Serum Potassium in the PARADIGM-HF trial.

BACKGROUND We studied the association between potassium and outcomes, the effect of sacubitril/valsartan on potassium, and whether potassium level modified the effect of sacubitril/valsartan in patients with heart failure and a reduced ejection fraction in PARADIGM-HF. AIMS We examined several outcomes including cardiovascular death, sudden-death, pump-failure death, non-cardiovascular death and heart failure hospitalization. METHODS 8399 patients were randomized to either enalapril or sacubitril/valsartan. Potassium 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 ≥5.5mmol/L) in various statistical models. Hyperkalemia was defined as K+ ≥5.5mmol/L and hypokalemia as K+ ≤3.5mmol/L. RESULTS Compared to potassium 4.1-4.9mmol/L, both hypokalemia (HR 2.40, 95%CI 1.84-3.14) and hyperkalemia (HR 1.42, 1.10-1.83) were associated with a higher risk of 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. CONCLUSIONS Although both higher and lower potassium were independent predictors of cardiovascular death, potassium abnormalities may mainly be markers rather than mediators of risk of death.