Highlights
- •Serum Lp(a) level was independently associated with unexplained ischemic stroke in young and middle-aged white adults.
- •By contrast, no association was detected between apo(a) isoform size and cryptogenic stroke in any race-ethnic group.
- •The findings support routine testing for Lp(a) in this setting, as more effective therapies to lower levels become available.
Abstract
Background and aims
Circulating lipoprotein (a) [Lp(a)] level relates inversely to apolipoprotein (a)
[apo(a)] size. Both smaller apo(a) isoforms and higher Lp(a) levels have been linked
to coronary heart disease and stroke, but their independent contributions are less
well defined. We examined the role of Lp(a) in younger adults with cryptogenic stroke.
Methods
Lp(a) and apo(a) isoforms were evaluated in a prospectively designed case-control
study of patients with unexplained ischemic stroke and stroke-free controls, ages
18 to 64. Serum Lp(a) was measured among 255 cases and 390 controls with both apo(a)-size
independent and dependent assays. Apo(a) size was determined by agarose gel electrophoresis.
Results
Cases and controls were similar in socio-demographic characteristics, but cases had
more hypertension, diabetes, smoking, and migraine with aura. In race-specific analyses,
Lp(a) levels showed positive associations with cryptogenic stroke in whites, but not
in the smaller subgroups of blacks and Hispanics. After full adjustment, comparison
of the highest versus lowest quartile in whites was significant for apo(a)-size-independent
(OR = 2.10 [95% CI = 1.04, 4.27], p = 0.040), and near-significant for apo(a)-size-dependent Lp(a) (OR = 1.81 [95% CI = 0.95,
3.47], p = 0.073). Apo(a) size was not associated with cryptogenic stroke in any race-ethnic
subgroup.
Conclusions
This study underscores the importance of Lp(a) level, but not apo(a) size, as an independent
risk factor for unexplained ischemic stroke in young and middle-aged white adults.
Given the emergence of effective Lp(a)-lowering therapies, these findings support
routine testing for Lp(a) in this setting, along with further research to assess the
extent to which such therapies improve outcomes in this population.
Keywords
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Article Info
Publication History
Published online: August 21, 2016
Accepted:
August 18,
2016
Received in revised form:
August 2,
2016
Received:
May 31,
2016
Identification
Copyright
© 2016 Elsevier Ireland Ltd. All rights reserved.
