Platelet Hypersensitivity in Acute Myocardial Infarction (M.I.) Patients (PTS)

A national multicentre controlled trial (ARIS) to determine the effect of sulfinpyrazone (S) (400 mg twice a day) on m.i. recurrence and cardiac death prevention is now in its 3rd year. Admission of new pts terminates on June 30, 1979. Various platelet (pi) and coagulatory parameters are measured in a randomised series of 175 pts at trial entry (10-20 days after m.i. episode) and at various times during treatment with S or placebo. This has provided the opportunity of comparing (factorial ANOVA analysis for unbalanced groups) basal results in m.i. pts and in 45 normal matching controls: no difference in pl count, pl retention and PTT; m.i. pts had significantly shorter bleeding time (146. 99±80,47 vs 264.11±112.98 sec), heparin thrombin clotting time (HTCT) (29. 97 + 16,47 vs 36,31±11.31), and significant increase of fibrinogenemia (339.85±179.94 vs 237. 85 + 35.77 mg%) and PF₄ release (37.30±15.13 is 28.00 ± 12.3.4 U/ml). ADP (0.2, 0.4 and 0.8 μM) produced pi aggregation curves in m. i. pts showing significantly increased 1 st wave slope with 0.2 μM and maximal extent at 0. 2 and 0.4 μM: significantly higher frequency of 2nd wave at 0.4 and 0.8 μM, Collagen (1.25, 2.5 and 5 μg) produced pl aggregation curves with significantly reduced lag period at 2.5 μg, steeper slope and higher maximal aggregation at 1.25 and 5 μg. The only important correlation (inverse) was between HTCT and PF₄ release in the m.i. group.