Can IV digoxin be initiated in an 85-year-old patient with paroxysmal atrial fibrillation (A fib) and persistent tachycardia despite bisoprolol (beta blocker) therapy, with concomitant hypotension?

From the Guidelines

IV digoxin can be considered for this 85-year-old patient with paroxysmal atrial fibrillation who has a rapid heart rate (160s) despite her usual 10 mg bisoprolol dose, especially given her borderline low blood pressure (SBP 90s, DBP 50s). A typical loading dose would be 0.25-0.5 mg IV given slowly over 5-10 minutes, with potential for additional doses of 0.125-0.25 mg every 4-6 hours until rate control is achieved, not exceeding 1.0-1.5 mg in 24 hours. Close monitoring of heart rate, blood pressure, and ECG is essential during administration. Digoxin is particularly useful in this scenario because it can slow the heart rate without significantly lowering blood pressure, unlike additional beta-blocker doses which could worsen hypotension. However, renal function should be assessed before administration as digoxin is primarily eliminated by the kidneys, and dose adjustments may be necessary in elderly patients with reduced renal function, as noted in the 2022 European Heart Journal review 1. Serum potassium and magnesium levels should also be checked, as hypokalemia and hypomagnesemia increase the risk of digoxin toxicity.

Some key considerations when using digoxin in elderly patients include the risk of bradycardia and AV block, as well as the potential for increased sensitivity to the drug due to age-related changes in cardiac ion channel expression and activity, as discussed in the 2022 European Heart Journal review 1. Additionally, the 2022 Circulation guideline 1 highlights the importance of initiating digoxin at a low dose and monitoring serum concentrations to minimize the risk of toxicity.

The benefits of using digoxin in this patient outweigh the risks, as it can provide effective rate control without exacerbating hypotension, and is supported by guidelines such as the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1. Overall, the use of IV digoxin in this scenario is a reasonable option, with careful monitoring and dose adjustment as needed.

From the FDA Drug Label

2.1 Important Dosing and Administration Information In selecting a digoxin dosing regimen, it is important to consider factors that affect digoxin blood levels (e.g., body weight, age, renal function, concomitant drugs) since toxic levels of digoxin are only slightly higher than therapeutic levels. Parenteral administration of digoxin should be used only when the need for rapid digitalization is urgent or when the drug cannot be taken orally.

The patient is an 85-year-old with known paroxysmal atrial fibrillation and is already on bisoprolol, which suggests that the need for rapid digitalization may not be urgent. However, the patient's rapid heart rate and low blood pressure may indicate a need for alternative or additional treatment.

• Key considerations: The patient's age, renal function, and concomitant medications (e.g., bisoprolol) should be taken into account when selecting a digoxin dosing regimen.
• Caution: The patient's low blood pressure (SBP 90s, DBP 50s) may increase the risk of digoxin toxicity, and the drug's effects on contractility and excitability of the heart should be carefully monitored. Given the patient's complex clinical presentation and the potential risks associated with digoxin, it is recommended to exercise caution and consider alternative treatment options or consult with a cardiologist before initiating IV digoxin 2.

From the Research

Patient Condition

The patient is an 85-year-old with known paroxysmal atrial fibrillation (AF) and a rapid heart rate in the 160s despite the usual 10 mg dose of bisoprolol. The patient's blood pressure is on the lower side, with systolic blood pressure (SBP) in the 90s and diastolic blood pressure (DBP) in the 50s.

Treatment Considerations

• The use of IV digoxin in this scenario is questionable due to the patient's paroxysmal AF and hypotension.
• According to 3, digoxin should not be used to treat patients with paroxysmal AF.
• However, 4 suggests that digoxin may be useful in the presence of hypotension or an absolute contraindication to beta-blocker treatment.
• 5 notes that digoxin therapy is inexpensive and well-tolerated and may result in considerable savings, but its use should be considered in patients with systolic heart failure who continue to have signs and symptoms despite therapeutic doses of ACE inhibitors or diuretics.
• The patient's hypotension, as indicated by SBP in the 90s and DBP in the 50s, is a concern, and the use of IV digoxin may need to be carefully considered in this context, as noted in 6, which found that home beta-blocker use was associated with hypotensive events.

Alternative Treatment Options

• The patient is already on bisoprolol, a beta-blocker, which is commonly used for rate control in AF.
• 7 suggests that initial treatment for AF is directed at controlling the ventricular rate, most often with a calcium channel blocker, a beta blocker, or digoxin.
• Given the patient's hypotension, alternative treatments such as calcium channel blockers or other rate-control medications may need to be considered, as noted in 3 and 7.