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 m(2) 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.