SAFETY OF DIFFERENT DOSAGES OF INTRAVENOUS ADENOSINE USED IN CONJUNCTION WITH DIAGNOSTIC MYOCARDIAL IMAGING TECHNIQUES

Study Objective. To determine the safety of three different dosage reg imens of intravenous adenosine. Design. Open-label, observational safe ty evaluation. Setting. University hospital-based department of nuclea r medicine. Patients. Cohort of 854 patients referred for myocardial p erfusion imaging to evaluate their coronary artery disease and who wer e judged unable to perform physical exercise Interventions. Subjects u nderwent myocardial perfusion imaging in conjunction with one of three intravenous dosage regimens: 1 = fixed dosage 140 mug/kg/minute for 6 minutes; 2 = dosage titration to a maximum of 140 mug/kg/minute; and 3 = dosage titration to a maximum of 200 mug/kg/minute. In regimens 2 and 3, maximum tolerated dosages were continued for a minimum of 3 min utes prior to radioisotope injection. Measurements and Main Results. A denosine-induced hemodynamic, electrocardiographic, and biochemical ch anges were measured. Adverse effects of the different adenosine dosage s were compared. Noncardiac side effects such as flushing, dyspnea, ne ck tightness, and lightheadedness occurred at a significantly higher r ate during regimens 2 and 3 than regimen 1. Chest pain and first- and second-degree atrioventricular block were also more frequent during re gimens 2 and 3. However, the frequency of other side effects such as c omplete heart block, hypotension, and ST segment depression did not di ffer among the regimens. High-dose adenosine was associated with a sig nificant 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 int erval in regimens 2 and 3 than regimen 1. Discontinuation of adenosine was infrequent (< 1 %) and did not differ among the regimens. Conclus ions. Adenosine-assisted myocardial perfusion imaging procedures are r elatively safe for evaluating coronary artery disease. Despite 82% of patients reporting at least one side effect, only 10 (< 1%) had to dis continue adenosine. No patient suffered any residual sequelae from the adverse effects. The fixed-dose regimen is associated with fewer subj ective side effects and is better tolerated than titration regimens. A ppropriate safety precautions should nonetheless be taken during adeno sine infusions.