title: Severe hyperkalemia can be detected immediately by quantitative electrocardiography and clinical history in patients with symptomatic or extreme bradycardia: a retrospective cross-sectional study.
abstract: OBJECTIVE
  Detecting severe hyperkalemia is challenging. We explored its prevalence in symptomatic or extreme bradycardia and devised a diagnostic rule.
  
  
  METHODS
  This retrospective cross-sectional study included patients with symptomatic (heart rate [HR] ≤ 50/min with dyspnea, chest pain, altered mentality, dizziness/syncope/presyncope, general weakness, oliguria, or shock) or extreme (HR ≤ 40/min) bradycardia at an emergency department for 46 months. Risk factors for severe hyperkalemia were chosen by multiple logistic regression analysis from history (sex, age, comorbidities, and medications), vital signs, and electrocardiography (ECG; maximum precordial T-wave amplitude, PR, and QRS intervals). The derived diagnostic index was validated using bootstrapping method.
  
  
  RESULTS
  Among the 169 participants enrolled, 87 (51.5%) were female. The mean (SD) age was 71.2 (12.5) years. Thirty-six (21.3%) had severe hyperkalemia. The diagnostic summed "maximum precordial T ≥ 8.5 mV (2)," "atrial fibrillation/junctional bradycardia (1)," "HR ≤ 42/min (1)," "diltiazem medication (2)," and "diabetes mellitus (1)." The C-statistics were 0.86 (0.80-0.93) and were validated. For scores of 4 or higher, sensitivity was 0.50, specificity was 0.92, and positive likelihood ratio was 6.02. The "ECG-only index," which sums the 3 ECG findings, had a sensitivity of 0.50, specificity of 0.90, and likelihood ratio (+) of 5.10 for scores of 3 or higher.
  
  
  CONCLUSIONS
  Severe hyperkalemia is prevalent in symptomatic or extreme bradycardia and detectable by quantitative electrocardiographic parameters and history.
authors.affiliation: Department of Emergency Medicine, Seoul National University School of Medicine, Seoul 110-799, Korea.
authors.forename: Sung-Bin
authors.initials: SB
authors.lastname: Chon
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kwak
authors.forename: Seung-Sik
authors.initials: SS
authors.lastname: Hwang
authors.forename: Won Sup
authors.initials: WS
authors.lastname: Oh
authors.forename: Jun-Ho
authors.initials: JH
authors.lastname: Bae
mesh_terms: D000368:Aged; D001919:Bradycardia / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology*; D015897:Comorbidity; D003430:Cross-Sectional Studies; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D006947:Hyperkalemia / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology*; D008297:Male; D008487:Medical History Taking; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D055986:Vital Signs
keywords: Bradycardia; Electrocardiography; Hyperkalemia; Sensitivity and specificity