Sodium thiosulfate delays the progression of coronary artery calcification in haemodialysis patients

Background. Coronary artery calcification (CAC) is prevalent among haemodialysis patients and predicts cardiovascular mortality. In addition to modifying traditional cardiovascular risk factors, therapy aimed at lowering serum phosphate and calcium-phosphate product has been advocated. Sodium thiosulfate, through its chelating property, removes calcium from precipitated minerals decreasing calcification burden in calcific uraemic arteriolopathy and soft tissue calcification. The effect of sodium thiosulfate on CAC in haemodialysis patients has never been studied. Methods. Eighty-seven stable chronic haemodialysis patients underwent multi-row spiral computed tomography and bone mineral density (BMD) measurement. Patients with a CAC score ≥300 were included to receive intravenous sodium thiosulfate infusion twice weekly post-haemodialysis for 4 months. CAC and BMD were re-evaluated at the end of the treatment course. Results. Progression of CAC occurred in 25% and 63% of the patients in the treatment and control group, respectively (P = 0.03). CAC score was unchanged in the treatment group but increased significantly in the control group. BMD of the total hip declined significantly in the treatment group. In multivariate analysis adjusted for factors that influenced CAC progression, therapy with sodium thiosulfate was an independent protective factor (odds ratio = 0.05, P = 0.04). Major side effects were persistent anorexia and metabolic acidosis. Conclusions. The effect of sodium thiosulfate in delaying the progression of CAC is encouraging and will require a larger study. Determination of the safe therapeutic window is necessary in order to avoid bone demineralization.