http://ats.ctsnetjournals.org/cgi/content/full/73/2/696-a

Cardiac valve replacement in patients on dialysis
Ryuji Higashita, MDa, Yasuo Takeuchi, MDa, Mamiko Ohara, MDb
a Department of Cardiovascular Surgery, Tokyo Women’s Medical University Daini Hospital, 2-1-10 Nishi-Ogu, Arakawa-ku, 116-8567 Tokyo, Japan
b Division of Renal Disease, Tokyo Metropolitan Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, 113-8677 Tokyo, Japan

e-mail: ryujihca@dnh.twmu.ac.jp

To the Editor

We read with great interest the article by Kaplon and colleagues [1] about cardiac valve replacement in patients on dialysis. We agree that the decision to replace the heart valve is based on the patient’s projected long-term survival. However, we would like to raise an important point concerning the author’s conclusion. We do not agree that all patients on dialysis have a limited life expectancy. Patients with end-stage renal disease (ESRD) in Japan, as well as in Europe, survive longer than patients in the United States. Although there are differences in patient populations and treatment regimens among countries, one study found that, after adjustment for age and the presence of diabetes, relative mortality risk for ESRD patients in the United States was 15% higher than that in Europe and 33% higher than that in Japan [2]. Another study, adjusted for comorbid conditions, found that the adjusted relative mortality risk for U.S. hemodialysis patients was 29% higher than for patients in Italy [3]. According to the 1999 annual survey of the Japanese Society for Dialysis Therapy (an overview of regular dialysis treatment in Japan), the annual mortality of patients who began dialysis therapy after 1983 in Japan was 9.7% as compared to 25% in the United States [1]. Survival rates of Japanese patients were 60.3% at 5 years, 42.3% at 10 years, and 31.6% at 15 years. In addition, when we consider expected long-term survival of dialysis patients, the etiology of renal failure should be taken into account. Based on the annual survey of the Japanese Society for Dialysis Therapy, long-term survival of the ESRD patients with diabetes mellitus is markedly worse than that of the ESRD patients whose renal dysfunction results from glomerulonephritis (24.9% versus 53.3% at 10 years).

The durability of biological prosthesis implanted in dialysis patients has not been clarified. In general, bioprosthetic heart valves function satisfactorily for 10 years in aged patients. Recently, actuarial freedom from structural valve deterioration (SVD) 17 years after aortic valve replacement (AVR) and 14 years after mitral valve replacement (MVR) with Carpentier-Edwards pericardial valve (Clinical Communique, Edwards Lifesciences, 2000) was reported to be 69% and 79%, respectively. Actuarial freedom from SVD 12 years after MVR with the Hancock II porcine valve (Clinical Compendium, Medtronic, 1999) was 82%. These results suggest that the bioprosthetic valves are more durable than before. Nevertheless, bioprostheses often fail relatively early in young patients. Furthermore, it has been reported that premature aortic valve calcification and mitral annular calcification occur frequently in dialysis patients and appear to be related to abnormal calcium and phosphate metabolism, and to increased mechanical stress on the valve cusps [4]. Therefore, there is a general concern that biologic valves will undergo accelerated degeneration in patients with ESRD owing to calcification, as suggested by Lamberti and associates [5]. We recently experienced a case, with a 14-year history of hemodialysis therapy, that required AVR for aortic stenosis; we chose the mechanical valve for this patient.

Thus, the choice of the type of valve should be individualized based on the expected long-term survival of the patient. It is reasonable that older patients with diabetic end-stage renal disease (relative short life expectancy) might be considered candidates for biologic valves.

References

Kaplon R.J., Cosgrove D.M., III, Gillinov A.M., Lytle B.W., Blackstone E.H., Smedira N.G. Cardiac valve replacement in patients on dialysis: influence of prosthesis on survival. Ann Thorac Surg 2000;70:438-441.
Held P.J., Brunner F., Odaka M., Garcia J.R., Port F.K., Gaylin D.S. Five-year survival for end-stage renal disease patients in the United States, Europe, and Japan. Am J Kidney Dis 1990;15:451-457.
Marcelli D., Stannard D., Conte F., Held P.J., Locatelli F., Port F.K. ESRD patient mortality with adjustment for comorbid conditions in Lombardy (Italy) versus the United States. Kidney Int 1996;50:1013-1018.
Maher E.R., Young G., Pugh S., Curtis J.R. Aortic and mitral valve calcification in patients with end-stage renal disease. Lancet 1987;2:875-877.
Lamberti J.J., Wainer B.H., Fisher K.A., Karunaratne H.B., Al-Sadir J. Calcific stenosis of porcine heterograft. Ann Thorac Surg 1979;28:28-32.