Mild hyperkalemia and outcomes in chronic heart failure: a propensity matched study.
BACKGROUND
Compared with serum potassium levels 4-5.5 mEq/L, those <4 mEq/L have been shown to increase mortality in chronic heart failure (HF). Expert opinions suggest that serum potassium levels >5.5 mEq/L may be harmful in HF. However, little is known about the safety of serum potassium 5-5.5 mEq/L.


METHODS
Of the 7788 chronic HF patients in the Digitalis Investigation Group trial, 5656 had serum potassium 4-5.5 mEq/L. Of these, 567 had mild hyperkalemia (5-5.5 mEq/L) and 5089 had normokalemia (4-4.9 mEq/L). Propensity scores for mild hyperkalemia were used to assemble a balanced cohort of 548 patients with mild hyperkalemia and 1629 patients with normokalemia. Cox regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for association between mild hyperkalemia and mortality during a median follow-up of 38 months.


RESULTS
All-cause mortality occurred in 36% and 38% of matched patients with normokalemia and mild hyperkalemia respectively (HR, 1.07; 95% CI, 0.90-1.26; P=0.458). Unadjusted, multivariable-adjusted, and propensity-adjusted HRs for mortality associated with mild hyperkalemia were 1.33 (95% CI, 1.15-1.52; P<0.0001), 1.16 (95% CI, 1.01-1.34; P=0.040) and 1.13 (95% CI, 0.98-1.31; P=0.091) respectively. Mild hyperkalemia had no association with cardiovascular or HF mortality or all-cause or cardiovascular hospitalization.


CONCLUSIONS
Serum potassium 4-4.9 mEq/L is optimal and 5-5.5 mEq/L appears relatively safe in HF. Despite lack of an intrinsic association , the bivariate association of mild-hyperkalemia with mortality suggests that it may be useful as a biomarker of poor prognosis in HF.
Ahmed
Mustafa I
MI
University of Alabama at Birmingham, Birmingham, Alabama 35294-2041, USA. aahmed@uab.edu
Ekundayo
O James
OJ
Mujib
Marjan
M
Campbell
Ruth C
RC
Sanders
Paul W
PW
Pitt
Bertram
B
Perry
Gilbert J
GJ
Bakris
George
G
Aban
Inmaculada
I
Love
Thomas E
TE
Aronow
Wilbert S
WS
Ahmed
Ali
A
D000368:Aged; D000407:Alabama / Q000453:epidemiology; D000465:Algorithms; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002908:Chronic Disease; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000097:blood / Q000401:mortality*; D006801:Humans; D006947:Hyperkalemia / Q000097:blood / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood*; D011237:Predictive Value of Tests; D011379:Prognosis; D018709:Statistics, Nonparametric
D015415:Biomarkers; D011188:Potassium