Impact of Serum Phosphate, Potassium and Other Electrolyte Levels on Sudden Cardiac Death and Cardiovascular Mortality in Haemodialysis and Peritoneal Dialysis: A Systematic Review and Meta-Analysis

<b>Background</b>: Dialysis patients have a very high burden of cardiovascular mortality, yet the contribution of specific serum electrolytes to sudden cardiac death (SCD) and cardiovascular death across haemodialysis (HD) and peritoneal dialysis (PD) remains uncertain. <b>Methods</b>: We conducted a PROSPERO-registered systematic review and meta-analysis (2010-2025) of cohort studies reporting adjusted hazard ratios (HRs) for the association between baseline or time-averaged serum electrolytes and cardiovascular mortality or SCD in adult maintenance HD and/or PD. Random-effects models with modality-specific and pooled analyses were applied. <b>Results</b>: Thirty-five cohorts (over 200,000 patients) met inclusion criteria. Across modalities, categorical analyses showed that high phosphate and low magnesium were consistently associated with approximately 2-fold higher cardiovascular mortality, while extreme potassium categories conferred similar excess risk, driven largely by PD. In HD, hypomagnesaemia and hyperphosphataemia were each associated with around 2-fold higher risk, and lower continuous sodium levels were linearly related to higher cardiovascular mortality. In PD, severe potassium abnormalities, hypomagnesaemia and high phosphate categories were strongly associated with cardiovascular death, and a lower Na/Cl ratio identified patients at particularly high risk. Heterogeneity was generally modest for categorical magnesium and phosphate, but substantial for some potassium and continuous-exposure models. Sensitivity analyses confirmed the robustness of key findings. <b>Conclusions</b>: Across HD and PD, abnormalities in phosphate, magnesium, potassium and sodium are strong and largely consistent markers of cardiovascular mortality, and likely SCD, with important modality-specific patterns. These data support intensified, modality-tailored management of electrolyte profiles as a central component of cardiovascular and SCD risk reduction in dialysis.