New oral anticoagulants for the treatment of acute venous thromboembolism: are they safer than vitamin K antagonists? A meta-analysis of the interventional trials.

New oral anticoagulants (NOACs) may represent an alternative to standard therapy with vitamin K antagonists (VKA). However, up to the present, it is unknown whether these drugs are safer than VKA. The aim of this study was to perform a meta-analysis of the interventional trials with NOACs vs VKA in patients with acute venous thromboembolism (VTE) to obtain the balance between clinical efficacy and complications. A meta-analysis of double blind randomized controlled trials (RCTs) was performed. We included RCTs that compared, in acute VTE, the beneficial and harmful effects of NOACs (ximelagatran, apixaban, dabigatran, edoxaban and rivaroxaban) vs VKA (warfarin). Seven studies including 29,482 patients were selected. Compared with warfarin, recurrent VTE and death from any cause were not significantly reduced by NOACs. Myocardial infarction was significantly increased with NOACs compared with warfarin (RR 2.55; 95% CI 1.1-5.6; p = 0.02). NOACs significantly reduced the major bleedings (RR 0.63; 95% CI 0.47-0.83; p = 0.001). This meta-analysis suggests that treatment with NOACs in patients with acute VTE is not inferior to conventional therapy with warfarin for recurrent VTE and death from any cause, but there might be an increased incidence of myocardial infarction.