Letters to the Editor: Autonomic nervous system in heart failure: an endless area of research/ The preserved autonomic functions may provide the asymptomatic clinical status in heart failure despite advanced left ventricular systolic dysfunction

Dear Editor, We read with attention a research article entitled as ‘The preserved autonomic functions may provide the asymptomatic clinical status in heart failure despite advanced left ventricular systolic dysfunction’ published in the latest issue of the journal and performed by Kocaman et al. (1). The researchers reported that the preserved autonomic functions were associated with the asymptomatic clinical status independently in patients with advanced left ventricular systolic dysfunction. The autonomic function was evaluated using the parameters of heart rate variability. The present study was a well-designed study and its method and discussion sections were described with a comprehensive manner (1). However, in a study assessing autonomic nervous system functions in a patient population with heart failure, we think that some important issues should be emphasized for readers to interpret more accurately the results of the study.