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The ABI: Standardizing Measurements & Interpretations

The ABI: Standardizing Measurements & Interpretations

When the ankle-brachial index (ABI) emerged in 1950, it was initially proposed for use as a noninvasive diagnostic tool for lower-extremity peripheral artery disease (PAD). Since then, studies have shown that the ABI is an indicator of atherosclerosis at other vascular sites, making it a useful prognostic marker for cardiovascular events and functional impairment, even in the absence of symptoms of PAD. In an issue of Circulation, the American Heart Association (AHA) released a scientific statement with standardized recommendations for measuring and monitoring the ABI. The recommendations provide protocols and thresholds for use in PAD and cardiovascular risk prediction, according to Michael H. Criqui, MD, MPH, FAHA, who co-chaired the writing committee that developed the scientific statement. “A lack of standards for measuring and calculating the ABI can lead to discrepancies that can significantly impact both prevention and treatment of cardiovascular disease,” he says. “The estimated prevalence of PAD may vary substantially according to the mode of ABI calculation.” Reducing Variation in ABI Technique Recent studies have revealed that techniques for performing the ABI vary from clinician to clinician. Several variables have been identified, including the position of patients during measurement, the sizes of the arm and leg cuffs, and the method of pulse detection over the brachial artery and at the ankles. Other variables include whether the arm and ankle pressures were measured bilaterally, which ankle pulses were used, and whether a single measure or replicate measures were obtained. Several recommendations have been endorsed by the AHA for measuring the ABI (Table 1). “These recommendations can serve as a guide to ensure that clinicians are measuring the ABI...

Women & Peripheral Arterial Disease: A Call to Action

About 8 million people in the United States have peripheral artery disease (PAD), a condition that, if left untreated, increases heart attack and stroke risks, severely limits walking ability, and causes tissue death requiring limb amputation. The prevalence of PAD is nearly equal between men and women (Figure). Only about 10% of individuals with PAD experience classic, recognized exertional claudication, and many people experience no symptoms at all. As a result, few individuals with PAD receive prompt diagnosis or treatment. “The mortality rate and healthcare costs associated with PAD are comparable to those of heart disease and stroke,” says Alan T. Hirsch, MD. “Women, in particular, suffer an immense burden from PAD, but current data suggest that most women remain unaware of their risk. PAD continues to go largely unrecognized and untreated in women.” An Important Scientific Statement on PAD In the March 20, 2012 issue of Circulation, the American Heart Association (AHA), in collaboration with the Vascular Disease Foundation and the P.A.D. Coalition, released a scientific statement on women and PAD. It recommends that healthcare providers proactively increase awareness of and test women at risk for PAD. It also calls for more women-focused research into the disease. “There is a great need to identify women with PAD and those who are at risk for it, especially African-American women, so that we can help lower cardiovascular ischemic event rates,” says Dr. Hirsch, who was the chair of AHA writing group that developed the call-to-action statement. “This may also reduce the loss of independent functional capacity and ischemic amputation rates.” He notes that women in the United States already attend...

Post-Exercise ABI Beneficial in PAD

Use of a post-exercise ankle brachial index (ABI) appears to be a powerful independent predictor of all-cause mortality among patients with peripheral arterial disease, or PAD, and provides additional risk stratification beyond the ABI at rest, according to findings from an observational analysis. Patients with an ABI of 0.85 or higher before and after exercise had a 10-year mortality rate of 32.7%, compared with a 41.2% rate, which was observed in patients with a normal ABI at rest but an ABI of less than 0.85 after exercise. An abnormal post-exercise ABI result independently predicted mortality (hazard ratio 1.3). Additional independent predictors of mortality...

Conference Highlights: 2010 Society of Interventional Radiology Meeting

The Society of Interventional Radiology held its 2010 annual meeting from March 13 to 18 in Tampa, Florida. The features below highlight some of the news emerging from the meeting. For more information on these items and other research that was presented, go to www.sirmeeting.org. » Preventing Strokes During Carotid Artery Stenting » Abnormal ABI Indicative of Cardiovascular Events » Vertebroplasty Relieves Pain for Osteoporotic VCFs Preventing Strokes During Carotid Artery Stenting The Particulars:Until recently, most carotid artery stenting procedures have been performed with filters in order to remove debris. The FDA has cleared a proximal cerebral protection device (Mo.Ma, Invatec) for use during carotid artery stenting. It suspends blood flow and prevents debris from traveling to the brain. Data Breakdown:Investigators evaluated the safety and effectiveness of the proximal cerebral protection device in 262 patients with carotid artery disease considered high risk. The 30-day major adverse cardiac and cerebrovascular events rate was 2.7%, a finding below the performance goal of 13% set before the start of the study. The major stroke rate was 0.9% through to the end of the trial; the death rate was also 0.9%. Take Home Pearls: Use of a proximal cerebral protection device may be able to prevent strokes during carotid stenting procedures. Results add to the body of data to support stenting as an alternative to surgery. Abnormal ABI Indicative of Cardiovascular Events [back to top] The Particulars:The ankle-brachial index (ABI) test is a noninvasive blood pressure reading in the ankle used to screen for peripheral artery disease (PAD). The ABI may provide another way to identify cardiovascular risks in older patients not considered...
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