Perfusion cardiac MR (CMR) using regadenoson as an adenosine receptor was shown to be safe with few adverse events in a clinical trial published in the July issue of the European Heart Journal-Cardiovascular Imaging.

Senior investigator Andrew E. Arai, MD, and colleagues at the Cardiovascular and Pulmonary Branch of the National Heart, Lung, and Blood Institute in Bethesda, Md., wanted to assess the safety and tolerability of regadenoson perfusion CMR. Their goal was to expand the body of knowledge about this approach as an alternative to adenosine, dipyridamole and nuclear imaging.

Researchers followed 728 patients at one center with a median age of 58 and 25 normal volunteers with a median age of 21 to determine the effects of regadenoson-induced CMR. They noted that the most common side effects with CMR using regadenoson were dyspnea, chest discomfort and headache. In their study, 30 percent of patients reported dyspnea, 27 percent of patients reported chest discomfort and 15 percent complained of headache.

There were no incidents of MI, death, ventricular tachycardia or ventricular fibrillation, stress-induced atrial fibrillation or high-grade atrioventricular block. Two notable events occurred during the study.

One patient experienced regadenoson-induced bronchospasm without having a history of chronic obstructive pulmonary disease (COPD) or asthma. The patient did, however, have a history of coronary artery disease. This appears to contradict regadenoson safety labeling, stating that it has been evaluated and is safe for patients with COPD and asthma and should not exacerbate these conditions, although no other patients in the study experienced these symptoms.

Another patient’s pre-existing heart failure worsened, requiring hospitalization. In re-reviewing the incident, the research team was unable to tell if it was due to stress-induced increase in blood pressure or whether it was a natural progression of the patient’s condition.

Effects on blood pressure between the patient group and the normal volunteers was reportedly not statistically significant. Heart rate response in normal volunteers had a higher median of around 71 percent compared to the patient group, at around 48 percent. Patients with diabetes and a body mass index of greater than 30 experienced a blunted heart rate response.

Regadenoson is approved by the FDA and in Europe for radionuclide myocardial perfusion imaging but its use in CMR is considered off-label.