The role of platelets in the initation of arterial
thrombosis is clear. In
venous thrombosis as well, platelets may in some circumstances play a significant role. For these reasons, and because of the complications and limitations of
anticoagulant therapy, antithrombotic trials have been launched with several agents which inhibit platelet function. Regarding postoperative
deep vein thrombosis, neither
aspirin nor
dipyridamole alone appears effective, although the combination offers promise. Results with
dextrans are conflicting. In recurrent idiopathic
deep vein thrombosis,
sulfinpyrazone may be beneficial. On the arterial side, transient cerebral ischemic attacks may be favorably affected by either
aspirin or
sulfinpyrazone. Prevention of
thromboembolism associated with prosthetic heart valves appears possible with combination
warfarin-
dipyridamole therapy, and the beneficial effect of
sulfinpyrazone on shortened platelet survival in this group suggests that this agent may also be effective.
Sulfinpyrazone may also be beneficial in preventing
thrombosis in arteriovenous canulas. The issue which has attracted the greatest attention and about which no clear answer exists at present is whether
antiplatelet agents can modify the course of acute
myocardial infarction. Several trials with
aspirin are currently underway, and it would be premature to recommend its use in this condition until the results of these trials are available, probably in 1975.