Background
Heart failure (HF) and atrial fibrillation (AF) are often concomitant and act in a vicious cycle. Atrial fibrillation is associated with greater functional limitations and increased morbidity and mortality in patients with HF. Moreover, AF associated with HF increases patients' physical inactivity, worsening their clinical condition, and prognosis. Exercise training is safe and has clear benefits in HF. However, these benefits have not been demonstrated when AF is associated with HF.
Case summary
We present the case of a 57-year-old man with permanent AF and HF with reduced ejection fraction, who underwent 12 weeks of exercise training that included cardiopulmonary exercise testing, neuromuscular sympathetic activity (NMSA), and muscle blood flow (MBF) before and after training.
Discussion
Exercise training was shown to have a potential benefit in reducing the activity of the sympathetic nerve and increasing muscle blood flow, as well as increasing VO2peak and decreasing the VE/VCO2 slope in a patient with AF associated with HF with reduced ejection fraction. These results may indicate favourable clinical implications in this group of patients.
The six-minute walk test (6MWT) is a simple assessment of physical capacity in patients with heart failure (HF) and can be performed in a hallway or on the treadmill 1 . It is suggested that the kind of effort during the 6MWT resemble the daily activities, enabling the patient to determine the rhythm of walking 2 .Carvalho et al 3 evaluated the reproducibility of the 6MWT in the hallway, as well as the correlation of the variables VO 2 , WD and HR in the sixth minute of the 6MWT with those of the cycle ergometer peak cardiopulmonary exercise testing (CPET) in HF. The authors demonstrated reproducibility between the 6MWTs and correlation with the CPET, concluding that the 6MWT is a reliable and low-cost assessment tool for the prescription of exercise in HF. However, the assessment of functional capacity in cycle ergometer shows a difference of 10 to 15% less when compared to that obtained with the treadmill test 4 . Thus, the correlation found in this study can be the difference between the types of tests. Moreover, the intensity of walking during the 6MWT in HF is influenced by verbal encouragement, as demonstrated by Guimarães et al 1 .Discussions about the reproducibility of the 6MWT are not recent, as well as its safe use in HF 2 . Nevertheless, in our country, there has been no longitudinal study involving a significant number of patients with HF of nonischemic, ischemic and chagasic etiology. Furthermore, the use of this test for exercise prescription is purely theoretical, making larger studies necessary to clarify its applicability for this purpose.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.