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 micrograms/kg/minute for 6 minutes; 2 = dosage titration to a maximum of 140 micrograms/kg/minute; and 3 = dosage titration to a maximum of 200 micrograms/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 in 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.