title: Effect of caffeine on intravenous adenosine-induced hyperemia in fractional flow reserve measurement.
abstract: BACKGROUND
  The interaction between caffeine and adenosine is still a matter of debate.
  
  
  OBJECTIVE
  We examined whether caffeine attenuated intravenous adenosine-induced hyperemia in the measurement of fractional flow reserve (FFR) and whether an increased dose of adenosine overcame the caffeine antagonism.
  
  
  METHODS
  FFR was measured using different adenosine doses (140, 175, and 210 μg/kg/min) and papaverine as a reference standard in patients with intermediate coronary stenoses, who refrained from caffeine for >24 h (no-caffeine group; n = 14) and those who consumed caffeine (caffeine group; n = 28).
  
  
  RESULTS
  The median caffeine level in the caffeine group was 2.9 mg/L (interquartile range, 1.8-4.6 mg/L). In the no-caffeine group, FFR with adenosine did not decrease above the dose of 140 μg/kg/min (0.769, 0.771, and 0.770 at 140, 175, and 210 μg/kg/min, respectively) and was not significantly different from that with papaverine (0.765). In the caffeine group, adenosine overestimated FFR (140 μg/kg/min: 0.813, P<.001; 175 μg/kg/min: 0.806, P<.01; 210 μg/kg/min: 0.794, P=.01) compared with papaverine (0.779). The difference in FFR between papaverine and 140 μg/kg/min dose of adenosine was significantly greater in the caffeine group than in the no-caffeine group (0.034 vs 0.004; P<.05).
  
  
  CONCLUSIONS
  Caffeine attenuates intravenous adenosine-induced hyperemia in FFR measurement. Even increased adenosine doses up to 210 μg/kg/min cannot fully surmount the antagonism.
authors.affiliation: Cardiovascular Center, Rakuwakai Otowa Hospital, Kyoto, 2, Otowachinji-cho, Yamashina-ku, Kyoto, 607-8062, Japan. matsumoto.hidenari@gmail.com.
authors.forename: Hidenari
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Nakatsuma
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Shimada
authors.forename: Shunpei
authors.initials: S
authors.lastname: Ushimaru
authors.forename: Mikiko
authors.initials: M
authors.lastname: Mikuri
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Matsuda
mesh_terms: D000241:Adenosine / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D000284:Administration, Oral; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002110:Caffeine / Q000097:blood / Q000494:pharmacology*; D017023:Coronary Angiography / Q000187:drug effects; D023921:Coronary Stenosis; D004305:Dose-Response Relationship, Drug; D005260:Female; D053805:Fractional Flow Reserve, Myocardial / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D006940:Hyperemia / Q000139:chemically induced* / Q000503:physiopathology*; D007262:Infusions, Intravenous; D007548:Isosorbide Dinitrate / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D010208:Papaverine / Q000494:pharmacology; D011292:Premedication; D011446:Prospective Studies
chemical_list: D002110:Caffeine; D010208:Papaverine; D007548:Isosorbide Dinitrate; D000241:Adenosine