ABC | Volume 114, Nº3, March 2020

Short Editorial Exercise and Six-Minute Walk Test in Lower Extremity Occlusive Peripheral Arterial Disease Tales de Carvalho 1, 2 Clínica de Prevenção e Reabilitação Cardiosport, 1 Florianópolis, SC – Brazil Universidade do Estado de Santa Catarina (UDESC-SC), 2 Florianópolis, SC – Brazil Short Editorial related to the article: Exercise Intensity during 6-Minute Walk Test in Patients with Peripheral Artery Disease Mailing Address: Tales de Carvalho • Avenida Jornalista Rubens de Arruda Ramos, 2354, apto 201. Postal Code 88015-705, Florianópolis, SC – Brazil E-mail: tales@cardiol.br , talescarvalho@icloud.com Keywords Peripheral Arterial Disease; Intermittent Claudication; Anaerobic Threshold; Exercise; Walk Test; Physical Activities of Daily Living. The article “Exercise Intensity During 6-min Test in Patients with Peripheral Artery Disease” 1 provides original, practically useful information to be considered in the diagnosis, prognosis and mainly in the functional assessment that allows a better prescription of physical exercise in the medical treatment of the disease. The study was conducted with the aim of determining whether overground walking would allows the detection of the first ventilatory threshold, also known as anaerobic threshold (AT), in symptomatic patients with lower extremity occlusive peripheral arterial disease (LE-OPAD). AT is a marker of exercise intensity, useful for the determination of the optimal zone for physical training focused on improvement in cardiorespiratory fitness. 2 LE-OPAD is an important public health problem. According to global epidemiology report, the disease affected 202 million individuals in 2010, and 237 million in 2015, with a 22% increase during this period. 3 The association of OPAD with major cardiovascular events (MACE) has been well documented; in the severe stage of the disease, with presence of critical ischemia, there is a high risk of cardiovascular events, lower limb amputation and death, 4 with association with elevated levels of cardiac troponin and N terminal pro-brain natriuretic peptide (NT-proBNP). 5 LE-OPAD is highly suspected in the presence of pain in lower limbs when walking, without apparent orthopedic problem, and an ankle brachial index (ABI) lower than 0.90 at rest. Walking tests should be performed to help in the diagnosis, particularly when the ABI is greater than 0.91, and in the functional classification and exercise prescription. 6 Field walking tests allow the identification of intermittent claudication, with determination of the distance walked to symptom onset (initial claudication) and to maximum functional limitation (absolute claudication). In treadmill tests, the measurement of the ABI has been proposed, both at rest and after exercise. The presence of the disease is strongly suspected when ABI is reduced by at least 20% and 30mmHg after exercise compared with rest. 7 However, resting ABI, which has been widely used in clinical practice, can produce false negative results, which is of particular importance in patients with poorly compressible arteries. In the study by Tóth-Vajna et al., 8 almost one fourth of the individuals with a diagnosis had poorly compressible arteries or was considered symptomatic with a negative ABI. Therefore, in case of suspicion of LE-OPAD, a deeper investigation is recommended despite normal ABI values. In symptomatic patients, exercise can affect morbidity and mortality, with improvement of symptoms and quality of life and increase of maximum walking distance, and thus must be part of the optimized treatment. 6,7 Therefore, all patients with intermittent claudication should receive optimized medical treatment, i.e., a combination of lifestyle changes with pharmacological therapy, considering the body of evidence showing a reduction in cardiovascular events and improvement of the outcomes related to the lower limbs. 9 Physical training has been shown to be safe, and the walking tests with claudication symptom induction considered the best option. 6,7 However, when walking tests cannot be performed, other exercises such as cycling, resistance exercise and exercises using an upper extremity ergometer have been shown effective. 5,6 It is worth mentioning that patients with critical ischemia cannot perform physical exercises, but should be considered eligible as soon as the interventionist approach is successfully completed. 10,11 Many clinical trials have consistently shown that supervised treadmill training improves the gait of patients with LE-OPAD. In a meta-analysis, Fakhry et al. 12 evaluated 1,054 patients from 25 studies and concluded this type of exercise training was effective in increasing maximum walking distance (mean increase of 180 meters) and pain-free walking distance (mean increase of 11 meters). 12 Three randomized clinical trials that evaluated 493 patients with LE-OPAD, showed that home-based exercise programs that included behavior change techniques, improved walking capacity, and higher performance gain on the six-minute walk test compared with supervised treadmill training. 13,14 In other words, while supervised treadmill walking programs are superior in the improvement of treadmill walking performance, the home-based programs are superior in improving overground walking, which is more related to daily life activities. 14 Although home-based overground walking programs have been recently shown effective in improving the performance in daily life activities, apart from being more convenient and cheaper compared with supervised treadmill exercise, 14 small older studies showed little or no benefit. Therefore, the American College of Cardiology/American Heart Association DOI: https://doi.org/10.36660/abc.20200068 493