NEW YORK (Reuters Health) – No matter whether they receive biological or mechanical prosthetic aortic valves, patients have generally similar survival and complication rates — until 10 years later, when rates of valve failure and reoperation increase with biological valves, Italian researchers say.

“Aortic valve choice in the ages between 55 and 70 years is very difficult, because…patients are no longer truly young and not yet truly old,” Dr. Paolo Stassano, at University Federico II School of Medicine, Naples, and associates point out. “This is the ‘threshold age’ where it is difficult to balance the risk of the anticoagulation therapy with the need for re-operation.”

Patients who receive biological valves take warfarin for 8 to 12 weeks, the authors note, whereas mechanical valves require ongoing anticoagulation.

Between 1995 and 2003, Dr. Stassano and his colleagues randomized 310 patients (155 in each group; ages 55 to 70) undergoing a single aortic valve replacement, with or without coronary artery bypass graft surgery, to receive either mechanical or biological valves. Each participant had not been able to decide between the two options, even after detailed discussions of the pros and cons, and had left the choice up to the surgeon.

In the Journal of the American college of Cardiology for November 10, the researchers report that at a mean follow-up of 106 months (range, 43 to 161), there was no difference between the two groups in survival or in rates of thromboembolism, bleeding, endocarditis, valve thrombosis, or major adverse valve-related events. Overall mortality rates at the late analysis were 27.5% and 30.6% with mechanical and biological prostheses, respectively.

Starting at 10 years, however, structural valve deterioration and reoperations became significantly more frequent in patients with biological valves. Specifically, there were no valve failures in the mechanical group, but the linearized rate of failure was 2.17%/patient-year in the biological group (p = 0.0001). The linearized reoperation rates per patient-year were 0.62% and 2.32% in the mechanical and biological groups, respectively (p = 0.0003).

Calling this study “an invaluable update” to older trials, Dr. Peter H. Stone from Brigham and Women’s Hospital, Boston writes in an editorial that “the very long-term outcomes will be very important to follow in the Stassano trial to further guide valve selection, because most of the middle-aged patients enrolled can be expected to survive well beyond 10 years post-operatively.”

He adds, “There are no major differences in terms of mortality between the two valve types, but patients receiving a bioprosthetic valve can be assured of developing structural valve deterioration after approximately 10 years and will require reoperation, whereas those patients taking warfarin…will likely develop more bleeding.”

Reference:
J Am Coll Cardiol 2009;54:1862-1868,1869-1871.