The ABI, a noninvasive test that can be performed in a medical office, is more closely associated with leg function in persons with peripheral arterial disease than is intermittent claudication or other leg symptoms. These data support the use of the ABI to identify abnormal lower-extremity function.
There is a wide range of leg symptoms in persons with PAD beyond that of classic IC. Comorbid disease may contribute to these symptoms in PAD. Functional impairments are found in every PAD symptom group, and the degree of functional limitation varies depending on the type of leg symptom.
Previous reports suggest that the severity of peripheral arterial disease (PAD), measured by the ankle–brachial index (ABI), is not associated with the magnitude of walking impairment, measured by treadmill testing. These prior studies have had small sample sizes and included only PAD participants with symptoms of intermittent claudication. We studied the association of the ABI with diverse measures of walking performance in a cross-sectional study of 156 participants with PAD with and without intermittent claudication symptoms. Outcomes included the Gardner–Skinner treadmill test, 6-minute walk, 4-meter walking velocity at usual and fastest pace, and the walking impairment questionnaire (WIQ). Adjusting for age, sex, race, comorbidities, leg symptoms, and other confounders, lower ABI values were associated with shorter distance achieved in the 6-minute walk (ABI < 0.50: 286 meters;ABI 0.50–0.70: 316 meters;ABI 0.71–0.95: 355 meters, p trend < 0.001), shorter maximal treadmill walking time (ABI < 0.50:6.0 minutes;ABI 0.50–0.70:6.9 minutes;ABI 0.71–0.95:8.3 minutes, p trend = 0.009), and lower WIQ distance scores (p trend = 0.007) among PAD participants. The ABI was not associated significantly with walking velocity over 4 meters, treadmill time to onset of leg symptoms, or the WIQ speed or stair-climbing scores. In conclusion, among 156 participants with PAD with and without intermittent claudication, lower ABI values are associated significantly with poorer walking endurance, assessed by three distinct measures.
OBJECTIVES
We studied associations of magnetic resonance imaging measurements of plaque area and relative percent lumen reduction in the proximal superficial femoral artery with functional performance among participants with peripheral arterial disease.
BACKGROUND
The clinical significance of directly imaged plaque characteristics in lower extremity arteries is not well established.
METHODS
A total of 454 participants with an ankle brachial index <1.00 underwent magnetic resonance cross-sectional imaging of the proximal superficial femoral artery and completed a 6-min walk test, measurement of 4-m walking velocity at usual and fastest pace, and measurement of physical activity with a vertical accelerometer.
RESULTS
Adjusting for age, sex, race, body mass index, smoking, statin use, comorbidities, and other covariates, higher mean plaque area (1st quintile [least plaque]: 394 m, 2nd quintile: 360 m, 3rd quintile: 359 m, 4th quintile: 329 m, 5th quintile [greatest plaque]: 311 m; p trend <0.001) and smaller mean percent lumen area (1st quintile [greatest plaque]: 319 m, 2nd quintile: 330 m, 3rd quintile: 364 m, 4th quintile: 350 m, 5th quintile: 390 m; p trend <0.001) were associated with shorter distance achieved in the 6-min walk test. Greater mean plaque area was also associated with slower usual-paced walking velocity (p trend = 0.006) and slower fastest-paced 4-m walking velocity (p trend = 0.003). Associations of mean plaque area and mean lumen area with 6-min walk distance remained statistically significant even after additional adjustment for the ankle brachial index and leg symptoms.
CONCLUSIONS
Among participants with peripheral arterial disease, greater plaque burden and smaller lumen area in the proximal superficial femoral artery are associated independently with poorer functional performance, even after adjusting for the ankle brachial index and leg symptoms.
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