Impact of caffeine ingestion on dipyridamole myocardial perfusion gated SPECT study

IntroductionDipyridamole is increasingly used for vasodilatation stress test. Caffeine diminishes its effect. At present, there is still no consensus as to whether and how long caffeine should be interrupted. We hypothesized that caffeine impacts the dypyridamole gated MPS findings in patients with coronary artery disease.MethodsThirty-six patients who had >50% stenosis in at least one vessel on coronary angiography (CAG) were included in our study. Gated MPS with standard dipyridamole stress test was used to assess myocardial perfusion defects and LVEF values before and after caffeine ingestion. Myocardial perfusion images and gated analyses were assessed visually and quantitatively. The results were analyzed by the t test for paired observations.ResultsThe mean serum caffeine levels were significantly higher 1 h after caffeine ingestion (1.10 ± 0.05 mg/L vs. 5.82 ± 1.80 mg/L) (p < 0.05). Heart rates and blood pressures changed significantly at both baseline and caffeine dipyridamole stress tests (p ≤ 0.05). The percentage of total perfusion defects (62%) at baseline gated MPS images was significantly higher than gated MPS with caffeine (34%) (p < 0.05). The LVEF was not significantly different between baseline dipyridamole (67.25 ± 2.61) and caffeine dipyridamole (63.81 ± 2.41) gated MPS studies. The mean transient ischemic dilatation (TID) was significantly lower at dipyridamole stress MPS (0.98 ± 0.01) than caffeine dipyridamole stress MPS (1.05 ± 0.02) (p ≤ 0.05).ConclusionsWe demonstrated that caffeine may cause attenuation of extent and severity of myocardial perfusion abnormalities during dipyridamole stress gated MPS study. Thus, patients should refrain from caffeine at least 1 day before the test.