Potassium and the use of renin-angiotensin-aldosterone system inhibitors in heart failure with reduced ejection fraction: data from BIOSTAT-CHF.

BACKGROUND: Hyperkalaemia is a common co-morbidity in patients with heart failure with reduced ejection fraction (HFrEF). Whether it affects the use of renin-angiotensin-aldosterone system inhibitors and thereby negatively impacts outcome is unknown. Therefore, we investigated the association between potassium and uptitration of angiotensin-converting enzyme inhibitors (ACEi)/angiotensin receptor blockers (ARB) and its association with outcome. METHODS AND RESULTS: Out of 2516 patients from the BIOSTAT-CHF study, potassium levels were available in 1666 patients with HFrEF. These patients were sub-optimally treated with ACEi/ARB or beta-blockers and were anticipated and encouraged to be uptitrated. Potassium levels were available at inclusion and at 9 months. Outcome was a composite of all-cause mortality and heart failure hospitalization at 2 years. Patients' mean age was 67 ± 12 years and 77% were male. At baseline, median serum potassium was 4.3 (interquartile range 3.9-4.6) mEq/L. After 9 months, 401 (24.1%) patients were successfully uptitrated with ACEi/ARB. During this period, mean serum potassium increased by 0.16 ± 0.66 mEq/L (P < 0.001). Baseline potassium was an independent predictor of lower ACEi/ARB dosage achieved [odds ratio 0.70; 95% confidence interval (CI) 0.51-0.98]. An increase in potassium was not associated with adverse outcomes (hazard ratio 1.15; 95% CI 0.86-1.53). No interaction on outcome was found between baseline potassium, potassium increase during uptitration, or potassium at 9 months and increased dosage of ACEi/ARB (Pinteraction > 0.5 for all). CONCLUSION: Higher potassium levels are an independent predictor of enduring lower dosages of ACEi/ARB. Higher potassium levels do not attenuate the beneficial effects of ACEi/ARB uptitration.