title: Submaximal adenosine-induced coronary hyperaemia with 12 h caffeine abstinence: implications for clinical adenosine perfusion imaging tests.
abstract: BACKGROUND
  Adenosine is widely used as a vasodilator agent in myocardial perfusion imaging. Caffeine inhibits the effect, but the time of caffeine abstinence needed is under discussion and varies from 12 to 24 h. Therefore, our aim was to examine whether the time of caffeine abstinence affects the hyperaemic response using quantification of coronary sinus flow (CS F) with cardiac magnetic resonance (CMR) during adenosine infusion.
  
  
  METHODS
  Healthy individuals (n = 16, eight females, age 41 ± 3 years) underwent two CMR examinations with 12 and 24 h of caffeine abstinence. CS F was quantified with phase-contrast velocity mapping (PC-)CMR during adenosine infusion (140 μg kg(-1)  min(-1) ) and rest and the CS F reserve between adenosine and rest was calculated. Myocardial perfusion (MP) was calculated as CS F × heart rate/left ventricular mass. Cardiac output (CO) was quantified using PC-CMR of the ascending aorta.
  
  
  RESULTS
  The CS F reserve was lower after 12 h abstinence compared to 24 h (4·31 ± 0·57 versus 5·32 ± 0·76, P = 0·03). In six of 16 subjects (38%), CS F reserve was >30% higher with longer caffeine abstinence. MP during adenosine was lower after 12 h compared to 24 h caffeine abstinence (3·59 ± 0·37 versus 4·23 ± 0·28 ml min(-1) g(-1) ; P = 0·046). The increase in CO during adenosine between the two occasions did not differ (55 ± 7% and 55 ± 6%, P = 0·11). Interobserver variability for CS F/heartbeat was -0·05 ± 1·00 ml.
  
  
  CONCLUSIONS
  Hyperaemia during adenosine is lower in some patients with 12 h of caffeine abstinence compared to 24 h. Longer caffeine abstinence, that is 24 h, is of value before pharmacological stress testing as the individual response is not known and the individual variation is large.
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Lund University Hospital, Lund University, Lund, Sweden.
authors.forename: Marcus
authors.initials: M
authors.lastname: Carlsson
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Lund University Hospital, Lund University, Lund, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Jögi
authors.affiliation: Philips Healthcare, Lund, Sweden.|Department of Medical Radiation Physics, Lund University, Lund, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Markenroth Bloch
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Lund University Hospital, Lund University, Lund, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Hedén
authors.affiliation: Department of Emergency Medicine, Lund University Hospital, Lund University, Lund, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Ekelund
authors.affiliation: Department of Medical Radiation Physics, Lund University, Lund, Sweden.|Department of Diagnostic Radiology, Lund University Hospital, Lund University, Lund, Sweden.
authors.forename: Freddy
authors.initials: F
authors.lastname: Ståhlberg
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Lund University Hospital, Lund University, Lund, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Arheden
mesh_terms: D000241:Adenosine / Q000008:administration & dosage*; D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D002110:Caffeine / Q000008:administration & dosage*; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology*; D004334:Drug Administration Schedule; D004347:Drug Interactions; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000187:drug effects* / Q000379:methods*; D008297:Male; D055414:Myocardial Perfusion Imaging / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D014665:Vasodilator Agents; D002110:Caffeine; D000241:Adenosine
keywords: coronary flow reserve; ischaemic heart disease; myocardial perfusion; stress testing