USMLE Step 2 CK Sample Question
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Your Free USMLE Step 2 Sample Question
A 71-year-old man comes to the emergency department because of acute-onset sharp chest pain that worsens with deep breathing. Five weeks ago, he was admitted to the hospital because of acute anterior myocardial infarction and underwent percutaneous coronary intervention. A drug-eluting stent was placed, and he was discharged to home on hospital day 4. The patient has a history of hypertension, hyperlipidemia, and type 2 diabetes mellitus and takes metformin, lisinopril, carvedilol, atorvastatin, prasugrel, and low-dose aspirin. He is alert and oriented. His temperature is 37.7°C (100.0°F), pulse is 101/min and regular, respirations are 16/min, and blood pressure is 137/84 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 98%. Physical examination shows no jugular venous distention or peripheral edema. Lungs are clear to auscultation. Cardiac examination discloses an S4 consistent with prior examination. Laboratory studies show:
| Hemoglobin | 14.2 g/dL |
| Leukocyte count | 13,100/mm3 |
| Platelet count | 330,000/mm3 |
| Creatinine | 1.1 mg/dL |
| Erythrocyte sedimentation rate | 42 mm/h |
Chest x-ray shows an enlarged cardiac silhouette. A 12-lead ECG shows sinus tachycardia with pathologic Q waves in leads V1 to V4 and nonspecific ST-segment changes. Echocardiography shows a small pericardial effusion without evidence of tamponade. The left ventricular ejection fraction is 52%. Which of the following is the most likely cause of this patient’s symptoms?
- A. Bacterial mediastinitis
- B. Immune-complex deposition
- C. Thrombosis formation
- D. Toxin accumulation
- E. Viral infection
The Answer and Explanation
Did you get it right? The correct answer is: B
| Post-cardiac Injury Syndrome | |
| Cause | Immune-complex deposition in the pericardium and/or pleuraCauses: Myocardial infarction (Dressler syndrome), cardiac surgery, percutaneous coronary intervention |
| Clinical Presentation | Onset is weeks to months after the causal eventPleuritic chest pain± fever and leukocytosis± diffuse ST-segment elevation on ECG |
| Imaging | Chest x-ray: Enlarged cardiac silhouette; pleural effusionEchocardiography: Pericardial effusion |
| Management | Usually self-limitingNonsteroidal anti-inflammatory drugs + colchicineCorticosteroids for refractory diseas |
This patient’s presentation with pleuritic chest pain and a pericardial effusion 5 weeks after a myocardial infarction (MI) is consistent with acute pericarditis secondary to post-cardiac injury syndrome (PCIS).
PCIS is caused by immune-complex deposition in the pericardium and pleura, and occurs as a result of immune system exposure to cardiac antigens. It often is caused by cardiac surgery, MI (Dressler syndrome), trauma, or percutaneous coronary intervention. Before symptom onset, patients typically have a latent period of several weeks to months. Once present, clinical findings include pleuritic chest pain and nonspecific signs of inflammation such as fever, leukocytosis, and increased inflammatory markers (eg, erythrocyte sedimentation rate, C-reactive protein). Troponin also may be mildly increased. Although widespread ST-segment elevation sometimes is seen, ECG most commonly shows nonspecific findings (as in this patient). Imaging findings include an enlarged cardiac silhouette on chest x-ray and a pericardial effusion on echocardiography.
PCIS typically is self-limiting, although some patients can develop chronic disease. First-line treatment involves a combination of nonsteroidal anti-inflammatory drugs and colchicine. Corticosteroids also can be used but typically are reserved for refractory cases.
Incorrect Answer Explanations
Answer A: Bacterial mediastinitis is not a common complication of MI or percutaneous coronary intervention. It typically occurs as a complication of cardiac surgery, and affected patients typically present within 2 weeks of surgery. Common clinical signs include fever, chest pain, purulent incisional discharge, and palpable crepitus.
Answer C: Pulmonary embolism (PE) can cause pleuritic chest pain and sinus tachycardia on ECG. However, affected patients also typically have tachypnea and hypoxia. Additionally, chest x-ray typically is normal in patients with a PE and does not show an enlarged cardiac silhouette. Pericardial effusions are uncommon.
Answer D: Although the exact mechanism is poorly understood, uremic pericarditis likely occurs because of toxin accumulation in patients with severe renal insufficiency. In addition to pericarditis, these patients also typically have other signs of uremia (eg, encephalopathy, coagulopathy) and renal failure (eg, volume overload, anemia, hyperkalemia). Because this patient has normal renal function, uremic pericarditis is unlikely.
Answer E: Although viral infection is the most common cause of acute pericarditis, it is less likely in this patient because of his recent history of MI and percutaneous coronary intervention. Additionally, in patients with acute pericarditis caused by viral infection, ECG typically shows diffuse ST-segment elevation (especially on the USMLE).
Bottom Line
Postcardiac injury syndrome is caused by immune-complex deposition, and affected patients typically present weeks to months following myocardial infarction (Dressler syndrome), cardiac surgery, or percutaneous coronary intervention. Clinical signs include pleuritic chest pain, and echocardiography shows a pericardial effusion. In most patients, the disease is self-limiting and can be managed with a combination of nonsteroidal anti-inflammatory drugs and colchicine.
TrueLearn Insight
Colchicine monotherapy can be used to prevent PCIS following cardiac surgery.
For more information, see:
Dressler syndrome: StatPearls
Post-cardiac injury syndromes: UpToDate
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