Durham, NC - Acute heart attack patients receive an average dose of radiation that is 30 percent of the recommended annual limit -- equal to 725 chest X-rays -- during an average hospital admission, according to researchers at Duke University Medical Center.

The study, presented at the American Heart Association's Scientific Sessions 2009, is the first to analyze radiation exposure throughout the course of a hospital stay instead of an individual procedure.

"In the past, there has been a lot of attention focused on analyzing radiation exposure per scan but we asked a different question: what is a patient's exposure per diagnosis?" said Prashant Kaul, MD, lead author of the study and a fellow in cardiovascular medicine at Duke.

"These findings reinforce that better tracking systems are needed to quantify the radiation dose a given patient is accumulating throughout the diagnostic process and to help clinicians weigh the risks and benefits of future imaging."

Lifetime exposure to large doses of ionizing radiation has been linked to the development of cancer.

While several billion imaging studies are performed worldwide each year, at least one-third are cardiovascular procedures.

The research team analyzed the average cumulative radiation dose for patients hospitalized with an acute heart attack, tracking 64,074 patients (23,394 women and 40,680 men) who were hospitalized at 49 U.S. academic hospitals enrolled in the University HealthSystem Consortium (UHC).

Over three and a half years, a total of 276,651 procedures involving radiation were performed on these patients

Researchers analyzed use of common diagnostic procedures involving ionizing radiation, such as chest X-rays, CT-scans, stress tests, diagnostic cardiac catheterization, and percutaneous coronary intervention (PCI).

On average, the cumulative radiation dose during a heart attack patient's hospitalization was approximately 14.5 millisieverts (mSv), a measure of radiation dose to tissue. Radiation workers have an annual limit of 50 mSv.

The Duke team cautions that more research is needed to understand why the amount of radiation patients receive varies.

"We are conducting an analysis to determine the underlying drivers, which may be patient-based, hospital-based or individual practice patterns," said Manesh R. Patel, MD, study co-author.

"In some cases, such as older patients with complex heart disease, extra testing may be necessary to make a diagnosis. However, we may also uncover opportunities to educate clinicians about safe and effective ways to utilize these procedures," he added.

Duke Clinical Research Institute funded the study.

At the AHA Scientific Sessions

Dr. Prashant Kaul's study on radiation dosage in diagnosing heart attack patients received national attention this week, but so he wasn't the only Duke cardiologist in the spotlight. Duke researchers are playing a prominent role at the American Heart Association's annual scientific sessions, held through Wednesday in Orlando, Fla. Below is a list of stories about some of the Duke research presented at the conference:

New Anti-Clotting Medication Not More Effective than Standard Care; Hint of Other Clinical Benefits

New Test May Predict Heart Disease Events and the Effect of Weight Loss on Insulin Resistance

New Heart Pump Extends Life of Heart Failure Patients