Why to evaluate the functional capacity in PAD patients?

In patients with peripheral arterial disease (PAD), the ability to perform physical exercise is an essential and most important indicator of a patient's health and quality of life. In many cases, there exists a discrepancy between lower extremity blood flow, the extent of arterial occlusion shown by morphological investigation and functional impairment. Reversal of lower extremity arterial obstruction with revascularization does not always reverse functional impairment of diseased leg. Further, training exercise and drug treatment can improve functional performance although they are not associated with an improvement in arterial obstruction. Therefore, the determination of functional impairment and its recovery after different therapeutic procedures should be determined using objective tests. The most frequently used functional tests are treadmill exercise testing and a 6-minute walk test. The constant load test, in which results are expressed as a walked distance, does not always permit an accurate assessment of the full range of functional impairment of PAD patients. Recently, as a substitute for a constant-load test, the graded treadmill test is used. With this test, it is possible to identify those individuals with exercise limitations who are not caused only by deterioration of the blood flow of lower limbs. The 6-minute walk test is simple to perform and requires minimal equipment. However, the correlation between the 6-minute walk test and the graded treadmill test is relatively weak, indicating that peak performance on a graded treadmill may reflect different pathophysiological mechanisms of limitations. In conclusion: for the determination of limitations of mobility and quality of life in patients with PAD, objective measures of functional impairment are needed. The determination of functional capacity is related to the quality of life and is a useful tool for investigation of the success of revascularization of peripheral arteries and conservative treatment.