Platelet survival, atherosclerotic intermittent claudication and ticlopidine

Platelet survival times were measured twice within 6 months using autologous 111-Indium-labelled platelets in 13 male patients diagnosed as stable intermittent claudicants. Linear, exponential, weighted mean and gamma function (multiple-hit) analyses were carried out on the data. Of these methods, exact mathematical models such as linear and exponential are unsuitable for the comparison of curves which may alter with treatment or disease progression. Weighted mean platelet survival correlated (r = 0.96) with platelet survival calculated by the precision reference method of analysis, gamma function. Statistics were expressed from gamma function analyses unless otherwise stated. Severity of claudication was measured by doppler; the ratio of brachial to mean ankle pressures was directly related to platelet survival (r = 0.84). In 7 patients, where duration of claudication was greater than 5 years, platelet survival was significantly reduced (P less than 0.02) compared with 6 newly diagnosed claudicants of less than 18 months duration. Six randomly selected patients were treated with 250 mg b.d. ticlopidine during one of the study periods. Ticlopidine significantly increased platelet survival (P less than 0.02) in all patients irrespective of disease duration or severity. The involvement of platelets in atherosclerosis observed in these claudicants, can be reduced by therapy with ticlopidine, however, the lack of clinical improvement following long-term drug treatment only confirms the platelet's secondary role in this disabling disease.