CaRES (Contrast Echocardiography Registry for Safety Surveillance): a prospective multicenter study to evaluate the safety of the ultrasound contrast agent definity in clinical practice.

Background: Definity (perflutren lipid microsphere) is an ultrasound contrast agent approved for use in patients with suboptimal echocardiograms to opacify the left ventricular chamber and to improve the delineation of the left ventricular endocardial border. This prospective, open-label, nonrandomized, multicenter, phase 4 surveillance registry study was conducted at 15 clinical sites in the United States and was designed to assess the risk for adverse cardiopulmonary events occurring during or within the initial 30 min after Definity administration in routine clinical practice.

Methods: Patients with suboptimal baseline images were consecutively approached regarding study participation. Safety monitoring including vital sign measurements, continuous electrocardiographic monitoring, and continuous oxygen saturation was initiated at baseline before Definity administration and then at regular intervals for 30 min after Definity injection. Patients were assessed for adverse events at 30 min after Definity administration and then contacted by telephone at 24 ± 4 hours to record any subsequent adverse events.

Results: A total of 1,060 patients were enrolled at 15 clinical sites. Of these, 1,053 (99.3%) received at least one dose of Definity and completed the study. No deaths, serious adverse events, or other significant adverse events occurred during this study. The overall adverse event rate was 10.8% (4.5% in patients undergoing rest echocardiography, 13% in patients undergoing rest and exercise stress echocardiography, and 27.7% in patients undergoing rest and pharmacologic stress echocardiography). The overall drug-related adverse event rate (patients with at least one adverse event reported by the principal investigator as related to Definity) was only 3.5%, and most of these (110 of 114 [96.5%]) were reported by the investigator as mild or moderate in intensity.

Conclusions: Definity is well tolerated in routine clinical practice in patients with a high prevalence of cardiopulmonary disease.