Rivaroxaban 2.5 mg. No justification for using this anticoagulant after an acute coronary syndrome

Aspirin is the antithrombotic drug of choice for preventing recurrences after a first acute coronary syndrome. The addition of clopidogrel, another antiplatelet agent, is helpful in case of angioplasty with stenting. Following the acute phase, warfarin, an anticoagulant, alone or in combination with aspirin, may be used only in specific situations, particularly for patients with a high thrombotic risk (due to atrial fibrillation for example). Rivaroxaban, an oral factor Xa inhibitor anticoagulant, has been authorised for use following an acute coronary syndrome, but at a new dose strength of 2.5 mg, in combination with aspirin alone or aspirin plus clopidogrel. Rivaroxaban has not been compared with warfarin in patients with a high thrombotic risk following an acute coronary syndrome. In a double-blind, randomised, placebo-controlled trial in 15 526 patients, who were not at particularly high risk of thrombosis, the addition of the rivaroxaban to aspirin or to aspirin plus clopidogrel appeared to reduce mortality during the first year of treatment (2.6% versus 3.8% with placebo). However, there is a large amount of missing data, exceeding the inter-group difference in the number of deaths, seriously undermining the results. In the subgroup of about 1000 patients in whom antiplatelet therapy consisted of aspirin alone, addition of rivaroxaban did not lead to a statistically significant decrease in the incidence of cardiovascular events or death. The addition of rivaroxaban increased the incidence of "clinically relevant" bleeding episodes, as defined in the study protocol (11.2% of patients per year in the rivaroxaban group versus 6.4% in the placebo group), as well as the incidence of major bleeding events (respectively 1.2% and 0.3% of patients per year) and intracranial haemorrhage (14 versus 5 cases). The patients selected for this trial were considered to have a low risk of bleeding, so the risk is likely to be higher in many patients who have had an acute coronary syndrome. In practice, it has not yet been demonstrated that adding rivaroxaban to aspirin or to aspirin plus clopidogrel is beneficial following an acute coronary syndrome. In addition, the bleeding risk is likely to be higher in routine practice than in the conditions under which the comparative trial was conducted. It is therefore best not to use rivaroxaban in this setting but to stick with best-known antithrombotic drugs.