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07/24/2009 - News

Is Coronary Artery Calcification (CAC) Screening Safe?

By: June Chen, MD

Computed tomography (CT) has been proposed as a routine screening tool for coronary artery calcification (CAC) as part of a comprehensive cardiovascular risk assessment in individuals without symptoms of heart disease.

Currently, the Screening for Heart Attack Prevention and Education (SHAPE) guidelines recommend CAC CT screening of all asymptomatic men aged 45 to 75 and all asymptomatic women aged 55 to 75. However, CAC CT is associated with a potential risk of radiation-induced cancer. In the July 13, 2009 issue of the Archives of Internal Medicine, scientists report that the radiation dose from a single CAC CT scan varies widely, depending on how the scan is performed.

Scientists from the National Institutes of Health and their colleagues calculated the radiation doses delivered to adult patients from a range of available CAC CT protocols. They found that the radiation dose from a single CAC CT scan varied more than 10-fold, depending on the protocol used. This wide variation in radiation dose also resulted in a wide variation in estimated radiation-induced cancer risk. The scientists calculated an estimated excess lifetime cancer risk of 42 cases per 100,000 men and 62 cases per 100,000 women due to CAC CT screening, assuming that screening was performed every five years.
 
If screening were performed according to the SHAPE guidelines, tens of millions of Americans would need to undergo CAC CT scans. Although CAC scoring (or, calcium scoring) can detect coronary artery disease in asymptomatic individuals, the benefits of CAC CT screening in reducing cardiovascular events or mortality have not yet been directly demonstrated in randomized clinical trials. Therefore, the potential risks of screening, including the risk of radiation-induced cancer, need to be considered along with the potential benefits.
 

Source:

Arch Intern Med. 2009;169(13):1188-1194.

Created on: 07/24/2009
Reviewed on: 07/24/2009

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