Abstract
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Objectives: Regadenoson is an adenosine A2A receptor agonist widely used as a pharmacologic stress agent for myocardial perfusion imaging (MPI). Approximately 3.4 million regadenoson pharmacologic stress tests were performed annually as of 2011. Caffeine is a nonspecific competitive antagonist of all adenosine receptor subtypes, thus caffeine is typically held 12-24 hours before stress with regadenoson. However, the effects of abrupt cessation of chronic caffeine intake are unknown. This study assesses the effect of chronic caffeine intake on symptoms and hemodynamic changes during stress testing with regadenoson.
Methods: Patients presenting for regadenoson stress MPI were asked their amounts of chronic caffeine intake. Chart review was used to collect data on demographics, comorbidities, and use of beta blockers. Data collected from the regadenoson stress test included symptoms, administration of aminophylline, heart rate (HR), blood pressure (BP), and arrhythmias. Chi-squared test and analysis of variance were used to analyze data divided into three categories of caffeine intake (< 200, 200-400, > 400 mg daily). Chi-squared test was used for nominal data and unpaired t-test for continuous data.
Results: Total of 101 patients were enrolled and 53% were men. 89% reported chronic caffeine intake, with 13% reporting heavy caffeine intake (>400mg daily). Last intake of caffeine was at least 12 hours prior to the test. During the test, 63% reported symptoms but the test was completed successfully in all patients. Chronic caffeine intake was associated with less chest pain (p=0.0013), less aminophylline administration (p=0.0371), lower resting and peak heart rate (p=0.0497 and 0.0314, respectively), and lower diastolic BP response (p=0.017). Heavy caffeine intake (>400 mg/day) was associated with more symptoms of headache (p=0.0383) and shortness of breath (p=0.006). No associations were found between chronic caffeine intake and arrhythmia, and systolic BP response.
Conclusions: Chronic caffeine intake prior to regadenoson stress MPI was very common, and abruptly stopping caffeine for MPI is safe and associated more with changes in symptoms rather than physiologic parameters. Indeed, chronic caffeine intake was associated with less aminophylline use and chest pain.