Electrolyte disturbances in heart failure: focus on sodium and potassium

This thesis investigated the interplay between sodium, potassium, and therapies for heart failure (HF). In Chapter 2, we showed, in an Asian cohort of patients with chronic HF, that hyperkalaemia was associated with diabetes mellitus, chronic kidney disease, and lower serum sodium concentrations. Additionally, we observed large international differences. Hypo- and hyperkalaemia were not related to worse prognosis compared to normokalaemia. In Chapter 3, we found similar results in patients with chronic heart failure from a European cohort. Most importantly, higher serum potassium levels at baseline showed to be an independent predictor of unsuccessful up-titration with ACEi/ARB. However, an increase in serum potassium during follow-up (i.e. titrating dosages of ACEi/ ARB) did not attenuate the beneficial effects of up-titration. In contrast, Chapter 4 tested the interference of potassium disturbances with HF therapy in patients hospitalized with acute HF. In this international cohort, over 50% of patients developed hypo- or hyperkalaemia at least once while hospitalized. Patients developing hyperkalaemia were more likely to have their MRA treatment being down-titrated or discontinued. Incident hyperkalaemia was no independent predictor of impaired prognosis, yet down-titration or discontinuation of the RAASi was. Even in patients with hyperkalaemia, the prognosis was better if dosages of MRA or ACEi/ARB remained constant or were increased. In Chapter 5, we showed that administering the SGLT2-inihibitor empagliflozin to patients with acute heart failure was well tolerated and increased cumulative urinary volume. Chapter 6 added on the findings of Chapter 5 by indicating that the higher urinary output was not the result of an increased natriuresis. Moreover, urinary osmolality remained similar between both groups. In Chapter 7, we found no effect of empagliflozin on serum and urinary potassium levels in patients with acute HF.