Effect of caffeine on ischemia detection by adenosine single-photon emission computed tomography perfusion imaging

OBJECTIVES The purpose of this research was to study the effect of one cup of coffee taken 1 h before adenosine stress on the results of myocardial perfusion imaging. BACKGROUND Caffeine is believed to attenuate the coronary hyperemic response to adenosine by competitive blockade of the A2a receptor. Caffeine is commonly withheld before adenosine single-photon emission computed tomography (SPECT) perfusion imaging so as not to mask ischemia detection. METHODS We studied the effect of one 8-oz cup of coffee taken 1 h before adenosine stress in patients who had demonstrable reversible defects on adenosine SPECT perfusion imaging performed while off caffeine. RESULTS There were 22 men and 8 women, age 64 +/- 9 years. The blood level of caffeine 1 h after intake was 3.1 +/- 1.6 mg/l. There were two patients with ST-segment depression before and one after caffeine intake (p = NS). The summed stress score (SSS) based on 17 segments (scale of 0 to 3, 3 being normal) was 44 +/- 5 before and 45 5 after caffeine (p = NS). The summed difference score was 3.8 +/- 1.9 before and. 3.9 +/- 2.3 after caffeine (p = NS), reflecting that around 50% of the perfusion abnormality was reversible before and after caffeine. Using polar maps, the perfusion abnormality was 12 +/- 10% at baseline and 12 +/- 10% after caffeine (p = NS) in agreement with SSS. The left ventricular ejection fraction by gated SPECT was 50 +/- 13% at baseline and 51 +/- 13% after caffeine (p = NS). CONCLUSIONS A cup of coffee does not mask the presence or severity of reversible defects induced by adenosine SPECT imaging.