Abstract P419: Urinary Na:K Excretion and the Risk of Cardiovascular Events in Patients With Chronic Kidney Disease

Abstract

Introduction: The risk of death from cardiovascular disease (CVD) is three times higher in patients with chronic kidney disease (CKD). Urine sodium and potassium excretion are altered in CKD and have been identified as CVD risk factors in other populations; therefore, they may represent therapeutic targets in persons with CKD. We aimed to examine the association between the ratio of urine Na-to-K (Na:K) with incident atrial fibrillation (AF), heart failure (HF), and myocardial infarction (MI) in patients with CKD. Methods: 2341 adults with CKD enrolled in the Chronic Renal Insufficiency Cohort free of CVD at study entry. Spot urinary Na:K ratio was measured from 24-hour collections and divided into quartiles. Outcomes included physician-adjudicated hospitalizations for AF, MI and HF (overall, preserved [HFpEF] and reduced ejection fraction [HFrEF]). Incidence rates (with 95% CI) were calculated per 1000 person-years. We performed Cox regression in a series of nested models, adjusting for demographics, habits, baseline comorbidities, kidney function and concurrent medications. Results: 586 participants were in the highest quartile of urinary Na:K excretion (mean age 54.3 (SD 11.7); 46% women (271 out of 586). Mean eGFR was lower in this group [49.5 (SD 19.4)] and 24-hour urine protein was higher [0.27 (IQR 0.08-1.19)] compared to lower quartiles. Rates of incident HF [18 (95% CI 7.5-12.5)] and MI [10 (95% CI 7.5-12.5)] were higher in persons with higher urine Na:K ratio (Fig 1). In adjusted models, the highest quartile (compared with the lowest quartile) of urine Na:K ratio was associated with AF (1.57, 95% CI 1.08-2.3) and HF (1.43, 95% CI 1.15-4.12). In sensitivity analyses, elevated urine Na:K was significantly associated with HFrEF (2.18, 95% CI in 1.15-4.12), but not HFpEF. Conclusions: Urinary Na:K excretion was associated with an increased incidence of atrial fibrillation and heart failure in persons with CKD free of CVD. Sodium and potassium represent possible modifiable risk factors for CVD prevention in patients with CKD.