Submaximal adenosine-induced coronary hyperaemia with 12 h caffeine abstinence: implications for clinical adenosine perfusion imaging tests

BackgroundAdenosine 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 24h. Therefore, our aim was to examine whether the time of caffeine abstinence affects the hyperaemic response using quantification of coronary sinus flow (CSF) with cardiac magnetic resonance (CMR) during adenosine infusion. MethodsHealthy individuals (n=16, eight females, age 413years) underwent two CMR examinations with 12 and 24h of caffeine abstinence. CSF was quantified with phase-contrast velocity mapping (PC-)CMR during adenosine infusion (140gkg(-1)min(-1)) and rest and the CSF reserve between adenosine and rest was calculated. Myocardial perfusion (MP) was calculated as C(S)Fxheart rate/left ventricular mass. Cardiac output (CO) was quantified using PC-CMR of the ascending aorta. ResultsThe CSF reserve was lower after 12h abstinence compared to 24h (431 +/- 057 versus 532 +/- 076, P=003). In six of 16 subjects (38%), CSF reserve was >30% higher with longer caffeine abstinence. MP during adenosine was lower after 12h compared to 24h caffeine abstinence (359 +/- 037 versus 423 +/- 028 mlmin(-1)g(-1); P=0046). The increase in CO during adenosine between the two occasions did not differ (55 +/- 7% and 55 +/- 6%, P=011). Interobserver variability for CSF/heartbeat was -005 +/- 100ml. ConclusionsHyperaemia during adenosine is lower in some patients with 12h of caffeine abstinence compared to 24h. Longer caffeine abstinence, that is 24h, is of value before pharmacological stress testing as the individual response is not known and the individual variation is large.