Chicago, IL—A study presented at the 2012 American College of Cardiology meeting potentially opens the door to all-oral therapy for the treatment of pulmonary embolism (PE), which would permit most of the treatment to take place outside of the hospital.
The current standard regimen for treating PE involves injections of enoxaparin (Lovenox) for 5 to 10 days followed by oral warfarin (Coumadin), a vitamin K antagonist, for 3 to 12 months.
In the EINSTEIN-PE study, a novel oral rivaroxaban (Xarelto) regimen proved noninferior to standard therapy in preventing recurrence of venous thromboembolism (VTE) in patients with primary PE, while causing less major bleeding, said lead investigator Harry R. Büller, MD, Professor of Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands.
“This study was undertaken so there is increased awareness that VTE or PE could be treated outside the hospital,” Dr Büller said. “Maybe the patient needs to be in the hospital for 1 day to be observed, but it is not necessary to have patients in the hospital for 5 to 10 days, as has been the practice. Therefore, we wanted to make this regimen very simple.”
In the United States, the average hospital stay for patients with symptomatic PE is 6 or 7 days, according to Dr Büller.
EINSTEIN-PE tested a regimen of oral rivaroxaban, 15 mg twice daily for 21 days followed by 20 mg once daily, versus standard therapy of enoxaparin twice daily for at least 5 days plus a vitamin K antagonist (warfarin or acenocoumarol [Sintrom, Sinthrome]) titrated to achieve an international normalized ratio (INR) of 2.0 to 3.0 in 4833 patients with objectively confirmed PE with or without deep vein thrombosis (DVT). Enoxaparin was discontinued when the INR was >2.0 for 2 consecutive days, and the patient had received enoxaparin for at least 5 days.
A previous study with rivaroxaban for patients with DVT (EINSTEINDVT) used rivaroxaban at 20 mg daily, which proved noninferior to standard medical therapy in reducing the risk of symptomatic recurrent VTE.
The new, more intense regimen in EINSTEIN-PE was developed from dose-ranging studies that found superior clot dissolution, said Dr Büller.
All patients were treated for 3, 6, or 12 months as determined by the clinician before entering the study.
The primary end point was first recurrence of symptomatic VTE, which was 2.1% in the rivaroxaban group and 1.8% in the enoxaparin/vitamin K antagonist group, which met the criterion for noninferiority of efficacy.
The principal safety outcome of major or nonmajor clinically relevant bleeding was similar in the 2 arms—10.3% with rivaroxaban and 11.4% with enoxaparin/vitamin K antagonist.
The frequency of major bleeding events, however, was reduced by 50% in the rivaroxaban group compared with the enoxaparin/vitamin K antagonist group.
Older patients (aged >75 years) had the greatest reduction in risk of bleeding with rivaroxaban: 23 major bleeding events with the enoxaparin vitamin K antagonist regimen versus 5 patients with rivaroxaban, Dr Büller said.
The intensified regimen of rivaroxaban during the first 3 weeks did not result in an increased rate of hemorrhage.