Myocardial oxidative stress in patients with active infective endocarditis.

Background: Infective endocarditis (IE) induces the rise of pro-inflammatory cytokines. Some of them can stimulate oxidants production in myocardium with subsequent peroxidative damage to various biomolecules. We compared indices of oxidative stress: H2O2, thiobarbituric acid-reactive substances (TBARs), thiols in myocardium specimens between patients with active IE and those with valvular heart disease (VHD) of rheumatic etiology who underwent surgical valve replacement.

Methods: 17 left ventricle papillary muscle specimens and 28 specimens of auricle of the right heart were collected from 45IE patients, and 16 papillary muscle and 12 auricle specimens from 28 VHD patients, respectively. Patients groups had similar NYHA functional class and majority of echocardiographic indices of heart morphology. H2O2 and TBARs were determined fluorometrically in myocardium homogenates whereas thiols with photometric method. Between and within groups comparisons and mutual correlations between variables were analyzed.

Results: H2O2 generation from all myocardium specimens and auricles was 2.14- and 2.59- times higher (p<0.001) in IE patients than in VHD group. Auricles had the highest H2O2 levels within IE group. TBARs were 10-times higher (p<0.05) in IE when compared to VHD group in auricles and papillary muscles. Thiols did not differ between groups. H2O2 positively correlated with TBARs and negatively with thiols in all IE myocardium specimens (r=0.31 and r=-0.46, p<0.05) and auricles (r=0.58 and r=-0.67, p<0.05), respectively. No such associations were noted in VHD specimens.

Conclusions: Active IE induces enhanced myocardial production of H2O2 and formation of TBARs which proves occurrence of oxidative stress in the heart.