STEMI

Objectives

To outline the management of patients presenting to deployed medical facilities with chest pain which is then confirmed to be ST elevation myocardial infarction (STEMI). 

Scope

This guideline intends to cover the initial investigations and management of patients presenting to the deployed medical treatment facilities with cardiac sounding chest pain which is then confirmed to be STEMI. It defines diagnosis of STEMI, initial management, and onward care. It does not include management of Non-STEMI cardiac chest pain presentations. For these patients, please refer to the acute coronary syndrome (ACS) guidelines.   

Audience

This guideline is intended for the use of registered healthcare professionals fulfilling a general role in forward medical locations or in an Emergency Department on deployed operations. 

Initial Assessment & Management

TIME IS CRITICAL 

3 Lead ECG AND/OR 12L ECG within 5 mins of presentation – reviewed by clinician  

Apply Automated External Defibrillator (AED) Pads  

If STEMI confirmed start immediate discussion with Medevac/Aeromed

Assess and Record 

Chest pain:

• Character: A heavy, pressure-like or squeezing discomfort.
• Site: Typically retrosternal (behind the sternum).
• Radiation: May radiate to the left arm, neck, jaw, or back.
• Intensity: Moderate to severe, often described as distressing and persistent.

Time: 

• Onset: Sudden onset, often occurring at rest or with minimal exertion.
  • Pain at rest or with minimal exertion indicates plaque instability or rupture and reduced coronary perfusion. 
  • In contrast stable angina is usually precipitated by a consistent amount of exertion or emotional stress and relieved by rest or nitrates within 5–10 minutes, reflecting a fixed coronary obstruction rather than an acute event.
• Duration: Typically lasts more than 20 minutes and does not fully resolve with rest or nitrates.

Symptoms: SOB, sweating, nausea, palpitations 

Differential diagnosis to consider (see separate guidelines)

Acute Coronary Syndrome – NSTEMI 

Aortic dissection  

Inflammatory conditions – Myocarditis/Pericarditis 

Pulmonary Embolism  

ROLE 1 

Immediate treatment – undertake concurrently 

Observations: Pulse, BP, Resp rate, Saturations, blood sugar

IV access   

Aspirin 300mg PO 

GTN spray S/L  

Oxygen - if saturations <92% 

IV morphine - as required for pain  

IV antiemetic - (post opiate and most pts will need when transported) 

Ensure continuous cardiac monitoring and availability of defibrillation

Monitor through AED pads if needed

Transfer IMMEDIATELY to R2/3/HNF as able – continuous monitoring while waiting 

Thrombolytic agents not available in the role 1 setting

Aeromed – will need consideration for definitive level care UK/Host Nation

Advanced Assessment & Management

Immediate treatment on arrival to Role 2– undertake concurrently 

• Observations: Pulse, BP, Resp rate, Saturations, Blood sugar 

• IV access – if not already obtained OR confirm patency if in situ 

• Aspirin 300mg PO – if not given earlier 

• GTN spray S/L – if pain ongoing  

• Oxygen - if saturations <92% 

• IV morphine - as required for pain  

• IV antiemetic - (post opiate and most pts will need to facilitate evacuation) 

Investigations *as available 

• Bloods – FBC, U&Es, LFTs, Glucose, Cardiac enzymes 

• Chest X-ray 

Review ECG and repeat 

STEMI NOT Confirmed?

• ECG Criteria not suggestive of STEMI 
• Admit to critical care area for monitoring 
• Manage as per ACS guidelines

STEMI Confirmed?

Give loading dose of second antiplatelet agent as determined by available formulary (adjust as per thrombolysis guidance if thrombolysis to be given) 

Thrombolyse within 12 hours of symptom onset AT LOCATION IF able AND Primary percutaneous coronary intervention (PPCI) not available within 120 minutes - thrombolysis guidelines below 

Thrombolysis – For STEMI Only 

Tenecteplase  is the first-choice thrombolytic agent 

Give WITH enoxaparin AND antiplatelets as described below 

Contraindications are: 

Tenecteplase: IV bolus given over 10 seconds.
 

Enoxoparin:

Give IV bolus enoxoparin 30mg (Adults 18–74 years, omit if 75 years or over)  

Follow with SC injection immediately, which is weight adjusted: 

• 1 mg/kg for 1 dose (max. per dose= 100 mg) SC injection  
• Reduced to 0.75mg/Kg if > 75 years of age
• THEN 1 mg/kg every 12 hours (max. per dose= 100 mg) for up to 8 days Maximum dose applies for the first two subcutaneous doses only. 

Antiplatlets: 

Ensure one off 300mg Aspirin has been given 

Give second antiplatelet - Clopidogrel 300mg ideally (omit if patient > 74 years) 

Post thrombolysis care:  

Ensure patient in critical care area 

Repeat ECG after 60 – 90 mins to confirm effectiveness 

Successful clinical reperfusion suggested by; 

1. Significant improvement in ischaemic chest pain
2. Greater than 50% reduction in ST segment elevation 

DO NOT REPEAT THROMBOLYSIS

• If ongoing myocardial ischaemia seek specialist advice/expediate transfer to cardiac centre: Dual antiplatelet therapy daily (DAPT) – Aspirin 75mg OD, Clopidogrel 75mg OD 

• High dose statin daily – Atorvastatin 80mg OD 

• Enoxaparin as above  

Prolonged Casualty Care

Evacuation

ALL cases of ACS (STEMI and NSTEMI) require evac to a cardiac centre ASAP 

Prolonged care 

Observe in critical care area with continuous ECG monitoring  

Resus equipment must be to hand including defibrillator 

Addition medication to include; statin, ACEi, Beta blocker though these are only available in role 3

Smoking cessation if this has been a risk factor  

Be wary of those with RV infarct – any drugs that reduce venous return, like nitrates or diuretics, can reduce cardiac output and precipitate shock

When compared with PPCI, thrombolysis treatment for STEMI is associated with a higher likelihood of complications including Myocardial rupture, severe mitral regurgitation and Ventricular septal defect