Plasma thioredoxin levels in patients with unstable angina.

Plasma levels of human thioredoxin are indicative of the responses against oxidative stress. We measured the plasma thioredoxin levels in patients with unstable angina in order to examine the relationships between subsequent clinical course and plasma thioredoxin levels before and after treatment for unstable angina. Blood was sampled both on admission and after treatment in 44 patients with unstable angina. In addition, blood samples were obtained from 41 patients with stable exertional angina and 41 patients with chest pain syndrome after admission. The plasma levels of thioredoxin were the highest in the unstable angina group among three groups (p<0.001). Treatment of unstable angina decreased the plasma thioredoxin levels (p<0.01). We divided the patients with unstable angina into two groups according to the plasma thioredoxin levels on admission and after treatment. There was a significant difference in Braunwald's classification between the high thioredoxin and the low thioredoxin group on admission, as analyzed by the chi2 test with Yates's correction (p<0.05). Moreover, there was a significant difference in incidence of recurrent anginal attacks at rest between the high thioredoxin and the low thioredoxin group after treatment, as analyzed by the chi2 test with Yates's correction (p<0.001). The present study demonstrated that plasma thioredoxin levels are significantly increased in patients with unstable angina compared to those with stable exertional angina and chest pain syndrome. Thioredoxin levels were associated with recurrent myocardial ischemia in patients with unstable angina.