Do risk factors for atherosclerosis affect the degeneration of the Hancock II porcine bioprosthesis after aortic valve replacement?

Aims: In a previous study we could demonstrate that cholesterol levels, smoking, diabetes mellitus and gender are risk factors for the degeneration of the Hancock extracorporeal pericardial valve implanted from 1984–85 at our institution. In this study we now investigated the influence of these risk factors on the degeneration of the Hancock II porcine bioprosthesis (Medtronic Inc.) implanted in the aortic position.

Methods: From 1979–90 a total of 240 patients underwent AVR with a Hancock II valve at our institution (75% male, mean age 65.4±10.1 years, range 33–85 years). Of these patients 37 had reoperations as a result of tissue failure 9.5±4.8 years postoperatively (range 0.1–18.8 years).

Results: Risk factors for valve degeneration were triglyceride levels >123mg/dl (p=0.021) and male sex (p=0.011) while cholesterol levels, smoking and diabetes mellitus did not show a significant influence. Patients with high triglyceride levels had to be reoperated after a mean of 6.7 years compared with 10.4 years of patients with low levels.

Conclusions: Although risk factors of atherosclerosis may still play a role in porcine bioprosthesis degeneration this correlation turned out to be much weaker if compared to the Hancock extracorporeal pericardial valve. Recently developed preservation techniques may have helped to make the Hancock II aortic valve more resistant against the impact of smoking, elevated cholesterol levels and diabetes mellitus.