JACC: Bioprosthetic aortic valves have more failure, reoperation

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Patients who have undergone an aortic valve replacement with either a bioprosthetic (BP) or mechanical valve display the same rates of adverse events, as well as similar survival rates after 13 years, but those who received a BP valve have more incidence of valve failure and reoperation, according to an eight-year study in Nov. 17 edition of the Journal of the American College of Cardiology.

Paolo Stassano, MD, from the department of cardiac surgery at the University Federico II in Naples, Italy, and colleagues conducted a randomized study consisting of 310 patients aged 55-70 years, in order to compare the long-term results of BP versus mechanical aortic valves.

The determined endpoints of the study were reoperation, valve failure and survival. Some complications associated with aortic valve replacement are similar between BP and mechanical prostheses, and others are more unique to one valve type or another, according to the authors, who wrote that this is an important factor for both patients and physicians in determining prosthesis selection prior to surgery.

From January 1995 to June 2003, the study focused on middle-aged patients who were faced with the decision of valve choice for their aortic valve replacement at two different centers. After a discussion with their surgeon, 35 percent of the patients were undecided as far as what valve would be right for their particular case. Overall, 327 patients gave their consent to take part in the study, and 17 patients were excluded at this point, to make up the 310 patients remaining in the study.

Patients were given a sealed envelope containing either a letter “M" for mechanical or a letter "B" for biological, and the envelopes where opened at least 24 hours prior to surgery. The patients were made aware of the type of valve chosen, and were given the opportunity to change their mind.

Exactly half of the study participants received a BP valve (155) and half received an mechanical valve (155). After a follow-up period of 13 years, there were no differences seen in the linearized rate of thromboembolism, bleeding, endocarditis and major adverse post-operative event between the mechanical and BP valve groups, according to the researchers. 

While there were no found differences in the survival rate of the two groups, the authors reported that reoperation and valve failure occurred more in the BP group than in the mechanical group (p = 0.0001 and p = 0.0003, respectively).

Perioperatively, the mechanical group had four deaths, compared to the BP group with six deaths. After a two-year follow-up period, there were 41 deaths in the mechanical group and 45 deaths in the BP group, according to the Stassano and colleagues. They said that further studies will offer a more thorough assessment of valve performance and the quality of life each will present over a greater period of time.