Major
digoxin × metoprolol
Cardiac glycosides (digitalis)×Selective β1-adrenoceptor blockers
Mechanism
Additive AV conduction slowing and heart rate reduction. In AF, synergistic ventricular rate control is beneficial, but in older patients there is risk of symptomatic bradycardia, second- or third-degree AV block, and asystole.
Management
Start both drugs at low doses. Check ECG at 1–2 weeks and after each dose increase. Target resting heart rate is 60–70/min in HF and 80–110/min in AF (RACE II). For syncope or heart rate below 50/min, reduce the dose or discontinue.
Sources
- RACE II Investigators: Lenient versus Strict Rate Control in Patients with Atrial Fibrillation (2010)— N Engl J Med 2010;362(15):1363–1373
- ESC: 2024 ESC Guidelines for the management of atrial fibrillation developed in collaboration with the EACTS (2024)— Eur Heart J 2024;45(36):3314–3414
- ESC: 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure (2021)— Eur Heart J 2021;42(36):3599–3726