Cancer Risk Related to Low-Dose Ionizing Radiation from Cardiac Imaging in Patients After Acute Myocardial Infarction

OBJECTIVES: Patients exposed to low-dose ionizing radiation from cardiac imaging and therapeutic procedures after acute myocardial infarction may be at increased risk of cancer.

METHODS:  Using an administrative database, we selected a cohort of patients who had an acute myocardial infarction between April 1996 and March 2006 and no history of cancer. We documented all cardiac imaging and therapeutic procedures involving low-dose ionizing radiation. The primary outcome was risk of cancer. Statistical analyses were performed using a time-dependent Cox model adjusted for age, sex and exposure to low-dose ionizing radiation from noncardiac imaging to account for work-up of cancer.

RESULTS: Of the 82 861 patients included in the cohort, 77% underwent at least one cardiac imaging or therapeutic procedure involving low-dose ionizing radiation in the first year after acute myocardial infarction. The cumulative exposure to radiation from cardiac procedures was 5.3 milli Sieverts (mSv) per patient-year, of which 84% occurred during the first year after acute myocardial infarction. A total of 12 020 incident cancers were diagnosed during the follow-up period. There was a dose-dependent relation between exposure to radiation from cardiac procedures and subsequent risk of cancer. For every 10 mSv of low-dose ionizing radiation, there was a 3% increase in the risk of age- and sex-adjusted cancer over a mean follow-up period of five years (hazard ratio 1.003 per milliSievert, 95% confidence interval 1.002-1.004).

CONCLUSIONS: Exposure to low-dose ionizing radiation from cardiac imaging and therapeutic procedures after acute myocardial infarction is associated with an increased risk of cancer.

PMID: 21324846

Jacobo Kirsch

Associate Center Director, Imaging Institute
Cardiopulmonary Imaging, Section Head
Cleveland Clinic Florida
Weston, FL
Posted in Computed Tomography, Health Policy, Invasive Imaging, Nuclear Imaging, Radiography and tagged , , , , .

One Comment

  1. The data in this study seems pretty solid. It has some caveats and it may be argued that it has some imperfections (such as the assumptions of radiation received by procedure rather than an actual measurement).

    I was a bit surprised that the group with no exposure was the oldest one and that “younger patients were more likely to be exposed to higher doses of radiation.”

    This interesting fact is briefly mentioned in the results, but not really discussed: “The level of exposure was higher among patients whose treating physician was a cardiologist than among those whose treating physician was a general practitioner.” I am not sure of what to make of this.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>