Levels of antithrombin III, alpha 2-macroglobulin, and alpha 1-antitrypsin in acute ischemic heart disease.

Since measurements of AT III and other possible coagulation inhibitors might provide an index of hypercoagulability, the goal was to measure over a 3-month period individual changes in blood levels of AT III, alpha 2-microglobulin, and alpha 1-antitrypsin in 51 patients with acute ischemic heart disease who were admitted to a Coronary Care Unit with the following diagnosis: unstable angina (26 patients), acute transmural myocardial infarction (20 patients), or subendocardial myocardial infarction (5 patients). Some patients received prophylactic antithrombotic therapy. AT III was measured by the von Kaulla, Owen, Thrombo-Screen, chromogenic, immunodiffusion, and immunoelectrophoretic methods. Alpha 2-macroglobulin and alpha 1-antitrypsin were measured by immunodiffusion. All inhibitors were measured on three different occasions: (1) on admission to hospital, (1) day of departure from hospital, and (3) at 3 months after hospitalization. Alpha 1-antitrypsin showed a significant increase compared to the control and remained elevated during the 3-month interval. Compared to normal control values, AT III was found to be significantly diminished when measured by one functional method (von Kaulla) in all three blood samples from patients with unstable angina and transmural myocardial infarction and by one immunological method (immunodiffusion) in patients with unstable angina, transmural myocardial infarction, and subendocardial myocardial infarction. Most methods determining functional AT III detected a significant increase 3 months after the acute ischemic episode; this rise was observed more often in patients with myocardial infarction than in those with unstable angina. Stepwise discriminant analysis separated the patients of the three groups. Subcutaneous heparin has no significant effect on AT III levels. Unexplained discrepancies still exist between the results obtained by various functional and immunological methods for determining AT III. It appears, however, that methods measuring functional AT III seem to be more suited than immunological methods to detect changes in AT III levels that might occur during and after an acute episode of ischemic heart disease.