Patients with On-X aortic heart valves may be able to reduce their regular blood-thinning medication regimen, thanks to an expanded labelling claim granted by the US Food and Drug Administration (FDA) to On-X Life Technologies.
Approximately 200,000 patients have received the company’s On-X replacement heart valves, which are bileaflet prosthetic valves made of pure pyrolytic carbon. While all mechanical heart valve patients must continuously take anticoagulant medications such as warfarin, the FDA’s new labelling expansion makes the On-X the only valve in the world that allows patients to be managed, starting three months after their surgery, at an international normalised ratio level of 1.5 to 2—closer to an unmedicated international normalised ratio, says the company. A blood test measures the length of time required for a patient’s blood to clot.
“On-X valves have a long history of excellent clinical performance and are especially appealing to patients who seek a single, life-long solution to their aortic heart valve problems,” said John Puskas, chair of Cardiothoracic Surgery at Mount Sinai Beth Israel Hospital in New York City, USA. “While anticoagulation therapy remains a necessity for mechanical valve recipients, the FDA’s new approval of a significantly lower international normalised ratio for On-X valves should really change the clinical landscape for many patients.”
Data published in 2014 in the Journal of Thoracic and Cardiovascular Surgery on On-X’s PROACT (prospective randomised On-X anticoagulation clinical trial) study affirmed that high-risk trial patients with On-X valves who reduced their regular blood-thinning medication dosage to maintain a lower of international normalised ratio 1.5 to 2 and took a low-dose aspirin experienced a 65% overall reduction in bleeding events with no increase in stroke rate.
Official clinical guidelines published jointly by the American Heart Association (AHA) and the American College of Cardiology (ACC) suggest that mechanical heart valves are the standard of care for patients younger than 60 years of age who require an aortic valve replacement. The guidelines, which focused on furnishing recommendations for optimal medical therapy for the first time, also indicated that mechanical valves were considered “reasonable” for patients from 60–70 years of age.
“The AHA-ACC guidelines affirm that mechanical valves are preferred for many younger patients with valvular heart disease,” says Blase Carabello, chair of the Cardiology Department at Mount Sinai Beth Israel Hospital in New York, USA. “While the AHA-ACC guidelines generally recommend an international normalised ratio target in the range of 2–3, patients who receive On-X valves with reduced anticoagulation medication levels should experience the added benefits of an enhanced quality of life along with diminished overall risk of medication-related bleeding complications.”
According to Clyde Baker, chief executive officer for On-X Life Technologies, some people choose animal tissue replacement valves in an attempt to avoid potential side effects associated with the blood-thinning medication warfarin, which is often marketed under the brand name Coumadin. He notes, however, that tissue valves are known to have a limited lifespan, with most structurally failing in less than 15 years in patients under 60 years of age. Tissue valve failure requires patients to undergo the risk, pain and expense of subsequent reoperation for new replacements. Additionally, many tissue valve patients also require warfarin in order to manage other conditions.
“On-X valves have been shown to cause less turbulence or blood damage than commonly seen in other mechanical heart valves,” says Jack Bokros, founder of On-X LTI, noting that a comprehensive 50-year retrospective study of mechanical heart valves presented in 2014 indicated that On-X’s valves had the lowest documented rate of valve thrombosis when compared to eight other competitive mechanical heart valves.
“Our On-X Aortic Heart Valve is the next evolution in implantable heart valves, representing a durable therapeutic solution that also improves patient safety by lowering the risk of bleeding events,” Baker concluded.