ESTIMATION OF HYDROGEN-PEROXIDE PLASMA-LEVELS IN PATIENTS EVALUATED FOR CORONARY HEART-DISEASE USING DIPYRIDAMOLE INFUSION FOLLOWED BY SPECT

Background: Prolonged ischemia leads to myocardial infarction and incr eased formation of toxic oxygen radicals. These substances exert delet erious effects on myocardial cells, contributing to reperfusion injury and generation of arrhythmia. Little information is available, howeve r, concerning the toxic oxygen species generated during transient isch emia. The purpose of our study was to estimate hydrogen peroxide plasm a levels in patients subjected to short-lasting ischemia induced by a dipyridamole stress test used for the diagnosis of coronary artery dis ease. Evaluation bf the performed test was carried out with (99)mTc-Se staMIBI followed by single photon emission computed tomography (SPECT) . Methods: Blood was obtained from peripheral veins of 53 patients (37 men and 16 women, mean age 49+/-11 years). Plasma hydrogen peroxide l evels were estimated by spectrophotometric methods: immediately before a dipyridamole challenge and after drug infusion. Results: Hydrogen p eroxide plasma levels in patients with a negative SPECT test were 23.5 +/- 3.0 mu mol/l (mean +/- SEM) and 21.0 +/- 2.9 after the dipyridamo le infusion (P = 0.474). Plasma concentrations of hydrogen peroxide in patients with a positive SPECT test were 30.5 +/- 4.6 and increased a fter dipyridamole challenge to 50.3 +/- 5.4 (P = 0.004). Further analy sis revealed that the observed difference cannot be attributed to prev ious history of myocardial infarction. Conclusions: Even transient myo cardial ischemia can generate toxic oxygen derivatives. Evaluation of plasma levels of hydrogen peroxide may be of clinical relevance in pat ients with suspected coronary artery disease.