CMC Cardiac Arrhythmia Management 2 — Questions and Answers
Question 1: A patient with atrial fibrillation has a heart rate of 130 bpm and is hemodynamically stable. The onset is confirmed to be 36 hours ago. What is the preferred initial management?
- Immediate electrical cardioversion without anticoagulation
- Rate control and anticoagulation per CHA2DS2-VASc score before cardioversion (Correct answer)
- IV adenosine to restore sinus rhythm
- IV digoxin for immediate rhythm conversion
Correct answer: Rate control and anticoagulation per CHA2DS2-VASc score before cardioversion
For atrial fibrillation with onset greater than 48 hours (or unknown duration), anticoagulation for at least 3 weeks or TEE to rule out thrombus is required before cardioversion due to risk of thromboembolism; rate control is appropriate in the interim.
Question 2: During post-cardiac surgery monitoring, a patient develops a wide-complex tachycardia at 200 bpm. Which ECG finding most strongly suggests ventricular tachycardia rather than SVT with aberrancy?
- QRS duration less than 120 ms
- AV dissociation visible on the tracing (Correct answer)
- Regular RR intervals
- Concordant positive precordial R waves
Correct answer: AV dissociation visible on the tracing
AV dissociation — independent atrial and ventricular activity — is a hallmark of ventricular tachycardia and essentially excludes supraventricular tachycardia with aberrant conduction.
Question 3: A patient with an implanted ICD receives multiple appropriate shocks for sustained VT. After stabilization, which long-term management strategy is most indicated to reduce recurrent ICD therapies?
- Increasing the ICD detection rate threshold only
- Catheter ablation of the VT focus (Correct answer)
- Discontinuing all antiarrhythmic medications
- Replacing the ICD with a pacemaker
Correct answer: Catheter ablation of the VT focus
Catheter ablation targets and eliminates the reentrant circuit or ectopic focus responsible for recurrent VT, significantly reducing ICD shocks and improving quality of life in patients with structural heart disease.
Question 4: Which AV block pattern is characterized by a progressively lengthening PR interval followed by a dropped QRS complex?
- First-degree AV block
- Mobitz type I (Wenckebach) second-degree AV block (Correct answer)
- Mobitz type II second-degree AV block
- Third-degree (complete) AV block
Correct answer: Mobitz type I (Wenckebach) second-degree AV block
Mobitz type I (Wenckebach) second-degree AV block features progressive PR interval lengthening until a P wave fails to conduct and a QRS is dropped, then the cycle repeats.
Question 5: A 68-year-old patient with hypertension and prior stroke has new-onset atrial fibrillation. What CHA2DS2-VASc score should prompt initiation of anticoagulation?
- Score of 0
- Score of 1 in males
- Score of 2 or greater (Correct answer)
- Score of 5 or greater
Correct answer: Score of 2 or greater
Current ACC/AHA guidelines recommend oral anticoagulation for patients with non-valvular AFib and a CHA2DS2-VASc score ≥2 in men (or ≥3 in women) due to meaningful annual stroke risk.
Question 6: Which antiarrhythmic drug classification includes agents that block sodium channels and slow phase 0 depolarization?
- Class II (beta-blockers)
- Class III (potassium channel blockers)
- Class I (sodium channel blockers) (Correct answer)
- Class IV (calcium channel blockers)
Correct answer: Class I (sodium channel blockers)
Class I antiarrhythmics (e.g., lidocaine, flecainide, procainamide) exert their effect by blocking fast sodium channels, slowing phase 0 of the cardiac action potential and reducing conduction velocity.
Question 7: A patient on telemetry shows a rhythm with no P waves, an irregularly irregular ventricular response, and fine fibrillatory baseline between QRS complexes. The ventricular rate is 88 bpm. Which condition best describes this rhythm?
- Atrial fibrillation with controlled ventricular rate (Correct answer)
- Multifocal atrial tachycardia
- Atrial flutter with variable block
- Junctional rhythm with PVCs
Correct answer: Atrial fibrillation with controlled ventricular rate
Atrial fibrillation with controlled ventricular rate presents as an irregularly irregular rhythm with absent discrete P waves, replaced by a chaotic fibrillatory baseline, and a ventricular rate within or near the normal range due to rate-controlling medications.
CMC Cardiac Arrhythmia Management 2
A patient with atrial fibrillation has a heart rate of 130 bpm and is hemodynamically stable.
The onset is confirmed to be 36 hours ago.
What is the preferred initial management?