Guideline 36: Antithrombotic Therapy

Antithrombotic Therapy
Section 8: Recurrent arterial thrombosis or embolism

Patients with recurrent arterial thrombosis or embolism should be carefully evaluated for:

compliance with antithrombotic prophylaxis
modifiable risk factors (smoking, blood pressure, lipids)
cardiac sources of peripheral embolism (echocardiography)
thrombophilias (see Table 4) in patients under 40 years ⁷³
arteritis (e.g. collagen disorders, syphilis)
malignant disease.

*	In patients with recurrent arterial thromboembolism despite aspirin or other antiplatelet agents, especially those with cardiac sources of embolism or thrombophilias, prophylactic warfarin (target INR 2.5, range 2.0-3.0) should be considered, balanced against the increased risk of bleeding.

* This is a grade A recommendation for atrial fibrillation or myocardial infarction (see section 3); grade C for patients with peripheral arterial thrombosis (see section 6.1).

In patients with recurrent arterial thrombosis or embolism despite warfarin at target INR of 2.5, range 2.0-3.0, either the addition of aspirin (75 mg/day), high-intensity warfarin (target INR 3.5, range 3.0-4.0), or (if there is further recurrence) high-intensity warfarin plus aspirin (75 mg/day) may be considered. Based on level III evidence¹⁹

The increased risk of bleeding with such regimens should be considered.

There is evidence from retrospective studies that in patients with lupus anticoagulants, a target INR of 3.5, range 3.0-4.0, is more effective in prevention of recurrent thrombosis than warfarin at INR range 2.0-3.0.¹³⁴