BACKGROUND: In patients hospitalized with heart failure
(HF) exacerbations, physicians routinely supplement
potassium to maintain levels ≥4.0 mEq/L. The evidence
basis for this practice is relatively weak. We aimed to
evaluate the association between serum potassium levels
and outcomes in patients hospitalized with HF.
METHODS: We identified patients admitted with acute HF
exacerbations to hospitals that contributed to an electronic
health record-derived dataset. In a subset of patients with
normal admission serum potassium (3.5-5.0 mEq/L), we
averaged serum potassium values during a 72-hour exposure
window and categorized as follows: <4.0 mEq/L (low
normal), 4.0-4.5 mEq/L (medium normal), and >4.5 mEq/L
(high normal). We created multivariable models examining
associations between these categories and outcomes.
RESULTS: We included 4,995 patients: 2,080 (41.6%),
2,326 (46.6%), and 589 (11.8%) in the <4.0, 4.0-4.5, and
>4.5 mEq/L cohorts, respectively. After adjustment for
demographics, comorbidities, and presenting severity, we
observed no difference in outcomes between the low and
medium normal groups. Compared to patients with levels
<4.0 mEq/L, patients with a potassium level of >4.5 mEq/L
had a longer length of stay (median of 0.6 days; 95%
CI = 0.1 to 1.0) but did not have statistically significant
increases in mortality (OR [odds ratio] = 1.51; 95%
CI = 0.97 to 2.36) or transfers to the intensive care unit
(OR = 1.78; 95% CI = 0.98 to 3.26).
CONCLUSIONS: Inpatients with heart failure who had mean
serum potassium levels of <4.0 showed similar outcomes
to those with mean serum potassium values of 4.0-4.5.
Compared with mean serum potassium level of <4.0, mean
serum levels of >4.5 may be associated with increased risk of
poor outcomes.
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