ITE Cardiovascular Medicine 4 — Questions and Answers
Question 1: A 60-year-old man with known CAD is prescribed ranolazine for refractory angina. Which mechanism of action explains its antianginal effect?
- Inhibition of L-type calcium channels reducing heart rate
- Inhibition of late sodium current reducing myocardial oxygen demand (Correct answer)
- Beta-1 receptor blockade reducing inotropy
- Nitric oxide-mediated coronary vasodilation
Correct answer: Inhibition of late sodium current reducing myocardial oxygen demand
Ranolazine inhibits the late inward sodium current (I_Na late), which reduces intracellular calcium overload and myocardial oxygen demand without significantly affecting heart rate or blood pressure.
Question 2: An 80-year-old woman with severe symptomatic aortic stenosis is deemed high surgical risk. Which factor most strongly favors TAVR over surgical AVR?
- Bicuspid aortic valve anatomy
- Severe peripheral vascular disease limiting transfemoral access
- Predicted operative mortality >8% using STS score (Correct answer)
- Presence of moderate aortic regurgitation
Correct answer: Predicted operative mortality >8% using STS score
High surgical risk (STS mortality score ≥8%) is the primary indication favoring TAVR, which has demonstrated non-inferior or superior outcomes in this population.
Question 3: A 44-year-old woman has recurrent syncopal episodes during emotional stress. ECG shows a prolonged QTc of 520ms. She is started on nadolol. Which additional measure is most important for preventing sudden death?
- Potassium supplementation to maintain K+ >4.5 mEq/L
- Implantable cardioverter-defibrillator placement
- Avoidance of all QT-prolonging medications (Correct answer)
- Left cardiac sympathetic denervation
Correct answer: Avoidance of all QT-prolonging medications
Avoidance of QT-prolonging drugs (antiarrhythmics, antibiotics, antiemetics, antipsychotics) is critical in congenital long QT syndrome to prevent torsades de pointes.
Question 4: A 67-year-old man undergoes coronary angiography and is found to have a 50% left main stenosis. FFR measurement yields 0.79. What is the most appropriate management?
- Medical therapy alone, as FFR >0.80 is non-ischemic
- Urgent CABG given left main disease
- PCI of the left main lesion (Correct answer)
- Repeat angiography in 6 months
Correct answer: PCI of the left main lesion
An FFR of 0.79 (≤0.80) indicates hemodynamically significant ischemia; left main disease with positive FFR warrants revascularization, with CABG preferred over PCI for left main.
Question 5: A 38-year-old man presents with fever, new murmur, and positive blood cultures for Streptococcus viridans. Echocardiography shows a 12mm vegetation on the mitral valve. Which finding would prompt urgent surgical consultation?
- Vegetation size >10mm alone
- Heart failure due to severe mitral regurgitation (Correct answer)
- Positive blood cultures persisting for 48 hours
- ESR greater than 100 mm/hr
Correct answer: Heart failure due to severe mitral regurgitation
Heart failure secondary to valve dysfunction from endocarditis is the most common indication for urgent surgery, as it significantly increases mortality without intervention.
Question 6: A 72-year-old man with peripheral artery disease and claudication at 1 block has an ABI of 0.55. He already walks regularly. What is the next best step in management?
- Aortofemoral bypass surgery
- Cilostazol 100mg twice daily (Correct answer)
- Aspirin 81mg plus clopidogrel 75mg
- Emergent vascular surgery referral for limb salvage
Correct answer: Cilostazol 100mg twice daily
Cilostazol, a phosphodiesterase-3 inhibitor, improves claudication symptoms and walking distance and is indicated for symptomatic PAD when exercise alone is insufficient.
Question 7: Which of the following best describes the mechanism of torsades de pointes in patients taking class IA antiarrhythmics?
- Excessive shortening of the QT interval leading to early repolarization
- Early afterdepolarizations due to prolonged repolarization triggering ventricular arrhythmia (Correct answer)
- Increased automaticity of Purkinje fibers causing focal tachycardia
- Re-entry through the bundle of His causing polymorphic VT
Correct answer: Early afterdepolarizations due to prolonged repolarization triggering ventricular arrhythmia
Class IA drugs block K+ channels, prolonging repolarization (QT interval), which can trigger early afterdepolarizations (EADs) that initiate torsades de pointes.
ITE Cardiovascular Medicine 4
A 60-year-old man with known CAD is prescribed ranolazine for refractory angina.
Which mechanism of action explains its antianginal effect?