USMLE Step 2 CK Medical Prep practice questions and answers 2026. Tap an option to test yourself — you'll see the correct answer and a plain-English explanation for every question. Free, no login.
Q1A 68-year-old man presents to the emergency department with sudden onset of severe chest pain radiating to his back. He describes it as tearing in quality. His blood pressure is 210/120 mmHg in the right arm and 160/90 mmHg in the left arm. What is the most likely diagnosis?
✓ Correct answer: D. Aortic dissection
The presentation of sudden tearing chest pain radiating to the back, along with significant blood pressure differences between arms (>20 mmHg), is highly suggestive of aortic dissection. This is a vascular emergency requiring prompt diagnosis and management.
Q2A 55-year-old man with a history of hypertension presents with dyspnea on exertion and orthopnea. Physical examination reveals bibasilar crackles, jugular venous distention, and a third heart sound. His ejection fraction is 30%. Which medication would be most appropriate to reduce mortality in this patient?
✓ Correct answer: C. ACE inhibitor
This patient has heart failure with reduced ejection fraction (HFrEF). ACE inhibitors have been shown to reduce mortality in patients with HFrEF and are first-line therapy along with beta-blockers. While loop diuretics improve symptoms, they have not been proven to reduce mortality.
Q3A 72-year-old woman presents with palpitations and dizziness. Her ECG shows irregularly irregular rhythm with no discernible P waves and a ventricular rate of 140 bpm. She has a history of hypertension and diabetes. Which of the following is the most appropriate initial management?
✓ Correct answer: B. Rate control with intravenous beta-blocker or calcium channel blocker
The patient has atrial fibrillation with rapid ventricular response. In hemodynamically stable patients, the initial management is rate control with intravenous beta-blockers or calcium channel blockers. Immediate cardioversion is reserved for hemodynamically unstable patients.
Q4A 45-year-old man presents with new-onset chest pain that worsens with inspiration and improves when leaning forward. His ECG shows diffuse ST-segment elevation. What is the most likely diagnosis?
✓ Correct answer: A. Acute pericarditis
The clinical presentation of chest pain worsening with inspiration and improving when leaning forward, along with diffuse ST-segment elevation on ECG, is characteristic of acute pericarditis. This differs from acute MI, which typically shows ST elevation in specific coronary artery distribution.
Q5A 50-year-old man with diabetes and hypertension presents with chest pain. His ECG shows ST-segment elevation in leads II, III, and aVF. Which coronary artery is most likely occluded?
✓ Correct answer: D. Right coronary artery
ST-segment elevation in leads II, III, and aVF indicates an inferior wall myocardial infarction, which is most commonly caused by occlusion of the right coronary artery. This pattern represents the classic ECG findings of an inferior STEMI.
Q6A 60-year-old woman presents with shortness of breath and lower extremity edema. Echocardiography reveals an ejection fraction of 60% with left ventricular hypertrophy and diastolic dysfunction. Which of the following is the most likely diagnosis?
✓ Correct answer: C. Heart failure with preserved ejection fraction (HFpEF)
The patient presents with heart failure symptoms (dyspnea, edema) but has a preserved ejection fraction (>50%) with evidence of diastolic dysfunction. This clinical picture is consistent with heart failure with preserved ejection fraction (HFpEF), which is commonly seen in elderly patients with hypertension.
Q7A 35-year-old man collapses during a basketball game. He is unconscious with no pulse. What is the most appropriate initial management?
✓ Correct answer: B. Immediate chest compressions and defibrillation if indicated
In a witnessed sudden cardiac arrest, immediate chest compressions and early defibrillation if a shockable rhythm is present (VF/VT) are the most important initial interventions. These actions significantly improve survival and are prioritized in basic life support protocols.
Q8A 75-year-old woman presents with exertional syncope. On examination, a harsh systolic crescendo-decrescendo murmur is heard at the right upper sternal border with radiation to the carotids. What is the most likely diagnosis?
✓ Correct answer: A. Aortic stenosis
Exertional syncope with a harsh systolic crescendo-decrescendo murmur at the right upper sternal border radiating to the carotids is classic for aortic stenosis. This is particularly common in elderly patients and is one of the triad of symptoms (syncope, angina, and heart failure) that indicate severe aortic stenosis.
Q9A 62-year-old man with a history of myocardial infarction presents with worsening dyspnea and orthopnea. His chest X-ray shows pulmonary edema and cardiomegaly. His ejection fraction is 25%. Which medication is contraindicated in this patient?
✓ Correct answer: D. Non-dihydropyridine calcium channel blocker
Non-dihydropyridine calcium channel blockers (verapamil, diltiazem) are contraindicated in heart failure with reduced ejection fraction as they have negative inotropic effects that can worsen heart failure. Beta-blockers, ACE inhibitors, and aldosterone antagonists are all part of guideline-directed medical therapy for HFrEF.
Q10A 40-year-old woman presents with palpitations. Her ECG shows a regular narrow complex tachycardia at 180 bpm with no visible P waves. After administration of adenosine, the rhythm converts to normal sinus rhythm. What is the most likely diagnosis?
✓ Correct answer: C. AV nodal reentrant tachycardia (AVNRT)
A regular narrow complex tachycardia that responds to adenosine is most consistent with AV nodal reentrant tachycardia (AVNRT). This is a type of supraventricular tachycardia that uses the AV node for reentry and is commonly seen in young to middle-aged adults without structural heart disease.
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