Studies highlight advances in diagnosis, medical therapy

Using radioactive tracers and drugs that cause the arteries to dilate, nuclear scanning is able to track blood flow throughout the heart muscle, in a test known as myocardial perfusion imaging (MPI).The RegEx trial is comparing an investigational vasodilator drug, regadenoson, against a commercially available alternative, adenosine. Regadenoson is both easier to administer than adenosine and more targeted to the arteries of the heart, a feature that is expected to minimize side effects.

The RegEx study involved 60 patients, all of whom had an adenosine scan while lying at rest on their back. Patients were then randomly assigned in a 2:1 ratio to regadenoson plus radioactive tracer (in preparation for nuclear scanning) or to matching placebos. All patients performed mild exercise. In the end, the randomization scheme resulted in 39 patients in the regadenoson-exercise-nuclear scanning group and 21 patients in the double placebo-exercise group.

Dr. Thomas and his colleagues found that regadenoson could be safely combined with exercise. In addition, patients reported greate acceptance of and fewer side effects with the regadenoson-exercise protocol than with the standard adenosine study. A full 70 percent of patients rated the regadenoson-exercise protocol as much better or somewhat better than the resting adenosine study. In addition, when three experts evaluated side-by-side images, 26 percent said the regadenoson images were of better quality; 74 percent said image quality was similar with the two imaging protocols.

"Adenosine MPI is a very good test. And the use of regadenoson makes MPI even better," Dr. Thomas said.

Dr. Thomas will present this study on Monday, March 26, at 1:45 p.m. in La Nouvelle Orleans C.

The American College of Cardiology (www.acc.org) represents the majority of board certified cardiovascular physicians in the United States. Its mission is to advocate for quality cardiovascular care through education, research, promotion, development and application of standards and guidelines- and to influence health care policy. ACC.07 and the i2 Summit is the largest cardiovascular meeting, bringing together cardiologists and cardiovascular specialists to share the newest discoveries in treatment and prevention, while helping the ACC achieve its mission to address and improve issues in cardiovascular medicine.