STEMI Diagnostic Criteria and Treatment
STEMI is diagnosed by ST elevation ≥2 mm in men or ≥1.5 mm in women in leads V2-V3, or ≥1 mm in other contiguous leads, combined with symptoms of myocardial ischemia, and requires immediate primary PCI within 120 minutes or fibrinolytic therapy within 10 minutes if PCI is unavailable. 1
Diagnostic Criteria
ECG findings must show ST elevation at the J point in at least 2 contiguous leads: 1
- ≥2 mm (0.2 mV) in men or ≥1.5 mm (0.15 mV) in women in leads V2–V3 1
- ≥1 mm (0.1 mV) in other contiguous chest leads or limb leads 1
- ST depression in ≥2 precordial leads (V1–V4) indicates posterior wall infarction requiring the same urgent approach 1
Clinical presentation typically includes: 1
- Chest pain/discomfort lasting 10-20 minutes or more, potentially radiating to neck, jaw, or left arm 1
- Atypical presentations in elderly may present as fatigue, dyspnea, faintness, or syncope 1
Cardiac biomarkers will be subsequently released, confirming myocardial necrosis 1
Immediate Treatment Algorithm
Step 1: Initial Pharmacotherapy (Administer Immediately)
Give these medications while arranging reperfusion: 1
- Aspirin 162-325 mg loading dose (chewed for faster absorption) 1
- P2Y12 inhibitor loading dose (preferably prasugrel or ticagrelor) 1, 2
- Morphine sulfate 2-4 mg IV, with 2-8 mg IV every 5-15 minutes as needed for pain 1
- Sublingual nitroglycerin 0.4 mg every 5 minutes, up to three doses if no contraindications 1
- Anticoagulant (unfractionated heparin, enoxaparin, or bivalirudin) 2
Step 2: Choose Reperfusion Strategy Based on Time
Primary PCI is the preferred strategy if it can be performed within 120 minutes of first medical contact: 1, 2, 3
- Alert the PCI center immediately and transfer directly to the catheterization laboratory, bypassing the emergency department 2
- Perform coronary angiography with intent to perform PCI 1
- Use radial access preferentially over femoral access to reduce bleeding complications 1, 2
- Implant drug-eluting stents as standard of care 1, 2
- Avoid routine thrombus aspiration during PCI 2
If PCI cannot be performed within 120 minutes, administer fibrinolytic therapy immediately (within 10 minutes of STEMI diagnosis): 1, 2
- Fibrinolytic therapy should be administered within 30 minutes of hospital arrival 1
- Transfer for rescue PCI if fibrinolysis fails, evidenced by cardiogenic shock, severe heart failure/pulmonary edema, or hemodynamically compromising ventricular arrhythmias 1
Step 3: Post-Reperfusion Care
Initiate these medications before discharge: 1
- Dual antiplatelet therapy (DAPT) with aspirin plus P2Y12 inhibitor (prasugrel or ticagrelor) for one year 1, 2
- Beta-blockers within 24 hours in hemodynamically stable patients 1
- ACE inhibitors or ARBs 1
- Statins 1
Special Considerations
For patients presenting 12-24 hours after symptom onset, primary PCI may still be considered if there is evidence of ongoing ischemia 2
Routine PCI of a totally occluded artery >24 hours after symptom onset in stable patients without signs of ischemia is not recommended 2
In cardiogenic shock, consider non-infarct-related artery PCI during the index procedure 2
Severe non-infarct-related artery stenosis should be considered for treatment before hospital discharge 2
Critical Pitfalls to Avoid
Do not delay reperfusion therapy due to atypical presentations or unusual ECG patterns—the 120-minute window is absolute 1, 2
Do not miss posterior MI—ST depression in anterior leads (V1-V3) represents posterior infarction requiring identical urgent reperfusion 1
Do not use deferred stenting strategies 2
Ensure equal treatment for both men and women—both genders receive equal benefit from reperfusion therapies 2