MajorClass III antiarrhythmics (Vaughan Williams)×Alpha and beta blocker (non-selective β + α1)
Updated · Methodology
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
The AEMPS label for carvedilol lists amiodarone among the drugs that raise the risk of atrioventricular conduction disturbances. 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.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- ESC: ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure (2021)– McDonagh TA et al. Eur Heart J 2021;42:3599-3726
- AEMPS: Ficha técnica: Carvedilol (nº registro 66230), sección 4.5 (2025)– AEMPS, CIMA, nº registro 66230, sección 4.5