OBJECTIVE We evaluate the clinical efficacy of sarpogrelate, an antiplatelet drug that improves red blood cell deformability, to reduce the intravascular hemolysis problems suffered frequently by patients implanted with heart valve prostheses. METHODS Subjects were 34 patients undergoing mechanical heart valve replacement and having serum lactate dehydrogenase concentrations 20% above the maximum normal range. METHODS Sarpogrelate was given daily, 100 mg orally for the first 6 months and 200 mg thereafter. RESULTS Average serum lactate dehydrogenase decreased significantly from 423 +/- 108 IU/l, to 391 +/- 83 IU/l with the 100 mg dose, and to 361 +/- 86 IU/l with the 200 mg dose. The percentage of reticulocytes decreased from 15.5 +/- 5.3/1000 to 15.3 +/- 5.7/1000 at the 100 mg dose and 13.1 +/- 4.0/1000 at the 200 mg dose. Serum iron concentrations increased significantly from 63.2 +/- 24.8 micrograms/dl to 76.2 +/- 16.2 micrograms/dl at the 100 mg dose, and to 70.9 +/- 26.2 micrograms/dl with the 200 mg dose. CONCLUSIONS Sarpogrelate is a useful drug for patients with implanted heart valve prostheses and subsequent high serum lactate dehydrogenase because it works as an antiplatelet drug and reduces mechanical hemolysis.