A propensity-matched study of the association of low serum potassium levels and mortality in chronic heart failure.

Pubmed ID: 17537738

Pubmed Central ID: PMC2771161

Journal: European heart journal

Publication Date: June 1, 2007

Affiliation: Department of Medicine, University of Alabama at Birmingham, 1530 Third Avenue South, Birmingham, AL 35294-2041, USA. aahmed@uab.edu

MeSH Terms: Humans, Male, Adult, Female, Aged, Aged, 80 and over, Cohort Studies, Middle Aged, Survival Analysis, Chronic Disease, Heart Failure, Hypokalemia

Grants: K23 AG019211, R01 HL085561, K23 AG019211-04, R01 HL085561-02, 5K23 AG 019211-04, 5R01 HL 085561-02, P50 HL 077100, P50 HL077100

Authors: Ekundayo OJ, Love TE, Ahmed A, Gheorghiade M, Zannad F, Tallaj J, Pitt B

Cite As: Ahmed A, Zannad F, Love TE, Tallaj J, Gheorghiade M, Ekundayo OJ, Pitt B. A propensity-matched study of the association of low serum potassium levels and mortality in chronic heart failure. Eur Heart J 2007 Jun;28(11):1334-43.



AIMS: Potassium homeostasis is essential for normal myocardial function, and low serum potassium may cause fatal arrhythmias. However, the association of low potassium and long-term mortality and morbidity in heart failure (HF) is largely unknown. METHODS AND RESULTS: We studied 6845 HF patients in the Digitalis Investigation Group trial with serum potassium levels < or =5.5 mEq/L. Of these, 1189 had low potassium (<4 mEq/L). Propensity scores for low potassium were calculated for each patient and were used to match 1187 low-potassium patients with 1187 normal-potassium (4-5.5 mEq/L) patients. Effects of low potassium on outcomes were assessed using matched Cox regression analyses. All-cause mortality occurred in 379 (rate, 1103/10 000 person-years) normal-potassium and 441 (rate, 1330/10 000 person-years) low-potassium patients, respectively, during 3437 and 3315 years of follow-up [hazard ratio (HR), 1.25; 95% confidence interval (CI), 1.07-1.46; P = 0.006]. Cardiovascular mortality occurred in 297 (864/10 000 person-years) normal-potassium and 356 (1074/10 000 person-years) low-potassium patients (HR, 1.27; 95% CI, 1.06-1.51; P = 0.009). Cardiovascular hospitalization occurred in 610 (rate, 2553/10 000 person-years) normal-potassium and 637 (rate, 2855/10 000 person-years) low-potassium patients (HR, 1.13; 95% CI, 0.99-1.29; P = 0.082). CONCLUSION: In a cohort of ambulatory chronic systolic and diastolic HF patients who were balanced in all measured baseline covariates, serum potassium <4 mEq/L was associated with increased mortality, with a trend towards increased hospitalization.