Serum Potassium and Cardiovascular Events in Heart Failure With Preserved Left Ventricular Ejection Fraction Patients

BACKGROUND Although serum potassium (sK) levels are closely associated with the prognosis of chronic heart failure patients, the clinical significance of sK levels in cardiovascular outcomes of heart failure with preserved ejection fraction (HFpEF) patients is not fully understood. METHODS This study was a retrospective, single-center, observational study. We enrolled 506 consecutive HFpEF patients admitted to Kumamoto University Hospital and divided them into four groups according to the quartiles of the sK levels at discharge (Q1: sK < 4.1 mEq/l, Q2: 4.1 <= sK < 4.4 mEq/l, Q3:4.4 <= sK < 4.7 mEq/l, and Q4: sK >= 4.7 mEq/l). RESULTS No significant differences were observed in the use of all drugs (loop diuretics, mineralocorticoid receptor antagonists, renin-angiotensin-aldosterone system inhibitors, calcium channel blockers, beta-blockers, and statins) among the four groups. Hemoglobin, the estimated glomerular filtration rate, and pulse wave velocity levels were lower, and the serum sodium levels were higher in the Q4 group compared with those in the Q2 group. Kaplan-Meier analysis revealed significantly higher probabilities of both cardiovascular and HF-related events In the Q1, Q3, and Q4 groups than those in the Q2 group. Multivariate Cox proportional hazard analysis revealed that the Q1, Q3, and Q4 groups had significantly and independently higher probabilities of cardiovascular events compared with those in the Q2 group, indicating a J-shaped association between sK levels and cardiovascular events. CONCLUSIONS sK levels at discharge could provide important prognostic information in regard to HFpEF. Further evaluation in a larger number of patients might be needed.