A Conversation with . . . Manuel D. Cerqueira, MD

How Lexiscan can improve MPI testing

Lexiscan (regadenoson) is administered through injection and used as a pharmacologic stress agent in radionuclide myocardial perfusion imaging (MPI). This drug has made the testing process easier and more effective for both patients undergoing stress tests and the professionals monitoring the procedure.

Manuel D. Cerqueira, MD, chairman of nuclear medicine at the Imaging Institute and a staff cardiologist at the Sydell and Arnold Miller Family Heart & Vascular Institute in Cleveland, is a proponent for the use of the new drug in clinical practice, and presented his opinions on Lexiscan based on his own research data and analysis.

Q   rt image: You recently presented an analysis of data from the pivotal trials for Lexiscan at the annual meeting for the American Society of Nuclear Cardiology (ASNC). What did the analysis show about Lexiscan?

A   Manuel D. Cerqueira: There were two phase-3 trials that were submitted to the Food and Drug Administration, and a compound was approved. What we presented at the ASNC meeting was some updated information on the completed trial: how often did people actually use aminophylline, which is a drug that can be used to reverse the effects of Lexiscan?

The patients had two IVs in their arm. This was a double-blind placebo controlled [test], so the patient and the investigators didn’t know whether the patient was actually getting adenosine, which is the conventional drug that people have been using for pharmacologic stress, or whether they were getting Lexiscan.

Statistically, people who got Lexiscan were more likely to get aminophylline, but the percentages in both of those were fairly small. It’s approximately 3 percent vs. 2 percent.

Q   image: What does this data mean for MPI?

A   Cerqueira: One of the nice things about the use of Lexiscan is that it is a fixed dose, which means everybody who gets the study gets the same dose. So if you weigh 90 pounds or if you weigh 390 pounds, you get the same dose of Lexiscan, whereas if you get adenosine, you have to calculate a weight-adjusted dose. You figure out how much the patient weighs, and you have to draw up a weight-adjusted dose from a vial. Then you have to administer it using a four- or a six-minute infusion. Whereas with Lexiscan, everybody gets the same dose, they just get it as a 10-second handheld infusion, and then 30 seconds into it you can inject a radiopharmaceutical. You actually cut the study time from six minutes with adenosine to one minute with Lexiscan, so it’s a much more efficient way to do the studies.

Q   image: In what ways does Lexiscan help nuclear cardiologists overcome issues that they face with MPI?

A   Cerqueira: If you look across the country, the preferred way to do these studies is to still do dynamic exercise, but if you look at the actual utilization, as many as half of all the studies done use pharmacologic stress. That’s because people are getting older, and they’re more likely to have strokes, they have joint problems, and they can’t do dynamic exercises.

At our practice, we’re doing more and more pharmacologic studies. With Lexiscan, the whole process is much more efficient. Now, the way that we do the studies takes less time. We don’t need the pump; we don’t need the IV tubing for the infusions. The patients actually spend less time actually getting the study done, and the preparation beforehand is much less, so that’s making us much more efficient, which is important. Also, there were a larger percentage of patients who felt better with Lexiscan than with the initial adenosine study, so there’s better patient tolerance.

Q   image: A prior history of unstable angina and female gender were the only predictors of increased aminophylline use in the Lexiscan group in your study. What precautions need to be taken prior to administering Lexiscan?

A   Cerqueira: The ASNC has put out guidelines to say that you need to monitor people for at least five minutes after you’ve stopped infusion, and that is standard operating procedure for stress testing. Similarly, if somebody has heart block and doesn’t have a pacemaker that’s working properly, those patients shouldn’t be done. If people have decompensated airway disease, if they come into your office and they’re markedly wheezing, even though the studies indicate that Lexiscan is safer overall than some of the other used agents, it’s not appropriate to treat those patients until they’re stable.

Q   image: Can you tell us what to expect from MPI and pharmacologic stress agents in years to come?

A   Cerqueira: Lexiscan is much more efficient than what we’re used to using with adenosine. In prior studies using dipyridamole, it has been shown that as many as 12 to 15 percent of the patients need to be reversed, but there are also some places using dipyridamole where 100 percent of the people get reversed. Here, we found that it was about 3.4 percent, which is a very small number, so we feel that we will be able to use this clinically without having to reverse the people with aminophylline in a large percentage.

– Richard Schupp is a freelance writer based in Allentown, Pa. Questions and comments can be directed to editorial@rt-image.com.