Can this patient start Xarelto (rivaroxaban) given their elevated von Willebrand factor, ristocetin cofactor, and factor VIII activity levels, as well as a diagnosis of easy bruising?

Rivaroxaban Should Not Be Started in This Patient Due to Elevated von Willebrand Factor and Factor VIII Levels

This patient should not start Xarelto (rivaroxaban) due to the significantly elevated von Willebrand factor, ristocetin cofactor, and factor VIII activity levels, which indicate a prothrombotic state and increased bleeding risk.

Laboratory Findings Analysis

The patient's laboratory results show:

• Von Willebrand Factor Antigen: 252% (reference range: 50-217%)
• Ristocetin Cofactor: 363% (reference range: 42-200%)
• Factor VIII Activity: 210% (reference range: 50-180%)

These elevated levels suggest a hypercoagulable state that could increase thrombotic risk, but paradoxically also increase bleeding risk when combined with anticoagulation 1.

Risk Assessment

Bleeding Risk

• The patient has a documented history of "easy bruising" (the reason for the coagulation testing)
• Elevated VWF and Factor VIII levels can cause platelet dysfunction despite their prothrombotic effects
• Adding rivaroxaban would significantly increase bleeding risk, particularly with these abnormal coagulation parameters

Drug Interactions and Contraindications

• Rivaroxaban is contraindicated in patients with clinically significant active bleeding 2
• The American College of Chest Physicians guidelines note that rivaroxaban should be used with caution in patients with bleeding disorders 1
• The combination of elevated coagulation factors and anticoagulation creates an unpredictable hemostatic environment

Management Recommendations

1. Hematology consultation is required before initiating any anticoagulant therapy in this patient
2. Further evaluation of the elevated VWF, ristocetin cofactor, and Factor VIII levels is needed to determine etiology
3. Consider alternative anticoagulation options only after the underlying coagulation abnormality is diagnosed and managed

Potential Causes of Elevated VWF/Factor VIII

Several conditions can cause elevated VWF and Factor VIII levels:

• Acute phase reaction/inflammation
• Malignancy
• Pregnancy
• Liver disease
• Stress
• Acquired von Willebrand syndrome

Clinical Approach

1. Delay anticoagulation until coagulation abnormalities are explained
2. Investigate underlying causes of elevated VWF and Factor VIII
3. Reassess anticoagulation need after diagnosis and treatment of underlying condition
4. Consider alternative anticoagulation strategies if absolutely necessary after hematology consultation

Common Pitfalls to Avoid

• Starting anticoagulation without investigating abnormal coagulation parameters
• Attributing easy bruising solely to anticoagulation rather than underlying disorder
• Failing to recognize that elevated VWF/Factor VIII can paradoxically increase both thrombotic and bleeding risks
• Ignoring the need for specialist consultation with these laboratory abnormalities

The European guidelines for management of bleeding in patients on oral anticoagulants emphasize that patients with abnormal coagulation parameters require careful evaluation before starting anticoagulants 1. The International Society on Thrombosis and Haemostasis recommends thorough evaluation of patient characteristics before prescribing novel oral anticoagulants 1.