What is the management plan for a patient with Myocardial Infarction (MI)?

Management of Myocardial Infarction

For patients with suspected MI and ST-segment elevation or new bundle-branch block, immediate reperfusion therapy (preferably primary PCI within 90 minutes) combined with aspirin 160-325 mg chewed immediately, dual antiplatelet therapy, beta-blockers, ACE inhibitors, and high-intensity statins forms the cornerstone of management that reduces mortality and improves outcomes. 1, 2

Immediate Recognition and Initial Actions (First Minutes to Hours)

Rapid Assessment and Monitoring

• Obtain a 12-lead ECG immediately to distinguish ST-elevation MI (STEMI) from non-ST-elevation MI (NSTEMI), as this fundamentally determines the reperfusion strategy 3, 1
• For inferior MI, obtain right-sided ECG leads (particularly V4R) to assess for right ventricular involvement, which occurs in up to 50% of inferior MIs and dramatically alters hemodynamic management 2
• Initiate continuous cardiac monitoring for arrhythmias and conduction disturbances, with emergency equipment readily available including atropine, transcutaneous pacing patches, transvenous pacemaker, defibrillator, and epinephrine 2

Immediate Pharmacological Interventions

• Administer aspirin 160-325 mg to be chewed immediately unless absolutely contraindicated—this is the single most important initial medication 1, 2
• Provide appropriate analgesia with narcotic medications (morphine or meperidine) to minimize pain and anxiety 2
• Begin intravenous nitroglycerin for 24-48 hours if no hypotension, bradycardia, or excessive tachycardia is present 2
• Critical caveat: Avoid nitrates entirely in patients with right ventricular infarction as they can cause profound hypotension by reducing preload 2

Reperfusion Strategy (Within 12 Hours of Symptom Onset)

For STEMI or New Bundle-Branch Block

• Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy when it can be performed within 90 minutes by skilled operators 1, 2
• If primary PCI cannot be performed within this timeframe, administer fibrinolytic therapy within 12 hours of symptom onset using a fibrin-specific agent (tenecteplase, alteplase, or reteplase) 1
• Reperfusion therapy offers little benefit beyond 12 hours from symptom onset 1

For Non-ST-Elevation MI

• Do not administer fibrinolytic therapy—these patients require a different therapeutic approach focused on antiplatelet therapy, anticoagulation, and risk stratification for possible invasive management 3

Comprehensive Pharmacological Management

Antiplatelet Therapy

• Continue aspirin 75-100 mg daily indefinitely after the initial loading dose 4, 1
• Initiate dual antiplatelet therapy (DAPT) with aspirin plus ticagrelor or prasugrel (or clopidogrel if unavailable) for 12 months after PCI 4, 1
• The evidence supports that 75-150 mg daily aspirin is as effective as higher doses for long-term treatment, with fewer side effects 5

Beta-Blockers

• Administer early intravenous beta-blocker therapy (e.g., metoprolol) followed by oral therapy if no contraindications exist 1, 2
• Beta-blockers are mandatory in all patients with heart failure or LVEF <40% unless contraindicated, and should be continued indefinitely 4
• Do not administer beta-blockers to patients in a low-output state due to pump failure 2

ACE Inhibitors

• Start ACE inhibitors within the first 24 hours of STEMI in patients with evidence of heart failure, LV systolic dysfunction (LVEF <40%), diabetes, or anterior infarction 4, 1
• Uptitrate aggressively toward target doses during follow-up 4
• Use ARBs if ACE inhibitors are not tolerated 4

Statins

• Start high-intensity statin therapy (atorvastatin 40-80 mg or rosuvastatin 20-40 mg) immediately with target LDL-C <1.8 mmol/L (70 mg/dL) 4, 1
• Continue long-term 1

Mineralocorticoid Receptor Antagonists

• Add in patients with EF <40% and heart failure or diabetes who are already on ACE inhibitor and beta-blocker, provided creatinine ≤2.5 mg/dL (men) or ≤2.0 mg/dL (women) and potassium ≤5.0 mEq/L 4

Anticoagulation

• Consider intravenous heparin, particularly if thrombolytic therapy was administered 2

Medications to Avoid

• Avoid calcium channel blockers as they have not been shown to reduce mortality and may be harmful 2
• Discontinue any nonsteroidal anti-inflammatory drugs (except aspirin) due to increased risks of mortality, reinfarction, and other complications 2

Special Considerations for Inferior MI with Right Ventricular Involvement

Recognition

• Look for the clinical triad of hypotension, clear lung fields, and elevated jugular venous pressure 2
• ST elevation ≥1mm in lead V4R is highly predictive of RV infarction 2
• Record lead V4R early as ST elevation can resolve within 10 hours 2

Hemodynamic Management

• Maintain RV preload through volume loading with IV normal saline for hypotension—this is fundamentally different from left ventricular MI management 2
• Avoid nitrates and diuretics entirely as they can cause profound hypotension by reducing preload 2
• Provide inotropic support with dobutamine if cardiac output fails to increase after volume loading 2
• Consider intra-aortic balloon pump for persistent shock 2

Conduction Disturbances

• Treat symptomatic sinus bradycardia (common in inferior MI) with IV atropine 0.5 mg, repeated up to 2.0 mg total 2
• Consider temporary pacing for symptomatic high-degree AV block, especially if unresponsive to atropine 2
• Maintain AV synchrony through AV sequential pacing for symptomatic high-degree heart block 2

Management of Complications

Heart Failure

• Administer a diuretic (usually intravenous furosemide) and an afterload-reducing agent 1

Cardiogenic Shock

• Consider intra-aortic balloon counterpulsation 1
• Perform emergency coronary angiography followed by PCI or CABG 1
• Consider pulmonary artery catheter monitoring for progressive hypotension unresponsive to fluid administration 2
• Use intra-arterial pressure monitoring 2

Pre-Discharge Evaluation

Cardiac Function Assessment

• Perform routine echocardiography to assess LV and RV function, detect mechanical complications, and exclude LV thrombus 4, 1
• Patients with EF 31-40% or lower require Holter monitoring for possible ICD consideration 4

Exercise Testing

• Perform submaximal exercise testing at 4-7 days or symptom-limited testing at 10-14 days before discharge or shortly thereafter 1

Long-Term Management and Cardiac Rehabilitation

Cardiac Rehabilitation: The Critical Intervention

• Enroll patients immediately in a structured cardiac rehabilitation program—this is a Class I recommendation that directly addresses mortality and functional recovery 4
• Cardiac rehabilitation should be performed 3-5 times per week for meaningful functional improvement 4
• Long-term reinforced programs (extending beyond standard 6-12 weeks) reduce cardiovascular mortality by 33%, non-fatal MI by 36%, and stroke by 32% 4
• Each single-stage increase in physical work capacity reduces all-cause mortality by 8-14% 4
• Cardiac rehabilitation reduces recurrent hospitalizations and healthcare expenditure while prolonging life 4

Lifestyle Modifications

• Encourage smoking cessation with repeated counseling combined with nicotine replacement, varenicline, or bupropion—nurse-directed protocols are effective 4, 1
• Recommend a Mediterranean-type diet low in saturated fat, high in polyunsaturated fat, and rich in fruits and vegetables 4, 1
• Fish oil n-3 polyunsaturated fatty acids (1 g daily) reduces all-cause mortality and sudden death, and fatty fish should be eaten at least twice weekly 4
• Encourage regular exercise (at least 20 minutes of brisk walking three times weekly) 1
• Advise patients to achieve ideal weight 1

Psychological Support

• Screen for depression systematically during hospitalization and monthly for the first year 4
• Treat depression with combined cognitive-behavioral therapy plus selective serotonin reuptake inhibitors when identified 4
• Screen for anxiety and sleep disorders 4

Follow-Up Schedule

• Schedule an early follow-up visit within 2-4 weeks to assess symptoms, medication tolerance, and titration needs 4
• Review medication list and uptitrate ACE inhibitors, beta-blockers, and statins toward target doses 4
• Assess functional class and exercise tolerance 4

Common Pitfalls to Avoid

• Most patients delay seeking medical care for 2 hours or more after symptom onset—emphasize the importance of rapid presentation 3, 1
• Do not administer nitrates in right ventricular infarction due to risk of profound hypotension 2
• Volume depletion may mask signs of RV involvement—maintain high clinical suspicion 2
• Limit physical activities for at least 12 hours after presentation 2