Clinical Summary

Heart failure: both hypokalaemia and hyperkalaemia tied to increased mortality

Antara Ghosh

Takeaway

In patients with new-onset heart failure in the United Kingdom, both hypokalaemia and hyperkalaemia were associated with increased mortality risk.
Additionally, hyperkalaemia was associated with increased likelihood of renin–angiotensin–aldosterone system inhibitor (RAASi) discontinuation.

Why this matters

Little is known about relationships between serum potassium and adverse clinical outcomes among European patients with heart failure.

Study design

Study used data from Clinical practice research datalink to evaluate 21,334 patients (aged ≥18 years) with newly diagnosed heart failure, with index date of heart failure between 2006 and 2015.
Serum potassium concentration of <3.5 mmol/L defined hypokalaemia; serum potassium intervals of ≥5.0 to <5.5, ≥5.5 to <6.0 and ≥6.0 mmol/L defined hyperkalaemia.
Primary outcome: all-cause mortality, major adverse cardiac events (MACE) incidence (composite of arrhythmia, heart failure, myocardial infarction and stroke) and RAASi discontinuation (first 90-day gap after estimated end-date of a RAASi prescription).
Funding: AstraZeneca.

Key results

9.2%, 35.9%, 12.8% and 3.6% patients experienced episodes of serum potassium <3.5, ≥5.0, ≥5.5 and ≥6.0 mmol/L, respectively.
Compared with serum potassium level 4.5 to <5.0 mmol/L (reference), adjusted incident rate ratios (aIRRs) for mortality were 1.98 (95% CI, 1.69–2.33), 1.23 (95% CI, 1.12–1.36), 1.35 (95% CI, 1.14–1.60) and 3.02 (95% CI, 2.28–4.02) for patients with serum potassium <3.5, ≥5.0 to <5.5, ≥5.5 to <6.0 and ≥6.0 mmol/L, respectively.
Compared with reference group, aIRRs for RAASi discontinuation were 1.32 (95% CI, 1.14–1.53) and 2.19 (95% CI, 1.63–2.95) among patients with serum potassium ≥5.5 to <6.0 and ≥6.0 mmol/L, respectively.
A non-significant relationship was observed between MACE and serum potassium levels.

Limitations

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