Physicians' Academy for Cardiovascular Education

Differential associations seen between Lp(a) levels and stroke, depending on AF-status

Associations of Lipoprotein(a) Levels With Incident Atrial Fibrillation and Ischemic Stroke: The ARIC (Atherosclerosis Risk in Communities) Study

Literature - Aronis KN, Zhao D, Hoogeveer RC et al., - J Am Heart Assoc. 2017;6:e007372. Originally published December 15, 2017

Background

Lipoprotein(a) [Lp(a)] has similar lipid composition to LDL-c, with the distinguishing apolipoprotein(a) covalently bound to apoB-100 [1]. Lp(a) has been associated with an increased risk of coronary heart disease (CHD) and stroke, and has increasingly been recognized as an important CV risk factor [2]. This is the result of both its proatherogenic effects as a lipoprotein and the prothrombotic effects, as a consequence of its resemblance to plasminogen. Mendelian randomization studies suggested a causal relationship of Lp(a) with CHD [3]. Other effects of Lp(a) on the CV system that have been described include calcific aortic sclerosis [4].

The link between Lp(a) and atrial fibrillation (AF) is unclear to date, and it has not been studied prospectively. Atherosclerotic CV disease and markers of atherosclerosis such as coronary calcium score and cIMT have been associated with AF [5,6], but the role of Lp(a) as an independent risk factor for AF remains to be elucidated. Although blacks and women have higher Lp(a) than whites and men, respectively, both former groups show lower incidences of AF. Limited data are also available on the relationship between Lp(a) and AF-related stroke.

This study aimed to prospectively evaluate associations between Lp(a) and incident AF and to assess potential interactions with race and sex. Moreover, associations between Lp(a) and stroke in persons with or without AF were assessed prospectively. Data of the biracial ARIC (Atherosclerosis

Risk in Communities) study [7] were benefitted from. For the primary aim, 9908 ARIC participants free of prevalent or incident AF were included (median follow-up: 13.9 years, IQR: 12.4-14.8), and for the second aim all ARIC participants free of prevalent or incident stroke were included (n=10127, median follow-up: 15.8 years, IQR: 13.6-16.7 years).

Main results

Conclusion

In this large community-based cohort, no association was observed between elevated Lp(a) levels and AF risk, in black nor whites, and in men nor women. Participants in the highest Lp(a) category (≥50 mg/dL) without AF did show a 40% higher risk of ischemic stroke, as compared with the lowest Lp(a) category (<10 mg/dL). This elevated risk is, however about 10-fold lower than the risk of stroke conveyed by AF itself.

References

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