Moderate
Amiodarone × carvedilol
Class III antiarrhythmics (Vaughan Williams)×Alpha and beta blocker (non-selective β + α1)
Mechanism
Additive bradycardia and QT effect from amiodarone, on top of carvedilol's negative chronotropy. Often used in heart failure with reduced ejection fraction and atrial fibrillation — an acceptable combination.
Symptoms
Bradycardia, dizziness, fatigue, near-syncope. QT prolongation on ECG. Dizziness, syncope, palpitations. Rarely: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.
Management
Start carvedilol at minimum dose (3.125 mg twice daily) with up-titration every 2 weeks. Check ECG and heart rate at 1 and 4 weeks. If heart rate falls below 50 bpm or 2nd/3rd-degree AV block develops, adjust both. Keep potassium and magnesium in the upper half of normal range.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Sources
- ESC: 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure (2021)– Eur Heart J 2021;42(36):3599–3726