Major
Amiodarone × Verapamil
Class III antiarrhythmics (Vaughan Williams)×Non-dihydropyridine calcium channel blocker
Mechanism
Additive suppression of sinus node and atrioventricular (AV) conduction. Symptomatic bradycardia, sinoatrial and AV block have been reported.
Symptoms
Bradycardia (heart rate below 50/min), dizziness, syncope. ECG: first- to second-degree AV block. Older patients: fall risk.
Management
Avoid the combination. In atrial fibrillation, choose one strategy: amiodarone for rhythm control, verapamil for rate control. Alternatives: a beta-blocker + digoxin or catheter ablation.