CAC Score Improves CV Risk Assessment Above Statin Guideline Indications
Does coronary artery calcium (CAC) provide additional information to current guidelines related to indication for statin therapy in primary prevention?
Data from the Heinz Nixdorf Recall Cohort, a population-based longitudinal study, were used for the present analysis. Participants 45-75 years of age were randomly selected from residence lists of three German cities and enrolled between December 2000 and August 2003. Participants were included in this analysis if they had no cardiovascular disease (CVD) or use of lipid-lowering therapy at baseline and completed a CAC score, which was assessed between 2000 and 2003. Subjects remained unaware of their initial CAC score. Statin indication was determined according to 2012 European Society of Cardiology (ESC) and 2013 American Heart Association/American College of Cardiology (AHA/ACC) guidelines, based on the participant’s individual baseline characteristics.
A total of 3,745 participants (mean age 59 years, 47% men) were included in the analysis. Over a mean follow-up of 10.4 years, a total of 131 fatal or nonfatal myocardial infarctions (MIs) and 241 CV events (MI, stroke, CV death) occurred. A total of 1,288 (34.4%) participants in the cohort were recommended for statin therapy according to ESC guidelines, and 2,101 (56.1%) were recommended for statin therapy according to AHA/ACC guidelines; this frequency of statin recommendation was lower according to ESC compared to AHA/ACC guidelines (34% vs. 56%; p < 0.0001). Low CAC score (<100) was common in patients with statin indication by both guidelines (59% for ESC, 62% for AHA/ACC). For ESC recommendations, CAC score differentiated risk for patients without a statin indication (1.0 [95% CI, 0.4-1.5] vs. 6.5 [95% CI, 4.1-8.9] coronary events per 1,000 person-years for CAC score of 0 vs. ≥100) and with a statin indication (2.6 [95% CI, 0.6-4.7] vs. 9.9 [95% CI, 7.3-12.5] per 1,000 person-years for CAC score of 0 vs. ≥100). Likewise, CAC score stratified proportions experiencing events in patients with statin indication according to AHA/ACC (2.7 [95% CI, 1.1-4.2] vs. 9.1 [95% CI, 7.0-11.0] per 1,000 person-years for CAC 0 vs. ≥100), whereas the event rate in patients without statin indication was low (1.1 [95% CI, 0.65-1.68] per 1,000 person-years).
The investigators concluded that current ESC and AHA/ACC guidelines lead to markedly different recommendations regarding statin therapy in a German primary prevention cohort. Quantification of CAC score in addition to the guidelines improves stratification between subjects at high versus low risk for coronary events, indicating that CAC scoring may help to match intensified risk factor modification to atherosclerotic plaque burden as well as actual risk, while avoiding therapy in subjects with low coronary atherosclerosis who have a low 10-year event rate.
These data suggest that CAC information may assist clinicians and their patients in deciding whether statin initiation in the primary setting is reasonable. CAC score together with guideline recommendations are warranted for further study.
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