Exercise therapy and cardiac, autonomic and systemic function in patients with chronic heart failure

Abstract

<b>Background</b> Exercise training is now accepted as a safe, adjunct therapy in stable heart failure patients. Acceptance of exercise training or therapy within this population is due to the benefits that have been demonstrated over the past three decades in trials and data syntheses presented in systematic reviews and meta-analyses. As new concepts emerge and with an increase in the number of trials comes the challenge of keeping up-to date with all the information, deciphering what's relevant, deciding how to interpret and apply the findings and what should happen next. Fortunately, the research methodologies of systematic review and meta-analysis provide a suitable platform for collecting, analysing and critically appraising studies. <br/> <b>Methods</b> An initial evidence mapping exercise identified the current level of research activity in regard to the synthesis of evidence focusing on the broad question of the benefits and/or effects of exercise training in heart failure patients. The objective of the exercise was to identify gaps in research synthesis and areas in which research synthesis would be valuable. A series of research syntheses were then conducted based on the identified gaps, using systematic reviews as the research methodology, and applying the statistical technique of meta-analysis where possible. <br/> <b>Results</b> While some of the effects of exercise training are now well established, e.g., improved functional capacity and quality of life, new trials and new concepts continue to emerge. Evidencing mapping highlighted a number of areas in which research synthesis was limited or out dated. The identified areas addressed the effect of exercise training on specific areas of cardiac, autonomic and systemic inflammatory markers in chronic heart failure patients; all associated with the pathogenesis and progression of heart failure. Evidence from systematic reviews and meta-analyses demonstrated that exercise training/therapy resulted in statistically significant improvements in: 1) endothelial function (FMD and EPCs), 2) direct (MSNA) and indirect (HRR, HRV) measures of autonomic function, 3) cardiac biomarkers (BNP, NT-proBNP) and 4) diastolic function, measured as E/E’. However, the evidence for improvements in a number of inflammatory markers was inconclusive, and limited evidence is currently available to allow for any conclusion to be drawn on the effect of exercise on emerging heart failure biomarkers. <br/> <b>Conclusion</b> This thesis utilised systematic reviews and meta-analyses as the research methodology to answer questions in relation to exercise training in heart failure patients. This work adds to the current evidence base by providing a robust synthesis of data in regard to effects of exercise training and therapy on endothelial function, autonomic function, inflammatory markers, biomarkers and diastolic function in heart failure patients.