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Lipoprotein(a) and peripheral atherosclerosis in older adults
K Sutton-Tyrrell1, R W Evans, E Meilahn
1Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, PA 15261, USA.
Insights
Elevated lipoprotein(a) [Lp(a)] levels are independently linked to peripheral atherosclerosis in older adults. This association is particularly strong for lower extremity arterial disease (LEAD), indicating Lp(a) as a significant risk factor.
Area of Science:
- Cardiovascular Medicine
- Gerontology
- Biochemistry
Background:
- Peripheral atherosclerosis, including carotid stenosis and lower extremity arterial disease (LEAD), is a significant health concern in older adults.
- Lipoprotein(a) [Lp(a)] is an emerging risk factor for cardiovascular disease, but its independent association with peripheral atherosclerosis requires further investigation.
Purpose of the Study:
- To investigate the association between elevated lipoprotein(a) [Lp(a)] levels and the prevalence and severity of carotid and lower extremity arterial disease (LEAD) in older adults.
- To determine if Lp(a) is an independent risk factor for peripheral atherosclerosis, even after controlling for other established risk factors.
Main Methods:
- Ancillary study to the Systolic Hypertension in the Elderly Program involving 369 subjects.
- Carotid stenosis assessed by Doppler ultrasound; LEAD assessed by ankle/arm index (AAI).
- Serum Lp(a) levels measured, with values >= 20 mg/dl considered elevated.
Main Results:
- A significantly higher rate of carotid stenosis was observed in subjects with elevated Lp(a) (24%) compared to those with normal Lp(a) (14%) (P=0.020).
- The association between Lp(a) and LEAD was stronger, with 36% prevalence of low AAI in subjects with elevated Lp(a) versus 14% in those with normal Lp(a) (P<0.001).
- Elevated Lp(a) was also associated with increased severity of LEAD, and these associations remained significant after adjusting for other risk factors.
Conclusions:
- Elevated lipoprotein(a) [Lp(a)] is independently associated with peripheral atherosclerosis in older adults.
- The relationship between Lp(a) and atherosclerotic disease is particularly pronounced in the lower extremities.
- Lp(a) may serve as a valuable independent biomarker for identifying individuals at higher risk for peripheral arterial disease.
Abstract:
As part of an ancillary study to the Systolic Hypertension in the Elderly Program, carotid and lower extremity arterial disease (LEAD) were evaluated in 369 subjects, 186 with a systolic blood pressure (SBP) > or = 160 mmHg, and 183 with SBP < 160 mmHg. Both groups had a diastolic blood pressure (DBP) < 90 mmHg. Internal carotid stenosis was identified by Doppler and LEAD was assessed using the ankle to arm systolic blood pressure ratio, commonly called the ankle/arm index (AAI). Lp(a) values were obtained from frozen sera and values > or = 20 mg/dl were considered elevated. Rates of carotid stenosis were 24% among those with an Lp(a) > or = 20 mg/dl and 14% among those with an Lp(a) level < 20 mg/dl (P = 0.020). The relationship between Lp(a) and LEAD was even stronger. Those with an Lp(a) > or = 20 mg/dl had a 36% prevalence of a low AAI vs 14% among those with a Lp(a) level < 20 mg/dl (P < 0.001). Lp(a) values were also associated with the severity of LEAD. Controlling for other risk factors did not reduce the association between either LEAD or carotid stenosis and an Lp(a) > or = 20 mg/dl. Thus, Lp(a) appears to be independently associated with peripheral atherosclerosis in older adults, both men and women. The relationship is particularly strong for atherosclerotic disease of the lower extremities.