Aim of prehospital care
In prehospital STEMI, what matters most is the time to reopening of the occluded vessel. This gives the team four tasks:
- confirm the diagnosis with the 12-lead ECG,
- stabilise the patient,
- start antiplatelet therapy,
- transfer directly to a centre with a cardiac catheterisation laboratory available around the clock.
Every intervention on scene must be judged by whether it delays reperfusion.
12-lead ECG: the diagnosis on scene
The 12-lead ECG is the key tool in acute coronary syndrome in prehospital emergency medicine.
- Record early: Obtain the ECG as soon as possible after first contact and document the time and findings.
- ST elevation: ST elevation is assessed in anatomically contiguous leads. Thresholds differ by lead, age and sex and should be checked in the current ESC guideline.
- Look for the mirror image: Reciprocal ST depression supports the diagnosis.
- Inferior infarction: Right precordial leads (e.g. V4R) indicate right ventricular involvement. This is therapeutically relevant, particularly for nitrate administration.
- Serial ECGs: Repeat the recording if symptoms persist and the initial ECG is inconclusive. A normal initial ECG does not exclude acute coronary occlusion.
- Telemetry: Where established regionally, transmit the ECG to the receiving centre. This speeds up decision-making and activation of the catheterisation laboratory.
STEMI equivalents on the ECG
Not every acute coronary occlusion shows classic ST elevation. The 2023 ESC guideline lists atypical ECG patterns that, in the appropriate clinical context, justify management as for STEMI.
| Finding | Suggests | Practice |
|---|---|---|
| ST depression in V1–V3 | isolated posterior infarction | record posterior leads V7–V9 |
| Bundle branch block (especially left bundle branch block) | ischaemia difficult to diagnose | if ongoing ischaemia is suspected, treat as STEMI, even with a known pre-existing block |
| Paced rhythm | ischaemia difficult to diagnose | as for bundle branch block: clinical picture decides, Sgarbossa criteria as an aid |
| ST elevation in aVR with widespread ST depression | left main or multivessel disease | rapid invasive assessment, particularly if unstable |
| Hyperacute T waves, de Winter pattern | early vessel occlusion | discussed in the literature as an equivalent; evidence and criteria inconsistent |
The Wellens pattern is not a STEMI equivalent in the strict sense. However, it indicates critical stenosis of the left anterior descending artery and requires prompt assessment.
Irrespective of ECG findings, the following signs are high-risk criteria according to ESC 2023 that favour an immediate invasive strategy:
- ongoing ischaemia despite treatment,
- haemodynamic instability,
- cardiogenic shock,
- life-threatening arrhythmias.
STEMI mimics and differential diagnoses
ST elevation also has other causes. These include:
- perimyocarditis,
- early repolarisation,
- left ventricular hypertrophy,
- hyperkalaemia,
- Brugada pattern,
- takotsubo syndrome,
- ventricular aneurysm.
Aortic dissection and pulmonary embolism carry particularly serious clinical consequences. If dissection is suspected, antiplatelet therapy is contraindicated. In case of doubt, consultation with the on-call interventional centre can help.
Basic measures
- Continuous monitoring of ECG, blood pressure and SpO₂.
- Keep defibrillator pads ready, as ventricular fibrillation is common in the early phase.
- Establish venous access.
- Give oxygen only for hypoxaemia, not routinely when saturation is normal. Target values according to the current guideline.
- Analgesia: Titrated opioids may be considered. They can delay absorption of oral P2Y12 inhibitors. Dosing according to the summary of product characteristics.
- Take a focused history: symptom onset, anticoagulation, bleeding risk, use of PDE-5 inhibitors.
Antiplatelet and antithrombotic therapy
Acetylsalicylic acid
According to ESC 2023, the loading dose is given as early as possible:
- 150–300 mg p.o., chewed,
- 75–250 mg i.v. if oral administration is not possible,
- thereafter 75–100 mg daily.
Practical note on i.v. administration: lysine acetylsalicylate 500 mg with 5 ml of solvent gives 87.5 mg/ml. 250 mg therefore corresponds to approximately 2.9 ml, not 2.5 ml. Prepare the solution freshly and administer through a 5-µm filter (e.g. filter needle) (summary of product characteristics). Some summaries of product characteristics state higher doses; the ESC dose is preferred.
Contraindications:
- hypersensitivity to salicylates (e.g. analgesic-induced asthma),
- active gastrointestinal bleeding or acute ulcer,
- haemorrhagic diathesis,
- suspected aortic dissection or intracranial haemorrhage.
P2Y12 inhibitors and anticoagulation
Routine prehospital pretreatment with a P2Y12 inhibitor before primary PCI is assessed only cautiously in the 2023 ESC guideline. It may be considered but is not standard. Regional protocols and agreement with the receiving centre are decisive.
The choice and timing of parenteral anticoagulation likewise depend on the regional concept. Doses should be taken from the current guideline or summary of product characteristics.
If fibrinolysis is planned, acetylsalicylic acid is given together with clopidogrel and an anticoagulant.
Symptomatic therapy
Glyceryl trinitrate
Glyceryl trinitrate relieves angina but does not improve prognosis. Its administration must not delay diagnosis or reperfusion. A prerequisite is a systolic blood pressure ≥ 90 mmHg.
- Spray: 1–3 puffs sublingually (0.4–1.2 mg; 0.4 mg per puff), according to the summary of product characteristics.
- Bite capsule: 1 capsule of 0.8 mg; check the product strength.
- i.v. via syringe driver: for ongoing ischaemia, hypertension or pulmonary congestion. Start at 10–20 µg/min (0.6–1.2 ml/h at 1 mg/ml), then titrate to blood pressure (ESC 2023).
Contraindications:
- hypotension, shock, marked hypovolaemia,
- right ventricular infarction, as these patients are preload-dependent,
- use of PDE-5 inhibitors: sildenafil or vardenafil within 24 h, tadalafil within 48 h.
Caution is required in severe aortic stenosis or hypertrophic obstructive cardiomyopathy. Give nitrates with the patient sitting or lying down.
Metoprolol
According to ESC 2023, metoprolol is not a routine drug. It may be considered in selected patients with planned primary PCI if
- there are no signs of acute heart failure,
- systolic blood pressure is above 120 mmHg,
- there are no contraindications.
According to the summary of product characteristics, 5 mg i.v. is given slowly at intervals of approximately 2 min, up to a maximum of 3 doses (15 mg). Check blood pressure and heart rate after each dose.
Contraindications:
- cardiogenic shock, decompensated heart failure, hypotension,
- symptomatic bradycardia, AV block II°/III°,
- severe bronchial asthma.
In cocaine or amphetamine intoxication, beta-blockers should be used only with caution.
Receiving hospital: correct triage
- Directly to the PCI centre: Bypass hospitals without a catheterisation laboratory if primary PCI can be reached in time.
- Pre-alert: Alert the catheterisation team early, ideally with a transmitted ECG. Where possible, bypass the emergency department and hand over directly in the catheterisation laboratory.
- Fibrinolysis: This is an option if primary PCI is not available in time. For time limits and contraindications, see ESC 2023 and the regional network protocol.
- Cardiogenic shock: The centre should provide comprehensive intensive care. Hypotension is treated with fluids as required and noradrenaline.
After resuscitation and ROSC
According to ERC/ESICM 2025, a 12-lead ECG should be recorded immediately after ROSC. This determines further management:
- ST elevation: immediate coronary angiography or PCI.
- No ST elevation, but high suspicion of acute coronary occlusion (e.g. ongoing ischaemia, haemodynamic or rhythm instability): consider emergency coronary angiography.
- No ST elevation, no urgent suspicion: delayed, non-emergency coronary angiography.
Prehospital targets after ROSC:
- SpO₂ 94–98 %,
- normocapnia,
- systolic blood pressure > 100 mmHg or MAP > 60–65 mmHg; the target may be individually higher.
No prehospital cooling with large volumes of cold intravenous fluid.
Practice checklist
- Record the 12-lead ECG early, add right precordial and posterior leads as needed, serial ECGs.
- Actively check for STEMI equivalents and mimics.
- Ensure readiness for defibrillation.
- Give acetylsalicylic acid unless contraindicated.
- Further antithrombotic therapy according to the network protocol.
- Nitrates only with adequate blood pressure, without RV infarction and without PDE-5 inhibitors.
- Transfer directly to the PCI centre and pre-alert.
References
- Byrne RA, Rossello X, Coughlan JJ et al. 2023 ESC Guidelines for the management of acute coronary syndromes. Eur Heart J 2023;44:3720–3826.
- Nolan JP, Sandroni C et al. European Resuscitation Council and European Society of Intensive Care Medicine Guidelines 2025 Post-Resuscitation Care. Resuscitation 2025 / Intensive Care Med 2025;51:2213–2288.
- Soar J, Böttiger BW et al. European Resuscitation Council Guidelines 2025 Adult Advanced Life Support. Resuscitation 2025;215 Suppl 1:110769 (Korrigendum 2026).
- Fachinformation Metoprololtartrat 1 mg/ml Injektionslösung (5 ml = 5 mg) – aktuelle Fassung prüfen.
- Fachinformation Glyceroltrinitrat-Spray 0,4 mg/Sprühstoß – aktuelle Fassung prüfen.
- Fachinformation Glyceroltrinitrat-Zerbeißkapseln 0,8 mg – Präparat, Verfügbarkeit in AT/DE und aktuelle Fassung prüfen.
This article does not replace clinical judgement in the individual case or the current summary of product characteristics and guidelines.
