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

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

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

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.

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