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Ankle Brachial Index May Affect CHD Risk Status


 

Major Finding: 11.3% of individuals classified as low risk and 12.8% of individuals classified as intermediate risk using the Framingham Risk Score had an abnormal ankle brachial index.

Data Source: A multicenter cross-sectional study of 822 individuals conducted in conjunction with a national free public PAD screening program conducted at 23 sites during 2007-2009.

Disclosures: Dr. Dhanghana reported that he has no relevant financial relationships.

TAMPA — More than 10% of patients with low to intermediate risk for coronary heart disease have an abnormal ankle brachial index, putting them at a higher risk for myocardial infarction and coronary death than predicted by conventional measures.

In a study of 822 individuals screened for peripheral artery disease (PAD), 11% of those with a low-risk Framingham Risk Score (FRS) for coronary disease and 13% of those with an intermediate-risk score had an abnormal ankle brachial index (ABI).

Abnormal ABI has been associated with increased risk of coronary heart disease events and mortality, even in individuals at low to intermediate CHD risk (JAMA 2008;300:197-208).

However, prevalence estimates of abnormal ABI among older screening populations with low-intermediate FRS have not been reported previously, Dr. Raj Dhangana said at the annual meeting of the Society of Interventional Radiology.

“The prevalence of abnormal ABI is high, even in those a without high Framingham Risk Score. … The use of abnormal ABI in screening has the potential to improve risk prediction,” according to Dr. Dhangana.

The findings are good news, given that at least 60% of CHD events occur in individuals who were not known to be at high risk (BMJ 2003;327:1267). In fact, almost two-thirds of events occur in individuals who are either at low or intermediate risk using the FRS (Am. Heart J. 2002;144:95-100).

The use of ABI for screening could help improve risk prediction for CHD, said Dr. Dhangana, a research fellow at Rhode Island Hospital in Providence.

The researchers analyzed data from the PEDAL Study (Population-Based Examinations to Determine Ankle-Brachial Index)—a multicenter, cross-sectional study conducted at 23 sites of the Legs for Life national free public PAD screening program in 2007-2009.

Patients were included in the analysis if they were at least age 18 years and if their ABI and FRS variables were available. Those with a history of diabetes, CHD, stroke, or athero- sclerotic vascular disease were excluded.

The FRS was calculated for each participant to determine 10-year risk of CHD. Based on their FRS, patients were stratified into three risk categories: low (less than 6%), intermediate (6%-19%), and high (at least 20%). An abnormal ABI was defined as less than 0.9 and/or greater than 1.4 in either leg.

A low FRS was observed in 256 individuals (31%), and 414 (50%) had an intermediate risk, Dr. Dhangana said.

Risk prediction could be improved if abnormal ABI is used in screening.

Source Society of Interventional Radiology/www.SIRweb.org

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