Author + information
- Justin D. Anderson, MD and
- Christopher M. Kramer, MD* ()
- ↵*University of Virginia Health System, Medicine and Radiology, P.O. Box 800170, Lee Street, Charlottesville, Virginia 22908-0001
We thank Dr. Abraham and colleagues for their interest in our paper (1). They suggest that proximal claudication may be in part responsible for functional limitation in patients with peripheral artery disease. We most certainly agree and have shown data to that effect in our paper (1). The measure of the runoff index from the magnetic resonance angiogram performed in each patient was an assessment of extent of peripheral atherosclerosis, corrected for the proximal nature of the disease (2). The more proximal the atherosclerosis, the worse was the score on the runoff index. The runoff index correlated with all of the outcome measures performed, including treadmill time, time to claudication, 6-min walk, and oxygen consumption (see Table 3 in Anderson et al. ). The perfusion measures made using magnetic resonance imaging in our study (1) were made at the calf muscle level and are thus certainly dependent on upstream macrovascular disease as well as local microvascular disease.
Abraham et al. also suggest that anemia could play a role in the functional capacity in peripheral artery disease patients, an excellent point. Unfortunately, we did not measure complete blood counts at the time of the imaging studies and thus do not have data to answer this particular question. They also assert that exercise-induced hypoxemia may contribute to exercise intolerance in peripheral artery disease patients. Although we agree with this in theory, with the low-to-moderate level of exercise performed by the patients in this particular study, they were generally limited far more by claudication than by cardiopulmonary symptoms. In summary, we would submit that our study did present data that integrated both “proximal and distal” assessment of the extent of atherosclerosis and its consequences using a comprehensive magnetic resonance imaging approach.
- American College of Cardiology Foundation