Screening for Heart Disease
By Matthew J. Budoff, MD, FACC
Matthew J. Budoff, MD, FACC
Professor of Medicine
David Geffen School of Medicine
Director of Cardiac CT
Harbor-UCLA Medical Center
Cardiovascular disease remains the leading cause of mortality in the U.S. and worldwide, and no widespread screening for this number one killer has been implemented.
Traditional risk factor assessment does not fully account for the coronary risk and underestimates the prediction of risk even in patients with established risk factors for atherosclerosis.
Coronary artery calcium (CAC) represents calcified atherosclerosis in the coronary arteries, and has been shown to be the strongest predictor of adverse future cardiovascular events. CAC consistently outperforms traditional risk factors, inflammatory biomarkers, and other tests of atherosclerosis such as carotid intimal media thickness (CIMT), endothelial function, and ankle-brachial index to predict future CV events.
It (CAC) has been incorporated into both the European and American guidelines for risk assessment.
CAC is the most robust test today to reclassify individuals based on traditional risk factor assessment and provides the opportunity to better strategize the treatments for these subjects (converting 77% of patients from intermediate risk to either high or low risk).
The risk for future adverse cardiovascular events increases with increasing CAC scores; however, the absence of CAC presents a very unique situation that is associated with very low risk status for the individual (10-year event rate of ~1%). It has been proposed that those without calcification may be at such a low risk status that further intervention with pharmacology may be unnecessary. The absence of CAC is associated with a very low risk of future cardiovascular events, presence of severe CAD, myocardial perfusion abnormalities, as well as likelihood of ACS.
The cumulative data provides strong confirmatory evidence that CAC is a strong predictor of events and that as radiation doses are being reduced to a minimum, may be a useful tool in the prevention of armamentarium to assess atherosclerosis progression non-invasively.
Based on available published evidence, CAC has been incorporated into the ACC/AHA guidelines for screening of asymptomatic individuals for CVD.
In this guideline, the cutpoint for CAC is >300, but this is too high a threshold for a score.
The MESA study demonstrated
1- a tenfold increased risk for calcium scores >100 and
2- a 14-fold increase for scores >300.
Both are at increased CV risk and both should be treated aggressively.
All other prospective studies (St Francis, Heinz-Nixdorff Recall Study, Dallas Heart, Rotterdam, and others)
demonstrate that 100 is an important cutpoint for increased CV risk.