AF AF Pharmacology & Medications 2 — Questions and Answers
Question 1: Which calcium channel blocker is used for rate control in AF but is contraindicated in heart failure with reduced ejection fraction?
- Amlodipine
- Verapamil (Correct answer)
- Nimodipine
- Felodipine
Correct answer: Verapamil
Verapamil (and diltiazem) are non-dihydropyridine calcium channel blockers used for rate control in AF but are contraindicated in HFrEF due to their negative inotropic effects.
Question 2: The 'pill-in-the-pocket' approach to rhythm control in AF typically uses which agent?
- Amiodarone
- Sotalol
- Flecainide or propafenone (Correct answer)
- Digoxin
Correct answer: Flecainide or propafenone
The pill-in-the-pocket strategy uses flecainide or propafenone taken as a single oral dose at AF onset to self-terminate infrequent, symptomatic AF episodes.
Question 3: Which score is used to assess bleeding risk before initiating anticoagulation in AF patients?
- CHA2DS2-VASc
- HAS-BLED (Correct answer)
- GRACE
- TIMI
Correct answer: HAS-BLED
The HAS-BLED score estimates annual bleeding risk in anticoagulated AF patients by scoring hypertension, renal/liver dysfunction, stroke history, bleeding history, labile INR, elderly age, and drug/alcohol use.
Question 4: Dofetilide is a Class III antiarrhythmic that requires initiation in a monitored hospital setting primarily because of the risk of:
- Atrial flutter conversion
- QT prolongation and torsades de pointes (Correct answer)
- Bradycardia-induced syncope
- Renal tubular necrosis
Correct answer: QT prolongation and torsades de pointes
Dofetilide can prolong the QT interval and precipitate torsades de pointes, requiring at least 3 days of in-hospital cardiac monitoring during initiation.
Question 5: What is the mechanism of action of ibutilide in AF management?
- Blocks sodium channels to slow conduction
- Activates slow inward sodium current and blocks potassium channels to prolong repolarization (Correct answer)
- Inhibits the AV node by blocking L-type calcium channels
- Stimulates vagal tone to slow ventricular rate
Correct answer: Activates slow inward sodium current and blocks potassium channels to prolong repolarization
Ibutilide is an IV Class III agent that prolongs cardiac repolarization by activating the slow inward sodium current and blocking potassium channels, enabling pharmacologic cardioversion of AF.
Question 6: A patient on rivaroxaban for AF needs an urgent procedure. Which reversal agent is specifically approved for rivaroxaban?
- Protamine sulfate
- Vitamin K
- Andexanet alfa (Correct answer)
- Idarucizumab
Correct answer: Andexanet alfa
Andexanet alfa (andexanet alfa) is an FDA-approved reversal agent for anti-Xa inhibitors, including rivaroxaban and apixaban.
AF AF Pharmacology & Medications 2
Which calcium channel blocker is used for rate control in AF but is contraindicated in heart failure with reduced ejection fraction?