The Mitroflow A12 and LX valves are bioprosthetic valves made by the Sorin Group. The Mitroflow valve is made of cow pericardium, the tissue sac, which surrounds the heart, placed over a polymer stent.
Bloomberg News reports the Mitroflow valves are used to replace diseased or damage heart valves and that they were approved for use in the United States in 2007. Cardiovascular Business reports studies have shown the Mitroflow valves deteriorate quicker and at a higher rate than expected.
Cardiac surgeons at Boston Children’s Hospital have warned against using the Mitroflow valve to replace aortic valves in children and young adults because it has been associated with rapid and symptomless deterioration. One death could be associated with this complication, according to Forbes.
In a letter to the America College of Cardiology, the cardiac surgeons warn that this fast, symptomless deterioration has only been found with Mitroflow valves and that they were alerted to the problem after a patient with a Mitroflow valve died and the valve was found to have an unusual calcified obstruction. The valve had appeared normal on echocardiogram just seven months earlier.
An editorial in the American Heart Association journal Circulation reports that use of the Mitroflow valves in younger people has increased in the last decade. Cardiovascular Business reports that the Boston surgeons found that 47% of Mitroflow valves showed signs of failure after a year and that 82% showed signs of failure after two years. Forbes reports that children and young adults with Mitroflow aortic valves should be monitored every four to six months and not annually, as is usual.
The authors of a French study, published in Circulation, report that frequent, accelerated Mitroflow valve deterioration was found in their study and that an “epidemic” of Mitroflow valve related deaths and revision surgeries can be expected.
Cardiovascular Business reported the study authors found that roughly two-thirds of the cases occurred in the smaller Mitroflow valves, 19mm and 21mm, and that six patients in the study died of valve-related causes.
A 2009 study published in the journal Interactive Cardiovascular and Thoracic Surgery found that the Mitroflow valve was associated with early calcification and does not perform as well in elderly patients. Another study published in 2011 in the Annuals of Thoracic Surgery found that 100% of Mitroflow valves had structural valve deterioration after two years of being implanted and that this is likely due to a design issue.
Cardiovascular Business reports that Mitroflow A12 and LX valves don’t have an antimineralization coating, which could help in reducing the calcification and accelerated deterioration seen in studies.