Dressler syndrome is one of those “post-MI complications” that shows up when you’ve finally moved on mentally from the acute event—then the patient comes back with chest pain and fever. On Step 1, it’s a classic autoimmune pericarditis scenario with a very testable timeline, symptom cluster, and treatment choice that isn’t the same as every other pericarditis vignette.
What is Dressler Syndrome?
Dressler syndrome (also called post–myocardial infarction syndrome) is a delayed, immune-mediated pericarditis that occurs weeks to months after myocardial injury, classically after an MI, but it can also follow:
- Cardiac surgery (postpericardiotomy syndrome)
- Trauma
- Any injury exposing cardiac antigens (e.g., percutaneous cardiac procedures)
High-yield definition:
Autoimmune fibrinous pericarditis occurring weeks to months after MI due to antibodies against exposed cardiac antigens.
Pathophysiology (the “why” that Step questions love)
Core mechanism: immune response to cardiac antigens
- Myocardial necrosis/injury exposes intracellular cardiac antigens
- Immune system forms anti-heart antibodies
- Immune complexes / inflammatory response targets the pericardium and pleura
- Results in fibrinous pericarditis ± pleuritis and effusions
Why the delayed timing matters
Unlike early post-MI pericarditis (within days, due to direct inflammation overlying the infarct), Dressler requires time for an adaptive immune response to develop—hence weeks to months.
Timeline: Dressler vs Early Post-MI Pericarditis (Must-know table)
| Feature | Early post-MI pericarditis | Dressler syndrome |
|---|---|---|
| Timing | 1–3 days after MI | 2–8 weeks (can be months) after MI |
| Mechanism | Direct inflammation over infarct | Autoimmune reaction to cardiac antigens |
| Symptoms | Pleuritic chest pain, rub | Pleuritic chest pain, fever, malaise |
| Associated findings | Usually localized | Pericardial ± pleural effusions, elevated ESR/CRP |
| Treatment (classic) | NSAIDs (careful) | High-dose aspirin (preferred post-MI) ± colchicine |
Exam tip: If the question stem emphasizes fever and weeks after MI, think Dressler.
Clinical Presentation
Symptoms
- Pleuritic chest pain (worse with inspiration, better sitting forward)
- Fever
- Dyspnea (often due to effusion or pain-limited breathing)
- Fatigue/malaise
Physical exam
- Pericardial friction rub (scratchy, best at left lower sternal border)
- Possible signs of effusion:
- Muffled heart sounds (larger effusion)
- Tachycardia
High-yield associations
- Pericarditis + pleuritis (patients may have pleuritic pain and small pleural effusions)
- Elevated inflammatory markers (ESR/CRP)
- Can be associated with pericardial effusion; rarely progresses to tamponade
Diagnosis: What confirms it on exams?
Dressler is largely a clinical diagnosis based on timing + features of pericarditis after myocardial injury.
Typical workup findings
ECG (acute pericarditis pattern)
- Diffuse ST-segment elevations (often concave up)
- PR segment depressions
- (Later) T-wave inversions after ST normalizes
Labs
- ↑ ESR / ↑ CRP
- Troponins: may be mildly elevated in pericarditis/myopericarditis, but in Dressler the key is timing and inflammatory picture rather than a new MI pattern.
Echocardiogram
- May show pericardial effusion
- Important if concern for tamponade physiology
Chest imaging
- Can show pleural effusions (supporting the pleuropericardial inflammation concept)
Differentiate from reinfarction (common trap)
Reinfarction tends to have:
- Localized ST changes in a coronary distribution (or new Q waves)
- Rising troponins/CK-MB in an acute pattern
- Often not diffuse ST elevation + PR depression
Treatment (Step-relevant and very testable)
First-line (post-MI preferred)
- High-dose aspirin
- Preferred because other NSAIDs can impair myocardial healing after MI in some contexts.
- Colchicine (often added to reduce recurrence in pericarditis)
If refractory/contraindicated
- Glucocorticoids (used selectively; can increase recurrence risk in idiopathic pericarditis, but may be needed in severe autoimmune cases)
If complications
- Pericardiocentesis if cardiac tamponade develops
High-Yield Complications & “Red Flags”
Pericardial effusion → tamponade (rare but critical)
Know tamponade findings:
- Hypotension
- JVD
- Muffled heart sounds (Beck triad)
- Pulsus paradoxus
- Echo: diastolic collapse of right atrium/ventricle
Constrictive pericarditis (less common here)
Chronic inflammation can lead to pericardial scarring/calcification. Classic findings include:
- Kussmaul sign
- Pericardial knock
- JVP elevation
USMLE “Buzzwords” and Classic Vignettes
Vignette pattern 1
6 weeks after an MI, patient returns with fever, pleuritic chest pain, and a pericardial friction rub. ECG shows diffuse ST elevations.
Answer: Dressler syndrome (autoimmune pericarditis)
Vignette pattern 2 (trap)
2 days after MI, pleuritic pain and rub.
Answer: Early post-MI pericarditis (direct inflammation), not Dressler.
Vignette pattern 3
Post–cardiac surgery patient weeks later with fever, pericarditis symptoms, and effusions.
Answer: Postpericardiotomy syndrome (same autoimmune concept as Dressler)
First Aid Cross-References (where this lives in your memory palace)
Use these as “anchors” in First Aid for the USMLE Step 1 (exact page numbers vary by edition):
- Cardiovascular → Pericardial disease
- Acute pericarditis ECG findings: diffuse ST elevation + PR depression
- Cardiovascular → Ischemic heart disease / MI complications
- Dressler syndrome as a late post-MI complication
- Inflammation/Immunology tie-in
- Type II/III immune-mediated injury concept (antibodies/immune complexes against self-antigens after tissue injury)
Memory hook:
Days = direct irritation (early post-MI pericarditis)
Weeks = antibodies (Dressler)
Quick High-Yield Summary (what to recall in 10 seconds)
- Dressler syndrome = autoimmune fibrinous pericarditis weeks to months after MI
- Symptoms: fever + pleuritic chest pain + friction rub
- ECG: diffuse ST elevation + PR depression
- Labs: ↑ ESR/CRP
- Tx: high-dose aspirin (post-MI preferred) ± colchicine
- Key differentiation: timing (weeks) and diffuse ECG changes vs reinfarction