Supervised Treadmill Exercise Therapy for Peripheral Artery Disease
Walking exercise is the most effective non-invasive therapy for improving maximal and pain-free walking distances in people with lower extremity peripheral artery disease (PAD). While both home-based and supervised treadmill walking exercise have been shown to improve pain-free and maximal walking distance in PAD, most randomized trials of walking exercise in patients with PAD have studied supervised treadmill exercise.
A meta-analysis by Fakhry et al., summarized 25 randomized clinical trials of supervised walking therapy (including 19 of supervised treadmill exercise) for 1,054 patients with PAD and intermittent claudication. who were randomized to either supervised walking exercise or a control group without exercise. The meta-analysis results showed that supervised exercise significantly improved maximal treadmill walking distance by 180 meters and pain-free walking distance by 128 meters, relative to the control group. Of the 21 trials that reported absolute data for change in maximal treadmill walking distance, 15 (71 percent) reported more than 50 percent improvement and five (21 percent) reported more than 100 percent improvement in maximal treadmill walking distance. Among the control groups, only one reported more than 50 percent improvement and none reported more than 100 percent improvement in maximal treadmill walking distance. In comparison, cilostazol, the only U.S. Food and Drug Administration approved medication for treating intermittent claudication symptoms that is currently recommended by clinical practice guidelines, provides approximately 25-40 percent improvement in treadmill walking distance.
When compared directly with endovascular revascularization, supervised treadmill exercise either had greater benefit or was not significantly different from endovascular revascularization for improving maximal treadmill walking distance in patients with PAD. For example, the CLEVER trial was a multicenter trial conducted in the U.S. that randomized 111 PAD patients with aortoiliac disease and claudication to six months of either supervised treadmill exercise, aortoiliac stenting or a control group. At six-month follow-up, both supervised exercise and the endovascular intervention significantly improved the primary outcome of maximal treadmill walking time, compared with the control group. Maximal treadmill walking distance improved more in the supervised treadmill exercise group than in the endovascular intervention group over that same timeframe, while most patients reported measures of walking ability and quality of life improved more in the endovascular intervention group than in the supervised exercise group.
Until recently, a significant barrier to PAD patients’ participation in supervised treadmill exercise programs was lack of medical insurance coverage for this therapy. However, as of 2017, the Centers for Medicare and Medicaid Services (CMS) provides coverage for supervised treadmill exercise therapy for PAD patients with ischemic leg symptoms. This newly available reimbursement improves access to supervised treadmill therapy and is expected to increase participation in supervised treadmill exercise programs by PAD patients. Clinicians should be prepared to refer patients with PAD for supervised treadmill exercise and should be familiar with characteristics of effective exercise programs. They should also be familiar with CMS policies regarding coverage.
Supervised treadmill exercise programs for patients with PAD are generally safe. Because of the common presence of co-existent coronary artery disease in patients with PAD, an exercise treadmill stress test should be performed prior to beginning a new exercise program. Despite the benefit of supervised exercise for ischemic leg symptoms, there is no evidence from randomized clinical trials that supervised treadmill exercise reduces mortality in patients with PAD.
Additional factors regarding supervised treadmill exercise should be considered. First, few studies have assessed the durability of benefit from supervised treadmill exercise. Second, supervised treadmill exercise should be offered in conjunction with lower extremity revascularization. Consistent clinical trial evidence demonstrates that patients who participate in supervised treadmill exercise combined with a revascularization procedure achieve greater improvement in treadmill walking than those who had either individual therapy.
Third, many patients with PAD may elect not to participate in supervised treadmill exercise. For these patients, home-based walking exercise may be a reasonable alternative. Fourth, results of randomized trials are inconsistent regarding their effect on physical activity in daily life for patients with PAD. The CLEVER trial reported no significant difference in physical activity in daily life for participants in the supervised exercise group compared with the control group or the endovascular revascularization group. Supervised treadmill exercise improves treadmill walking ability more than any other outcome, and further work is needed to identify an exercise intervention that increases all aspects of functioning in daily life for patients with PAD, including physical activity and quality of life.
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Keywords: ACC Publications, Cardiology Interventions, Intermittent Claudication, Peripheral Arterial Disease, Exercise Test, Coronary Artery Disease, Centers for Medicare and Medicaid Services, U.S., Quality of Life, Follow-Up Studies, United States Food and Drug Administration, Exercise Therapy, Tetrazoles, Medicaid, Primary Prevention, Preventive Health Services, Preventive Medicine, Secondary Prevention
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