MRCP Part 1 Cardiology 1 — Questions and Answers
Question 1: A 60-year-old man presents with central chest pain radiating to the jaw, diaphoresis, and an ECG showing ST elevation in leads II, III, and aVF. Which coronary artery is most likely occluded?
- Left anterior descending artery
- Right coronary artery (Correct answer)
- Left circumflex artery
- Left main stem
Correct answer: Right coronary artery
Inferior STEMI (ST elevation in II, III, aVF) is most commonly caused by occlusion of the right coronary artery (RCA), which supplies the inferior wall of the left ventricle in the majority of patients (right-dominant circulation).
Question 2: Which drug class is absolutely contraindicated in acute decompensated heart failure with cardiogenic shock?
- Loop diuretics
- Vasopressors
- Beta-blockers (Correct answer)
- Angiotensin-converting enzyme inhibitors
Correct answer: Beta-blockers
Beta-blockers are absolutely contraindicated in acute decompensated heart failure with cardiogenic shock because their negative inotropic and chronotropic effects further reduce cardiac output in an already compromised heart. They may be initiated after stabilisation.
Question 3: A 45-year-old woman has recurrent palpitations. A 24-hour Holter shows intermittent delta waves and short PR interval. What is the diagnosis?
- Lown-Ganong-Levine syndrome
- Wolff-Parkinson-White syndrome (Correct answer)
- Complete heart block
- Brugada syndrome
Correct answer: Wolff-Parkinson-White syndrome
Wolff-Parkinson-White syndrome is characterised by a delta wave (slurred upstroke of QRS), short PR interval (<120ms), and wide QRS. It results from an accessory conduction pathway (Bundle of Kent) bypassing the AV node.
Question 4: What is the mechanism of action of digoxin in atrial fibrillation?
- Direct cardioversion to sinus rhythm
- Blocks sodium-potassium ATPase, increasing vagal tone and slowing AV node conduction (Correct answer)
- Blocks beta-adrenergic receptors at the AV node
- Prolongs the action potential in atrial tissue
Correct answer: Blocks sodium-potassium ATPase, increasing vagal tone and slowing AV node conduction
Digoxin inhibits the Na+/K+ ATPase pump, leading to increased intracellular sodium, reduced calcium efflux, and enhanced cardiac contractility. In AF, it slows ventricular response by increasing vagal tone and reducing AV node conduction velocity.
Question 5: In a patient with HOCM, which intervention is most likely to worsen outflow tract obstruction?
- Beta-blockers
- Valsalva manoeuvre (Correct answer)
- Squatting
- Exercise in a supine position
Correct answer: Valsalva manoeuvre
Valsalva manoeuvre reduces venous return, decreasing LV preload. In HOCM, reduced LV cavity size worsens the dynamic outflow tract obstruction. Squatting increases preload and reduces obstruction. Beta-blockers reduce the obstruction by slowing heart rate and reducing contractility.
Question 6: Which ECG finding is most specific for hyperkalaemia?
- Prolonged QTc
- Peaked T waves (Correct answer)
- Shortened PR interval
- U waves
Correct answer: Peaked T waves
Tall, peaked (tented) T waves are the earliest and most characteristic ECG change in hyperkalaemia. As potassium rises further, the PR prolongs, QRS widens, P waves disappear, and a sine wave pattern can develop, eventually leading to VF.
MRCP Part 1 Cardiology 1
A 60-year-old man presents with central chest pain radiating to the jaw, diaphoresis, and an ECG showing ST elevation in leads II, III, and aVF.
Which coronary artery is most likely occluded?