EKGs for the USMLE: Exam Questions and Preparation
How EKGs are tested on the USMLE, the findings to know, a preparation approach and original practice questions with explained answers.
Electrocardiograms are the most common image on the clinical Steps. Most questions need only a few findings: the rhythm, the rate, the axis, the intervals and the location of any ST change.
Image-based questions appear on every Step: an ECG tracing, a radiograph, a photograph of the skin, a view of the retina, or a microscopic slide. The skill is the same each time: describe what you see in a fixed order, name the finding, then use it to answer the clinical question. This site does not host exam images, so each finding below is described in words, as many exam stems also do. Practice with an image-rich question bank and the official USMLE sample items to build your pattern recognition. The practice questions here are original and are not real exam items.
How EKGs is tested
A stem gives a tracing or describes it and asks for the rhythm, the vessel involved, or the next step. Electrolyte and drug effects on the ECG are also tested.
High-yield topics
- A fixed reading routine: rate, rhythm, axis, intervals, then ST and T waves
- Atrial fibrillation, atrial flutter, supraventricular tachycardia and ventricular arrhythmias
- First-degree, second-degree (Mobitz I and II) and third-degree heart block
- Localizing myocardial infarction by lead groups
- Hyperkalemia, hypokalemia, hypocalcemia and drug effects
- Pericarditis, Wolff-Parkinson-White syndrome, long QT syndrome and torsades de pointes
Preparation approach
- Read every tracing in the same order so no step is skipped under time pressure.
- Learn the lead groups and the coronary artery each one points to.
- Make a short list of the ECG signs of electrolyte disturbances and review it often.
- Practice with real tracings, then say aloud what you see before looking at the options.
Practice questions
Question 1
A stable man has a heart rate of 130/min and an irregularly irregular rhythm with no discernible P waves. What is the most appropriate initial treatment?
- A. Synchronized cardioversion immediately
- B. Intravenous adenosine
- C. Rate control with a beta-blocker or a calcium channel blocker
- D. Atropine
- E. Defibrillation
Answer: C. This is atrial fibrillation in a stable patient, so rate control is first. Anticoagulation depends on stroke risk, using a score such as CHA2DS2-VASc.
Question 2
A man with end-stage kidney disease has weakness. His ECG shows peaked T waves and a widened QRS complex. What is the most appropriate first step?
- A. Oral potassium binder only
- B. Intravenous calcium gluconate
- C. Intravenous furosemide
- D. Observation
- E. Repeat the ECG in 6 hours
Answer: B. ECG changes of hyperkalemia need immediate membrane stabilization with intravenous calcium. Insulin with glucose and other measures then lower the potassium.
Question 3
An ECG shows ST-segment elevation in leads V1 through V4. Occlusion of which artery is most likely?
- A. Right coronary artery
- B. Left anterior descending artery
- C. Left circumflex artery
- D. Posterior descending artery
- E. Right marginal artery
Answer: B. ST elevation in the anterior precordial leads indicates an anterior infarction, usually from the left anterior descending artery.
Make it a plan
Add a short daily image block to your study routine. See our Step 1 and Step 2 CK preparation timelines for schedules and weekly milestones. This article is general educational guidance and not an individualized study plan.
Educational content only. Confirm current exam requirements with USMLE.