Measurement of beta-thromboglobulin and platelet factor 4 to follow up patients with artificial heart valves

Abstract

Efficient antithrombotic therapies are necessary for the prevention of thrombotic complications in patients with artificial heart valves. Antiplatelet drugs are commonly used since platelet activation is a feature frequently found in these pathologic conditions. The measurement of beta TG and PF4 is useful for the diagnosis of platelet activation, which may increase the thrombotic risk. Two commercially available ELISA kits for beta TG and PF4 were tested and compared with the corresponding RIA methods used previously. Coefficients of correlation were 0.976 for beta TG and 0.985 for PF4. Both methods gave identical results, although RIA was expressed in nanograms per milliliter, whereas ELISA results were in international units per milliliter by comparison with International Standards. For both parameters 1 IU/ml was found to be almost equal to 1 ng/ml. beta TG was elevated in the group of patients with heart valves (57.28 IU/ml); so was PF4 but to a lesser extent (11.28 IU/ml). The mean concentrations on a normal population were, respectively, 22.40 (+/- 5.15) IU/ml and 4.10 (+/- 2.02) IU/ml. The monitoring of patients with heart valves allowed the identification of two distinct groups: those who had persistent elevated levels of beta TG and PF4, and those whose levels of the same parameters were in the subnormal ranges. All the thrombotic complications were observed in the first group and were preceded by an elevation of platelet markers. beta TG was the most predictive and correlated closely with the evolution of the clinical state. Cerebrovascular accidents were the commonly observed complications. These patients were treated by hypocoagulant therapy and with antiplatelet drugs.(ABSTRACT TRUNCATED AT 250 WORDS)