Association of baseline serum sodium with long-term outcomes in newly diagnosed coronary heart disease patients without heart failure: a prospective cohort study

Abstract Sodium is crucial for maintaining cardiovascular health, especially in relation to heart failure. The impact of baseline serum sodium concentrations on the outcomes of newly diagnosed coronary heart disease (CHD) without heart failure remains unclear. This prospective cohort study included 681 patients who were newly diagnosed with CHD. Cox proportional hazards models and restricted cubic spline (RCS) analysis were used to assess the relationship between serum sodium concentrations and major adverse cardiovascular events. The improvement in traditional prediction models by the addition of serum sodium concentrations was assessed using changes in the C-statistic, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). During a median follow-up of 51.04 months (IQR: 40.88–53.80 months), 131 events were recorded. Multivariate Cox proportional hazards models showed that the L2 group (136–138.9 mmol/L) had the highest MACE risk. Compared to L2, the hazard ratios (HRs) and 95% confidence intervals (CIs) for the L1 (130–135.9 mmol/L), L3 (139–140.9 mmol/L), L4 (141–142.9 mmol/L), and L5 (143–147.0 mmol/L) groups were 0.31 (0.14–0.70, P = 0.005), 0.48 (030–0.78, P = 0.003), 0.56 (0.34–0.92, P = 0.022), and 0.37 (0.22–0.64, P