One-third of maximum radiation dose obtained in single heart attack hospitalisation

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 analyse 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 analysing 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 ionising 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 analysed the average cumulative radiation dose for patients hospitalised with an acute heart attack, tracking 64,074 patients (23,394 women and 40,680 men) who were hospitalised at 49 US 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 analysed use of common diagnostic procedures involving ionising radiation, such as chest X-rays, CT-scans, stress tests, diagnostic cardiac catheterisation and percutaneous coronary intervention (PCI).

On average, the cumulative radiation dose during a heart attack patient’s hospitalisation 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 utilise these procedures," he added.

(Source: Duke University Medical Center: November 2009)