Rationale and design of PROACT Xa: A randomized, multicenter, open-label, clinical trial to evaluate the efficacy and safety of apixaban versus warfarin in patients with a mechanical On-X Aortic Heart Valve
Bibliographic record
Abstract
Vitamin K antagonists are the only approved oral anticoagulants for long-term prophylaxis against valve thrombosis and thromboembolism in patients with a mechanical heart valve. Despite the proven efficacy and safety of anticoagulation with the oral direct factor Xa inhibitor apixaban compared with warfarin in high-risk populations including subjects with atrial fibrillation or with venous thromboembolism, it remains unknown whether patients with a mechanical heart valve can be safely managed with apixaban. The On-X Aortic Heart Valve and On-X Ascending Aortic Prosthesis with the Vascutek Gelweave Valsalva Graft may have lower rates of valve thrombosis and thromboembolism than conventional bileaflet and tilting disc valves due its unique pyrolytic carbon composition and flared inlet design. DESIGN: PROACT Xa is a randomized, multicenter, open-label, active-controlled trial comparing apixaban with warfarin in patients with an On-X Aortic Heart Valve or On-X Ascending Aortic Prosthesis with the Vascutek Gelweave Valsalva Graft. The study will randomize approximately 1,000 patients from approximately 60 sites in North America who underwent aortic valve replacement at least 3 months prior. Patients will be randomized 1:1 to receiving apixaban 5 mg twice daily or warfarin with a target international normalized ratio of 2.0-3.0. The last randomized participant will be followed for at least 2 years. The primary efficacy outcome is the composite of valve thrombosis and valve-related thromboembolism, and the primary safety outcome is major bleeding. Assuming the primary outcome occurs in warfarin-anticoagulated patients at a rate of 1.75%/patient-year, the study has more than 90% power to assess noninferiority of apixaban treatment with an absolute noninferiority margin of 1.75%/patient-year. A second co-primary analysis is to compare the hazard rate for the apixaban arm to twice the objective performance criterion for thromboembolism and valve thrombosis, that is, 3.4%/patient-year. SUMMARY: PROACT Xa will determine whether patients with an On-X Aortic Heart Valve can be anticoagulated with apixaban as an alternative to warfarin.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".