STEMI Management Pathway

Primary PCI–first reperfusion strategy with antiplatelet / anticoagulant / fibrinolytic options

DOOR-TO-BALLOON TARGET ≤90 MIN (≤120 MIN IF TRANSFER)

Flowchart

First medical contact — 12-lead ECG within 10 min. STEMI = ST elevation ≥1mm in ≥2 contiguous leads, new LBBB with high clinical suspicion, or posterior MI pattern.

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Immediate therapy (all patients) — Aspirin 162–325mg chewed once. Nitroglycerin 0.4mg SL q5min ×3 prn (hold if SBP<90, suspected RV/inferior infarct, recent PDE5-inhibitor use). O₂ only if SpO₂<90%. Morphine prn pain only after nitrates fail.

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Reperfusion decision — Can primary PCI be performed within 90 min of first medical contact (120 min if transfer)?

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YES → PRIMARY PCI

Cath lab activation. Antiplatelet + anticoagulant per PCI columns in table below. Radial access preferred.

NO → FIBRINOLYSIS

Door-to-needle ≤30 min. Fibrinolytic + antiplatelet/anticoagulant per fibrinolysis columns below. Transfer for angiography 2–24h if successful, immediate rescue PCI if failed (ST resolution <50% at 60–90 min).

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Post-reperfusion / inpatient therapy — High-intensity statin, beta-blocker, ACEI/ARB if indicated, aldosterone antagonist if indicated (see table).

Medication Reference

Antiplatelet — P2Y12 inhibitor (added to aspirin)

Drug	Dose	Note
TicagrelorBrilinta	Load 180mg PO Maintain 90mg PO BID	PREFERRED — PCI Avoid if prior ICH; dyspnea is a common side effect; not validated with fibrinolysis.
PrasugrelEffient	Load 60mg PO Maintain 10mg PO OD (5mg if wt<60kg or age≥75)	ALTERNATIVE — PCI only Contraindicated with prior stroke/TIA; not for fibrinolysis or pre-angiography NSTE-ACS.
ClopidogrelPlavix	Load 600mg PO (PCI) or 300mg if fibrinolysis/age≥75 Maintain 75mg PO OD	USE WITH FIBRINOLYSIS or if ticagrelor/prasugrel unavailable Slower onset; CYP2C19 polymorphism causes variable response.

Anticoagulant

Drug	Dose	Note
UFH	Bolus 60 IU/kg IV (max 4000) Infusion 12 IU/kg/hr (max 1000), titrate to aPTT	STANDARD — PCI Watch for HIT with prolonged infusion.
EnoxaparinLovenox	PCI: 0.5mg/kg IV bolus Fibrinolysis: 30mg IV bolus + 1mg/kg SC q12h (no bolus, 0.75mg/kg SC q12h if age≥75; 1mg/kg SC OD if CrCl<30)	ALTERNATIVE Requires renal dose adjustment.
BivalirudinAngiox	0.75mg/kg IV bolus + 1.75mg/kg/hr infusion during PCI	HIGH BLEEDING RISK / HIT HISTORY Stent thrombosis risk if stopped abruptly post-PCI.

Fibrinolytic (only if primary PCI not achievable in time window)

Drug	Dose	Note
TenecteplaseMetalyse	Single IV bolus by weight: 30mg (<60kg) / 35mg / 40mg / 45mg / 50mg (≥90kg) Half dose if age≥75	PREFERRED — fibrin-specific Absolute CI: any prior ICH, active bleeding, suspected aortic dissection.
AlteplaseActilyse	15mg IV bolus, then 0.75mg/kg over 30min (max 50mg), then 0.5mg/kg over 60min (max 35mg)	ALTERNATIVE — fibrin-specific Same contraindications as above.
Streptokinase	1.5 million units IV over 60 min	LOWER COST, still used in Thai MOPH hospitals Not fibrin-specific (more hypotension/systemic bleeding); contraindicated if given within prior 6 months (antibody-mediated resistance).

Adjunctive therapy (start within 24h, post-reperfusion)

Drug	Dose	Note
AtorvastatinLipitor	80mg PO OD (or Rosuvastatin/Crestor 20–40mg OD)	High-intensity statin regardless of baseline LDL.
MetoprololBetaloc	25–50mg PO BID	Avoid routine IV beta-blocker — COMMIT trial showed increased cardiogenic shock risk in unstable patients. Hold if signs of HF/low-output state.
Enalapril / RamiprilACEI	Low dose, titrate up	Indicated if anterior MI, LVEF≤40%, HF, or diabetes. Hold if SBP<100; monitor renal function/K⁺.