Dynamic thiol/disulphide homeostasis in patients with hypertrophic cardiomyopathy

Background In addition to the genetic complexity of hypertrophic cardiomyopathy (HCM), there must be other disease-modifying factors that contribute to its highly variable clinical and phenotypic expression. The authors aimed to investigate serum thiol/disulphide homeostasis as a proxy for oxidative stress using a novel automated assay in patients with HCM. Methods This cross-sectional study was conducted on 119 patients with HCM and 52 without HCM. The methods used to measure dynamic thiol/disulphide homeostasis as calorimetric and duplex quantities were developed in 2014. Results Median serum native thiol levels were significantly lower in patients with HCM than in those without (312.5 μmol/L [285–370 μmol/L] vs 421 μmol/L [349–469.5 μmol/L]; p < 0.001). Serum total thiol levels and disulphide levels were considerably lower than those in the control group ([844.68 ± 195.99 μmol/L vs 1158.92 ± 243.97 μmol/L; p < 0.001], [259.13 ± 65.66 μmol/L vs 375.02 ± 79.99 μmol/L; p < 0.001], respectively). Serum disulphide/native thiol ratios and disulphide/total thiol ratios were significantly lower in HCM patients than in controls (0.80 ± 0.09 vs 0.92 ± 0.05; p < 0.001 and 0.31 [0.30–0.32] vs 0.32 [0.32–0.33]; p < 0.001). Finally, reduced thiol ratios were higher and oxidized thiol ratios were significantly lower in patients with HCM than in controls. Conclusions Despite the fact that antioxidant capacity was impaired, the extracellular environment remained in a reducing state by keeping serum disulphide/native thiol ratios low. Therefore, the authors speculate that HCM may behave similarly to tumours with respect to serum thiol-disulphide levels.