Comparison of the Safety of Adenosine and Regadenoson in Patients Undergoing Outpatient Cardiac Stress Testing

tudy Objective To compare the adverse effect profiles of adenosine and regadenoson in patients undergoing outpatient cardiac stress testing. Design Single-center retrospective cohort study. Setting Two outpatient clinics, both of which are part of a single tertiary academic medical health system; one clinic exclusively used adenosine for cardiac stress testing, and the other clinic exclusively used regadenoson. Patients A total of 489 patients who underwent an outpatient cardiac stress test between January 1, 2014, and December 31, 2014; of those patients, 254 received adenosine and 235 received regadenoson. Measurements and Main Results Baseline characteristics were similar between groups, except for chronic kidney disease (p<0.001), congestive heart failure (p=0.041), and mean age (p=0.004). The primary outcome was the occurrence of adverse effects—arrhythmia, chest pain or tightness, dizziness, dyspnea, flushing, or headache, and use of the rescue agent aminophylline—in the adenosine and regadenoson groups. A significantly higher proportion of patients who were given regadenoson during cardiac stress testing experienced at least one adverse effect compared with patients who underwent an adenosine stress test (79.6% vs 31.5%, p<0.001). The patients given regadenoson experienced a significantly higher occurrence of arrhythmia (30.6% vs 16.1%, p<0.001), dyspnea (66.0% vs 17.7%, p<0.001), and headache (25.1% vs 3.1%, p<0.001), and they had a significantly higher rate of aminophylline rescue use (19.2% vs 0.8%, p<0.001). A secondary objective evaluated the financial impact of each agent, and adenosine exhibited a medication price that was more than $100/patient lower than regadenoson based on the average wholesale price. Conclusion Among patients undergoing an outpatient pharmacologic stress test, the use of adenosine was associated with a lower occurrence of adverse effects and lower rate of a rescue agent use and may provide a potential medication cost savings opportunity compared with regadenoson.