February 20, 2020Open Access

Association Between Potassium Level and Outcomes in Heart Failure with Reduced Ejection Fraction: A Cohort Study from the Swedish Heart Failure Registry

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Heart failure with reduced ejection fraction (HFrEF) (n=13015). Intervention: Baseline potassium level vs. Optimal potassium level (4.2 mmol/L) or normal range (3.5-5.0 mmol/L). Primary outcome: All-cause mortality at 30 days, 12 months, and maximal follow-up.

Key Result

In patients with heart failure with reduced ejection fraction, the relationship between baseline potassium level and mortality was U-shaped, with an optimal potassium value of 4.2 mmol/L associated with the lowest risk of mortality.

Study Design

Type

Cohort (n=13,015)

Multicenter

Yes

Structured PICO

Does baseline potassium level affect all-cause mortality in patients with HFrEF?

Population

13,015 patients with heart failure with reduced ejection fraction (EF <40%) from the Swedish Heart Failure Registry, followed for a median of 2.0 years.

Exposure

Baseline potassium levels (assessed as continuous variable and categorical: <3.5, 3.5-5.0, 5.1-5.5, >5.5 mmol/L)

Comparator

Normokalaemia (3.5-5.0 mmol/L) or reference value of 4.2 mmol/L

Outcome

All-cause mortality at 30 days, 12 months, and maximal follow-uphard clinical

In patients with HFrEF, the relationship between potassium levels and mortality is U-shaped with an optimal value of 4.2 mmol/L, suggesting a narrower optimal range than traditionally defined.

Limitations

Results from the SwedeHF Registry may not be generalizable to other populations or geographic regions.
Patient population is from 2006-2012, prior to the introduction of sacubitril/valsartan.
Registry participation is voluntary and may not capture all care.
Missing data for some variables led to exclusions.
Mode of death was not examined.
Mixture of serum and plasma potassium measurements.
Possibility of residual unmeasured confounders.
Single baseline potassium value used, which may fluctuate over time.

Abstract

AIMS: Hyperkalaemia and hypokalaemia are common in heart failure and associated with worse outcomes. However, the optimal potassium range is unknown. We sought to determine the optimal range of potassium in patients with heart failure and reduced ejection fraction (5.0 mmol/L. Potassium 5.0 mmol/L were more common with lower estimated glomerular filtration rate and heart failure of longer duration and greater severity. The potassium level associated with the lowest hazard risk for mortality at 30 days, 12 months, and maximal follow-up was 4.2 mmol/L, and there was a steep increase in risk with both higher and lower potassium levels. In adjusted strata analyses, lower potassium was independently associated with all-cause mortality at 12 months and maximal follow-up, while higher potassium levels only increased risk at 30 days. CONCLUSION: In this nationwide registry, the relationship between potassium and mortality was U-shaped, with an optimal potassium value of 4.2 mmol/L. After multivariable adjustment, hypokalaemia was associated with increased long-term mortality but hyperkalaemia was associated with increased short-term mortality.

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Cite This Study

Cooper et al. (Thu,) conducted a cohort in Heart failure with reduced ejection fraction (HFrEF) (n=13,015). Baseline potassium level vs. Optimal potassium level (4.2 mmol/L) or normal range (3.5-5.0 mmol/L) was evaluated on All-cause mortality at 30 days, 12 months, and maximal follow-up. In patients with heart failure with reduced ejection fraction, the relationship between baseline potassium level and mortality was U-shaped, with an optimal potassium value of 4.2 mmol/L associated with the lowest risk of mortality.

synapsesocial.com/papers/6a35dc6921d3e324cb731840 https://doi.org/https://doi.org/10.1002/ejhf.1757