Serum potassium in the PARADIGM-HF trial

AIMS: The associations between potassium level and outcomes, the effect of sacubitril-valsartan on potassium level, and whether potassium level modified the effect of sacubitril-valsartan in patients with heart failure and a reduced ejection fraction were studied in PARADIGM-HF. Several outcomes, including cardiovascular death, sudden death, pump failure death, non-cardiovascular death and heart failure hospitalization, were examined.

METHODS AND RESULTS: A total of 8399 patients were randomized to either enalapril or sacubitril-valsartan. Potassium level at randomization and follow-up was examined as a continuous and categorical variable (≤3.5, 3.6-4.0, 4.1-4.9, 5.0-5.4 and ≥5.5 mmol/L) in various statistical models. Hyperkalaemia was defined as K+  ≥5.5 mmol/L and hypokalaemia as K+  ≤3.5 mmol/L. Compared with potassium 4.1-4.9 mmol/L, both hypokalaemia [hazard ratio (HR) 2.40, 95% confidence interval (CI) 1.84-3.14] and hyperkalaemia (HR 1.42, 95% CI 1.10-1.83) were associated with a higher risk for cardiovascular death. However, potassium abnormalities were similarly associated with sudden death and pump failure death, as well as non-cardiovascular death and heart failure hospitalization. Sacubitril-valsartan had no effect on potassium overall. The benefit of sacubitril-valsartan over enalapril was consistent across the range of baseline potassium levels.

CONCLUSIONS: Although both higher and lower potassium levels were independent predictors of cardiovascular death, potassium abnormalities may mainly be markers rather than mediators of risk for death.