Coronary Artery Calcium score stratifies CVD risk also in absence of dyslipidemia
Subclinical atherosclerosis also seen in patients without dyslipidemia. CAC measurement may improve CVD risk stratification.
Dyslipidemia, Coronary Artery Calcium, and Incident Atherosclerotic Cardiovascular Disease: Implications for Statin Therapy from the Multi-Ethnic Study of Atherosclerosis.Literature - Martin et al., Circulation Oct 2013 - Circulation. 2013 Oct 20
Martin SS, Blaha MJ, Blankstein R et al.
Circulation. 2013 Oct 20. [Epub ahead of print]
Background
International clinical practice guidelines highlight the importance of matching the use and intensity of statin therapy with the absolute risk of atherosclerotic cardiovascular disease (CVD)[1-4]. Indeed patients with similar absolute risks of CVD, who achieved similar absolute LDL-c reductions, have benefitted to a similar extend from therapy in trials, irrespective of baseline level of dyslipidemia [5].Coronary artery calcium (CAC) is a non-invasive measure of subclinical coronary atherosclerosis, which improves absolute risk assessment, in addition to traditional risk factors [6-9]. It is of particular use in individuals at intermediate risk [8,9], and seems superior to other novel risk markers [9]. Guidelines therefore now recommend (class IIa recommendation) CAC measurement in asymptomatic intermediate-risk patients (10-20% 10-year risk) and (class IIb) low- to intermediate-risk patients (6-10% 10-year risk) [10].
CAC measurement is currently not recommended in dyslipidaemia guidelines [1-4]. In order to explore its potential role in such guidelines, this study evaluated the relationship between CAC and dyslipidemia in relation to CVD outcomes in the Multi-ethnic Study of Atherosclerosis (MESA)[6,11]. Dyslipidemia was categorized as the number of lipid abnormalities (LAs): high LDL-c, low HDL-c and/or high triglyceride levels, since counting LAs may reflect the way that clinicians and patients think about increasing burden of dyslipidemia. In parallel, dyslipidemia was also classified by TC/HDL-c quartiles.
Main results
- Of 6814 adults (45-85 years old), free of clinical CVD, of the general population that enrolled in this study, 36% participants had 0 LA, 37% had 1 LA, 22% had 2 LA and 6% had 3 LA.
- 58% of individuals without LA had CAC=0. CAC scores of 1-99 and >100 were seen in 22% and 20% respectively in individuals with 0 LA. In subjects with 3 LA, the respective prevalences were 29% and 21%. Categorising dyslipidemia by TC/HDL-c quartiles yielded similar results.
- CVD rate was 7.1 per 1000 person-years (py, 95%CI: 5.8-8.7) for those without LA, and 9.3 (95%CI: 7.8-11.0), 11.6 (95%CI: 9.5-14.2) and 13.9 (95%CI: 9.8-19.8) per 1000 py in those with 1, 2 and 3 LA respectively.
CVD event rates were 3.0 per 1000 py (95%CI: 2.4-3.9) for those with CAC=0, and 9.8 (95%CI: 8.0-12.0) and 26.5 (95%CI: 23.0-30.5) per 1000 py in those with CAC of 1-99 and >100 respectively.
- Individuals with no LA and CAC>100 had a higher event rate as compared to individuals with 3 LA but CAC=0 (22.2 vs. 6.2 vs. 1000 py).
- The ‘hard CVD event’ rates (myocardial infarction, resuscitated cardiac arrest, stroke, CV death) were 2.5 per 1000 py (95%CI: 1.9-2.3) in subjects with CAC=0, 7.7 per 1000 py (95%CI: 6.1-9.6) in those with CAC=1-99 and 16.9 per 1000 py (95%CI: 14.2-20.1) in those with CAC>100.
Conclusion
This study evaluated two paradigms of risk assessment in the multi-ethnic, asymptomatic general adult community: dyslipidemia (risk factor) and CAC (measurable atherosclerosis). CAC stratifies CVD risk irrespective of the burden of dyslipidemia, and regardless of how dyslipidemia is defined.About one in five individuals without any dyslipidemia by traditional definitions, had CAC>100, and high absolute CVD risk. Detecting subclinical atherosclerosis by CAC may facilitate more reliable risk assessment, and prioritising statin treatment in high-risk individuals.
References
1. Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report. National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). Circulation. 2002;106:3143-421.
2. Grundy SM, Cleeman JI, Merz CN, et al; Coordinating Committee of the National Cholesterol Education Program. Circulation. 2004;110:227-39.
3. European Association for Cardiovascular Prevention & Rehabilitation, Reiner Z, Catapano AL, De Backer G, et al; ESC Committee for Practice Guidelines (CPG) 2008-2010 and 2010-2012 Committees. ESC/EAS Guidelines for the management of dyslipidaemias: the Task Force for the management of dyslipidaemias of the European Society of Cardiology (ESC) and the European Atherosclerosis Society (EAS). Eur Heart J. 2011;32:1769-1818.
4. Genest J, McPherson R, Frohlich J, et al. 2009 Canadian Cardiovascular Society/Canadian guidelines for the diagnosis and treatment of dyslipidemia and prevention of cardiovascular disease in the adult - 2009 recommendations. Can J Cardiol. 2009;25:567-79.
5. Cholesterol Treatment Trialists’ (CTT) Collaboration, Baigent C, Blackwell L, Emberson J, et al. Efficacy and safety of more intensive lowering of LDL cholesterol: a meta-analysis of data from 170,000 participants in 26 randomised trials. Lancet. 2010;376:1670-81.
6. Detrano R, Guerci AD, Carr JJ, et al. Coronary calcium as a predictor of coronary events in four racial or ethnic groups. N Engl J Med 2008;358:1336-45.
7. Polonsky TS, McClelland RL, Jorgensen NW, et al. Coronary artery calcium score and risk classification for coronary heart disease prediction. JAMA. 2010;303:1610-16.
8. Greenland P, LaBree L, Azen SP, et al .Coronary artery calcium score combined with Framingham score for risk prediction in asymptomatic individuals. JAMA. 2004;291:210-5.
9. Yeboah J, McClelland RL, Polonsky TS, et al. Comparison of novel risk markers for improvement in cardiovascular risk assessment in intermediate-risk individuals. JAMA 2012;308:788-95.
10. Greenland P, Alpert JS, Beller GA, et al; American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. 2010 ACCF/AHA guideline for assessment of cardiovascular risk in asymptomatic adults: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2010; 122: e584-636.
11. Bild DE, Detrano R, Peterson D, et al. Ethnic differences in coronary calcification: the Multi-Ethnic Study of Atherosclerosis (MESA). Circulation. 2005;111:1313-20.