Circ: AMI patients exposed to high cumulative rad exposure
Cardiac CT with Somatom Definition
Image source: Siemens Healthcare
Researchers have found that acute MI (AMI) inpatients in the U.S. are exposed to an average radiation dose of 15 mSv as a result of multiple cardiovascular and noncardiovascular procedures, according to a study in the Nov. 23 issue of Circulation.

Prashant Kaul, MD, from Duke University Medical Center in Durham, N.C., and colleagues discovered that little was known about the cumulative radiation dose of patients admitted with AMI.

In that regard, they reviewed records of 49 University HealthSystem Consortium member hospitals from 2006 to 2009 for inpatient procedures involving ionizing radiation that included chest radiograph, CT scans, radionuclide imaging, diagnostic cardiac catheterization and PCI.

The 64,071 patients in the study had a median age of 65 years and underwent more than 275,000 procedures involving ionizing radiation, for a median of 4.3 procedures per patient per admission. Median length of stay was four days.

Two-thirds of the patients had invasive catheterization, while just over half had CT scans, mostly body examinations.

Investigators found a median cumulative effective radiation dose of 15.02 mSv per patient per AMI admission. They also found post-procedural bleeding to be a significant predictor of radiation exposure, together with post-procedural mechanical complications resulting from device implantation.

Patients with higher underlying clinical complexity, which researchers defined by severity of illness scores, had significantly higher radiation exposure and higher mortality.

They concluded, "Efforts should be made to understand the risks and benefits of radiation exposure per episode of care for acute myocardial infarction."

In an accompanying editorial, William Wijns, MD, PhD, and Youri Popowski, MD, from the Cardiovascular Center Aalst in Belgium and Hopitaux Universitaires Geneva in Switzerland, respectively, noted that the 15 mSv average "is five times the annual background level and a third of the annual limit for radiation workers."

They said that most studies focus on radiation exposure for individual diagnostic tests and their associated doses in isolation. "We believe a more important and actionable consideration may be the total cumulative radiation exposure that a patient receives during an episode of care for a given diagnosis."

Wijns and Popowski further wrote, "Rather than merely tracking total cumulative radiation exposure longitudinally, this new paradigm lends itself to an improved understanding of the specific predictors of radiation exposure by addressing radiation exposure per episodes of care. In so doing, we hope that ordering healthcare providers might also be encouraged to carefully consider the appropriateness of tests involving radiation and become even more mindful of their potential risks."