What is the management strategy for acute myocardial infarction (AMI)?

Management of Acute Myocardial Infarction

Primary PCI is the recommended reperfusion strategy for patients with STEMI unless the anticipated time from STEMI diagnosis to PCI-mediated reperfusion exceeds 120 minutes, in which case immediate fibrinolysis should be initiated. 1

Initial Diagnosis and Assessment

• Twelve-lead ECG recording and interpretation should be performed as soon as possible at the point of first medical contact, with a maximum target delay of 10 minutes 1
• ECG monitoring with defibrillator capacity should be initiated as soon as possible in all patients with suspected STEMI 1
• In patients without characteristic ST elevation but with clinical presentation compatible with ongoing myocardial ischemia and ECG changes such as bundle branch block, hyperacute T-waves, or isolated ST-depression in anterior leads, a primary PCI strategy should be followed 1

Reperfusion Strategy

Primary PCI

• Reperfusion therapy is indicated in all patients with symptoms of ischemia lasting less than 12 hours and persistent ST-segment elevation 1
• Patients should be transferred directly to the catheterization laboratory, bypassing the emergency department 1
• Technical aspects:
  • Routine radial access and drug-eluting stent implantation are the standard of care 1
  • Routine thrombus aspiration or deferred stenting are contraindicated 1

Fibrinolysis

• If primary PCI cannot be performed within 120 minutes of STEMI diagnosis, fibrinolytic therapy should be initiated within 10 minutes of diagnosis 1
• A fibrin-specific agent (tenecteplase, alteplase, or reteplase) is recommended 1
• All patients should be transferred to a PCI-capable center immediately after fibrinolysis 1
• Rescue PCI is indicated immediately when fibrinolysis has failed (<50% ST-segment resolution at 60-90 minutes) or if hemodynamic/electrical instability occurs 1

Antithrombotic Therapy

For Primary PCI

• Aspirin (oral or IV if unable to swallow) should be administered as soon as possible 1
• A potent P2Y12 inhibitor (prasugrel or ticagrelor, or clopidogrel if these are unavailable) should be given before or at the time of PCI 1
• Anticoagulation with unfractionated heparin (enoxaparin or bivalirudin as alternatives) 1

For Fibrinolysis

• Oral or IV aspirin is indicated 1
• Clopidogrel is indicated in addition to aspirin 1
• Anticoagulation with enoxaparin (preferred) or unfractionated heparin should be continued until revascularization or for the duration of hospital stay up to 8 days 1

Early In-Hospital Management

• Patients should be monitored for at least 24 hours after reperfusion therapy 1
• Routine echocardiography should be performed during hospital stay to assess LV and RV function, detect mechanical complications, and exclude LV thrombus 1
• For pain management, morphine can be administered in small doses (2-4 mg) as needed 1
• Intravenous nitroglycerin should be administered for 24-48 hours, particularly in patients with hypertension or heart failure 1

Pharmacological Therapy

• Beta-blockers:

  • For early treatment of MI, metoprolol should be administered intravenously as three bolus injections of 5 mg each at approximately 2-minute intervals, followed by oral therapy 2
  • Oral beta-blockers are indicated in patients with heart failure and/or LVEF <40% 1
  • IV beta-blockers must be avoided in patients with hypotension, acute heart failure, AV block, or severe bradycardia 1

• ACE inhibitors:

  • Should be started within the first 24 hours in patients with evidence of heart failure, LV systolic dysfunction, diabetes, or anterior infarct 1
  • ARBs (preferably valsartan) are an alternative for patients intolerant to ACE inhibitors 1

• Statins:

  • High-intensity statin therapy should be started as early as possible and maintained long-term 1
  • Target LDL-C should be <1.8 mmol/L (70 mg/dL) or a reduction of at least 50% if baseline is between 1.8-3.5 mmol/L 1

Long-term Management

• Dual antiplatelet therapy (DAPT):

  • Aspirin (75-100 mg daily) plus a P2Y12 inhibitor should be continued for 12 months 1
  • A proton pump inhibitor is recommended in combination with DAPT for patients at high risk of gastrointestinal bleeding 1

• Secondary prevention measures:

  • Smoking cessation with support, nicotine replacement therapies, varenicline, and bupropion 1
  • Participation in a cardiac rehabilitation program 1
  • Diet low in saturated fat and cholesterol 1

Management of Complications

• Heart failure:

  • Diuretics (usually IV furosemide) and afterload-reducing agents should be administered 1
  • For cardiogenic shock, consider hemodynamic support devices and emergency coronary angiography followed by PCI or CABG 1

• Right ventricular infarction:

  • Aggressive intravascular volume expansion with normal saline and inotropic agents if hypotension persists 1

• Recurrent chest pain:

  • If due to pericarditis, high-dose aspirin (650 mg every 4-6 hours) 1
  • If due to myocardial ischemia, treat with IV nitroglycerin, analgesics, and antithrombotic medications 1

Special Considerations

• Patients with MINOCA (Myocardial Infarction with Non-Obstructive Coronary Arteries):

  • Additional diagnostic tests should be performed to identify the etiology and tailor appropriate therapy 1

• Patients on oral anticoagulants, with renal insufficiency, or elderly:

  • Special attention to dose adjustment of pharmacological therapies 1

• Patients with diabetes:

  • Require additional attention to management 1