Effectiveness of the serum ratio of l-cysteine to glutathione for the prediction of cardiovascular events.

Aminothiols play an important role in the antioxidant defense system. Their serum profile may be a predictor of prognosis and cardiovascular events. This study followed-up 262 patients (202 men; age, 65 ± 13 years) who had been treated for cardiovascular disease. The patients were divided into two groups by the median total l-cysteine to total glutathione (tCySH/tGSH) ratio in serum at enrollment. There were 32 (11%) all-cause deaths, 20 (8%) cardiovascular deaths, and 32 (12%) major cardiovascular events in 5.5 ± 3.2 years. Twenty-nine (11%) patients were hospitalized for heart failure. The high tCySH/tGSH ratio group (≥80.70) had a higher incidence of all-cause death than the low tCySH/tGSH ratio group (<80.70; log-rank test, p = 0.025). Multivariate Cox regression analysis adjusted for age, sex, body mass index, current smoking, renal function, and log₁₀-transformed brain natriuretic peptide showed that the tCySH/tGSH ratio had predictive value for all-cause death, cardiovascular death, and heart failure. The adjusted hazard ratio for heart failure for the high versus low tCySH/tGSH ratio groups was 3.071 (95% confidence interval: 1.186-7.952; p = 0.021). The tCySH/tGSH ratio may be an useful biomarker to assess prognosis, cardiovascular events, and heart failure.