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ST-elevation myocardial infarction (STEMI) or non-ST-elevation acute coronary syndrome (NSTEACS): Rapid overview of emergency management

ST-elevation myocardial infarction (STEMI) or non-ST-elevation acute coronary syndrome (NSTEACS): Rapid overview of emergency management
Initial assessment:
  • Obtain 12-lead ECG within 10 minutes of arrival; repeat at least every 15 to 30 minutes if initial ECG is nondiagnostic but clinical suspicion remains high (initial ECG often not diagnostic).
    1. STEMI: ≥0.1 mV (≥1 mm) in all leads other than V2 to V3.
    2. For leads V2 to V3, ≥0.2 mV (≥2 mm) in males ≥40 years, ≥0.25 mV (≥2.5 mm) in males <40 years, ≥0.15 mV (≥1.5 mm) in females.
    3. If ECG suspicious but not diagnostic, repeat ECG at least every 15 to 30 minutes and consult cardiologist early.
    1. Non-STEMI: 2 anatomically contiguous leads with presumed new horizontal or down-sloping ST depression ≥0.05 mV (≥0.5 mm) and/or T wave inversion ≥0.1 mV (≥1 mm) with prominent R wave or R/S ratio >1.
  • Obtain emergency cardiology consultation for ACS patients with cardiogenic shock, heart failure, or sustained ventricular tachyarrhythmia.
Initial interventions:
  • Assess and stabilize airway, breathing, and circulation.
  • Attach cardiac and oxygen saturation monitors; provide supplemental oxygen as needed to maintain O2 saturation >94%. Establish IV access.
  • Treat sustained ventricular arrhythmia rapidly according to ACLS protocols.
  • Give aspirin 162 to 325 mg (nonenteric coated) to be chewed and swallowed (unless there is a compelling contraindication, such as history of anaphylaxis or aortic dissection is suspected). If oral administration is not feasible, give as rectal suppository.
  • Perform focused history and examination: Look for signs of hemodynamic compromise and left heart failure; determine baseline neurologic function, particularly if fibrinolytic therapy is to be given.
  • Obtain blood for cardiac biomarkers (high-sensitivity troponin preferred), electrolytes, hematocrit/hemoglobin. Perform coagulation studies for patients taking anticoagulants or as otherwise indicated (eg, known coagulopathy).
  • If patient has persistent chest discomfort, hypertension, or hypoxia from pulmonary edema, give 1 sublingual nitroglycerin tablet (0.3 to 0.4 mg) every 5 minutes for 3 doses or administer 1 translingual spray (0.4 mg/spray) onto or under the tongue every 5 minutes for 3 doses. Contraindications to nitroglycerin include hypotension, right ventricular infarction, recent use of phosphodiesterase inhibitors (eg, for erectile dysfunction). May use IV nitroglycerin for persistent symptoms.
  • Treat left heart failure if present: Give afterload-reducing agent (eg, nitroglycerin sublingual tablet and/or IV drip starting at 5 to 10 mcg/minute provided no hypotension and no phosphodiesterase inhibitors [eg, for erectile dysfunction]; titrate drip up quickly based on response); give loop diuretic (eg, IV furosemide); administer noninvasive positive pressure ventilation (eg, BPAP) to appropriate patients.
  • Morphine (initial dose of 2 to 4 mg IV, followed by 2 to 8 mg IV every 5 to 15 minutes as needed) may be given for the relief of severe, persistent chest pain not relieved by other means, but should not be given routinely.
Acute management STEMI:
  • Select reperfusion strategy: Primary PCI strongly preferred, especially for patients with cardiogenic shock, heart failure, late presentation, or contraindications to fibrinolysis. Activate cardiac catheterization team as indicated. For patients with symptoms for ≥12 hours, fibrinolytic therapy is not indicated, but emergent PCI should be performed as soon as possible for patients with evidence of ongoing ischemia.
  • Treat with fibrinolysis if PCI unavailable within 120 minutes of first medical contact, symptoms <12 hours, and no contraindications.*
  • Give oral antiplatelet therapy (in addition to aspirin):
    1. Patients treated with fibrinolytic therapy: For patients ≤75 years, give clopidogrel loading dose of 300 mg orally once. For patients >75 years, give clopidogrel 75 mg orally once.
    2. Patients treated with primary PCI or without reperfusion therapy: Give ticagrelor loading dose of 180 mg orally once or prasugrel loading dose of 60 mg orally once (contraindications to prasugrel include prior stroke or TIA, active pathological bleeding, age ≥75 years, weight <60 kg). For patients at high risk of bleeding or those for whom prasugrel or ticagrelor cannot be used, we give clopidogrel loading dose of 600 mg orally once.
    3. For patients treated with primary PCI, reasons to defer administration until after angiography include uncertainty of diagnosis or if the administration would lead to delay in transfer for PCI.
  • Give anticoagulant therapy:
    1. For patients treated with primary PCI, we prefer UFH. Bivalirudin can be used in patients with prior history of heparin-induced thrombocytopenia.
      • Dosing of UFH:
        • No planned glycoprotein IIb/IIIa inhibitor use (preferred): Initial IV bolus of 70 to 100 units/kg (maximum 10,000 units).
        • Planned glycoprotein IIb/IIIa inhibitor use: Initial IV bolus of 50 to 70 units/kg (maximum 7000 units).
        • Additional heparin may be given in the catheterization laboratory based on the results of ACT monitoring.
      • Dosing of bivalirudin: Initial bolus of 0.75 mg/kg IV immediately prior to procedure, followed by 1.75 mg/kg/hour (for patients with CrCl <30 mL/min or on hemodialysis, decrease infusion rate to 1 mg/kg/hour or 0.25 mg/kg/hour, respectively).
    2. For patients treated with fibrinolysis, and who are likely to have PCI thereafter, we prefer UFH. For patients who are unlikely to undergo angiography or PCI, we prefer enoxaparin or fondaparinux.
      • Dosing of UFH: Initial IV bolus of 60 units/kg (maximum of 4000 units), followed by an IV infusion of 12 units/kg/hour (maximum 1000 units/hour) adjusted to achieve a goal aPTT of approximately 50 to 70 seconds (1.5 to 2 times control).
      • Dosing of enoxaparin:
        • Patients <75 years: Loading dose of 30 mg IV once administered with the first maintenance dose of 1 mg/kg SUBQ every 12 hours; maximum of 100 mg for the first 2 subcutaneous doses only.
          • Dose adjustment for kidney impairment (CrCl <30 mL/minute): Loading dose of 30 mg IV once administered with the first maintenance dose of 1 mg/kg SUBQ every 24 hours.
        • Patients ≥75 years: No IV loading dose. Administer 0.75 mg/kg SUBQ every 12 hours; maximum of 75 mg for the first 2 doses only.
          • Dose adjustment for kidney impairment (CrCl <30 mL/minute): No IV loading dose. Administer 1 mg/kg SUBQ every 24 hours.
        • For patients who will receive PCI after therapeutic enoxaparin, we initiate UFH during PCI if the last enoxaparin dose was more than 6 hours prior, rather than maintain anticoagulation with enoxaparin.
      • Dosing of fondaparinux: 2.5 mg IV once, followed by 2.5 mg SUBQ every 24 hours; avoid with CrCl <30 mL/minute.
    3. For patients not receiving reperfusion therapy, we use enoxaparin or UFH.
      • Dosing of enoxaparin: Dosing same as for patients treated with fibrinolysis (refer to section 2 above).
      • Dosing of UFH: Initial IV bolus of 50 to 70 units/kg (maximum of 5000 units), followed by an IV infusion of 12 units/kg/hour adjusted to achieve a goal aPTT of approximately 50 to 70 seconds (1.5 to 2 times control).
Acute management of NSTEACS (unstable angina) or NSTEMI:
  • Give antiplatelet therapy (in addition to aspirin):
    1. Patients not treated with an invasive approach: Give ticagrelor loading dose of 180 mg orally once. For patients who are at high risk (eg, recurrent ischemic discomfort, dynamic ECG changes, or hemodynamic instability), consider adding a GP IIb/IIIa inhibitor (in such cases, urgent angiography is the usual approach to management). In patients who cannot take ticagrelor, clopidogrel loading dose of 300 mg orally once is a reasonable option.
    2. For patients managed with an invasive approach: Give a P2Y12 inhibitor after angiography and prior to PCI; the choice of agent depends on the planned revascularization strategy.
    3. If angiography will likely be delayed by at least 24 hours, it is reasonable to begin P2Y12 inhibitor therapy at the time of diagnosis; give ticagrelor loading dose of 180 mg orally once. In patients who cannot take ticagrelor, clopidogrel loading dose of 300 mg orally once is a reasonable option.
  • Give anticoagulant therapy:
    1. For patients undergoing an invasive strategy (angiography within 48 hours), we suggest initial anticoagulation with UFH. In a patient with a history of heparin-induced thrombocytopenia, other reasonable options include bivalirudin, argatroban, or fondaparinux; specific choice of agent depends on ease of dosing, familiarity, and cost.
      • Dosing of UFH: Initial IV bolus of 60 units/kg (maximum of 5000 units), followed by an IV infusion of 12 units/kg/hour (maximum 1000 units/hour) adjusted to achieve a goal aPTT of approximately 50 to 70 seconds (1.5 to 2 times control).
      • Dose of bivalirudin: In most circumstances, use of bivalirudin is limited to anticoagulation during PCI and immediately thereafter. If bivalirudin is given in the emergency department, give initial IV bolus of 0.1 mg/kg, followed by an IV infusion of 0.25 mg/kg/hour before angiography. If PCI is performed, an additional 0.5 mg/kg bolus is given and the infusion rate is increased to 1.75 mg/kg per hour.
    2. For patients receiving a noninvasive approach, we suggest either UFH, enoxaparin, or fondaparinux.
      • Dosing of UFH: Initial IV bolus of 60 units/kg (maximum 5000 units), followed by an IV infusion of 12 units/kg/hour (maximum 1000 units/hour) to achieve a goal aPTT of approximately 50 to 70 seconds.
      • Dosing of enoxaparin: 1 mg/kg SUBQ every 12 hours. Dose adjustment for kidney impairment (CrCl <30 mL/minute): 1 mg/kg SUBQ every 24 hours.
      • Dosing of fondaparinux: 2.5 mg SUBQ every 24 hours; avoid with CrCl <30 mL/minute.
Other important considerations:
  • Cocaine-related ACS: Give benzodiazepines (eg, diazepam 5 to 10 mg IV every 3 to 5 minutes, lorazepam 1 to 2 mg IV every 3 to 10 minutes) as needed to alleviate symptoms; give standard therapies (eg, aspirin, nitroglycerin) but do not give beta blockers.
  • Stop NSAID therapy if possible.
  • Correct any electrolyte abnormalities, especially hypokalemia and hypomagnesemia, which often occur together.

ACLS: advanced cardiac life support; ACS: acute coronary syndrome; ACT: activated clotting time; aPTT: activated partial thromboplastin time; BPAP: bilevel positive airway pressure; CrCl: creatinine clearance; ECG: electrocardiogram; GP: glycoprotein; IV: intravenous; NSAID: nonsteroidal anti-inflammatory drug; NSTEACS: non-ST elevation acute coronary syndrome; NSTEACS: non-ST-elevation acute coronary syndrome; NSTEMI: non-ST segment elevation myocardial infarction; PCI: percutaneous coronary intervention; STEMI: ST-elevation myocardial infarction; SUBQ: subcutaneously; TIA: transient ischemic attack; UFH: unfractionated heparin.

* Major contraindications to fibrinolysis include history of intracranial hemorrhage, cerebrovascular malformation, or intracranial malignancy; ischemic stroke in the previous 3 months but not within the last 3 hours; symptoms or signs of aortic dissection; active bleeding; significant closed-head or facial trauma in the preceding 3 months. Refer to UpToDate table on absolute and relative contraindications to the use of thrombolytic therapy in patients with acute ST-elevation myocardial infarction for an exhaustive list.

¶ Repeated doses of low molecular weight heparin in patients with kidney insufficiency leads to accumulation and increased risk of bleeding to varying degrees. By contrast, UFH is not dependent primarily upon kidney function for clearance and may be a preferred option for patients with CrCl <30 mL/minute.

Graphic 75032 Version 38.0

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