Augmentation index, pulse pressure amplification and superoxide anion production in patients with coronary artery disease

Background: Free oxygen radicals appear to be involved in several processes that contribute to atherogenesis and increased arterial stiffness. Methods: The aim of our study was to evaluate arterial stiffness and the production of superoxide anions by activated polymorphonuclear neutrophils (PMN) obtained from patients with stable coronary artery disease (CAD). Thirty four consecutive patients were studied (21 men, 13 women, mean age 58 years) who underwent coronary angiography. Arterial stiffness was assessed by pulse wave analysis using a validated system (Sphygmocor Mx, AtCor Medical). Superoxide anion production by activated neutrophils was determined by a spectrophotometric method involving the measurement of cytochrome C reduction. The extent of coronary narrowing was estimated by calculation of the Gensini score. Results: Superoxide anion production by stimulated PMN showed a significant positive correlation with the augmentation index (AIx) and a significant negative correlation with pulse pressure amplification (PPA), (r=0.4, p=0.02; r=−0.5 and p=0.0026 respectively). In multivariable analyses, after adjustment for age, gender and Gensini score, superoxide anions and BMI were significant predictors of AIx (R2=57.37%, p=0.001) and PPA (R2=49.04%, p=0.008). Superoxide anion production was significantly higher in the middle (52.0±5.8 nmol O2−/2.5×106 PMN/30 min) and upper teriles (62.7±5.6) of AIx in comparison with the first tertile 31.8±4.1 (p≤0.05, p≤0.001). Moreover, superoxide anion production in the highest tertile of PPA was significantly lower (35.6±4.3 nmol O2−/2.5×106 PMN/30 min) than that in the tertile (60.8±6.2, p≤0.05). Neither the augmentation index nor pulse pressure amplification correlate with the severity of coronary atherosclerosis as indicated by the Gensini score. Conclusions: markers of arterial stiffness, AIx and pulse pressure amplification correlate with superoxide anion production but not with the severity of atherosclerosis in coronary arteries.