title: Vitamin D status and coronary flow reserve measured by positron emission tomography: a co-twin control study.
abstract: BACKGROUND
  Vitamin D insufficiency is associated with increased cardiovascular events in the general population. Additionally, low serum 25-hydroxyvitamin D [25(OH)D] is associated with endothelial dysfunction and arterial stiffness. However, little is known about the association between serum 25(OH)D level and myocardial blood flow.
  
  
  OBJECTIVE
  Our objective was to examine the association between serum 25(OH)D levels and coronary flow reserve (CFR) measured by (13)N-positron emission tomography in asymptomatic middle-aged male twins.
  
  
  METHODS
  The Emory Twin Study is a cross-sectional study of soldiers from the Vietnam Era Registry.
  
  
  METHODS
  The study was conducted at the General Clinical Research Center, Emory University, Atlanta, GA.
  
  
  METHODS
  A total of 368 middle-aged male twins were enrolled for the study. Serum 25(OH)D levels were measured in all subjects and classified as vitamin D insufficiency [25(OH)D <30 ng/ml] or sufficiency [25(OH)D ≥30 ng/ml]. Positron emission tomography with [(13)N]ammonia was used to evaluate myocardial blood flow at rest and after adenosine stress. CFR was measured as the ratio of maximum to rest myocardial blood flow.
  
  
  METHODS
  Primary outcome was CFR measurement.
  
  
  RESULTS
  Mean overall serum 25(OH)D concentration was 37.0 ± 21.4 ng/ml; 167 twins (45%) were vitamin D insufficient. CFR was significantly lower in subjects with vitamin D insufficiency compared with subjects with vitamin D sufficiency (2.41 vs. 2.64; P = 0.007), even after adjustment for traditional cardiovascular risk factors, serum PTH, calcium, and phosphorus levels, and season. An abnormal CFR (CFR <2) was more prevalent in subjects with vitamin D insufficiency than with vitamin D sufficiency (31 vs. 20%; P = 0.03). In addition, in vitamin D status-discordant twin pairs, CFR was significantly lower in the vitamin D-insufficient twin than in the vitamin D-sufficient co-twin (2.35 vs. 2.58; P = 0.037).
  
  
  CONCLUSIONS
  Vitamin D insufficiency is associated with lower CFR in men. This association may help explain some of the increased cardiovascular risk reported in individuals with vitamin D insufficiency.
authors.affiliation: Division of Cardiology, Department of Medicine, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: Cristina
authors.initials: C
authors.lastname: Karohl
authors.forename: Viola
authors.initials: V
authors.lastname: Vaccarino
authors.forename: Emir
authors.initials: E
authors.lastname: Veledar
authors.forename: Jack
authors.initials: J
authors.lastname: Goldberg
authors.forename: Vin
authors.initials: V
authors.lastname: Tangpricha
authors.forename: Antonio
authors.initials: A
authors.lastname: Bellasi
authors.forename: Paolo
authors.initials: P
authors.lastname: Raggi
mesh_terms: D002318:Cardiovascular Diseases / Q000097:blood / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D016022:Case-Control Studies; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000502:physiology; D003430:Cross-Sectional Studies; D004200:Diseases in Twins / Q000097:blood / Q000150:complications / Q000000981:diagnostic imaging / Q000453:epidemiology; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D012039:Regional Blood Flow; D014427:Twins / Q000706:statistics & numerical data; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications / Q000000981:diagnostic imaging / Q000453:epidemiology
chemical_list: D014807:Vitamin D