SIR: ABI testing can better predict those at risk for coronary disease

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Testing patients for peripheral arterial disease (PAD) via abnormal ankle brachial index (ABI) exams can identify patients at risk for future cardiac events who were not considered at high-risk by Framingham risk assessments, according to results of a clinical trial presented March 15 at the 35th annual scientific meeting of the Society of Interventional Radiology in Tampa, Fla.

Timothy P. Murphy, MD, of the Rhode Island Hospital in Providence, R.I., and colleagues aimed to compare the results of Framingham Risk Score (FRS) and ABI tests for their ability to predict cardiovascular disease (CVD) in patients. “Traditional risk scoring algorithms, such as FRS, are known to have low sensitivity for predicting risk of fatal or non-fatal cardiovascular events, “according to Murphy.

During the trial, the researchers evaluated data from the previously conducted PEDAL study that enrolled 822 patients without known CVD or diabetes and screened for PAD with ABI.

"With the help of the simple ankle-brachial index (ABI) test, a comparative blood pressure reading in the arm and ankle that is used to screen for peripheral arterial disease, thousands of lives can possibly be saved," Murphy noted.

The study placed patients in three categories of risk: low, medium or high after testing with Framingham. Of the participants, 31.1 percent were classified as being low risk and 50.3 percent as intermediate risk. Abnormal ABIs were observed in 11.3 percent and 12.8 percent of these patients, respectively.

Additionally, 10 percent of the 822 trial participants had an abnormal ABI but were classified as having low or intermediate risk as identified by FRS and would not be considered for aggressive therapy.

According to Murphy, 1.1 million Americans suffer from heart attacks annually and two-thirds of these patients are not known to be at high risk for adverse events.

"Any methods to improve identification of individuals who are otherwise not considered at high risk for heart attack—based on Framingham risk factors—would have significant public health impact,” said Murphy. "Early detection is paramount. Primary preventions, such as initiating lifestyle changes and medical intervention directed at modifying risk factors (smoking cessation, blood glucose and blood pressure control, lowering cholesterol and exercise)—can be started before costlier and more intensive interventions are needed," he concluded.