Case Presentation, Continued
Frank’s laboratory results — including electrolytes, blood urea nitrogen, and fasting blood glucose — are all within normal limits. His creatinine clearance (CrCl) is moderately impaired at 50 mL/min.
An echocardiogram shows mild concentric left ventricular hypertrophy and mild left atrial enlargement; the results are otherwise within normal limits. CHA2DS2-VASc is used to calculate stroke risk. Frank has a score of 2, which is considered “moderate-high” risk. HAS-BLED is used to calculate bleeding risk. Frank has a score of 2, which indicates that anticoagulation therapy can be considered. However, he is at moderate risk for major bleeding.
What would you do next?
- No anticoagulation therapy is needed at this time
- Start aspirin
- Start warfarin
- Start direct-acting oral anticoagulant (DOAC)
Overview of Treatment Options for Stroke Prevention in Nonvalvular Atrial Fibrillation
Prior to initiating antithrombotic therapy, patients should be assessed for stroke risk and bleeding risk. Evidence-based guidelines recommend using the CHA2DS2-VASc score for stroke risk stratification in patients with nonvalvular AF (NVAF) (Table 1).1,5,6 The CHA2DS2-VASc score is preferred over the CHADS2 score due to the broader score range and larger number of risk factors included.1
Hemorrhage risk can be assessed using bleeding risk scores such as HAS-BLED or others.1,5 Clinicians should discuss the risk of both stroke and bleeding with all patients considering anticoagulation therapy. If anticoagulation therapy is deemed appropriate for a patient, several options are available. Antithrombotic agents routinely used for the prevention of thromboembolism in patients with NVAF include warfarin, DOACs (direct thrombin and factor Xa inhibitors), and antiplatelet drugs (aspirin and clopidogrel).
Warfarin is a vitamin K antagonist that acts on multiple sites in the coagulation cascade. It has been the main option for stroke prevention in patients with AF for decades. Compared with placebo, warfarin reduces the relative risk of ischemic and hemorrhagic stroke by as much as 64%, which corresponds to an absolute risk reduction of 2.7% per year.7 Warfarin is also inexpensive, readily available, and has an easy-to-administer antidote.8 Although warfarin is highly effective, it is also cumbersome to use due to a narrow therapeutic index that necessitates frequent monitoring and dose adjustments. It also interacts with numerous foods and drugs. These limitations have translated into poor patient adherence, which is especially important for patients with a CHA2DS2-VASc score ³2.9