What is the management approach for a 56-year-old man with a history of acute myocardial infarction, currently presenting with fever, flu-like illness, chest pain, and a friction rub, who is already on beta-adrenergic blocking agent and aspirin therapy?

Management of Post-MI Pericarditis (Dressler's Syndrome)

This patient presenting with fever, chest pain, and a friction rub three weeks after acute myocardial infarction most likely has post-MI pericarditis (Dressler's syndrome), and should be treated with high-dose aspirin (650 mg every 4 to 6 hours) while continuing his beta-blocker therapy. 1

Clinical Recognition

This presentation is classic for post-MI pericarditis occurring in the subacute phase (1-6 weeks post-infarction):

• Friction rub over the precordium is the pathognomonic physical finding that distinguishes pericarditis from recurrent myocardial ischemia 1
• Fever and flu-like symptoms are common but present in only 25% of acute pericarditis cases, so their presence supports but is not required for diagnosis 2
• Chest pain occurring three weeks post-MI with a friction rub strongly suggests pericarditis rather than reinfarction 1

Critical Diagnostic Distinction

The key clinical decision is differentiating pericarditis from recurrent myocardial ischemia, as management differs substantially:

Features Favoring Pericarditis (This Patient):

• Friction rub present 1
• Timing at 3 weeks post-MI (typical for Dressler's syndrome) 1
• Flu-like prodrome 2

Features That Would Suggest Recurrent Ischemia:

• Absence of friction rub 1
• Hemodynamic instability 1
• New ECG changes suggesting acute ischemia 1

Recommended Treatment Algorithm

Primary Therapy: High-Dose Aspirin

Administer aspirin 650 mg every 4 to 6 hours for pericarditis pain 1

• This is substantially higher than the standard post-MI aspirin dose of 160-325 mg daily 1
• The higher dose is specifically indicated for pericarditis-related chest pain 1
• Continue this regimen until symptoms resolve, typically several days to weeks 1

Continue Existing Medications

Maintain the beta-adrenergic blocker and standard-dose aspirin (160-325 mg daily) for post-MI secondary prevention 1, 3, 4

• Beta-blockers reduce morbidity and mortality post-MI and should not be discontinued 1, 3
• The combination of beta-blockers with thrombolytic therapy and aspirin is well-tolerated in 85% of patients 5

Medications to Avoid

Do NOT use NSAIDs other than aspirin, as they increase mortality, reinfarction risk, and other complications post-MI 6

Avoid calcium channel blockers, as they have not been shown to reduce mortality and may be harmful in post-MI patients 1, 7, 3

When to Escalate Care

Consider Recurrent Ischemia If:

• Chest pain persists despite high-dose aspirin 1
• Hemodynamic instability develops 1
• New ECG changes appear 1

If recurrent ischemia is suspected, treat with intravenous nitroglycerin, analgesics, and antithrombotic medications (aspirin, heparin), and consider urgent coronary angiography with revascularization 1

Monitor for Complications:

• Cardiac tamponade (occurs in 5% of pericarditis cases): look for hypotension, elevated jugular venous pressure, and muffled heart sounds 2
• Recurrent pericarditis (occurs in 13% of cases): may require prolonged anti-inflammatory therapy 2

Common Pitfalls to Avoid

Do not confuse pericarditis with acute MI: Modern pericarditis presentations often lack classic features like fever (present in only 25%) and friction rub (present in only 18%), making misdiagnosis as MI common 2

Do not stop beta-blockers: These are essential for post-MI mortality reduction and should be continued indefinitely unless contraindicated 1, 3, 4

Do not use standard-dose aspirin for pericarditis pain: The anti-inflammatory dose (650 mg every 4-6 hours) is required, not the antiplatelet dose (160-325 mg daily) 1

Troponin elevation may occur in pericarditis (27% of cases) and does not necessarily indicate MI or predict worse outcomes 2