2023Valve disease863 patients

PROACT Xa

Therapy group: Mechanical valve anticoagulation · Therapy: Apixaban vs warfarin in On-X aortic valve

In patients with an On-X mechanical aortic valve, apixaban was less effective than warfarin at preventing valve thrombosis and thromboembolism; the trial stopped early.

Published in NEJM Evid (2023)

Question: To determine whether patients with an On-X mechanical aortic valve can be safely and effectively anticoagulated with apixaban instead of warfarin.
Design: Randomized, open-label (unmasked), active-controlled, parallel-arm phase 3 trial that enrolled 863 participants. It was stopped early because of an excess of thromboembolic events in the apixaban group; median follow-up was 13.5 months.
Population: Patients with an On-X mechanical aortic valve implanted at least 3 months before enrollment. The vast majority (94%) were taking aspirin.
Intervention: Apixaban 5 mg twice daily.
Control: Warfarin with a target INR of 2.0 to 3.0.
Primary outcome: Composite of valve thrombosis or valve-related thromboembolism, analyzed both for noninferiority versus warfarin and against an objective performance criterion (OPC).
Results: There were 26 primary end-point events: 20 (in 16 participants) with apixaban (4.2%/patient-year; 95% CI 2.3 to 6.0) and 6 (in 6 participants) with warfarin (1.3%/patient-year; 95% CI 0.3 to 2.3). The difference was 2.9 (95% CI 0.8 to 5.0), and neither the noninferiority nor the OPC success criteria were met.
Safety: Major bleeding occurred at 3.6%/patient-year with apixaban and 4.5%/patient-year with warfarin.
Conclusion: Apixaban did not demonstrate noninferiority to warfarin and was less effective at preventing valve thrombosis or thromboembolism in patients with an On-X mechanical aortic valve.
Why it matters: It confirmed that direct oral anticoagulants are not a valid alternative to vitamin K antagonists in patients with mechanical heart valves, and that warfarin remains the reference treatment in this population.

Card generated automatically with AI from the abstract of the original publication and the trial registry; every figure was checked against those sources. It may contain errors: verify the data at the source before using it for clinical decisions.

Generated on October 18, 2026

Sources

Original publication on PubMed (PMID 38320162) ↗Apixaban or Warfarin in Patients with an On-X Mechanical Aortic Valve.
Journal article (DOI) ↗
ClinicalTrials.gov record (NCT04142658) ↗

Videos explaining it

5 Minutos em Valvopatias: Proact Xa, Heyde Syndrome e TAVI in Cardiogenic Shock

Ensino InCor · Ensino InCor ↗7:42Video page

Source: Ensino InCor · YouTube
Date: 5 Jul 2024
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Videos explaining it

If you don't see subtitles in your language, turn on auto-translate from the player's settings gear (⚙).

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Android phone: Settings → Accessibility → Live Caption (on many models a captions button also appears when you press the volume key). Some models, such as Pixel or recent Samsung Galaxy phones, can also translate them.
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