfer)
- <=120 min
- Fibrinolysis door-to-needle
- <=30 min when PCI is not timely
- Aspirin loading dose
- 162-325 mg chewed, non-enteric-coated (per order)
Priority nursing actions
- Get the 12-lead ECG read within 10 minutes and activate the STEMI/cath-lab pathway with a structured SBAR
- Continuous cardiac monitoring with pads/defibrillator at the bedside — be ready to defibrillate pulseless VT/VF without delay
- Establish IV access, draw serial troponin, and give ASA + ordered P2Y12 inhibitor, anticoagulant and analgesia using the rights of medication administration
- Oxygen only if SpO2 <90% or respiratory distress — routine oxygen is not indicated in normoxic ACS
- Monitor continuously for dysrhythmia, hypotension, and bleeding; reassess against the reperfusion clock
Common NGN / NCLEX traps
- Giving routine oxygen to a normoxic patient (SpO2 >=90%) — no longer recommended
- Giving nitroglycerin in suspected inferior/RV MI or recent PDE-5 inhibitor use — can cause profound hypotension
- Dismissing atypical symptoms in women, older adults, or people with diabetes and missing the MI
- Reaching for morphine first — guidelines de-emphasize it; it can mask ischemic pain and slow oral antiplatelet absorption
- Treating a normal first troponin as "rules out MI" — never wait for troponin to act on a clear STEMI ECG
For practicing nurses
What’s changed (if you trained a while ago)
- Oxygen is selective, not routine — give only for SpO2 <90% or respiratory distress (2025 ACC/AHA ACS Guideline).
- P2Y12 loading now prefers ticagrelor or prasugrel over clopidogrel in eligible PCI candidates; the old 300 mg clopidogrel PCI default is out (600 mg if clopidogrel is used).
- ACOMI patterns (De Winter, Wellens, posterior MI) are recognized as STEMI-equivalents that warrant emergent cath-lab activation despite not meeting classic mm criteria.
- High-sensitivity troponin 0/1-h and 0/2-h pathways are now standard, and a liberal transfusion threshold (hemoglobin <10 g/dL) is supported in hospitalized AMI (AABB / ACC/AHA 2025).
On the floor (practical pearls)
- Speed of the ECG is your job: door-to-ECG <=10 min is the single nursing action that most compresses ischemic time.
- Hold nitroglycerin and recheck for SBP <90 mmHg, HR <50 or >100, suspected RV/inferior MI, or a PDE-5 inhibitor in the last 24-48 h — check BP before and after every dose.
- Dual antiplatelet plus an anticoagulant makes bleeding the dominant iatrogenic risk: watch IV/puncture sites, gums, GI, and for any new neuro deficit or severe headache; hold the offending infusion and notify the provider.
- After fibrinolysis, any new neurologic deficit means possible intracranial hemorrhage — stop the infusion and get an urgent CT; avoid unnecessary IM injections and venipuncture.
- Persistent or recurrent chest pain with ongoing ST elevation = failed reperfusion or re-occlusion — get a STAT repeat ECG and troponin and re-activate the cath lab.
- Chart the times: symptom onset, arrival, ECG, STEMI activation, drug administration, and reperfusion — the time stamps are the quality metric.
Key references
- 2025 ACC/AHA/ACEP/NAEMSP/SCAI Guideline for Acute Coronary Syndromes, Circulation, 2025
- Fourth Universal Definition of Myocardial Infarction, ESC/ACC/AHA/WHF, 2018
- AHA Mission: Lifeline / ACLS systems-of-care time goals, American Heart Association
- Lewis's Medical-Surgical Nursing (Harding et al.), Elsevier, 2023
- Davis's Drug Guide for Nurses, F.A. Davis, 2024
Sources: Based on the 2025 ACC/AHA/ACEP/NAEMSP/SCAI ACS Guideline, the Fourth Universal Definition of MI, AHA Mission: Lifeline, and Lewis’s / Brunner & Suddarth’s Medical-Surgical Nursing.
