title: Association of Asymptomatic Bradycardia With Incident Cardiovascular Disease and Mortality: The Multi-Ethnic Study of Atherosclerosis (MESA).
abstract: OBJECTIVE
  Bradycardia has been associated with lower cardiovascular disease (CVD) risk in selected populations. There is a paucity of information available about heart rate (HR) less than 50 beats per minute (bpm) among middle-aged or older adults.
  
  
  OBJECTIVE
  To determine whether asymptomatic bradycardia was associated with a lower cardiovascular risk profile, less subclinical atherosclerosis, and decreased incident CVD and mortality.
  
  
  METHODS
  This retrospective analysis includes 6733 participants of the Multi-Ethnic Study of Atherosclerosis, which recruited men and women free of clinical cardiovascular disease ages 45 to 84 years from 2000 to 2002 and followed them over 10 years for incident CVD events and mortality. The HR was measured by baseline electrocardiogram. The analysis was performed in June 2014.
  
  
  METHODS
  The association between HR categories with CVD events and all-cause mortality were examined using Cox proportional hazards models adjusted for potential confounders and mediators.
  
  
  RESULTS
  The 6733 participants had a mean (SD) age of 62 (10.2) years; 47% were male. The mean (SD) HR was 63 (9.5) bpm among the 5831 participants not taking an HR-modifying drug; 5.3% had an HR lower than 50 bpm. Preliminary results revealed significant interaction for HR categories according to use of HR-modifying drugs for mortality (P = .002); thus, all further analyses were stratified. An HR of less than 50 bpm was not associated with incident CVD in either subgroup (participants taking or not taking HR-modifying drugs). Among participants not taking HR-modifying drugs, the fully adjusted mortality risk was not different for an HR less than 50 bpm (hazard ratio, 0.71 [95% CI, 0.41-1.09]; P = .12) and increased among those with an HR greater than 80 bpm (hazard ratio, 1.49 [95% CI, 1.08-2.05]; P = .01) (reference HR, 60-69 bpm). Among the 902 participants taking HR-modifying drugs there was an elevated mortality risk associated with an HR less than 50 bpm (hazard ratio, 2.42 [95% CI, 1.39-4.20]; P = .002) and with an HR greater than 80 bpm (hazard ratio, 3.55 [95% CI, 1.65-7.65]; P = .001) (reference HR, 60-69 bpm).
  
  
  CONCLUSIONS
  In a contemporary, community-based cohort, bradycardia was generally not associated with incident CVD or mortality except for a potential adverse association between bradycardia among those taking HR-modifying drugs.
authors.affiliation: Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Ajay
authors.initials: A
authors.lastname: Dharod
authors.affiliation: Section of Cardiology, Wake Forest School of Medicine, Winston-Salem, North Carolina3Department of Epidemiology and Prevention, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Elsayed Z
authors.initials: EZ
authors.lastname: Soliman
authors.affiliation: Section of Cardiology, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Farah
authors.initials: F
authors.lastname: Dawood
authors.affiliation: Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Haiying
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Medicine, Columbia University, New York, New York6Department of Epidemiology, Columbia University, New York, New York.
authors.forename: Steven
authors.initials: S
authors.lastname: Shea
authors.affiliation: Department of Medicine/Cardiology, Johns Hopkins Health System, Baltimore, Maryland8Department of Epidemiology, Johns Hopkins Health System, Baltimore, Maryland.
authors.forename: Saman
authors.initials: S
authors.lastname: Nazarian
authors.affiliation: Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina3Department of Epidemiology and Prevention, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Alain G
authors.initials: AG
authors.lastname: Bertoni
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058070:Asymptomatic Diseases / Q000453:epidemiology; D050197:Atherosclerosis / Q000453:epidemiology; D001919:Bradycardia / Q000453:epidemiology*; D005006:Ethnicity / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009026:Mortality; D012189:Retrospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology