Antiplatelet Agents as Secondary Thromboprophylaxis after Anticoagulant Treatment for Thrombosis.

Patients suffering an unprovoked VTE event have high risk of recurrence after anticoagulation cessation especially in the first two-year period. Our study examined whether secondary thromboprophylaxis with antiplatelet drugs reduces the relapse risk.

STUDY DESIGN: We studied 53 patients, 25 men and 28 women, (group A), with median age of 41(18–74) years. 31 received aspirin at 100mg while 22 received clopidogrel at 75mg after anticoagulant therapy for VTE. We compared them with 77 patients (group B) who did not receive any thromboprophylaxis after VTE with a median age of 40(18–82) years. Of group B, 56 were men while 21 were women. In 51 out of 130 patients we monitored D-dimers, F1+2 prothrombin fragments, and TAT (thrombin-antithrombin) complexes as prothrombotic and fibrinolysis markers. Failure was determined as VTE recurrence or elevation of prothrombotic markers in the first 2year period.

RESULTS: In 4 patients of group A (7,5%) we noticed marked elevation of prothrombotic markers and they were turned to anticoagulation, and in 3 marker elevation subsided by changing the antiplatelet agent (aspirin to clopidogrel). 1 patient stopped prophylaxis due to hemorrhage while none relapsed. In group B VTE recurrence was noticed at 27(36%, p<0,0002). In both groups late recurrence (> 2 years) was observed at 27,6% of 130 patients.

CONCLUSIONS: Low dose aspirin or clopidogrel administration is safe and effective as thromboprophylaxis after anticoagulation for first venous thromboembolic event. Markers as D-dimers, F1+2, TAT, have prognostic significance and are valuable tools in patient monitoring. Patient follow-up has to be long-standing because VTE recurrence risk persists through the years.