Clinical Value of Heart Rate Variability Indexes to Predict Outcomes After Exercise Training in Chronic Heart Failure

Study Overview
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Brief Summary
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Controlled exercise training is a valuable therapeutic addition to pharmacological treatment in most patients with chronic heart failure, reducing long-term mortality, preventing cardiac remodeling and improving functional capacity. Despite 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 exercise, probably due to several differences in the subpopulations enrolled. The investigators hypothesize that some Heart Rate Variability indexes could be valid tools to optimize the selection and follow-up of chronic heart failure patients to training

Detailed Description
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Forty subjects followed in a University Heart Failure Management Program were prospectively included. All patients were evaluated before the randomization and after 24 weeks from enrollment. The investigators performed a detailed anamnesis and complete physical examination, Doppler echocardiography, Stress Testing, 6-minute walk test, heart rate variability analysis, and quality of life test. Patients were randomized either to a training group: performing a supervised training program, or a control group receiving usual care. All patients received an optimal pharmacologic treatment including diuretics, angiotensin converting enzyme inhibitors or angiotensin receptor blockers and beta-adrenergic blocking agents. All patients included in the training group attended a supervised program 3-days/week during 24 weeks (68-74 sessions). Physical aerobic training appears to impart beneficial changes in autonomic control of patients with chronic heart failure through both parasympathetic and sympathetic control of hear rate. These effects produce changes in several Heart Rate Variability indices as HF and rMSSD related with parasympathetic tone.

Official Title
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Clinical Value of Heart Rate Variability Indexes to Predict Outcomes After Exercise Training in Chronic Heart Failure

Conditions
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Heart Failure, Systolic Heart Failure

Intervention / Treatment
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* Behavioral: Cardiac Rehabilitation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: subjects followed in a University Heart Failure Management Program maintained sinus rhythm New York Heart Association Functional Class (NYHA) I to III and LVEF≤40% documented by echocardiogram optimal pharmacologic treatment Exclusion Criteria: history of stroke, myocardial infarction or extended anterior myocardial scar revascularization procedures or recurrent angina within previous 3 months orthopedic impairment alcohol or drug abuse; implant of pacemaker or cardioverter-defibrillator (AICD); frequently ventricular dysrhythmias, atrial flutter or fibrillation insulin-dependent diabetes mellitus; severe chronic obstructive pulmonary disease or renal dysfunction comorbid non-cardiac disease limiting short term survival previous enrollment in an ET program subjects at great propensity for noncompliance

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Usual Care<br>usual care and no changes in their previous physical activity | |
| Active Comparator: Cardiac Rehabilitation<br>Exercise Training program on a 3-days/week basis during 24 weeks (68-74 sessions). Each session started with a 10-min warm-up walking period followed by 20-min of breathing exercises and free non-resistance movements of limbs. This stage was followed by pedaling during 20-minutes at a circuit resistance training protocol using a stationary cycle-ergometer. Each session ended with a cool down period (5-minutes) including diverse stretching maneuvers of engaged muscle groups. The initial bicycle-ergometer workload (WL) was defined as 50% of the maximum achieved in the previous stress testing | Behavioral: Cardiac Rehabilitation<br>* All patients included in this group attended a supervised exercise training program. A cardiologist supervised the hole training sessions. Blood pressure, pulse rate, oxygen saturation, and body weight were measured in each session. The modified Borg scale was used to measure the perceived exercise intensity<br>* Other names: Educational approach;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Clinical Events | Change in New York Heart Association Functional Class; Number of hospitalizations 6 months before and after the date of enrollment; temporary or permanent withdrawal from the study protocol (due to persistent atrial or ventricular arrhythmias; worsening of congestive heart failure symptoms; myocardial infarction; unstable angina; need of cardiac interventions: pacemaker, implantable cardioverter defibrillator, coronary revascularization or cardiac transplantation; stroke or transient ischemic attack; severe peripheral intermittent claudication or death observed during training or follow-up sessions | 6 month | 
| Mean heart rate | the mean value of the12-min Electrocardiogram-recordings was considered the resting heart rate (beats per minute) | 6 month | 
| 6 minute walk test | walking along a 20-meter long corridor at their own pace, with the aim of covering as much ground as possible in 6 minutes. The distance walked was expressed in meter | 6 month | 
| left ventricular ejection fraction | The area-length method was measured to obtain biplane left ventricle volumes. Left Ventricle ejection fraction was derived from the standard equation (%) | one year | 
| quality of life | All the subjects completed the Short-Form 36 Health Survey (SF-36), available in its Spanish version, for measuring physical and mental quality of life | 6 month | 
| Stress Test | symptom limited exercise testing, measured in metabolic unit (MET) | 6 month | 
| square root of the mean squared successive differences of R-R intervals (rMSSD) | short-term continuous electrocardiographic recordings were performed for heart rate variability analysis. In the time domain, the square root of the mean squared successive differences of R-R intervals (rMSSD) were calculated. Units: ms | 6 month | 
| Heart rate power high-frequency (HF) | The high-frequency (HF), from 0.15 to 0.40 Hz of the power spectral analysis were calculated. Units: ms2/Hz | 6 month | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Heart rate variability, Systolic heart failure, Physical exercise, Parasympathetic indexes