Definition
• Total coronary thrombosis, angina usually at rest >30 min, ST elevations, +troponin
Evaluation
• ≥0.2 mV precordial leads, ≥0.1 mV limb leads, & ≥0.5 mV in R-sided & posterior leads in at least 2 contiguous leads
Treatment
• Decide whether the pt will receive lysis or PCI as soon as possible
• If PCI is to be performed, call cardiology/PCI lab (if one is available) as early as possible (potentially even before the pt arrives in the ED – if reliable prenotification of STEMI via EMS)
• If pt will be transferred for PCI, call for transfer early, & ensure their door-to-balloon time is <90 min
• Antithrombotic/adjunctive therapy, should not delay transfer for PCI
Routine Medical Therapies “MONAB”
• Morphine: Drug of choice for pain relief in pts w/ STEMI; typical dose 0.05–0.1 mg/kg IV
• O2: Appropriate only in hypoxic pts w/ O2 saturation <90%, as routine O2 use may cause higher risk of death for pts w/ confirmed AMI
• Nitrates: No mortality benefit, but may ameliorate sxs; typical dose 0.4 mg SL q5min × 3 doses; CI w/ hypotension, RV infarct, concomitant PD inhibitor use w/i 24–48 h.
• Aspirin: 23% ↓ in death (ISIS-2, Lancet 1988;2:349); typical dose 162–325 mg PO
• Beta-blockers: Oral BB should be administered w/i 24 h of STEMI w/o CIs. Routine IV should not be used & recommended in those w/o CIs or w/ ongoing ischemia. Increased risk of cardiogenic shock in those >70 y/o, SBP <120 mmHg, HR >110 bpm (COMMIT/CCS-2, Lancet 2005;366:1622); when used, typical dose Metoprolol tartate 5 mg IV
• Other: Often started as inpts include oral BBs, statins, ACE inhibitors/ARBs
Fibrinolysis
• Fibrinolytic therapy should be given to pts w/ STEMI & onset of sxs w/i previous 12 h when it is anticipated that primary PCI cannot be performed w/i 120 min of 1st medical contact
• Indications: Sx <12 h & either STE ≥1 mm in ≥2 contig. Leads or LBBB not known to be old; benefit if sx >12 h less clear; reasonable if persistent up to 24 h sx & STE.
• Door-to-needle time should be ≤30 min
• ∼20% ↓ mortality in anterior MI or new LBBB; 10% ↓ mortality in IMI
• ∼1% risk of ICH; high-risk groups include elderly (∼2% if >75 yr), women, low weight
• Fibrin-specific lytic (front-loaded tPA) 14% ↓ mortality c/w SK (1% abs Δ; GUSTO, NEJM 1993;329:673) although ↑ ICH (0.7% vs. 0.5%); 3rd-generation bolus lytics easier to administer, but no more safe or efficacious
• Fibrinolytic agents:
Tenecteplase (TNK-tPA): Single IV weight-based bolus
30 mg for weight <60 kg
35 mg for 60–69 kg
40 mg for 70–79 kg
45 mg for 80–89 kg
50 mg for ≥90 kg
Reteplase (rPA): 10 U + 10 U IV bolus given 30 min apart
Alteplase (tPA): Bolus 15 mg, infusion 0.75 mg/kg for 30 min (max 50 mg), then 0.5 mg/kg (max 35 mg) over 60 min; total dose not to exceed 100 mg
Adjunctive Antithrombotic Therapy for Fibrinolytic Therapy
• ASA (162–325 mg PO) & Clopidogrel (300 mg LD for pts ≤75 y/o, 75 mg for pts >75 y/o) should be administered to pts w/ STEMI who receive fibrinolytic therapy (ISIS-2, Lancet 1988;2:349; CLARITY-TIMI 28, NEJM2005;352:1179; COMMIT, Lancet 2005;366:1607)
• Pts w/ STEMI undergoing reperfusion w/ fibrinolytic therapy should receive anticoagulation therapy for minimum of 48 h, w/ recommended regimens:
UFH weight-based infusion w/ IV bolus 60 U/kg (max 4000 U) followed by infusion of 12 U/kg/h (max 1000 U) to maintain aPTT ∼50–75 s for 48 h or until revascularization
Enoxaparin: If <75 y/o, 30 mg IV bolus, then 15 min later, 1 mg/kg SC q12h; if >75 y/o; no bolus, 0.75 mg/kg SC q12h; if CrCl <30 mL/min, 1 mg/kg q24h
Fondaparinux: Initial 2.5 mg IV, then 2.5 mg SC the following day, CI in CrCl <30
Indications for Transfer for Angiography After Fibrinolysis
• Immediate transfer for cardiogenic shock or severe acute HF irrespective of time delay from MI onset
• Urgent transfer for failed reperfusion or reocclusion
• As part of an invasive strategy in stable pts w/ PCI b/w 3 & 24 h after successful fibrinolysis
Primary PCI (NEJM 2007;356:47)
• Should be performed w/i 90 min of arrival by skilled operator at high-volume center
• Superior to lysis: 27% ↓ death, 65% ↓ re-MI, 54% ↓ stroke, 95% ↓ ICH (Lancet 2003;361:13)
• Transfer to center for 1° PCI may also be superior to lysis (DANAMI-2, NEJM 2003;349:733) if can achieve acceptable door-to-balloon times (as above)
Adjunctive Antithrombotic Therapy for Primary PCI
• ASA 162–325 mg PO (crushed/chewed) should be given before primary PCI (Circulation 1987;76:125; Eur Heart J. 2009;30:900; NEJM 2010;363:930)
• A loading dose of a P2Y12 receptor inhibitor should be given as early as possible or at the time of primary PCI in pts w/ STEMI:
• Clopidogrel 600 mg PO (NEJM 2010;363:930; ARMYDA-6 MI, J Am Coll Cardiol 2011;58:1592; CURRENT-OASIS 7, Lancet 2010;376:1233)
• Prasugrel 60 mg PO (NEJM 2007;357:2001; TRITON-TIMI, Lancet 2009;373:732); should not be used in pts w/ a prior h/o stroke or TIA
• Ticagrelor 180 mg PO (PLATO, Circulation 2010;122:2131)
*(Consider deferring decision regarding timing of P2Y12 receptor inhibitor use to cardiology, given potential need for CABG)
• It is reasonable to begin tx w/ an IV GPIIb/IIIa receptor antagonist in the precatheter setting to pts w/ STEMI for whom primary PCI is intended (JAMA 2004;292:362; RELAx-AMI, J Am Coll Cardiol2007;49:1517)
• Abciximab: 0.25 mg/kg bolus, then 0.125 mcg/kg/min (max 10 mcg/min)
• Tirofiban (high-bolus dose): 25 mcg/kg IV bolus, then 0.15 mcg/kg/min; ↓ by 50% in CKD
• Eptifibatide: (double bolus): 180 mcg/kg IV bolus, then 2 mcg/kg/min; a 2nd 180 mcg/kg bolus given 10 min after 1st bolus; ↓ by 50% in CKD, avoid in dialysis pts
• For pts undergoing primary PCI, the following anticoagulant regimens are recommended:
• UFH w/ GP IIb/IIIa inhibitor: 50–70 U/kg bolus to achieve therapeutic ACT
• UFH w/o GP IIb/IIIa inhibitor: 70–100 U/kg bolus to achieve therapeutic ACT
• Bivalirudin: 0.75 mg/kg IV bolus, then 1.75 mg/kg/h infusion w/ or w/o UFH; preferred over UFH w/ GP IIb/IIIa inhibitor in pts at high risk of bleeding
Nonprimary PCI
• Facilitated PCI: Lytic before PCI harmful (Lancet 2006;367:569; Lancet 2006;367:579), & partial dose lytic no better than no lytic (FINESSE, NEJM 2008;358:2205); upstream GPI also shows increased mortality
• Rescue PCI (after full dose lytics & persistent STEMI or cx): Beneficial if <50% ST segment resolution by 90 min (NEJM 2005;353:2758)
• Routine angio ± PCI w/i 24 h of successful lysis: ↓ D/MI/Revasc (Lancet 2004;364:1045)
• Late PCI (median day 8) of occluded infarct-related artery: No benefit (NEJM 2006;355:2395)
Disposition
• Admit to cardiology → cath lab → CCU
Pearls
• Mortality 6% w/ reperfusion tx (PCI or lytic), ∼20% w/o
• Predictors of mortality: Age, time to therapy, anterior MI, LBBB, heart failure (Circulation 2000;102:2031)
Guideline: O’Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of STEMI: A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2013;61(4):e78–e140.