Abstract
Study Objective. To determine the safety of three different dosage regimens of intravenous adenosine. Design. Open-label, observational safety evaluation. Setting. University hospital-based department of nuclear medicine. Patients. Cohort of 854 patients referred for myocardial perfusion imaging to evaluate their coronary artery disease and who were judged unable to perform physical exercise. Interventions. Subjects underwent myocardial perfusion imaging in conjunction with one of three intravenous dosage regimens: 1 = fixed dosage 140 μg/kg/minute for 6 minutes; 2 = dosage titration to a maximum of 140 μg/kg/minute; and 3 = dosage titration to a maximum of 200 μg/kg/minute. In regimens 2 and 3, maximum tolerated dosages were continued for a minimum of 3 minutes prior to radioisotope injection. Measurements and Main Results. Adenosine-induced hemodynamic, electrocardiographic, and biochemical changes were measured. Adverse effects of the different adenosine dosages were compared. Noncardiac side effects such as flushing, dyspnea, neck tightness, and lightheadedness occurred at a significantly higher rate during regimens 2 and 3 than regimen 1. Chest pain and first- and second-degree atrioventricular block were also more frequent during regimens 2 and 3. However, the frequency of other side effects such as complete heart block, hypotension, and ST segment depression did not differ among the regimens. High-dose adenosine was associated with a significant increase in serum uric acid, a significant decrease in blood glucose, and a significant increase in serum triglyceride levels. Mean changes in hemodynamics and electrocardiographic intervals were also not different among the groups except for a greater increase PR interval in regimens 2 and 3 than regimen 1. Discontinuation of adenosine was infrequent (<1%) and did not differ among the regimens. Conclusions. Adenosine-assisted myocardial perfusion imaging procedures are relatively safe for evaluating coronary artery disease. Despite 82% of patients reporting at least one side effect, only 10 (<1%) had to discontinue adenosine. No patient suffered any residual sequelae from the adverse effects. The fixed-dose regimen is associated with fewer subjective side effects and is better tolerated than titration regimens. Appropriate safety precautions should nonetheless be taken during adenosine infusions.