title: Dobutamine Stress Echocardiography: Impact of Abnormal Blood Potassium Levels on Cardiac Arrhythmias.
abstract: BACKGROUND
  Guidelines suggest that an abnormal blood potassium level is a relative contraindication to performing dobutamine stress echocardiography (DSE). However, this has not been previously studied.
  
  
  METHODS
  We reviewed a consecutive series of patients who had potassium testing within 48 hours of undergoing DSE for the evaluation of myocardial ischemia over a 10-year period (N = 13,198). Normal potassium range in our laboratory is 3.6-5.2 mmol/L. Hemolyzed samples were not included. The association of potassium levels with the development of supraventricular and ventricular arrhythmias was assessed.
  
  
  RESULTS
  The incidence of clinically significant arrhythmias was very low (supraventricular tachycardia/atrial fibrillation, 4.9%; nonsustained ventricular tachycardia, 2.9%; sustained ventricular tachycardia or ventricular fibrillation, 0.1%), confirming the overall safety of DSE. Most arrhythmias (88%) occurred in patients with normal potassium levels, and arrhythmia rates remained low in patients with potassium abnormalities. Patients with hyperkalemia had a lower risk of developing mild (odds ratio [OR], 0.39; 95% CI, 0.22-0.71) and severe (OR, 0.13; 95% CI, 0.01-0.68) supraventricular arrhythmias as well as mild ventricular arrhythmias (OR, 0.58; 95% CI, 0.40-0.83). Even though events were rare, patients with severe hypokalemia (potassium levels ≤ 3.1 mmol/L) had an increased risk of supraventricular arrhythmia and ventricular ectopy.
  
  
  CONCLUSIONS
  DSE is safe even in the setting of abnormalities in blood potassium concentrations, and hence cancellation of DSE in patients with potassium abnormalities does not appear warranted. Elevated potassium levels are associated with lower rates of clinically significant supraventricular and ventricular arrhythmias. While remaining at relatively low risk, patients with very low potassium levels (≤3.1 mmol/L) at the time of DSE have a modestly increased risk of arrhythmia. Consideration could be given to correcting severe hypokalemia prior to DSE.
authors.affiliation: Division of Cardiovascular Ultrasound, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota.
authors.forename: Jared G
authors.initials: JG
authors.lastname: Bird
authors.affiliation: Division of Cardiovascular Ultrasound, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota.
authors.forename: Robert B
authors.initials: RB
authors.lastname: McCully
authors.affiliation: Division of Cardiovascular Ultrasound, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Pellikka
authors.affiliation: Division of Cardiovascular Ultrasound, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota. Electronic address: kane.garvan@mayo.edu.
authors.forename: Garvan C
authors.initials: GC
authors.lastname: Kane
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000097:blood / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015415:Biomarkers / Q000097:blood; D015984:Causality; D015897:Comorbidity; D000075202:Contraindications; D025401:Echocardiography, Stress / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007008:Hypokalemia / Q000097:blood* / Q000000981:diagnostic imaging / Q000453:epidemiology*; D015994:Incidence; D008297:Male; D008910:Minnesota / Q000453:epidemiology; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D011188:Potassium / Q000097:blood; D011379:Prognosis; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D011188:Potassium
keywords: Arrhythmia; Echocardiography; Electrolytes; Fibrillation; Outcomes; Stress testing