Atrial fibrillation is a common persistent arrhythmia. It can significantly increase the risk of stroke. Novel oral anticoagulants (NOACs) are widely used in clinical practice for atrial fibrillation anticoagulation due to their superior safety and ease of administration. The four commonly used NOACs are dabigatran, which directly inhibits thrombin, and rivaroxaban, apixaban and edoxaban, which inhibit factor Xa.
Pharmacokinetics of NOACs and the Effect of Antiarrhythmic Drugs (AADs) on Their Anticoagulant Effect.
The selection of NOACs should consider factors such as bioavailability, potential drug interactions along metabolic pathways, elimination half-life, and the presence of antagonists. In the absence of clear indications, reducing or increasing the dose will increase adverse events without increasing safety. Different NOACs have different metabolic characteristics. When used in combination with antiarrhythmic drugs (AADs), attention should be paid to the effect of AADs on NOAC blood concentrations, and appropriate drug selection and dosage adjustments should be made.
**White indicates no drug interactions. Gray indicates no data. Yellow indicates use with caution. Orange indicates low dose (Dabigatran) or reduced dose (Edoxaban). Red indicates contraindication, as it is not recommended due to increased blood drug concentration.
What is the NOAC dosage?
Improper use of NOAC dosage may have adverse consequences for patients with atrial fibrillation. Off-label use of low-dose NOACs increases the risk of stroke. Off-label use of higher-dose NOACs increases the risk of major bleeding. Therefore, correct use of NOACs and minimizing adverse outcomes in patients with atrial fibrillation are crucial.
How to choose between NOACs and warfarin for elderly patients with atrial fibrillation?
For elderly patients with atrial fibrillation, NOAC anticoagulation therapy is preferred. It recommends anticoagulation therapy with dabigatran etexilate, rivaroxaban, or edoxaban. If warfarin is used, the INR should be maintained at 2.0–3.0 or 1.6–2.5 (for patients ≥ 75 years of age or those at high risk of bleeding with a HASBLED score ≥ 3).
Management of Anticoagulation-Related Bleeding:
1. Minor bleeding related to NOACs: Discontinue medication for 12–24 hours if necessary.
2. Moderate to severe bleeding: Consider using blood products, hemodialysis, etc., depending on the anticoagulant used.
3. Life-threatening bleeding: Use specific antagonists (vitamin K, edasuzumab, or andexanet-Ξ±, etc.).
Whether or when to resume anticoagulation therapy after bleeding requires careful consideration of the patient's thrombotic and bleeding risks.
Switching between anticoagulants: Switching between different anticoagulants should follow the principle of not affecting the effectiveness of anticoagulation therapy and minimizing the risk of bleeding.
