What are the guidelines for managing myocardial infarction (MI)?

Guidelines for Managing Myocardial Infarction

The cornerstone of MI management is immediate reperfusion therapy with primary PCI as the preferred strategy when available within 120 minutes of first medical contact, or fibrinolytic therapy within 30 minutes of hospital arrival if PCI cannot be performed within this timeframe. 1

Initial Diagnosis and Assessment

• Twelve-lead ECG recording and interpretation should be performed within 10 minutes of first medical contact 2
• ECG monitoring with defibrillator capacity should be initiated immediately in all suspected STEMI patients 2
• Routine oxygen is not recommended in patients with SaO2 ≥90% 2
• Echocardiography should be performed during hospitalization to assess LV and RV function and detect complications 2

Reperfusion Strategy

Primary PCI (Preferred Strategy)

• Indicated for all patients with symptoms of ischemia ≤12 hours duration and persistent ST-segment elevation 2
• Regional networks should be designed to deliver PCI expeditiously with 24/7 service availability 2
• Patients should bypass emergency department and be transferred directly to catheterization laboratory 2
• Also recommended for patients with resuscitated cardiac arrest and ECG consistent with STEMI 2

Antithrombotic Therapy with Primary PCI

• Aspirin (oral or IV) should be administered immediately 2
• A potent P2Y12 inhibitor (preferably prasugrel or ticagrelor) should be given before or at the time of PCI 2
• Anticoagulation with unfractionated heparin, enoxaparin, or bivalirudin should be used 1
• Fondaparinux is not recommended for primary PCI 2

Fibrinolytic Therapy (When PCI Cannot Be Performed Timely)

• Should be initiated within 12 hours of symptom onset and preferably in pre-hospital setting 2
• A fibrin-specific agent (tenecteplase, alteplase, or reteplase) is recommended 2
• Aspirin (oral or IV) and clopidogrel should be administered 2
• Anticoagulation with enoxaparin (preferred) or UFH should be continued until revascularization or hospital discharge (up to 8 days) 2
• Transfer to a PCI-capable center following fibrinolysis is indicated in all patients immediately 2
• Rescue PCI is indicated if fibrinolysis fails (<50% ST-segment resolution at 60-90 min) 2
• Angiography and PCI of the infarct-related artery should be performed 2-24 hours after successful fibrinolysis 2

Post-MI Hospital Care

• Patients should be monitored for at least 24 hours after reperfusion therapy 2
• Emergency angiography and PCI are indicated for recurrent ischemia or evidence of reocclusion after initial successful fibrinolysis 2
• Targeted temperature management is indicated for resuscitated cardiac arrest patients who remain unresponsive 2
• Pre-hospital cooling using rapid infusion of cold IV fluid is not recommended 2

Secondary Prevention Medications

1. Antiplatelet Therapy

   • Low-dose aspirin (75-100 mg) indefinitely 2
   • DAPT (aspirin plus ticagrelor/prasugrel/clopidogrel) for 12 months 2
   • PPI recommended in combination with DAPT for patients at high risk of GI bleeding 2

2. Beta-Blockers

   • Indicated for patients with heart failure and/or LVEF <40% 2
   • IV beta-blockers must be avoided in patients with hypotension, acute heart failure, AV block, or severe bradycardia 2

3. Statins

   • High-intensity statin therapy should be started as early as possible 2
   • LDL-C goal of <1.8 mmol/L (70 mg/dL) or reduction of at least 50% if baseline is 1.8-3.5 mmol/L 2

4. ACE Inhibitors/ARBs

   • ACE inhibitors should be started within 24 hours of STEMI in patients with heart failure, LV systolic dysfunction, diabetes, or anterior infarct 2
   • ARBs (preferably valsartan) are alternatives for ACE inhibitor-intolerant patients 2

5. MRAs (Mineralocorticoid Receptor Antagonists)

   • Recommended for patients with LVEF <40% and heart failure or diabetes 2

Lifestyle Modifications

• Smoking cessation with support, nicotine replacement therapies, varenicline, and bupropion 2
• Participation in a cardiac rehabilitation program 2
• Regular physical activity and exercise 1
• Diet low in saturated fat and cholesterol 1

Special Considerations

• MINOCA (MI with Non-Obstructive Coronary Arteries): Additional diagnostic tests should be performed to identify etiology 2
• Right ventricular infarction: Should be treated with intravascular volume expansion and inotropic agents if hypotension persists 2
• NSAIDs should be avoided in post-MI patients due to increased risk of reinfarction, CV-related death, and all-cause mortality 3

Common Pitfalls to Avoid

1. Delaying reperfusion therapy - every minute counts for myocardial salvage
2. Failing to recognize right ventricular infarction, which requires different management (volume expansion rather than nitrates)
3. Using NSAIDs for pain management in post-MI patients
4. Administering routine oxygen to patients with normal oxygen saturation
5. Missing the opportunity for rescue PCI when fibrinolysis fails
6. Delaying transfer to PCI-capable centers after fibrinolysis

By following these guidelines systematically, clinicians can optimize outcomes for patients with myocardial infarction, reducing mortality and improving quality of life.