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
   1. Esp for SpO2 <90%
2. ASA 162-325mg chewable or 600mg PR
3. Plavix
   1. Loading dose
      1. 300mg
      2. 600mg if PCI anticipated
      3. No loading dose if >75yr receiving fibrinolytics
4. NTG
5. Morphine
6. 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

1. Fibrinolytics within 30mins
2. PCI within 90mins

Fibrinolysis

Inclusion

1. <12 hours from the onset of chest pain (lasting 30 minutes) and:
2. ST elevation of ≥1mm in 2 contiguous limb or precordial leads
3. New left bundle branch block

Exclusion

1. ABSOLUTE
   1. Any prior ICH
   2. Known structural CNS lesion (e.g. AV malformation, intracranial neoplasm)
   3. Ischemic stroke <3 months (excluding acute ischemic stroke within last 3h)
   4. Suspected aortic dissection
   5. Active bleeding or bleeding diathesis (excluding menses)
   6. Significant closed-head/facial trauma < 3months
2. RELATIVE
   1. SBP >180 mmHg
   2. DBP >110 mmHg
   3. CPR >10min
   4. <4wk from major trauma/surgery or GI/GU bleed
   5. Current use of anticoagulants
   6. Pregnancy
   7. Active peptic ulcer (guaiac positive)
   8. Ischemic stroke in past 3 months
   9. Dementia or other known intracranial pathology not noted above
   10. Noncompressible vascular punctures w/in past 3 weeks
   11. Prior exposure (> 5 days) or prior allergic reaction to streptokinase or anistreplase (if taking these agents)

Source

ACC/AHA Practice Guidelines 2004/5

EBM 6/09