PEROXIDE PLASMA-LEVEL IN PATIENTS WITH CORONARY HEART-DISEASE AS A POSSIBLE INDICATOR OF ISCHEMIA DURING EXERCISE TEST

Background: This study evaluated the possible changes in production of free oxygen species during myocardial ischemia in the course of exerc ise testing of ischemic coronary disease. Methods: Exercise testing wa s performed on 58 patients with suspected ischemic coronary disease. P lasma hydrogen peroxide (H2O2) level was assayed according to Frew et al. (Anal Chim Acta 1983, 155:139-150) in venous blood samples obtaine d before the test, at submaximal and maximal work loads, and after 30 minutes of rest. Results: Hydrogen peroxide plasma level significantly increased (P < 0.001) at maximal work load in patients with positive exercise test results. Patients with negative exercise test results in itially manifested a higher H2O2 level that dropped during maximal wor k load. Conclusions: The rise in plasma H2O2 level during myocardial i schemia indicates that intensification of oxygen free radical producti on occurs. This may be the result of hypoxanthine conversion by xanthi ne oxidase, catecholamine auto-oxidation, polymorphonuclear neutrophil activation, and/or derangement within mitochondrial electron transfer . The noticed difference between patients with a positive exercise tes t and those diagnosed as without ischemia may be of clinical relevance .