What is the management of acute infarction (myocardial infarction, ischemic stroke, peripheral arterial infarction)?

Management of Acute Infarction

ST-Elevation Myocardial Infarction (STEMI)

Primary percutaneous coronary intervention (PCI) within 90-120 minutes of first medical contact is the definitive reperfusion strategy for all STEMI patients presenting within 12 hours of symptom onset. 1, 2

Immediate Reperfusion Decision Algorithm

If PCI-capable facility accessible within 120 minutes:

• Perform primary PCI within 90 minutes of first medical contact 1, 2
• Target first medical contact to device time ≤90 minutes 2
• Transfer directly to catheterization laboratory, bypassing emergency department 2

If PCI cannot be performed within 120 minutes:

• Initiate fibrinolytic therapy immediately, preferably in pre-hospital setting 1, 2
• Use fibrin-specific agents: tenecteplase, alteplase, or reteplase 2, 3
• For patients ≥75 years, reduce tenecteplase dose by 50% to minimize stroke risk 3
• Transfer ALL patients to PCI-capable center immediately after fibrinolysis 1, 3

Immediate Pharmacotherapy (Administer Simultaneously)

Antiplatelet therapy:

• Aspirin 150-325 mg oral or IV immediately 1, 2
• Potent P2Y12 inhibitor (prasugrel 60 mg loading or ticagrelor) before or at time of PCI 1, 2
• If using clopidogrel: 600 mg loading dose is superior to 300 mg, reducing 30-day mortality (1.9% vs 3.1%), reinfarction (1.3% vs 2.3%), and stent thrombosis (1.7% vs 2.8%) without increased bleeding 4
• Clopidogrel is only acceptable if prasugrel/ticagrelor unavailable or contraindicated 1

Anticoagulation:

• Unfractionated heparin as weight-adjusted IV bolus followed by infusion for primary PCI 1

Symptom management:

• Morphine 4-8 mg IV with additional 2 mg doses at 5-15 minute intervals for pain/anxiety 1
• Do NOT give routine oxygen unless SaO2 <90% 1

Post-Fibrinolysis Management Algorithm

At 60-90 minutes after fibrinolysis:

• Assess ST-segment resolution in lead with greatest initial ST elevation 3

If <50% ST-segment resolution (failed fibrinolysis):

• Perform rescue PCI immediately 3

If ≥50% ST-segment resolution (successful fibrinolysis):

• Perform angiography and PCI of infarct-related artery between 2-24 hours 2, 3

Emergency angiography indications (perform immediately regardless of timing):

• Heart failure or cardiogenic shock 1, 3
• Hemodynamic instability 3
• Electrical instability 3
• Worsening or recurrent ischemia 3

Long-Term Antithrombotic Strategy

Dual antiplatelet therapy (DAPT) for 12 months:

• Aspirin 75-100 mg daily plus ticagrelor or prasugrel (or clopidogrel if unavailable/contraindicated) 1
• Add proton pump inhibitor for patients at high gastrointestinal bleeding risk 1
• Critical caveat: Avoid omeprazole or esomeprazole with clopidogrel as they significantly reduce antiplatelet activity 5
• Consider CYP2C19 genetic testing if using clopidogrel; poor metabolizers should receive alternative P2Y12 inhibitor 5

Special Considerations

STEMI without chest pain:

• Treat identically to typical STEMI—absence of chest pain does NOT change management urgency 1
• ST elevation on ECG signifies complete coronary occlusion requiring immediate reperfusion regardless of symptoms 1

Late presentation (>12 hours):

• Consider reperfusion if clinical/ECG evidence of ongoing ischemia 2
• Do NOT perform routine PCI in asymptomatic patients >48 hours after STEMI with occluded infarct-related artery 2, 3

Non-ST-Elevation Acute Coronary Syndrome (NSTEMI/Unstable Angina)

Clopidogrel 300 mg loading dose followed by 75 mg daily in conjunction with aspirin reduces MI and stroke rates. 5

• Administer aspirin 160-325 mg initially, then 75-162 mg daily indefinitely 6
• For aspirin-allergic patients, use clopidogrel as alternative 6

Ischemic Stroke

For acute ischemic stroke in setting of recent MI, alteplase can be administered provided anterior wall myocardial involvement has been carefully evaluated. 7

• Patients are at increased risk of stroke for up to 3 months following MI 7
• Aggressive AMI treatment including reperfusion therapy decreases AIS risk 7

Established Peripheral Arterial Disease or Prior MI/Stroke

For secondary prevention in patients with established PAD or history of MI/stroke, clopidogrel 75 mg daily without loading dose reduces recurrent MI and stroke. 5, 8

• Dual antiplatelet therapy (clopidogrel plus aspirin) in patients with documented prior MI, ischemic stroke, or symptomatic PAD significantly reduces cardiovascular death, MI, or stroke (7.3% vs 8.8%) compared to aspirin alone 9
• Moderate bleeding increases with dual therapy (2.0% vs 1.3%) but severe bleeding rates remain similar 9