## Complications of Acute Myocardial Infarction **Key Point:** Dressler syndrome (post-MI pericarditis) typically occurs **1–2 weeks to several months** after acute MI — NOT within 1–2 weeks as stated in Option A. The classic teaching is that Dressler syndrome presents **weeks to months** post-infarction (most commonly 2–10 weeks), distinguishing it from early pericarditis (which occurs within the first 1–4 days due to direct epicardial inflammation). ### Timing of Post-MI Pericarditis | Type | Timing | Mechanism | |---|---|---| | **Early pericarditis** | 1–4 days post-MI | Direct epicardial inflammation from transmural necrosis | | **Dressler syndrome** | 2 weeks to months (classically 2–10 weeks) | Autoimmune (anti-myocardial antibodies) | Option A is **FALSE** because it states Dressler syndrome occurs "within 1–2 weeks," which is too early. The autoimmune mechanism is correct, but the timing is wrong — Dressler syndrome is a delayed phenomenon occurring weeks to months after MI. ### Why the Other Options Are TRUE (and thus not the answer) - **Option B (Cardiac rupture, 3–5 days, transmural):** Correct. Free wall rupture peaks at 3–5 days post-MI, when the necrotic myocardium is maximally softened before adequate fibrosis. Transmural infarcts are at highest risk. *(Robbins & Cotran Pathologic Basis of Disease, 10th ed.)* - **Option C (Papillary muscle rupture → acute MR, more common in inferior MI):** TRUE overall. The **posteromedial papillary muscle** has a single blood supply (RCA/PDA), making it more vulnerable to ischemia than the anterolateral papillary muscle (dual supply from LAD and LCx). Posteromedial PM rupture is therefore more common in **inferior wall MI** (RCA territory). This is a correct general statement. *(Harrison's Principles of Internal Medicine, 21st ed.)* - **Option D (Free wall rupture >90% mortality):** Correct. Ventricular free wall rupture leads to hemopericardium and cardiac tamponade; mortality exceeds 90% without immediate surgical repair. **Clinical Pearl:** The posteromedial papillary muscle is supplied solely by the posterior descending artery (RCA in right-dominant circulation), making it more susceptible to ischemic rupture than the anterolateral papillary muscle, which has dual blood supply. This is why papillary muscle rupture is more common in inferior MI overall — a well-established fact in cardiology (Braunwald's Heart Disease, 12th ed.). **High-Yield:** For NEET PG/INI-CET, remember that Dressler syndrome = **delayed** (weeks to months), autoimmune, with fever, pleuritis, and pericarditis. Early post-MI pericarditis (days 1–4) is a separate entity caused by direct inflammation, not autoimmunity.
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