Mosaic Mitral Valve: Long-Term Outcomes in Patients Under 65

Background:

Within the U.S., the prevalence of valvular heart disease is estimated at 2.5% with an abrupt increase after the age of 65 years, predominantly due to degenerative etiologies. In patients with significant valve insufficiency or stenosis where repair or reconstruction is not feasible, valve replacement is the most offered solution. The two types of heart valves offered to patients include mechanical or bioprosthetic. The major advantage of bioprosthetic heart valves in comparison to mechanical valves is the lack of post-operative anticoagulant therapy. However, the major disadvantage of bioprosthetic heart valves lie in their reduced durability compared to mechanical valves, with reoperation rates of ~10% at 10 years and up to 30% at 15 years.

The use of porcine bioprosthetic heart valves for cardiac valve replacement first appeared in the late 1960s and have been widely used since due to the avoidance of anticoagulant therapy. One of the major drawbacks associated with bioprosthetic valves is structural valve deterioration (SVD) which can lead to reduced valve durability, necessitating reoperation. The causes of SVD are poorly understood, however, it is thought to result from the accumulation of calcium and lipids on the valve surface. The Medtronic Mosaic mitral bioprosthetic valve is a 3rd-generation, stented porcine heart valve that was originally approved for clinical use in the U.S. in 2000. These valves are treated with a 0.2% glutaraldehyde solution stabilizing the tissue by cross-linking free lysine residues. In addition, the valve is treated with alpha-amino oleic acid (AOATM) which has been shown to mitigate leaflet calcification in animal studies. Long term clinical safety and efficacy of the Mosaic valve in the aortic position is well documented throughout the literature however, few studies exist detailing performance in the mitral position. Moreover, even fewer studies exist detailing overall valve survival in patients under 65 due to the more common recommendation of the use of mechanical valve replacement in this population. The purpose of this study is to examine long-term outcomes in patients who have received the Mosaic mitral valve bioprosthetic and were under the age of 65 at placement.

Significance:

The investigation of the Medtronic mosaic heart valve in the mitral position will allow for a better assessment of product performance and its impact on patient outcomes. Results can inform physicians on the longevity of the product when used in the mitral position allowing for more accurate prediction of replacement time. In addition, the results may provide further information to the safety and efficacy of placement in the mitral position in patients under the age of 65, a population in which mechanical valves are more prevalent.