Oxidative stress in patients with unstable angina.
The aim of this study was to determine whether oxidative stress occurs in unstable angina. Thirty patients with unstable angina class B (Braunwald classification) were prospectively studied. Control groups consisted of 23 patients presenting with stable angina and of 21 age-matched healthy volunteers. Upon admission and every 8 h for 24 h, blood samples were drawn for the determination of plasma malondialdehyde (MDA) levels, Se-glutathione peroxidase (GPX) activity, erythrocyte reduced glutathione (GSH) concentrations, erythrocyte GPX and superoxide dismutase (SOD) activities. Coronary angiograms were performed within 4 days of admission in 26 out of the 30 patients included in the study. Nine of these 30 patients were subsequently identified as presenting a non-Q wave myocardial infarction and were separately examined. On admission, only plasma MDA levels and erythrocyte GSH concentrations differed among groups. Plasma MDA levels of patients presenting with unstable angina (P < 0.01) and acute myocardial infarction (P < 0.05) were higher than those of patients with stable angina and of normal volunteers, whereas there was no difference in these parameters between unstable angina and non-Q wave myocardial infarction groups. Erythrocyte GSH concentration was lower in all patient groups as compared to normal subjects. ANOVA for repeated measures showed no difference between admission and subsequent levels for all parameters. Finally, no difference was observed for any of the parameters when anti-ischaemic or anti-aggregant treatment before admission, or the number of affected vessels on coronary angiograms, were considered. We conclude that an oxidative stress can be evidenced in patients with unstable angina or acute myocardial infarction.