ST-segment elevation myocardial infarction

Diagnosis

1. ≥ 1-mm (0.1mV) ST-segment elevation in at least 2 anatomically contiguous limb leads (aVL to III, including -aVR)
2. ≥ 1-mm ST-segment elevation in a precordial lead V4 through V6
3. ≥ 2-mm (0.2mV) ST-segment elevation in V1 through V3
4. a new left bundle branch block

ACC/AHA, ESC

DDx

1. Myocardial ischemia or infarction
2. Noninfarction, transmural ischemia (Prinzmetal's angina pattern or acute takotsubo cardiomyopathy)
3. Acute myocardial infarction (MI)
4. Post-MI (ventricular aneurysm pattern)-Previous MI with recurrent ischemia in the same area-Acute pericarditis-Normal "early repolarization variants"
5. Left ventricular hypertrophy or left bundle branch block (only V1-V2 or V3)-Myocarditis (may look like myocardial infarction or pericarditis)
6. Brugada patterns (V1-V3 with right bundle branch block-appearing morphology)
7. Myocardial tumor
8. Myocardial trauma
9. Hyperkalemia (only leads V1 and V2)
10. Hypothermia (J wave/Osborn wave)

Treatment

Adjunctive

1. O2
2. ASA 162, 325chewable PO or 600mg PR; Plavix 300 or 600mg if ASA allergy
3. NTG
4. Morphine
5. BBlocker:
   1. PO within 24 hours
   2. IV beta-blocker is reasonable for patients who are hypertensive in the absence of:
      1. signs of heart failure
      2. evidence of a low cardiac output state
      3. post beta-blocker cardiogenic shock risk factors (age > 70 years, systolic blood pressure < 120 mm Hg, sinus tachycardia > 110 bpm or heart rate < 60 bpm, increased time since onset of symptoms of STEMI)
      4. other relative contraindications to beta blockade (PR interval > 0.24 s, second- or third-degree heart block, active asthma, or reactive airway disease)

Anticoagulants

1. Heparin (UFH)
   1. Bolus 60U/kg (max: 4000U)
   2. 12U/kg/h (max: 1000U/h)
   3. NB: monitor PTT: 50-70s
2. LMWH
   1. <75yo with serum Cr < 2.5 mg/dL (men) or < 2.0 mg/dL (women):
      1. 30mg IV bolus, followed by 1mg/kg SC q12h
   2. ≥ 75yo: 0.75-mg/kg SC q12h
   3. CrCl < 30 mL/min: 1mg/kg SC qd
   4. NB: note renal clearance
3. Fondaparinux
   1. Cr < 3.0 mg/dL: 2.5mg IV bolus, then 2.5-mg SC qd, started 24 hr after bolus
   2. NB: monitor anti-Xa levels
4. Bivalirudin
   1. 0.75-mg/kg IV bolus, followed by 1.75 mg/kg/h
   2. CrCl < 30 mL/min: 0.75-mg/kg IV bolus, followed by 1.0 mg/kg/h

Antiplatelet

1. GPIIB/IIIa Inhibitors: Abciximab (ReoPro®), Eptifibatide (Integrilin®), Tirofiban (Aggrastat®)
   1. Given right before PCI
   2. Defer to cardiologist
2. Clopidogrel (Plavix®)
   1. 300mg po x1 (onset 2h, peak 6-15h)
   2. 600mg po x1 (faster onset)

Definitive

Fibrinolytics within 30mins

OR

PCI within 90mins

Source

DONALDSON (adapted from ACC/AHA Practice Guidelines 2004/5), EBM 6/09