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

Study 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.