CAC Score Improves Risk Assessment Above Statin Indication
To what degree is there a difference in indication for statin therapy by European Society of Cardiology (ESC) versus American Heart Association/American College of Cardiology (AHA/ACC) guidelines, and what is the potential additional role of coronary artery calcification (CAC) score over updated guidelines in a primary prevention cohort?
In 3,745 subjects (59 ± 8 years of age, 47% men) participating in the Ruhr area of Germany population-based longitudinal Heinz Nixdorf Recall study without cardiovascular disease (CVD) or lipid-lowering therapy at baseline, CAC score was assessed between 2000 and 2003. Subjects remained unaware of their initial CAC score. Statin indication was determined according to 2012 ESC and 2013 AHA/ACC guidelines, based on the subject’s individual baseline characteristics. Endpoints were defined as incident coronary events, stroke, or CV death.
The frequency of statin recommendation was lower according to ESC compared with AHA/ACC guidelines (34% vs. 56%; p < 0.0001), whereas low CAC score (<100) was common in subjects with statin indication by both guidelines (59% for ESC, 62% for AHA/ACC). During 10.4 ± 2.0 years of follow-up, 131 myocardial infarctions (MIs) (event rate 3.50%), and 241 hard CV events (MI, stroke, CV death; event rate 6.43%) occurred. For ESC recommendations, CAC score differentiated risk for subjects without (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 0 vs. ≥100) and with 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 0 vs. ≥100). Likewise, CAC score stratified proportions experiencing events subjects 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 score 0 vs. ≥100), whereas event rate in subjects without statin indication was low (1.1 [95% CI, 0.65-1.68] per 1,000 person-years).
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 that have a low 10-year event rate.
The added benefit of CAC scoring for assessing value of statins in this German cohort is similar to that provided in the US MESA and Dallas Heart studies. CAC has been shown to be the best predictor of future coronary events, in the general population, the elderly, and in persons with diabetes. Additionally, a low CAC score is associated with decrease in overall and cancer mortality.
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