34th Bethesda Conference: Executive summary--can atherosclerosis imaging techniques improve the detection of patients at risk for ischemic heart disease?

This document presents the summary findings from the 34th Bethesda Conference: “Can Atherosclerosis Imaging Techniques Improve the Detection of Patients at Risk for Ischemic Heart Disease?” This conference, comprised of five writing groups, began the process of formulating report outlines and documents in January 2002. The conference, held October 7, 2002, at the Heart House in Bethesda, Maryland, allowed for open discussion, constructive commentary, and the formulation of summary comments resulting in the documents presented in this report. The purpose of Bethesda Conference 34 (BC 34) was to review the current status and controversies within the integration of atherosclerosis imaging into clinical cardiovascular medicine. Each Task Force was also specifically charged with developing recommendations on “Future Directions” for the field of atherosclerosis imaging, as appropriate within the scope of issues they considered. Although it is recognized that atherosclerosis imaging, including many different emerging technologies, may enhance the detection and treatment of patients at risk for coronary heart disease (CHD), much remains unknown about these modalities despite the fact that many are rapidly moving into broad clinical use. Further consideration of these tests as clinical tools extends prior efforts such as the Prevention V Conference of the American Heart Association, and the National Cholesterol Education Program, Adult Treatment Panel III guidelines. The latter treatment guidelines focused particular attention on the relevance of diagnosing subclinical atherosclerosis for altering lipid treatment goals by designating that aortic, peripheral, and carotid artery disease were considered to represent “Coronary Heart Disease Equivalents” because the level of CHD risk and CHD event rates associated with these conditions is approximately equivalent to the level of risk seen in stable CHD. Thus, screening for atherosclerosis in other vascular regions has been considered for CHD risk evaluation. The BC 34 brought together the multidisciplinary expertise of pathologists, epidemiologists, imaging experts, experts in disease detection and treatment, clinical trialists, and outcomes researchers to work together for the common goal of crystallizing the current science, addressing the many unanswered questions on the appropriate clinical use of the available imaging modalities, and envisioning the future of this discipline. For the purpose of this Bethesda Conference, we adhered to the use of the term “coronary heart disease” (CHD) defined as cardiac events or symptoms related to myocardial ischemia and/or injury due, in the vast majority of cases, to atherosclerosis. Such events include unstable angina, myocardial infarction (MI), and sudden death due to ischemic heart disease. It is important to recognize that coronary atherosclerosis, ischemia, and events exist as a continuum. The former need not necessarily lead to the latter, while the latter is virtually always preceded by the presence of the former. Thus, the challenge is not only to “detect” coronary atherosclerosis, but also to “predict” which individuals, in whom coronary atherosclerosis is detected, will progress to develop events. Finally, the use of global risk scores, such as the Framingham Risk Score, was considered as the most appropriate initial assessment of all patients undergoing coronary risk screening. Additional testing, such as imaging, must provide incremental riskprediction information to the Framingham Risk Score. A modification to this subgrouping has recently been suggested to improve CHD risk assessment in asymptomatic people. This approach considers a less than 0.6% per year (less than 6% over 10 years) risk for coronary events as “low-risk,” 0.6% to 2.0% per year (6% to 20% over 10 years) risk is termed “intermediate risk,” and individuals with greater than or equal to 2.0% per year (greater than or equal to 20% over 10 years) risk are “high-risk.” We have adopted these risk groupings for this Bethesda Conference.