Peripheral arterial disease (PAD) is a chronic condition caused by atherosclerotic narrowing and blocking of the peripheral arteries. The most common manifestation of PAD is intermittent claudication (IC), which is marked by exertional discomfort in the leg or buttock muscles. Typically, complaints are provoked by walking and resolve after a brief rest. These symptoms limit walking ability leading to functional disability in daily life. Treatment of IC aims at reducing symptoms and thereby improving walking capacity and health-related quality of life (QoL). Thus, disease severity and treatment outcomes are expressed by walking distance limitations on standardized treadmill tests, and patient reported outcome measures reflecting health-related QoL.
Over the past decade, supervised exercise therapy (SET) and endovascular revascularization (ER) have been shown to be equally effective with respect to improving walking distance and QoL in multiple trials. As SET is the non-invasive, less costly option, current (inter-)national guidelines recommend SET as primary treatment in the management of patients with IC. The most recent guidelines of the Dutch Society of Vascular Surgery advocate a 3 to 6-month trial of SET, saving invasive treatment for patients unresponsive to exercise therapy. Revascularization aims to eliminate the hemodynamically significant stenosis in the affected leg to alleviate symptoms. With SET both legs, as well as the general cardiopulmonary condition of the patient, are trained. The exact working mechanisms of exercise therapy are unclear, but several modes of action have been proposed. These include: enlargement of existing collateral vessels, angiogenesis, improved bioenergetics of skeletal muscles, enhanced nitric oxide (NO) endothelium-dependent vasodilatation, improved hemorrheology, and an altered pain threshold. Evidently, these effects appear independent from the location of the atherosclerotic lesion.
The evidence regarding the entire IC population unequivocally appoints a trial of SET as primary treatment. Yet, most studies examining SET programs do not specify the anatomic distribution of disease. Therefore, some clinicians argue that for patients with aortoiliac disease a lower threshold to initiate invasive treatment is warranted. This claim is based on two arguments: (1) outcomes of ER for iliac stenosis are relatively favorable compared to femoropopliteal stenosis (with 4-year patency rates of 70%), and (2) individuals with aortoiliac disease might experience less improvement after exercise training as they have more ischemic muscle mass during walking and are often more symptomatic than those with more distal disease. To examine these arguments, the SUPER study was initiated comparing SET with ER for patients with IC due to an iliac artery obstruction. However, the premise that SET is less effective in case of aortoiliac disease is not based on empirical evidence as of yet. Greenhalgh et al. reported the outcome of SET for aortoiliac and femoropopliteal disease separately, from a trial comparing SET with ER. While they made no formal comparison between outcomes in both anatomic groups, no apparent difference in effectiveness can be noted.
Based on the proposed working mechanisms and available evidence an inferior effect of SET due to lesion location cannot be assumed. To expand the clinical knowledge on this subject the current ELECT Registry is initiated. The aim of the ELECT Registry is to determine the effect of the location of stenosis (femoropopliteal versus aortoiliac versus multilevel disease) on the outcomes of SET in patients with IC (PAD Fontaine 2, Rutherford I-III), by recording the clinical outcomes from ‘real world’ subjects treated with SET, applying a minimal amount of subject selection criteria.