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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 exercise testing of ischemic coronary disease. MethodsExercise testing was performed on 58 patients with suspected ischemic coronary disease. Plasma hydrogen peroxide (H2O2) level was assayed according to Frew et al. (Anal Chim Acta 1983, 155:139–150) in venous blood samples obtained 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 initially manifested a higher H2O2 level that dropped during maximal work load. Conclusions:The rise in plasma H2O2 level during myocardial ischemia indicates that intensification of oxygen free radical production occurs. This may be the result of hypoxanthine conversion by xanthine oxidase, catecholamine auto-oxidation, polymorphonuclear neutrophil activation, and/or derangement within mitochondrial electron transfer. The noticed difference between patients with a positive exercise test and those diagnosed as without ischemia may be of clinical relevance.