Evidence for greater burden of peripheral arterial disease in lower extremity arteries of spinal cord-injured individuals

Bell JW, Chen D, Bahls M, Newcomer SC. Evidence for greater burden of peripheral arterial disease in lower extremity arteries of spinal cord-injured individuals. Am J Physiol Heart Circ Physiol 301: H766-H772, 2011. First published July 8, 2011; doi:10.1152/ajpheart.00507.2011.-Spinal cord injury leads to increased risk for cardiovascular disease and results in greater risk of death. Subclinical markers of atherosclerosis have been reported in carotid arteries of spinal cord-injured individuals (SCI), but the development of lower extremity peripheral arterial disease (PAD) has not been investigated in this population. The purpose of this study was to determine the effect of spinal cord injury on ankle-brachial index (ABI) and intima-media thickness (IMT) of upper-body and lower-extremity arteries. We hypothesized that the aforementioned measures of lower-extremity PAD would be worsened in SCI compared with controls and that regular participation in endurance exercise would improve these in both groups. To test these hypotheses, ABI and IMT were determined in 105 SCI and compared with 156 able-bodied controls with groups further subdivided into physically active and sedentary. ABIs were significantly lower in SCI versus controls (0.96 +/- 0.12 vs. 1.06 +/- 0.07, P < 0.001), indicating a greater burden of lower-extremity PAD. Upper-body IMTs were similar for brachial and carotid arteries in controls versus SCI. Lower extremity IMTs revealed similar thicknesses for both superficial femoral and popliteal arteries, but when normalized for artery diameter, individuals with SCI had greater IMT than controls in the superficial femoral (0.094 +/- 0.03 vs. 0.073 +/- 0.02 mm/mm lumen diameter, P < 0.01) and popliteal (0.117 +/- 0.04 vs. 0.091 +/- 0.02 mm/mm lumen diameter, P < 0.01) arteries. The ABI and normalized IMT of SCI compared with controls indicate that subclinical measures of lower-extremity PAD are worsened in individuals with SCI. These findings should prompt physicians to consider using the ABI as a screening method to detect lower-extremity PAD in SCI.