title: Functional outcome in chronic heart failure after exercise training: Possible predictive value of heart rate variability.
abstract: BACKGROUND
  Controlled exercise training (ET) is a valuable therapeutic addition to pharmacological treatment in most patients with chronic heart failure (CHF), reducing long-term mortality, preventing cardiac remodelling and improving functional capacity. Despite the fact that the mechanism underlying its benefits might be multifactorial, a sustained improvement in autonomic balance is usually attributed as a major effect. Nevertheless, not all eligible subjects show the same response to ET, probably due to several differences in the subpopulations enrolled. We hypothesize that some heart rate variability (HRV) indexes could be valid tools to optimize the selection and follow-up of CHF patients receiving ET intervention.
  
  
  METHODS
  Forty patients with CHF and left ventricular ejection fraction (LVEF)≤40% under complete evidence-based pharmacological treatment were included; 20 were assigned to a program of controlled ET on a 3-times/week basis during 24 weeks, training group (TG) and 20 received a standard follow-up program, control group (CG). In each patient, full clinical assessments, echocardiography, HRV analysis and 6-minute-walk test were performed at the beginning and the end of the study.
  
  
  RESULTS
  After 24 weeks, patients in the TG showed a significant improvement in LVEF, 6-minute walk test, functional class of symptoms and HRV parasympathetic related indices (HF and rMSSD). Patients in the CG did not exhibit any improvement in the aforementioned indices and experienced more adverse events. Moreover, an initial value of HF<150 ms2/Hz or rMSSD<20ms predicted better outcomes of the ET program, including improvements in systolic function, the distance walked in 6minutes, and the functional class of symptoms, along with a reduction in clinical events.
  
  
  CONCLUSIONS
  In CHF patients, HRV indexes related to parasympathetic function are valid and clinically useful tools to select and follow-up those candidates that could experience superior functional improvement after ET.
authors.affiliation: Cátedra de Cardiología, Centro Cardiovascular Universitario, Hospital de Clínicas, Universidad de la República, 2870, Avenida Italia, 11600 Montevideo, Uruguay; Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay. Electronic address: cardiofisiologia@gmail.com.
authors.forename: Roberto
authors.initials: R
authors.lastname: Ricca-Mallada
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
authors.forename: Edurado R
authors.initials: ER
authors.lastname: Migliaro
authors.affiliation: Unidad Multidisciplinaria de Insuficiencia Cardiaca, Hospital de Clínicas, Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Silvera
authors.affiliation: Laboratorio de Exploración Funcional Respiratoria. Hospital de Clínicas, Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay.
authors.forename: Lilian
authors.initials: L
authors.lastname: Chiappella
authors.affiliation: Laboratorio de Exploración Funcional Respiratoria. Hospital de Clínicas, Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay.
authors.forename: Rossana
authors.initials: R
authors.lastname: Frattini
authors.affiliation: Cátedra de Cardiología, Centro Cardiovascular Universitario, Hospital de Clínicas, Universidad de la República, 2870, Avenida Italia, 11600 Montevideo, Uruguay.
authors.forename: Federico
authors.initials: F
authors.lastname: Ferrando-Castagnetto
mesh_terms: D000368:Aged; D002908:Chronic Disease; D005080:Exercise Test; D005081:Exercise Therapy; D005260:Female; D006333:Heart Failure / Q000188:drug therapy / Q000503:physiopathology* / Q000534:rehabilitation*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011237:Predictive Value of Tests; D020127:Recovery of Function; D013318:Stroke Volume
keywords: Clinical value; Exercise; Heart failure; Heart rate variability; Parasympathetic indexes