CAC score improves coronary and CV risk assessment above statin indication by ESC and AHA/ACC primary prevention guidelines

Mahabadi AA, Mohlenkamp S, Lehmann N, et al.
JACC: Cardiovasc Imaging 2016;published online ahead of print

Background

The AHA/ACC and the ESC guidelines recommend statin therapy for cholesterol-lowering, but use different eligibility criteria [1,2].

In addition to estimation of risk using traditional risk factors, the coronary artery calcification (CAC) score is an independent predictor for CV events and was demonstrated to improve CV risk stratification [3,4].

In this study, the difference in indication for statin therapy based on AHA/ACC versus ESC guidelines was quantified in a European primary prevention cohort of 3,575 patients without statin therapy at baseline. The follow-up period was 10.4 ± 2.0 years. In addition, CAC scores were used for the risk stratification in subjects with and without statin indication according to both guidelines.

Main results

• Overall, the indication for statin therapy was present in 34.4% of individuals based on ESC guidelines, and in 56.1% of individuals based on AHA/ACC guidelines. Out of all subjects with a subsequent coronary event, 46% were not eligible for statin therapy based on the ESC guidelines (event rate 2.44%), whereas 15% were not eligible for statin therapy based on the AHA/ACC guidelines (event rate 1.15%).

• The 10-year coronary event rate was 10-fold higher for subjects with CAC ≥400 compared to subjects with CAC score of 0. The coronary event rate increased with CAC score but not with statin indication by either guideline. The frequency of events for subjects with CAC score <100 was low (≤ 3.3%) regardless of statin indication. Results were similar for hard CV events but discrimination by CAC score was not as distinct.

• For subjects without statin indication according to ESC guidelines, the coronary event rate was low when CAC score (categorized into 0, 1-99 and ≥100) was low. In contrast, the event rate was considerably higher for those without statin indication but CAC score ≥100 (4.3 per 1,000 person-years). Numbers needed to treat (NNT) to prevent 1 event within 10 years, assuming that 30% of events could be prevented when taking a statin: ≤100 for subjects with CAC ≥100, irrespective of presence or absence of statin indication.

• In patients without statin indication based on AHA/ACC guidelines, the coronary event rate and the frequency of high CAC scores were low (event rate: 3.1 per 1,000 person-years). A CAC score of 0 was associated with a very low event rate. Treating only subjects with CAC ≥100, would have the ability to improve the NNT by reducing the number of subjects qualified for intensified risk modification from 2,101 to 800.

Conclusion

Current ESC and AHA/ACC recommendations led to significantly different eligibility for statin therapy in a primary prevention cohort. CAC scores improved risk stratification for coronary events independently of statin indication based on both guidelines, and might lead to significant improvement of risk prediction for specific subgroups, especially in addition to the European recommendations. 

Find this article online at JACC Cardiovasc Imaging

References

1. Perk J, De Backer G, Gohlke H, et al. European Guidelines on cardiovascular disease prevention in clinical practice (version 2012). The Fifth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of nine societies and by invited experts). Eur Heart J 2012;33:1635–701.
2. Stone NJ, Robinson J, Lichtenstein AH, et al. 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2014;63:2889–934.
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4. Erbel R, Mohlenkamp S, Moebus S, et al. Coronary risk stratification, discrimination, and reclassification improvement based on quantification of subclinical coronary atherosclerosis: the Heinz Nixdorf Recall study. J Am Coll Cardiol 2010;56:1397–406.