Dr. Joanna Chikwe and colleagues at Mount Sinai recently compared outcomes in several thousand patients who underwent biological or mechanical mitral valve replacement in New York State (JAMA 2015:323:1435-42). They found no survival difference in the first 30 or 90 days after surgery, or even at 15 years among patients aged 50-69 years. Indeed, a critical review of any study that has shown a survival advantage of the mechanical valve would find that the advantage occurred within the first few months after surgery, making it likely that such differences are due to patient selection, or other systematic bias, rather than a prostheses effect.
Mayo Clinic investigators, including Dr. Thoralf M. Sundt III, reported that among a cohort that received a mechanical valve, with an average age of 65 years, 16% had had a stroke at 5 years, compared with 8% of the biological valve group (J. Am. Coll. Cardiol. 2008;51:1203-11). You can only imagine what would happen at 10 or 20 years. They followed the data out to 10 years for thromboembolic events; that rate was 30% in the mechanical valve group. They concluded, “the mechanical valve is the least desirable correction of mitral regurgitation.”
As for managing anticoagulation, the literature provides no evidence that self-testing is superior to clinic testing. A trial published in the New England Journal of Medicine involving more than 2,000 patients, 700 of whom had a mechanical valve, showed a higher rate of stroke in patients who were randomized to home-INR monitoring compared with INR in the clinic. (N. Engl. J. Med. 2010;363:1608-20). Self-testing did not delay the time to first stroke, bleeding, or death.
Anticoagulation can be problematic if the patient needs to undergo another operation or medical procedure later, especially on an emergent basis. If the patient with a mechanical valve stops anticoagulation for even a short period of time, the risk of valve thrombosis is great. A patient with a biological valve can stop anticoagulation for a week or more without any consequence.
Finally, I relate the story of a man who could not bear the clicking sound of his mechanical valve. He asked for a new valve, but the surgeon would not take his request seriously. The man was taking drugs and started treatment for posttraumatic stress disorder. After 3 years, he killed himself. How many times have we sat down and talked to patients about what the clicking sound can do to them? Why don’t we make more of this? The patient should be given more choice.
Dr. Anyanwu is with the department of cardiac surgery, Mount Sinai Medical Center, New York. He has no relationships to disclose.