Best Antithrombotic Therapy in Patients With Acute Venous ThromboEmbolism While Taking Antiplatelets

Overview

Venous thromboembolism (VTE) and atherosclerotic cardiovascular disease share common risk factors and frequently coexist in the same patients. Their management requires use of antithrombotic agents: anticoagulant therapy (AC) for secondary prevention of VTE recurrence, antiplatelet (AP) for secondary prevention of major adverse ischemic cardiovascular and cerebrovascular event (MACCE) in patients with atherosclerotic cardiovascular disease (coronary artery disease, atherosclerotic cerebrovascular disease, lower extremity peripheral arterial disease). Side effects of antithrombotic drugs are the 1st cause of emergency admission and hospitalization for an adverse drug reaction (mainly bleeding), and the combination of AC with AP strongly increases this risk.

Up to one third of VTE patients receive concomitant AP therapy, with conflicting results on patient outcomes. Concomitant therapy (AC+AP) has been associated with a higher risk of bleeding (up to 3-fold) when aspirin was associated with vitamin-K antagonist (VKA) in a multicenter cohort study, or with direct oral anticoagulants (DOACs) for acute VTE in a post-hoc subgroup analysis. Conversely, patients with acute VTE in whom clinicians decided to maintain AC+AP were found to have an increased risk of MACCE without any higher risk of bleeding, in a multicenter registry. However, in most cases, the type (aspirin or another) and indication (primary versus secondary prevention) of AP was unknown, as was the duration of the combination AC+AP, and therefore these observational results may be confounded. Therefore, there is persistent equipoise regarding the benefit/risk of combining an antiplatelet therapy with anticoagulation in patients undergoing treatment for VTE, when there is a prior history of atherosclerotic cardiovascular disease. This may explain why clinical practice varies widely. Considering the conflicting data about the risk of bleeding in patients on AP therapy for secondary prevention, who need to start full-dose anticoagulant therapy for acute VTE, a randomized trial comparing the two strategies, in patients with acute VTE and with history of stable atherosclerotic cardiovascular disease is needed and justified. The investigators hypothesize that a strategy based on the prescription of a full-dose AC therapy alone will decrease the risk of bleeding, when compared to the the strategy of combined AP and full-dose AC therapies, and that this strategy will translate in a positive net clinical benefit (a composite of clinically relevant bleeding, recurrent venous thromboembolism, and major adverse ischemic cardiovascular and cerebrovascular events).