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
-Myocardial ischemia or infarction
-Noninfarction, transmural ischemia (Prinzmetal's angina pattern or acute takotsubo cardiomyopathy)
-Acute myocardial infarction (MI)
-Post-MI (ventricular aneurysm pattern)-Previous MI with recurrent ischemia in the same area-Acute pericarditis-Normal "early repolarization variants"
-Left ventricular hypertrophy or left bundle branch block (only V1-V2 or V3)-Myocarditis (may look like myocardial infarction or pericarditis)
-Brugada patterns (V1-V3 with right bundle branch block-appearing morphology)
-Myocardial tumor
-Myocardial trauma
-Hyperkalemia (only leads V1 and V2)
-Hypothermia (J wave/Osborn wave)
Treatment===Adjunctive===
O2
ASA 162, 325chewable PO or 600mg PR; Plavix 300 or 600mg if ASA allergy
NTG
Morphine
BBlocker:
-PO within 24 hours;
-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
Heparin (UFH)
-Bolus 60U/kg (max: 4000U)
-12U/kg/h (max: 1000U/h)
NB: monitor PTT: 50-70s
LMWH
<75yo with serum Cr < 2.5 mg/dL (men) or < 2.0 mg/dL (women):
-30mg IV bolus, followed by 1mg/kg SC q12h
≥ 75yo: 0.75-mg/kg SC q12h
CrCl < 30 mL/min: 1mg/kg SC qd
NB: note renal clearance
Fondaparinux
-Cr < 3.0 mg/dL: 2.5mg IV bolus, then 2.5-mg SC qd, started 24 hr after bolus
NB: monitor anti-Xa levels
Bivalirudin
-0.75-mg/kg IV bolus, followed by 1.75 mg/kg/h
-CrCl < 30 mL/min: 0.75-mg/kg IV bolus, followed by 1.0 mg/kg/h
Antiplatelet
GPIIB/IIIa Inhibitors: Abciximab (ReoPro®), Eptifibatide (Integrilin®), Tirofiban (Aggrastat®)
-Given right before PCI
-Defer to cardiologist
Thienopyridines
Clopidogrel (Plavix®)
-300mg po x1 (onset 2h, peak 6-15h)
-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