Clinical study in anti thrombo embolic therapy and effect of dipyridamole on platelet function in patients with heart valve prostheses

Tokumo, M.

Okayama Igakkai Zasshi 89(9-10): 1119-1136


ISSN/ISBN: 0030-1558
Accession: 004972787

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Over a 10 yr period, 83 patients had prosthetic valve replacements (44 aortic, 31 mitral, 5 tricuspid and 3 combined). The frequency of thromboembolism was studied using warfarin potassium with dipyridamole (225 mg/day), warfarin, dipyridamole, and in those receiving neither drug. After an average follow-up of 53 mo. there was no significant incidence of thromboembolic complications in the aortic group. The mitral warfarin with dipyridamole group revealed significantly reduced incidence of thromboembolic deaths in comparison with the patients not receiving anticoagulants followed-up for an average of 62 mo. There were no other significant correlations with or without use of anticoagulants. The effect of dipyridamole on platelet function was studied in 23 patients with prosthetic valves, who had received warfarin anticoagulant therapy. Platelet adhesiveness was estimated and platelet aggregation was measured by the turbidometric method. Patients (9) of the aortic group revealed no significant change in platelet adhesiveness or aggregation. Platelet adhesiveness remained unchanged by dipyridamole administrations (450 mg/day). Aggregation in patients receiving dipyridamole (333-450 mg/day) was statistically reduced in comparison with normal control percent aggregation. There were no significant differences with the 150-450 mg/day group. Platelet adhesiveness in 14 patients of the mitral group receiving dipyridamole (150 mg/day) was increased statistically. Platelet adhesiveness was reduced to a mean normal retention by 225 mg/day dipyridamole. Further ingestion of dipyridamole 450 mg/day made no difference. Platelets treated with dipyridamole (150-225 mg/day) showed significantly shortened RT (reaction time to the maximum aggregation) and b/2T (reaction half-time to the maximum aggregation). After administration of 375 mg/day dipyridamole, the platelet aggregation curve showed the prolongation of RT and b/2T to a normal mean of aggregation. Further administration (450 mg/day) revealed significantly reduced percent aggregation in comparison with the normal control. Dipyridamole (300 mg/day), which influenced platelet behavior, is advisible for aortic patients. Warfarin anticoagulants are necessary with the combined use of dipyridamole (450 mg/day) for mitral patients.