Mechanical Heart Valves Better Than Biological Ones

A new study suggests that mechanical valve prostheses last longer and have a better survival record than biological valve prostheses.

Researchers at Karolinska Institutet (Solna, Sweden) and Karolinska University Hospital (Stockholm, Sweden) conducted a study among 4,545 patients (50–69 years of age) who underwent aortic valve replacement (AVR) with bioprosthetic or mechanical valves in Sweden between 1997 and 2013; in all, 60% of the patients received mechanical valves and 40% received bioprostheses. The patients were distributed to 1,099 propensity score-matched patient pairs to investigate long-term all-cause mortality outcomes.

The results showed that 16% of the mechanical valve group and 20% of the bioprosthetic group died during a mean follow-up period of 6.6 years. Long-term survival was higher in the mechanical than in the bioprosthetic group when evaluated at five, 10, and 15 years, with an overall hazard ration of 1.34. There was no difference in stroke outcomes, but patients who received bioprostheses had a higher risk of aortic valve reoperation and a lower risk of major bleeding. The study was published on November 12, 2015, in European Heart Journal.

“Biological valve prostheses have been used more and more in young patients in recent years, partly because these patients don't have to take blood thinners,” said lead author Natalie Glaser, MD, a PhD student at the Karolinska Institutet department of molecular medicine and surgery, and a physician at the Karolinska University Hospital department of cardiothoracic surgery. “Our research shows that mechanical valve prostheses should be the preferred option for young patients.”

“We show that patients who had received a mechanical prosthesis had better survival rates than those who had received a biological prosthesis,” added senior author cardiac surgeon Ulrik Sartipy, MD, of the Karolinska University Hospital department of cardiothoracic surgery. “Our results are important since the trend in Sweden and abroad in recent years has been towards a greater use of biological valve prostheses in relatively young patients, which has no backing in clinical therapy guidelines.”

While mechanical valves are the longest lasting type of replacement valve, patients will usually require blood thinners to stop clots from forming, as they can lodge in valve flaps or hinges which can cause malfunction or form emboli. Bioprosthetic tissue valves can last 10–20 years, but usually do not require long-term use of medication. On the other hand, in a young person a bioprosthetic valve will usually need replacement later in life.

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Karolinska University Hospital