Abstract
TS20
Introduction: Our institution provides care for patients with varying levels of physical condition, with many patients unable to exercise for nuclear stress tests. To simulate exercise and stress the heart, LEXISCAN® (regadenoson) is administered to induce increased heart rate [1]. LEXISCAN® precautions indicate the drug may cause common adverse reactions including dyspnea, headache, flushing, dizziness, angina pectoris, and nausea [1]. In order to combat these adverse reactions, our department instituted a protocol in which the patient walks on a treadmill at one mile per hour during the injection. However, due to patient acuity, many patients are unable to walk safely or follow instructions.
During the period of induced stress, if a patient experiences an adverse reaction, aminophylline is administered. Aminophylline is an adenosine antagonist used to reverse the effects of LEXISCAN® by shortening the duration of increased coronary blood flow [2]. This research evaluates whether performing adjunct low-level exercise during injection reduces the need for aminophylline.
Methods: Retrospectively, 450 stress tests utilizing LEXISCAN® were reviewed from June 21, 2022 to November 27, 2022. For each patient, the following was noted: patient participation in low-level exercise, aminophylline administration, and symptoms the patient experienced.
Results: Of 450 stress tests utilizing LEXISCAN®, 180 patients completed low-level exercise (40.0%), and 270 did not (60.0%). Of the 180 low-level exercisers, 13 received aminophylline (7.2%) and 167 did not (92.8%). Of the 270 that did not complete low-level exercise, 46 received aminophylline (17.0%) and 224 did not (83.0%). Although the most common symptom was dyspnea (table 1), the low-level exercise population experienced more dyspnea/shortness of breath, flushing/warmth, headache, dizziness, and lightheadedness than the group that did not perform the low-level exercise (table 1). Additionally, a greater percentage of the group that did not exercise (11.9%) experienced no symptoms versus the group that did complete low-level exercise (9.4%) (table 1).
Table 1. Percent of the population that did and did not complete adjunct low-level exercise that experienced symptoms due to administration of LEXISCAN®.
Conclusions: Using a binomial regression model, the variation between completing low-level exercise during LEXISCAN® injection and the administration of aminophylline is statistically significant. Patients who exercised were 0.38 (0.20 – 0.73, 95% C.I.) as likely to need aminophylline compared to those that did not exercise (p = 0.00332). This indicates that completing adjunct low-level exercise during use of LEXISCAN® reduces the need to administer aminophylline. The probability that a patient that does not exercise will require aminophylline is 0.17, and 0.072 for those who did exercise. However, analysis indicates that there is no relationship between completing low-level exercise and the incidence rate of symptoms experienced by the patient. Patients who exercised were 1.28 (0.68 - 2.41, 95% C.I.) times more likely to have symptoms as patients who did not exercise (p = 0.423); however the results were not significant. The probability that a patient who does not exercise will have symptoms is 0.88, and 0.905 for those who do exercise. Data analysis does not provide conclusive evidence that completing low-level exercise during an injection of LEXISCAN® will increase the number of symptoms a patient experiences. The symptoms experienced by patients can vary due to a multitude of factors including patient sex, weight, preexisting comorbidity, and ability to conduct mild exercise.