From the Guidelines
For a 75-year-old patient with newly diagnosed atrial fibrillation on Eliquis (apixaban) and metoprolol with an AFib burden less than 1%, initial evaluation should include a comprehensive assessment of comorbidities and risk factors, as outlined in the 2024 ESC guidelines for the management of atrial fibrillation 1.
Key Tests
- A comprehensive metabolic panel to assess kidney and liver function, as apixaban dosing depends on renal function, is essential, as emphasized by the need to manage comorbidities and risk factors in the AF-CARE pathway 1.
- A complete blood count to establish baseline hemoglobin levels before anticoagulation, considering the potential for bleeding risk, which should be managed to improve safety, as noted in the guidelines 1.
- Thyroid function tests should be performed, as thyroid disorders can trigger or worsen AFib, aligning with the focus on conditions associated with AF, such as hypertension, heart failure, diabetes mellitus, obesity, obstructive sleep apnoea, physical inactivity, and high alcohol intake 1.
- An echocardiogram is crucial to evaluate cardiac structure and function, particularly to assess for valvular disease, left atrial size, and left ventricular function, which is part of the initial evaluation and risk stratification process 1.
- A 12-lead ECG should be obtained to document the arrhythmia and establish baseline QT interval and conduction parameters, supporting the diagnosis and management of AFib, as clinical AF requires confirmation on an ECG device to initiate risk stratification and AF management 1.
Ongoing Monitoring
- Periodic monitoring of renal function every 3-6 months is important, as declining kidney function may necessitate apixaban dose adjustment, reflecting the need for dynamic evaluation and reassessment of therapy 1.
- Regular monitoring of heart rate and symptoms is needed to assess metoprolol efficacy and adjust rate control therapy as necessary, considering the use of beta-blockers, digoxin, or diltiazem/verapamil as initial therapy in the acute setting or as a sole treatment strategy to control heart rate and symptoms 1. Despite the low AFib burden, these tests and ongoing monitoring are crucial because even paroxysmal AFib carries stroke risk in elderly patients, and proper anticoagulation management requires ongoing assessment of bleeding risk versus stroke prevention benefit, in line with the guidelines' emphasis on safety and anticoagulation in AF management 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Testing Recommendations for Atrial Fibrillation
For a 75-year-old patient with new atrial fibrillation (AFib) started on Eliquis (apixaban) and metoprolol, with an AFib burden of less than 1%, the following tests are recommended:
- Laboratory methods to monitor apixaban treatment, such as trough plasma apixaban concentrations determined by liquid chromatography-tandem mass-spectrometry (LC-MS/MS) or Anti-factor Xa assay 2
- Renal function tests, such as creatinine clearance, to assess the patient's kidney function and adjust apixaban dosing if necessary 3
- Regular monitoring of bleeding risk, as patients with AFib taking apixaban are at increased risk of bleeding, particularly if they are also taking medications like diltiazem 4
- Assessment of cognitive function, as some studies suggest that apixaban may have a positive effect on cognitive function in patients with AFib 5
Considerations for Apixaban Treatment
When treating a 75-year-old patient with AFib with apixaban, consider the following:
- Age-related changes in renal function and apixaban exposure 6, 3
- Potential interactions with other medications, such as diltiazem, which may increase the risk of bleeding 4
- Regular monitoring of apixaban concentrations and adjustment of dosing as needed to minimize the risk of bleeding or stroke 2
Additional Testing
Additional testing may be necessary to assess the patient's overall cardiovascular risk and to guide treatment decisions, such as: