Effects of Digoxin on Heart Rate in Atrial Fibrillation and Heart Failure
Digoxin effectively slows ventricular rate at rest in patients with atrial fibrillation (AF) and is particularly indicated for patients with heart failure (HF), left ventricular dysfunction, or sedentary individuals, but should not be used as the sole agent for rate control in paroxysmal AF. 1
Effects on Heart Rate in Atrial Fibrillation
- Digoxin slows rapid ventricular response rate in a linear dose-response fashion from 0.25 to 0.75 mg/day in patients with chronic AF 2
- Digoxin is useful for initial control of ventricular rate in patients with rapid AF and may be considered in decompensated HF patients prior to initiation of a beta-blocker 1
- Intravenous administration of digoxin is recommended to control heart rate acutely in patients with AF and HF who do not have an accessory pathway 1
- Digoxin's ability to control ventricular rate is primarily due to its vagotonic effect on the atrioventricular node 3
- Digoxin is less effective at controlling heart rate during exercise or high sympathetic states compared to beta-blockers or calcium channel blockers 3, 4
Effects on Heart Rate in Heart Failure
- Digoxin is effective following oral administration to control heart rate at rest in patients with AF and is indicated for patients with HF, left ventricular dysfunction, or sedentary individuals 1
- In patients with symptomatic HF and AF, digoxin may be used to slow a rapid ventricular rate 1
- In patients with AF and an LVEF < 40%, digoxin should be used to control heart rate in addition to, or prior to a beta-blocker 1
Clinical Recommendations for Rate Control
For patients with AF and HF:
For optimal rate control:
- A combination of digoxin and either a beta-blocker or nondihydropyridine calcium channel antagonist is reasonable to control heart rate both at rest and during exercise 1
- In the longer term, a beta-blocker, either alone or in combination with digoxin, is the preferred treatment for rate control in patients with an LVEF < 40% 1
Important Limitations and Caveats
- Digoxin should not be used as the sole agent to control ventricular response in patients with paroxysmal AF 1
- Recent evidence from the RATE-AF trial showed that low-dose digoxin (mean dose 161 μg/day) was as effective as bisoprolol for heart rate control in elderly patients with permanent AF and symptoms of HF, with similar resting heart rates at 6 months (76.9/min vs 74.8/min) 5
- Digoxin was associated with fewer adverse events compared to bisoprolol in the RATE-AF trial 5
- In patients with AF and HF, digoxin use for rate control is not associated with increased all-cause mortality 6
- Digoxin can cause atrial and ventricular arrhythmias, particularly in the context of hypokalemia, requiring careful monitoring of serum electrolytes and renal function 1
Dosing Considerations
- Starting dose: Loading doses are generally not required in stable patients with sinus rhythm 1
- Maintenance dose: 0.25 mg daily is commonly used in adults with normal renal function 1
- Reduced dosing (0.125 or 0.0625 mg daily) is recommended for elderly patients and those with renal impairment 1
- Therapeutic serum concentration should be between 0.6 and 1.2 ng/mL 1
- The elderly have reduced elimination of digoxin, requiring conservative dosing and therapeutic monitoring 3
Monitoring
- Regular monitoring of serum electrolytes and renal function is mandatory 1
- Assessment of heart rate control during exercise and adjustment of pharmacological treatment is useful in symptomatic patients during activity 1
- Early recognition of potential digoxin toxicity is essential (confusion, nausea, anorexia, visual disturbances) 1, 7