Do Mechanical Aortic Valves Eclipse Biologic Valves? By Kevin Self Reviewed by Elizabeth Klodas, MD, FACC  and   A new study suggests that mechanical valves may offer a slight advantage over biological valves in patients 55 to 70 years of age, but the difference is small and patients should discuss the decision with their physician.

Which aortic valve replacement (AVR) choice reigns supreme — the mechanical (artificial) vs. the biological (living tissue) valve — has been debated in the medical community for decades. Although there is no definitive answer, there is a general consensus that the mechanical one is generally preferred for younger patients, while the biological one is preferred in older patients. But what about the patients in the middle?

Patients age 55 to 70 years old fall into that middle ground where they are no longer considered young and not yet considered old. And they have some tough decisions to make.  Mechanical valves are long lasting, but require life-long anticoagulation with medications such as warfarin.  Warfarin therapy requires regular blood tests and increases the risk of bleeding.  Biological valves don’t require long term warfarin treatment, but are not long lasting, potentially fating middle aged individuals to repeat valve replacement in later years. Unfortunately, for middle aged individuals, there’s little guidance in the medical literature regarding which approach is best for them.

A recent study, however, focused specifically on this group and examined what, if any, benefits there were for AVR patients who chose mechanical or biological valves.  Investigators from Italy examined the outcomes of 310 middle aged patients who underwent AVR between 1995 and 2003.  Half got tissue valves and half received mechanical replacements.  Overall, outcomes were quite similar between the two valve types, especially in the first 10 years after surgery.

“Above all else, the results of the study confirm the importance of having a thorough conversation with your cardiac surgeon explaining — in detail — your life-style choices and expectations for the future,” says Dr. Paulo Stassano, lead author of the study. Ultimately, there are so many variables that come into play when making this decision, that there is not one correct and universal answer.

Mechanical Has the Edge?

Dr. Stassano’s article suggests that across a number of categories — such as major adverse events, bleeding and thrombosis (blood clots in blood vessels) — there is no significant difference between mechanical and biological valves.

The only exception would be in the case of valve failures/reoperations, where the rate of primary valve failure and reoperation was significantly greater in patients with biological valves.

“In the end, if the patient can sustain a well managed blood-thinning regimen, the data suggests they choose a mechanical aortic valve,” says Stassano. “However, they should remember that the ‘ideal’ heart valve substitute has not yet been found and they should weigh all options before making a decision.”

Rely on the Patient/Physician Conversation

In an accompanying editorial to Stassano’s article, Dr. Peter H. Stone from Brigham & Women’s Hospital, Harvard Medical School and author of an editorial suggests that there is still no clear winner as far as which valve truly reigns supreme. The new research updates  the data comparing these two prosthetic valve types and presents outcomes based upon current surgical techniques and available valves.  “Patients and physicians can now have a discussion about valve selection using current information,” concludes Dr. Stone.

The study results are published in the November 10, 2009 issue of the Journal of the American College of Cardiology.

Sources: 

Stassano P et al. Aortic Valve Replacement: A Prospective Randomized Evaluation of Mechanical Versus Biologic Valves in Patients Ages 55 to 70 Years. Journal of the American College of Cardiology, 2009.

Stone, PH. Current Selection of Optimal Prosthetic Aortic Valve Replacement in Middle Aged Patients: Still Dealer’s Choice. Journal of the American College of Cardiology, 2009.

Paulo Stassano, MD, associate professor of cardiac surgery, University Federico II, Naples, Italy..

Peter H. Stone, MD, Brigham & Women’s Hospital, Harvard Medical School, Cardiovascular Division, Boston, MA.