Two articles in the Society of Interventional Radiology's flagship publication, the Journal of Vascular and Interventional Radiology, report on studies related to peripheral arterial disease or PADcoinciding with the approach of September's National PAD Awareness Month. In one study, researchers determined that Framingham Risk Score metrics (historically the gold standard in predicting 10-year cardiovascular risk) alone may not be enough to definitively say whether an individual may face a future cardiovascular event. The second study examined the success of a treatment option for what could be a serious complication of PAD. For more than a decade SIR has sponsored Legs For Life, a national screening program designed to detect peripheral arterial disease early, when lifestyle changes and medication could improve symptoms and possibly circumvent serious consequences.
"As these studies show, early detection and intervention is crucial to a good outcome. An integrated program like Legs For Life assists communities with early detection and management of peripheral arterial disease," explained Sanjay Misra, M.D., FSIR, chair of SIR's PAD Service Line.
"The Society of Interventional Radiology's Legs For Life national screening program wants to make individuals aware of the existence of undetected health problems, help identify whether they have PAD and encourage them to seek follow-up with their primary care doctor and an interventional radiologist," said the interventional radiologist at the Mayo Clinic and Foundation for Medical Education and Research in Rochester, Minn. "The publicas well as the medical communityneed to understand the importance of the diagnosis of PAD in terms of symptoms and, more importantly, in how a diagnosis of PAD brings added risk of heart attack, stroke and death," he explained.
An estimated 10 million people suffer from PADa common yet serious disease that is an indicator for heart attack (the leading cause of death in the United States) and strokeand many with the disease may be unaware that they have it. Peripheral arterial disease develops mostly as a result of atherosclerosis or hardening of the arteries, which occurs when cholesterol and scar tissue build up, forming plaque that narrows and clogs the arteries, slowing blood flow to the legs. Symptomssuch as leg pain while walking, numbness and tingling in the lower legs and feet, coldness in the lower legs and feet, or ulcers or sores on the legs or feet that don't healcould be PAD warning signs. Risk factors such as smoking, diabetes, high blood pressure, high blood cholesterol and obesity are associated with increased risk of heart attack and are routinely monitored by doctors to identify at-risk patients. However, about two-thirds of coronary events occur in individuals not known to be at high risk and physicians know that often, by the time that heart problems are detected, atherosclerosis is usually quite advanced, having progressed for decades.
A common formula called the Framingham Risk Score is used to estimate the 10-year cardiovascular risk of an individual. "Traditional risk-scoring algorithms, such as the Framingham Risk Score, have low sensitivity for predicting risk of fatal or nonfatal cardiovascular events," stressed Rajoo Dhangana, M.D., at Bridgeport Hospital in Bridgeport, Conn., one of the authors of the study, "Prevalence of Abnormal Ankle Brachial Index Among Individuals With Low or Intermediate Framingham Risk Scores."
"Ankle brachial index, a noninvasive and simple screening test for peripheral arterial disease, compares blood pressure reading in the arm and ankle. This is shown to have potential to improve identification of individuals who are otherwise not considered to be at high risk for heart attacks," explained Dhangana.
Screening programs such as SIR's Legs For Life often use an ankle brachial index to determine how well the blood is flowing and if additional tests are needed. The ABI is a direct measure of fatty plaque buildup in leg arteries and an indirect gauge of plaque accumulations throughout the entire cardiovascular system. Because atherosclerosis is a systemic disease, women and men developing plaque in their legs are likely to have plaque building up in the carotid arteries, which can lead to stroke, or in the coronary arteries, which can lead to heart attack, explained Dhangana.
"Evaluating the connection between peripheral arterial disease and heart disease is important, as an abnormal ankle brachial index is associated with a higher risk of cardiovascular disease and is considered a marker for coronary heart disease or its equivalent," Dhangana said.
In the study, Dhangana and fellow researchers examined the Framingham Risk Score variables from 822 participants, (women, 69.7 percent; non-Hispanic white, 89.7 percent) without known cardiovascular disease or diabetes. The participants' Framingham Risk Scores alone showed 463 (56.3 percent) were deemed to be at low risk; 212 (25.8 percent) at intermediate risk; and 147 (17.9 percent) were at high risk. When researchers examined the ABI scores of these three groups during evaluations at 23 Legs For Life sites across the United States, explained Dhangana, abnormal ABI readings were recorded in 12.3 percent of those deemed low risk and in 12.2 percent of those categorized as intermediate risk, using Framingham scores alone. "By itself, Framingham assessment is not 100 percent accurate in predicting a future coronary event," said Dhangana. "Ankle brachial index testing should be an important part of the screening process because even those identified as low risk with Framingham metrics could face coronary heart disease in the future," he said.
Early detection of PAD is important because when individuals are at significantly increased risk preventive measures can be taken. Since the leg pain caused by PAD is one indicator for heart attack and stroke, interventional radiologists can partner with primary care doctors, who may not be aware ofor able to administernoninvasive tests like the ABI in managing patients' vascular disease. When PAD is diagnosed, physicians may first recommend lifestyle changes (smoking cessation, blood glucose and blood pressure control, lowering cholesterol and exercise) and medical intervention (such as blood thinners or drugs that dilate an affected artery), all of which can be started before costlier and more intensive interventions are needed. If necessary, interventional radiologists can perform minimally invasive treatments such as angioplasty and/or stenting (inserting a tiny mesh tube) to open a blocked artery in the leg and restore blood flow.
Researchers noted that sometimes, when lifestyle changes to combat PAD are unsuccessful in stemming the disease's progression, dangerous aorto-iliac lesionswounds on or near pelvic arteriesmay develop. In "Bifurcated Endograft in Aorto-iliac Type C and D Lesions: Long-term Results," Tobias Zander, M.D., an interventional radiologist with the department of endovascular therapy, Hospiten Rambla, Tenerife, Spain, examined the use of a forked (bifurcated) prosthesis (an artificial device or mechanism that replaces a missing or damaged body part) as an alternative to bypass surgery on these types of lesions.
"In this study, a type of prosthesis that is normally used to treat aneurysm of the lower aorta, but has also been employed successfully for the treatment of these lesions, was placed in 14 patients with no related amputation or death," explained Zander. "Patients were followed up for an average of 62 months. Occlusion (a blockage of the prosthesis) was noted in only two individuals, and both of those were subsequently treated with complete relief of their symptoms. These positive results reveal a minimally invasive treatment that may be an alternative to traditional surgery," noted Zander.
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Society of Interventional Radiology