title: Association of Serum Magnesium on Mortality in Patients Admitted to the Intensive Cardiac Care Unit.
abstract: Although electrolyte disturbances may affect cardiac action potential, little is known about the association between serum magnesium and corrected QT (QTc) interval as well as clinical outcomes.
  
  
  
  A consecutive 8498 patients admitted to the Mayo Clinic Hospital-Rochester cardiac care unit (CCU) from January 1, 2004 through December 31, 2013 with 2 or more documented serum magnesium levels, were studied to test the hypothesis that serum magnesium levels are associated with in-hospital mortality, sudden cardiac death, and QTc interval.
  
  
  
  Patients were 67 ± 15 years; 62.2% were male. The primary diagnoses for CCU admissions were acute myocardial infarction (50.7%) and acute decompensated heart failure (42.5%), respectively. Patients with higher magnesium levels were older, more likely male, and had lower glomerular filtration rates. After multivariate analyses adjusted for clinical characteristics including kidney disease and serum potassium, admission serum magnesium levels were not associated with QTc interval or sudden cardiac death. However, the admission magnesium levels ≥2.4 mg/dL were independently associated with an increase in mortality when compared with the reference level (2.0 to <2.2 mg/dL), having an adjusted odds ratio of 1.80 and a 95% confidence interval of 1.25-2.59. The sensitivity analysis examining the association between postadmission magnesium and analysis that excluded patients with kidney failure and those with abnormal serum potassium yielded similar results.
  
  
  
  This retrospective study unexpectedly observed no association between serum magnesium levels and QTc interval or sudden cardiac death. However, serum magnesium ≥2.4 mg/dL was an independent predictor of increased hospital morality among CCU patients.
authors.affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minn.
authors.forename: Niyada
authors.initials: N
authors.lastname: Naksuk
authors.affiliation: Mayo Medical School, Mayo Clinic College of Medicine, Rochester, Minn.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Hu
authors.affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minn; Department of Medicine, Cleveland Clinic, Ohio; CharlesMedLab, Cleveland, Ohio.
authors.forename: Chayakrit
authors.initials: C
authors.lastname: Krittanawong
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minn; Department of Internal Medicine, Mary Imogene Bassett Healthcare, Cooperstown, NY.
authors.forename: Charat
authors.initials: C
authors.lastname: Thongprayoon
authors.affiliation: Division of Hospital Internal Medicine, Department of Medicine, Mayo Clinic, Rochester, Minn; Division of Cardiovascular Diseases, Lahey Hospital and Medical Center, Burlington, Mass.
authors.forename: Sunita
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minn.
authors.forename: Jae Yoon
authors.initials: JY
authors.lastname: Park
authors.affiliation: Division of Cardiovascular Diseases, Lahey Hospital and Medical Center, Burlington, Mass.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Rosenbaum
authors.affiliation: Mayo Medical School, Mayo Clinic College of Medicine, Rochester, Minn.
authors.forename: Prakriti
authors.initials: P
authors.lastname: Gaba
authors.affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minn.
authors.forename: Ammar M
authors.initials: AM
authors.lastname: Killu
authors.affiliation: Division of Cardiovascular Diseases, Lahey Hospital and Medical Center, Burlington, Mass.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Sugrue
authors.affiliation: Division of Internal Medicine, Department of Medicine Education, University of Minnesota Twin Cities, Minneapolis; Division of Gastroenterology, Department of Medicine, Mayo Clinic, Rochester, Minn.
authors.forename: Thoetchai
authors.initials: T
authors.lastname: Peeraphatdit
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minn.
authors.forename: Vitaly
authors.initials: V
authors.lastname: Herasevich
authors.affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minn.
authors.forename: Malcolm R
authors.initials: MR
authors.lastname: Bell
authors.affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minn.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Brady
authors.affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minn.
authors.forename: Suraj
authors.initials: S
authors.lastname: Kapa
authors.affiliation: Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minn; Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minn. Electronic address: asirvatham.samuel@mayo.edu.
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Asirvatham
mesh_terms: D000368:Aged; D003325:Coronary Care Units / Q000706:statistics & numerical data*; D016757:Death, Sudden, Cardiac / Q000453:epidemiology; D004562:Electrocardiography; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008274:Magnesium / Q000097:blood*; D008297:Male; D012189:Retrospective Studies
chemical_list: D008274:Magnesium
keywords: Acquired long-QT syndrome; Hypermagnesemia; Hypomagnesemia; Magnesium; Mortality; QTc interval; Sudden cardiac death; Ventricular arrhythmias