Take-home Messages:

• The presence of lower-leg peripheral arterial disease (PAD) greatly increases CV risk.
• Cardiologists should check for PAD in patients referred from primary care because it is a commonly missed diagnosis.
• Recently updated guidelines provide a thorough overview of the diagnosis and management of PAD.

The prevalence of peripheral arterial disease (PAD) is greater than that of HF or stroke (and comparable to the prevalence of MI), affecting approximately 8-12 million Americans. In people with lower-limb PAD, the risk of experiencing a major CV event (ie, MI, stroke, or vascular-related death) is about 5% per year. However, for individuals with critical limb ischemia and the lowest ankle brachial index (ABI), annual mortality soars to approximately 25%.

While intermittent claudication is the classic sign of PAD, in fact only 10-15% of people with PAD have the intermittent claudication; about 40% of PAD patients do not complain of leg pain at all, while the remaining 45-50% report a variety of leg symptoms other than classic claudication.

Is the prognosis better in asymptomatic patients? No. As Issam Moussa, MD, explained in a recent review of PAD guidelines presented at AHA 2011, the progression of the underlying PAD is identical whether or not the patient has leg symptoms.

This helps explain why patients referred from primary care should be checked for PAD in the cardiologist’s office. It’s a diagnosis often missed in general practice: In one analysis of data from Harvard’s PARTNERS program, fewer than 50% of patients with PAD were aware of their condition while physicians were aware of PAD in only 30% of their afflicted patients (Figure 1).¹ So, the majority of patients with PAD are not being diagnosed at the primary care level.

Cardiologists are doing a better job, but a surprisingly large number of PAD patients are still being missed. Moussa and colleagues reviewed a total of 800 patients at high risk for PAD who were referred for coronary angiography but without prior diagnosis of PAD.² Evaluation involved a medical history, a questionnaire to assess symptoms and functional status, and measurement of ABI. PAD was considered present if the ABI was 0.90 or less, which is based on guidelines.

In this study, the prevalence of previously unrecognized PAD was 15% (95% CI: 12.6-17.7) and was highest among patients >70 years of age (25.2%) and in women (23.3%).

Who’s at Risk?

• Age <50 years with diabetes, and one additional risk factor (eg, smoking, dyslipidemia, hypertension, or hyperhomocysteinemia)
• Age 50 to 69 years and history of smoking or diabetes
• Age 70 years and older
• Leg symptoms with exertion (suggestive of claudication) or ischemic rest pain
• Abnormal lower extremity pulse examination
• Known atherosclerotic coronary, carotid, or renal artery disease

The risk factors for atherosclerosis-related PAD are similar but not identical to those risk factors related to atherosclerosis in general (Figure 2). This is especially true in terms of the predictive strength of individual risk factors compared to those for CHD. Diabetes and cigarette smoking are stronger risk factors for PAD than for CHD.

Indeed, smoking is the single most important modifiable risk factor for developing PAD. Smoking facilitates the progression of PAD, reduces the durability of revascularization procedures, increases the rate of limb amputation, and adversely impacts mortality. However, aggressive management of all CV risk factors is critical in the patient with PAD to not only prevent peripheral disease progression, but also to prevent major CV events, such as MI or stroke.

Focused Update

The 2011 PAD guidelines focused update for managing PAD makes a variety of recommendations related to diagnostic methods and treatment elated to lower-limb PAD.

Diagnostic Methods

• ABI, toe-brachial index, and segmental pressure examination
• pulse volume recording
• noninvasive imaging studies (eg, duplex ultrasound, computed tomographic angiography, or magnetic resonance angiography) or digital subtraction angiography

Treatment

• smoking cessation
• antiplatelet and antithrombotic therapy
• for critical limb ischemia: endovascular and open surgical treatment for limb salvage

General Principles of Management
    for Patients with Intermittent Claudication

• risk factor modification (pharmacotherapy)
• supervised exercise training and symptom-directed pharmacotherapy (usually cilosazol 100 mg BID) Note: The guidelines state that the usefulness of unsupervised exercise programs is not well established as an effective initial treatment modality for patients with intermittent claudication.
• assess to determine need for revascularization
• surgical versus endovascular revascularization

Surgical Interventions are Indicated for Patients
  with Symptoms of Claudication Who

• have significant functional disability that is vocational or lifestyle limiting
• are unresponsive to exercise or pharmacotherapy
• have a reasonable likelihood of symptomatic improvement

References:

1. Hirsch AT, Criqui MH, Treat-Jacobson D, et al. Peripheral arterial disease detection, awareness, and treatment in primary care. JAMA 2001;286:1317-24.
2. Moussa ID, Jaff MR, Mehran R, et al. Prevalence and prediction of previously unrecognized peripheral arterial disease in patients with coronary artery disease: the Peripheral Arterial Disease in Interventional Patients Study Catheter Cardiovasc Interv 2009;73:719-24.
3. Rooke TW, et al. 2011 ACCF/AHA Focused Update of the Guideline for the Management of Patients With Peripheral Artery Disease (updating the 2005 guideline): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2011;58:2020-45. http://content.onlinejacc.org/cgi/content/full/58/19/2020

Keywords: Intermittent Claudication, Stroke, Atherosclerosis, Ankle Brachial Index, Angiography, Digital Subtraction, Risk Factors, Peripheral Arterial Disease, Lower Extremity, Smoking, Coronary Angiography, Diabetes Mellitus, Primary Health Care

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