[Platelet functions in patients with acute myocardial infarction]

The changes of platelet functions including platelet membrane microviscosity (PMMV), plasma 5-HT, plasma TXB2 and 6-K-PGF1a were studied in 30 cases of AMI and 13 cases of unstable angina (UA), 20 normal subjects as control. After onset of AMI, PMMV, plasma 5-HT, 6-k-PGF1a all increased quickly, especially on the 1st day (P less than 0.001-0.01). During 3 weeks observation, only 6-K-PGF1a decreased to the normal level on 14th day. There were no obvious decrease of plasma TXB2, 5-HT and PMMV. It showed that in acute phase of AMI without intervention of any antiplatelet drugs the platelets were activated continuously. Plasma 5-HT was the most sensitive predictor for the severity of AMI as observed by the comparison between the cases with complications and serum peak CK greater than 1000 U/L, and those without complications and peak CK less than 1000 U/L (P less than 0.001-0.05). The great change of PMMV was a bad prognosis. In patients with UA, during acute myocardial ischemia, the platelets were also activated significantly, but the extent was not as high as that in AMI.