Lp(a) cut-off values are applicable to calcific aortic valve disease in white and black individuals

Cao J, Steffen BT, Budoff M, et al.
Arterioscler Thromb Vasc Biol. 2016;36: published online ahead of print

Background

Subclinical CAVD, that is present in 15% to 40% of adults depending on age and race/ethnicity, and is expected to increase with the aging population,  may advance to valve stenosis and obstruction [1,2]. Aortic valve calcification (AVC) is a subclinical from of calcific aortic valve disease (CAVD) and an independent risk factor for CV disease [3,4]. AVC can progress to CAVD, particularly if certain CHD risk factors are present, like for example age, sex, hypertension, smoking, type II diabetes, hypercholesterolemia, and elevated concentrations of Lp(a)  [5,6]. However, it has not been investigated whether the Lp(a) cut-off values used in clinical laboratories (30 and 50 mg/dL) contribute to the identification of subclinical CAVD and its severity. Another open question is related to the potential differences between multiple races/ethnicities. Race-based differences in median Lp(a) levels have been reported according to which, black individuals typically have two- or three-fold higher Lp(a) levels compared with whites or Hispanics [7]. Interestingly, these Lp(a) levels did not translate into a two- or three-fold higher CHD risk [8].
In this analysis, the relationship between elevated Lp(a) levels and the presence of subclinical CAVD and the degree of AVC was examined in 4,678 participants of the Multi-Ethnic Study of Atherosclerosis (MESA).

Main results

• Associations between Lp(a) levels and the presence of AVC:

• in the entire sample: adjusted RR: 1.11; 95% CI: 1.02–1.21; P=0.02
• in white participants: RR: 1.19; 95% CI: 1.06–1.33; P=0.0023
• in black participants: RR: 1.26; 95% CI: 0.97–1.65; P=0.088
• in Hispanics or Chinese Americans: no significant associations

• The conventional 30 mg/dL Lp(a) clinical cutoff:  

• was associated with AVC in white participants (RR: 1.56; 95% CI: 1.24–1.96)  
• was borderline significant in black participants (RR: 1.55; 95% CI: 0.98–2.44, P=0.059)  

• Whites with levels ≥50 mg/dL also showed higher prevalence of AVC (RR: 1.72; 95% CI: 1.36–2.17) than those below this level
• Lp(a) (per 1 log unit) was associated with the severity of AVC:

• in black participants: OR: 1.48; 95% CI: 1.18–1.87
• in white participants: OR: 1.33; 95% CI: 1.17–1.51

Conclusion

In a large multiethnic cohort, significant associations between Lp(a) levels and subclinical CAVD were observed in black and white individuals, but not in Hispanic and Chinese Americans. The Lp(a) cutoff values that are currently used to assess CV risk seem to be applicable to CAVD, although race/ethnicity may be important in the selection of these cut-off values.

Find this article online at http://atvb.ahajournals.org/content/early/2016/03/03/ATVBAHA.115.306683.abstract

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