Research Article: Association of hypokalemia with an increased risk for medically treated arrhythmias

Date Published: June 17, 2019

Publisher: Public Library of Science

Author(s): Colin T. Phillips, Junmei Wang, Leo Anthony Celi, Zhengbo Zhang, Mengling Feng, Florian B. Mayr.

http://doi.org/10.1371/journal.pone.0217432

Abstract

Potassium replenishment protocols are often employed across broad patient populations to prevent cardiac arrhythmias. Tailoring potassium thresholds to specific patient populations would reduce unnecessary tasks and cost. The objective of this retrospective cohort study was to determine the threshold at which hypokalemia increases the risk for medically treated arrhythmias in cardiac versus medical and surgical intensive care units.

Patients captured in the publicly available Philips eICU database were assessed for initiation of either intravenous amiodarone, adenosine, ibutilide, isoproterenol, or lidocaine as a surrogate for a clinically significant arrhythmia. A landmark time-to-event analysis was conducted to investigate the association of serum potassium values and time-marked administration of an antiarrhythmic drug. Analysis was adjusted for comorbidities, the use of vasopressor agents, diuretics, as well as age, gender and severity of illness.

Among 20,665 admissions to cardiac intensive care units, 1,371 (6.6%) were treated with either amiodarone, adenosine, ibutilide, isoproterenol, or lidocaine. For potassium values of ≥3.0<3.5mEq/L, antiarrhythmic treatment occurred at an increased rate compared to a baseline of ≥4.0≤5.0mEq/L (HR 1.23, 95% CI 1.01–1.51; P = 0.04). For admissions to medical and surgical intensive care units, 2,100 of 69,714 patients (3.0%) were treated with either amiodarone, adenosine, ibutilide, isoproterenol, or lidocaine. Potassium values of ≥3.0<3.5mEq/L were also associated with an increased hazard of treatment (HR 1.26, 95% CI 1.09–1.45; P = 0.002). In both cohorts, worsening hypokalemia was associated with an increased risk of antiarrhythmic drug treatment. In neither cohort were there statistically significant differences for serum potassium values of ≥3.5<4.0 and a baseline of ≥4.0≤5.0mEq/L. The proportion of patients initiated on vasopressors or inotropes was over four-fold higher in those treated with one of the antiarrhythmic drugs in both cohorts. Serum potassium levels <3.5mEq/L were associated with an increased hazard for treatment with specific antiarrhythmic drugs in a large cohort of patients admitted to both a cardiac as well as medical and surgical intensive care units. Potassium thresholds may be individualized further based on risk of relevant outcomes.

Partial Text

Serum hypokalemia is associated with an increased risk of cardiac arrhythmias and sudden cardiac death[1–4]. Potassium homeostasis plays a central role in dysrhythmias, highlighted by seminal observational studies and 2 recent large retrospective cohort studies and a study within the MERLIN-TIMI 36 trial[5–9]. These rigorous studies do not rule out the possibility that hypokalemia is an epiphenomenon and did not measure the serum potassium value at the time of the dysrhythmia but rather at the time of admission, or averaged over the hospitalization [7,8,10].

Of 20,665 eICU admissions to cardiac ICUs fulfilling the inclusion and exclusion criteria, 1,371 (6.6%) patients were treated with one of the antiarrhythmic drugs of interest (Fig 1). Of 69,714 eICU admissions to either medical or surgical ICUs, 2,100 (3.0%) patients were treated with one of the antiarrhythmic drugs (Fig 1).

Serum potassium levels <3.5mEq/L were associated with an increased hazard for initiation of either amiodarone, adenosine, ibutilide, isoproterenol, or lidocaine compared to a reference range of ≥4.0≤5.0mEq/L in both a cardiac ICU and medical and surgical ICU cohort. There was no statistically significant difference for values between ≥3.5<4.0mEq/L. In both cohorts, the proportion of patients initiated on vasopressors or inotropes within 1 day was over four-fold higher in those treated with one of the antiarrhythmic drugs. Hypokalemia <3.5mEq/L was associated with increased risk for medically treated arrhythmias in patients admitted to cardiac and medical and surgical ICUs compared to a reference range of ≥4.0≤5.0mEq/L. In both ICU cohorts, worsening hypokalemia resulted in an increased rate of treatment. The proportion of patients treated with intravenous vasopressors, inotropes, or furosemide was four-fold higher in those treated with antiarrhythmic drugs. This approach can be employed to limit application of thresholds and tailoring potassium replenishment based on admission unit, risk factors, and diagnosis.   Source: http://doi.org/10.1371/journal.pone.0217432

 

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