Standard- and Low-Dose Rivaroxaban in Atrial Fibrillation

Study Questions:

What is the efficacy and safety of low- as compared with standard-dose rivaroxaban in Asian patients with atrial fibrillation (AF)?

Methods:

The investigators used an administrative database to evaluate the study question among Taiwanese patients who were prescribed rivaroxaban for AF. Patients with competing indications for oral anticoagulation (e.g., venous thromboembolism) and end-stage renal disease were excluded. Patients were classified as taking low-dose (10 mg per day) or standard-dose (15 or 20 mg per day) rivaroxaban. The primary safety outcome was hospitalizations for major and nonmajor bleeding. The primary efficacy outcome was thromboembolism (myocardial infarction [MI], ischemic stroke, and systemic embolism).

Results:

A total of 6,558 patients were included in the analysis: 2,373 (36%) in the low-dose group and 4,185 (64%) in the standard-dose group. Among the latter group, 887 patients (21%) were prescribed the 20 mg dose and 3,298 (79%) patients the 15 mg dose. Before adjustment, patients in the low-dose group were older and had a higher mean CHA2DS2-VASc score. There was no difference in the primary safety outcomes of major and nonmajor bleeding. There was no difference in the incidence of ischemic stroke among the two groups. However, there was a higher incidence of MI in the low-dose rivaroxaban group (2.3; 95% confidence interval, 1.1-4.5; p = 0.022).

Conclusions:

The authors concluded that in an Asian population with AF, low-dose rivaroxaban was associated with similar risks of bleeding and ischemic stroke, but a higher risk of MI.

Perspective:

Although direct oral anticoagulants are effective in preventing stroke, they are of course associated with a risk of bleeding. Physicians caring for Asian patients with AF may be concerned about a higher risk of bleeding, and may opt for a less intensive oral anticoagulation regimen (e.g., aiming for international normalized ratio of about 1.8 instead of 2 in patients taking warfarin). Such a cautious approach is manifest in the current study in that the 20 mg dose, indicated in patients with preserved renal function, was prescribed in only 14% of the study population despite the fact that chronic kidney disease was present in only 16% of patients. Such imbalance among other factors such as age reminds us that these data were gleaned from an observational and not a randomized trial. Thus, the finding of a slightly higher risk of MI (cumulative incidence of 1% vs. 0.5%) should be interpreted cautiously. It is also reasonable to conclude that the prevailing practice of choosing the dose of rivaroxaban in an Asian population with AF was associated with similar risks of bleeding and ischemic stroke among the low- and standard-dose groups.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Prevention, Pulmonary Hypertension and Venous Thromboembolism, Anticoagulation Management and Atrial Fibrillation, Anticoagulation Management and Venothromboembolism, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Anticoagulants, Arrhythmias, Cardiac, Atrial Fibrillation, Brain Ischemia, Embolism, Hemorrhage, Kidney Failure, Chronic, Myocardial Infarction, Primary Prevention, Renal Insufficiency, Chronic, Stroke, Vascular Diseases, Venous Thromboembolism, Warfarin


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