PROACT clinical trial results published for On-X mechanical mitral valve


Artivion has announced the publication of PROACT clinical trial results in The Annals of Thoracic Surgery.

The publication, titled Low-dose versus standard warfarin after mechanical mitral valve replacement: A randomised controlled trial, highlighted outcomes from the multicentre, non-inferiority, two-arm study which assessed whether, after an On-X mechanical mitral valve replacement, patients could be safely managed with lower-intensity warfarin plus aspirin. The results were published online and presented at the 58th annual meeting of The Society of Thoracic Surgeons (STS 2022; 29–30 January, virtual).

The On-X mechanical heart valve PROACT clinical trial was a two-armed, multicentre, non-inferiority trial to determine if patients with an On-X mechanical mitral valve replacement can be safely managed with lower-intensity warfarin plus aspirin.

After On-X mechanical mitral valve replacement followed by at least three months of standard anticoagulation, 401 patients at 44 North American centres were randomised to low-dose warfarin or standard-dose warfarin. All patients were prescribed aspirin 81mg daily and encouraged to use home international normalised ratio (INR) testing. Mean patient follow-up was 4.1 years with a maximum follow-up of eight years. No differences in bleeding, valve thrombosis, or thromboembolism rates were observed between patient groups treated with low-dose versus standard-dose warfarin.

“The PROACT Mitral results add to the data from clinical trials we have sponsored showing that patients with our On-X heart valves can be safely maintained with lower anticoagulation levels than required for competitors’ mechanical valves. We continue investing in scientific studies to improve and simplify the lives of prosthetic heart valve patients. In addition, the ongoing PROACT Xa trial aims to prove that patients with the On-X aortic valve can be safely maintained on apixaban, without the need for routine anticoagulation blood tests,” said Pat Mackin, chairman, president and CEO of Artivion.

Michael WA Chu, chair of Cardiac Surgery at London Health Sciences Centre, Western University, London, Canada, and lead author for the PROACT mitral clinical trial, said: “This randomised trial has very important and reassuring findings for patients with unrepairable mitral valve disease. Patients with an On-X mechanical mitral valve can be reassured that a lower INR target is safe, without any increased risk of blood clots or stroke, which may help to alleviate some of the concerns with anticoagulation management with a mechanical valve.

“We believe this research represents one of the most important advances in the clinical management of mechanical mitral valves over the past two decades and will potentially have important practice and guideline changing implications. We are proud to have presented it at the Society of Thoracic Surgeons’ Annual Meeting along with simultaneous publication in The Annals of Thoracic Surgery.”

Artivion is the new name for CryoLife, following a rebranding in January 2022.


  1. I am a participant in the Proactive Xa study pitting warfarin against apixaban. I wonder when preliminary results will be released.


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