The most important takeaway of this new AHA statement is raising awareness of the implications of radiation exposure resulting from the many noninvasive and invasive CV diagnostics we put our patients through. This is far from being a trivial concern. It is estimated that more than 3 million patients per year present to primary care doctors or cardiologists with symptoms suggestive of obstructive coronary disease that may require further evaluation with diagnostic tests involving radiation, not to mention other CV conditions leading to additional tests. Also, tests beget more tests, compounding the problem of cumulative radiation exposure.
While a lot of the information being highlighted in the statement may already be alluded to in various other guidance documents, this statement is bringing the concerns of radiation exposure to center stage and is a call to action to bring the patient, as well as the clinician, into the decision making process. This is critical. We are not thinking about radiation risk enough when ordering tests for our patients. As the statement recommends, clinicians as well as patients need a better understanding of the topic to make informed decisions. For example, evidence shows that nuclear imaging tests performed to detect suspected CAD more than tripled between 1990 (3 million) and 2002 (9.3 million), despite the fact that objective findings of ischemia declined from 30% (1991) to 5% (2009). This highlights the fact that nuclear stress tests are increasingly being used in patients with progressively lower risk, calling into question appropriate use of testing. Are patients really informed? Probably not!
The statement also highlights the many challenges of measuring and tracking radiation exposure. The 30 or so reference documents the reader is referred to for further information on the topic highlight the need for next steps: Now that we’ve raised awareness about the concern over radiation exposure from CV tests, we need to take action and follow through on the recommendations. One priority is to have a condensed resource for patients and clinicians to explicitly clarify radiation exposure associated with medical tests and to better understand the impact of their age, gender, repeated tests, etc., on lifetime risk. There’s a real need for such a focused resource.
The recommendations for optimizing the performance of CV diagnostics, for educating health care providers, including technicians, and for mandating that radiation safety be part of a curriculum earlier on in training are areas that will impact and ultimately minimize radiation exposure. It will take time to implement such measures nationally.
Tracking radiation exposure in our patients in clinical trials or clinical practice is an important next step to quantify exposure and risk. In practical terms, we must define metrics and implement practical tools for clinicians and patients that would enable precise measures of radiation exposure and lifelong cancer risk. That’s a gap that needs to be filled.
Noninvasive imaging tests are here to stay; and, as discussed in the statement, optimizing imaging technology is critical in reducing risk. Not mentioned in the statement, however, are newer diagnostic methods that may not expose the patient to radiation. The Corus CAD, as an example, is a validated gene expression test derived from a simple blood test designed to exclude or rule out obstructive CAD that does not expose the patient to any radiation and may optimize the evaluation of our patients while reducing risk. We need to push such innovative diagnostic research forward if we are to have a meaningful impact on reducing our patient’s risk from medical imaging.
Alexandra J. Lansky, MD, FESC, FACC
Director, Yale Heart and Vascular Clinical Research Program, Yale School of Medicine
Associate Professor of Medicine, Yale-New Haven Hospital
Disclosures: Lansky reports no relevant financial disclosures.