Standard of Care for Acute Myocardial Infarction
For STEMI, primary percutaneous coronary intervention (PCI) within 90 minutes of first medical contact is the definitive standard of care, while high-risk NSTEMI requires early invasive strategy with coronary angiography within 24 hours. 1, 2
Immediate Assessment (First 10 Minutes)
Obtain and interpret a 12-lead ECG within 10 minutes of first medical contact to differentiate STEMI from NSTEMI and identify STEMI equivalents (hyperacute T-waves, posterior MI, multilead ST depression with ST elevation in aVR, or new left bundle branch block). 1, 2, 3
Administer aspirin 162-325 mg (chewed) immediately upon suspicion of acute MI, as this reduces mortality regardless of reperfusion strategy. 2, 3
Initiate continuous ECG monitoring with defibrillator capacity to detect and treat life-threatening arrhythmias. 2, 3
Provide supplemental oxygen only if oxygen saturation is <90%, as routine oxygen administration in normoxic patients provides no benefit. 3
STEMI Reperfusion Strategy
Primary PCI is mandatory for STEMI and must be performed within 90 minutes of first medical contact when at a PCI-capable facility, or within 120 minutes when transfer is required. 1, 2, 3
When Primary PCI is Preferred:
Transfer immediately to a PCI-capable center if first medical contact-to-device time can be achieved within 120 minutes. 1, 3
For patients presenting within 12 hours of symptom onset, primary PCI significantly reduces mortality compared to no reperfusion. 1
Primary PCI is superior to fibrinolysis for patients presenting 3-12 hours after symptom onset. 1
Primary PCI is mandatory regardless of time delays for patients with cardiogenic shock, acute severe heart failure, or contraindications to fibrinolysis. 1, 3
When Fibrinolytic Therapy is Indicated:
Administer fibrinolytic therapy within 30 minutes of hospital arrival if anticipated first medical contact-to-device time exceeds 120 minutes and symptom onset is within 12 hours. 1, 3
Fibrinolytic therapy demonstrates comparable mortality benefit to primary PCI when administered within 2-3 hours of symptom onset. 1
Fibrinolytic therapy is absolutely contraindicated in patients with acute stroke, recent intracranial hemorrhage, or active bleeding. 4, 5
After fibrinolysis, perform rescue PCI if ST-segment elevation persists after 45-60 minutes, indicating failed reperfusion. 3
NSTEMI Risk Stratification and Invasive Strategy
High-risk NSTEMI patients (GRACE score >140 or TIMI risk score >4) require early invasive strategy with coronary angiography within 24 hours. 2
Immediate Invasive Approach (Within 2 Hours):
- Refractory angina despite maximal medical therapy 2
- Hemodynamic instability or cardiogenic shock 2
- Acute heart failure 2
- Life-threatening ventricular arrhythmias 2
Early Invasive Approach (Within 24 Hours):
- Elevated cardiac troponin with dynamic ECG changes 2
- GRACE score >140 or TIMI risk score >4 2
- Diabetes mellitus with high-risk features 2
Adjunctive Pharmacotherapy
Antiplatelet Therapy:
Administer dual antiplatelet therapy (DAPT) with aspirin plus a P2Y12 inhibitor (ticagrelor, prasugrel, or clopidogrel) immediately upon diagnosis. 2, 6
Ticagrelor or prasugrel are preferred over clopidogrel for more potent platelet inhibition, unless contraindications exist. 2
Continue DAPT for 12 months unless bleeding complications occur. 4
Avoid glycoprotein IIb/IIIa inhibitors in patients with acute stroke due to dramatically increased intracranial hemorrhage risk. 4
Anticoagulation:
Administer unfractionated heparin (60-100 U/kg IV bolus) or low-molecular-weight heparin during the acute phase. 2, 3
Continue anticoagulation throughout hospitalization and during PCI procedures. 2
Additional Medical Therapy:
Initiate high-intensity statin therapy immediately, regardless of baseline lipid levels. 4, 2
Start oral beta-blocker within 24 hours once hemodynamically stable (avoid IV beta-blockers in acute phase). 4
Begin ACE inhibitor within 24 hours if no contraindications, particularly with anterior MI, heart failure, or LVEF ≤40%. 4
PCI Technical Considerations
Use radial artery access preferentially over femoral access to minimize bleeding complications. 4
Implant drug-eluting stents as standard of care for both STEMI and NSTEMI. 4
Avoid routine thrombus aspiration, as it does not improve outcomes and may increase stroke risk. 4
Perform PCI only on the culprit vessel during the acute phase; staged revascularization of non-culprit lesions can be performed later if needed. 1
Critical Pitfalls to Avoid
Never delay ECG acquisition beyond 10 minutes, as this is the single most important diagnostic step that determines all subsequent management. 1, 2, 3
Never administer fibrinolytic therapy to patients with acute stroke, as this is an absolute contraindication that dramatically increases mortality from intracranial hemorrhage. 4, 5
Do not miss STEMI equivalents on ECG (hyperacute T-waves, posterior MI, multilead ST depression with ST elevation in aVR), as these require immediate reperfusion identical to traditional STEMI. 1, 2
Avoid delaying transfer decisions while waiting for cardiac biomarker results in STEMI patients, as ECG findings alone are sufficient to initiate reperfusion therapy. 3
Do not overlook high-risk NSTEMI patients who present with ongoing chest pain, hemodynamic instability, or heart failure, as they require immediate invasive management within 2 hours, not delayed angiography. 2
Never use glycoprotein IIb/IIIa inhibitors in patients with recent stroke or high bleeding risk, as hemorrhagic complications outweigh any antiplatelet benefit. 4
Avoid administering oxygen to patients with normal oxygen saturation (≥90%), as this provides no benefit and may cause harm. 3
Time Metrics and Quality Measures
The Vienna STEMI Registry demonstrated that implementation of guideline-based care with organized networks reduced in-hospital mortality from 16% to 9.5%, primarily by increasing reperfusion rates from 66% to 86.6%. 1
Key time targets that directly impact mortality: