title: The association of serum magnesium and mortality outcomes in heart failure patients: A systematic review and meta-analysis.
abstract: BACKGROUND
  Low serum magnesium (Mg) has been independently shown to increase risk of heart failure (HF), but data on the association between serum Mg concentration and the outcome of patients with HF are conflicting. The purpose of this systematic review and meta-analysis was to estimate the prognostic effects of hypermagnesemia and hypomagnesemia on cardiovascular (CV) mortality and all-cause mortality (ACM) of patients with HF.
  
  
  METHODS
  Relevant studies were identified from Medline and Scopus databases. Included and excluded criteria were defined. Effects (i.e., log [risk ratio [RR]]) of hypomagnesemia and hypermagnesemia versus normomagnesemia were estimated using Poisson regression, and then a multivariate meta-analysis was applied for pooling RRs across studies. Heterogeneity was explored using a meta-regression and subgroup analysis.
  
  
  RESULTS
  On analysis, 7 eligible prospective studies yielded a total of 5172 chronic HF patients with 913 and 1438 deaths from CV and ACM, respectively. Most participants were elderly men with left ventricular (LV) ejection fraction ≤40%. Those patients with baseline hypermagnesemia had a significantly higher risk of CV mortality (RR, 1.38; 95% confidence interval [CI], 1.07-1.78) or ACM (RR, 1.35; 95% CI, 1.18-1.54) than those with baseline normomagnesemia. However, baseline hypomagnesemia was not associated with the risk of CV mortality (RR, 1.11; 95% CI, 0.79-1.57) and ACM (RR, 1.11; 95% CI, 0.87-1.41). A subgroup analysis by Mg cutoff suggested a dose-response trend for hypermagnesemia effects, that is, the pooled RRs for CV mortality were 1.28 (95% CI, 1.05-1.55) and 1.92 (95% CI, 1.00-3.68) for the cutoff of 0.89 to 1.00 and 1.05 to 1.70 mmol/L, respectively.
  
  
  CONCLUSIONS
  The present systematic review and meta-analysis suggested that, in HF patients, hypermagnesemia with serum Mg ≥ 1.05 mmol/L was associated with an increased risk of CV mortality and ACM but this was not observed for hypomagnesemia. This finding was limited to the elderly patients with chronic HF who had reduced LV systolic function.
authors.affiliation: Section for Clinical Epidemiology and Biostatistics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok Division of Cardiovascular Medicine, Department of Medicine, Faculty of Medicine, HRH Princess Maha Chakri Sirindhorn Medical Center, Srinakharinwirot University, Ongkharak, Nakhon Nayok Department of Family Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University Cardiology Unit, Department of Pediatrics, Faculty of Medicine Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand Department of Internal Medicine "F", Assaf Harofeh Medical Center (Affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel), Zerifin, Israel Center for Clinical Epidemiology and Biostatistics, The School of Medicine and Public Health, the University of Newcastle, Newcastle, NSW, Australia.
authors.forename: Teeranan
authors.initials: T
authors.lastname: Angkananard
authors.forename: Thunyarat
authors.initials: T
authors.lastname: Anothaisintawee
authors.forename: Sudarat
authors.initials: S
authors.lastname: Eursiriwan
authors.forename: Oleg
authors.initials: O
authors.lastname: Gorelik
authors.forename: Mark
authors.initials: M
authors.lastname: McEvoy
authors.forename: John
authors.initials: J
authors.lastname: Attia
authors.forename: Ammarin
authors.initials: A
authors.lastname: Thakkinstian
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002423:Cause of Death; D018450:Disease Progression; D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000401:mortality* / Q000503:physiopathology; D006801:Humans; D008274:Magnesium / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012720:Severity of Illness Index; D012737:Sex Factors; D016019:Survival Analysis
chemical_list: D015415:Biomarkers; D008274:Magnesium