Serum Potassium Levels and Risk of Sudden Cardiac Death Among Patients With Chronic Kidney Disease and Significant Coronary Artery Disease

Introduction Chronic kidney disease (CKD) patients have increased risks of sudden cardiac arrest and sudden cardiac death (SCA/SCD) that are not explained by traditional risk factors. We examined associations between serum potassium and SCA/SCD in a large cohort of patients with coronary artery disease (CAD) and moderate CKD. Methods Among 22,009 patients who underwent cardiac catheterization at our institution between 1999 and 2011, 6181 patients had an estimated glomerular filtration rate of ≤60 ml/min per 1.73 m2 and were not receiving renal replacement therapy. The risk of SCA/SCD and all-cause mortality associated with potassium concentration was evaluated at the time of cardiac catheterization (baseline) and most proximate to SCA/SCD events. Covariate-adjusted Cox models were used to examine relationships between baseline potassium measurements and outcomes. A propensity score-matched, case-control design was used to assess risk associations of potassium measurements obtained proximate to SCA events. Results In the baseline potassium analysis, compared with levels in the normal range, there was no significant risk association between hyperkalemia (>5 mEq/l) or hypokalemia (<3.5 mEq/l) and SCA/SCD or all-cause death after covariate adjustment. In the proximate potassium analysis, hyperkalemia occurred more frequently than hypokalemia (16.7% vs. 3%), and was associated with a doubling in SCA/SCD risk (adjusted odd ratio: 2.37; 95% confidence interval: 1.33-4.23) whereas there was no significant relationship between hypokalemia and outcome. Discussion Among CKD patients with significant CAD, elevated serum potassium levels >5.0 mEq/l are common and are associated with an increased short-term risk of SCA/SCD. Early detection and treatment of hyperkalemia may reduce the high risk of SCD among CKD patients.