[Evaluation of antiplatelet drugs on platelet functions--comparison between ticlopidine and dipyridamole after prosthetic valve replacement].

We examined the efficacy of antiplatelet drugs after prosthetic valve replacement. As an early postoperative group (group E), 49 patients were divided into four groups. In group A only warfarin was given. In group B warfarin and dipyridamole 300 mg/day, in group C warfarin and ticlopidine 300 mg/day, in group D warfarin and ticlopidine 600 mg/day were administered respectively. As a late postoperative group (group L), 45 patients with prosthetic valves were divided into two groups. In group I dipyridamole 300 mg/day in group II ticlopidine 300 mg/day were administered. Both group I and II received warfarin. In group E platelet counts and platelet aggregability were examined to 22 POD. In group L starting two years after valve replacement, platelet counts were examined eight times by three-month intervals, and platelet aggregability, platelet adhesiveness were investigated 36 months in group I and 27 months in group II postoperatively. Results are the following. 1) Neither ticlopidine nor dipyridamole had any effects on the platelet counts through the postoperative period. 2) In the early postoperative period, the administration of antiplatelet drugs to groups B, C, and D suppressed platelet aggregability more than group A. 3) Ticlopidine (groups C and II) reduced ADP and collagen aggregabilities compared with dipyridamole (group B and I) both in the early and late postoperative period. 4) Ticlopidine 300 mg/day (group C) and ticlopidine 600 mg/day (group D) had no difference in ADP and Collagen aggregabilities. 5) No significant difference was shown between dipyridamole (group I) and ticlopidine (group II) in platelet adhesiveness.(ABSTRACT TRUNCATED AT 250 WORDS)