Allocation of statin therapy for the primary prevention of atherosclerotic cardiovascular disease (ASCVD) in borderline- and intermediate-risk patients has traditionally been based on population-based global risk assessment and other clinical and laboratory characteristics. Patient-specific treatment decisions are needed to provide maximal benefit and avoid unnecessary treatment. Guideline-based lipid management proposes that coronary artery calcium scoring is reasonable to implement in patients with a 10-year risk of 5.0% to 19.9% (borderline to intermediate risk) by using the pooled cohort equations when the decision about whether to initiate statin therapy is uncertain. We report data from both observational studies and a large primary prevention randomized controlled trial that support the position that this decision is, in fact, uncertain in about half of such patients because of risk misclassification. Such misclassification can be largely avoided by more widespread implementation of coronary calcium scoring, which helps to identify those with coronary artery calcium scores of 0, a finding associated with a less than 5.0% 10-year probability of an ASCVD event. Deferral of statin therapy in such patients, in the absence of smoking, diabetes, or a family history of premature ASCVD, provides more individualized and appropriate care and avoids the expense and potential adverse effects of statin therapy in those with low potential for absolute risk reduction. A rationale is also provided for the importance of coronary artery calcium scoring in women 50 years and older, possibly in place of 1 screening mammogram in women at least 55 years of age to avoid incremental radiation exposure, on the basis of the substantially higher lifetime risk of morbidity and mortality from ASCVD than from breast cancer. In patients with borderline or intermediate ASCVD risk, coronary artery calcium scoring should be used, whenever possible, as an aid to rational statin allocation for the primary prevention of ASCVD.
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