Major
Amiodarone × Bisoprolol
Class III antiarrhythmics (Vaughan Williams)×Selective beta-adrenergic blockers
Mechanism
Additive bradycardia and AV conduction suppression. Bisoprolol is a selective beta-blocker; amiodarone non-competitively blocks β-receptors and suppresses the AV node.
Symptoms
Bradycardia (heart rate below 50/min), dizziness, syncope. ECG: first- to second-degree AV block. Older patients: fall risk.
Management
The combination is appropriate in cardiology (atrial fibrillation, post-infarction). Reduce bisoprolol by 25–50% when starting amiodarone. Check pulse and ECG at 1 and 4 weeks.