Moderate
Bisoprolol × Dronedarone
Selective beta-adrenergic blockers×Class III antiarrhythmic
Mechanism
Additive bradycardia. Dronedarone itself causes bradycardia via β-receptor blockade and AV node suppression. The combination increases symptomatic bradycardia and AV block risk.
Symptoms
Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk. With additional antihypertensives: bradycardia (pulse below 60/min).
Management
When dronedarone starts, reduce bisoprolol by 25%. Check pulse and ECG at 1 and 4 weeks. If pulse drops below 50 or second-degree AV block appears, adjust further.