An Expensive Way to Evaluate Cardiovascular Risks!
abstract & commentary
Synopsis: Data from Electron Beam Computed Tomography (EBCT) is a modest predictor of future cardiovascular events.
Source: Wong ND, et al. Am J Cardiol 2000;86:495-498.
Recent reports support a relationship between coronary artery calcification (CAC) in predicting the future incidence of cardiovascular disease events in asymptomatic persons. This report expands on previously reported preliminary findings by Wong and colleagues.1
The study population was derived from a series of 2016 men and women, primarily self-referred or referred by their physician for EBCT coronary calcium screening.
Wong et al evaluated the relation of CAC to future cardiovascular disease events in 926 asymtomatic persons (735 men and 191 women, mean age 54 years) who underwent a baseline EBCT. All subjects in the report returned a follow-up questionnaire 2-4 years (mean, 3.3 years) after scanning, inquiring about myocardial infarction, stroke, and revascularization. Approximately 60% of the men and 40% of the women had positive scans at baseline. Twenty-eight cardiovascular events occurred. The presence of CAC and an increasing score (increase in degree of calcification) was related to the occurrence of new myocardial infarction (P < 0.05), and total cardiovascular events (P < 0.001). Those with the highest quartile score had a relative risk of 4.5. These events were adjusted for age, gender, and coronary risk factors.
Comment by Ralph R. Hall, MD, FACP
In their discussion, Wong et al make several relevant observations. To begin with, although cardiovascular events occur with greater frequency in those with CAC, they still do occur in those with little or no CAC. Second, and very importantly, CAC did not provide incremental information over risk factors in predicting cardiovascular events.
During the recruitment of patients who were ultimately in this study, I heard the radio announcements advertising the merits of EBCT. The advertisements left no question that this procedure was of merit. It is likely that those attracted to this procedure by these advertisements were highly motivated to do something about their disease, if they indeed had CAC. Some physicians who referred patients for this study did so at the patients’ request. Therefore, after the procedure it is likely that many of these persons undertook preventive measures that would have lowered their incidence of cardiovascular events. This may have lowered the number of cardiovascular events that did occur and significantly altered the results of this study.
In any event, this is an expensive method of selecting patients for primary or secondary prevention measures.
1. Wong ND, et al. Am J Cardiol 1996;78:1220-1223.