Hyperkalemia as a limiting factor of neurohormonal blockade/modulation in everyday clinical practice.

Introduction And Objectives: Neurohormonal blockade (NB)/modulation is the combination of two renin-angiotensin-aldosterone system inhibitors (RAASi) with a beta blocker. It is the core therapy for heart failure with reduced ejection fraction (HFrEF). While improving long term prognosis, it also induces hyperkalemia (serum K >5.0 mEq/L) due to RAASi effects. This may cause lethal arrhythmias and increase mortality in the short term. Thus, hyperkalemia frequently leads to withholding or reducing the intensity of neurohormonal blockade/modulation, which is associated with worsening long term prognosis. We assessed the relevance of hyperkalemia as a limiting factor of neurohormonal blockade/modulation in real life clinical conditions.

Methods: We reviewed the medical records of HFrEF patients attending a HF clinic at a tertiary Portuguese hospital during 2018 (n=240). The number of patients not tolerating maximal neurohormonal blockade/modulation due to hyperkalemia was determined. The incidence and characteristics of hyperkalemia episodes were also assessed.

Results: Only six patients (3%) achieved maximal doses of neurohormonal blockade/modulation. Hyperkalemia was the limiting factor in 48 (20%) patients. A total of 185 hyperkalemia episodes occurred in 100 (42%) patients. Forty-five (24%) episodes were moderate or severe (serum K >5.5 mEq/L). In these HFrEF patients, the co-existence of hypertension, diabetes or renal failure was associated with the occurrence of hyperkalemia.

Conclusions: In daily clinical practice, hyperkalemia is frequent and limits neurohormonal blockade/modulation by leading to the withholding or reducing of the intensity of RAAS inhibition. Considering the negative prognostic impact associated with sub-optimal neurohormonal blockade/modulation, addressing hyperkalemia is an important issue when treating HFrEF patients.