Investigation of factors associated with autonomic nervous system function in patients with rheumatoid arthritis
[Thesis]
Osailan, Ahmad
University of Birmingham
2017
Thesis (Ph.D.)
2017
Rheumatoid Arthritis (RA) patients have high risk for cardiovascular diseases (CVD). Poor autonomic nervous system (ANS) function, (increased sympathetic and reduced parasympathetic activity) is a factor contributing to the risk for CVD in RA. The first experimental chapter includes a cross-sectional study in which the association between a measure of myocardial ischemia during an exercise tolerance test (ETT) and resting heart rate variability (HRV) was explored in 96 RA patients. Myocardial ischemia was associated with reduced HRV. The second chapter examined the parasympathetic reactivation using heart rate recovery (HRR) following ETT, and multiple factors association with HRR. Multivariate analyses revealed no factor was independently associated with HRR, but it was the overall CVD risk and disease related burden that contributed to variability in HRR. In the third chapter, the effects of a three-month exercise intervention on HRR, CVD risks, inflammation, and measures of wellbeing were investigated in 62 RA patients. Exercise reduced some CVD risk factors and improved some measures of wellbeing, however, HRR and cardiorespiratory fitness did not improve. In the last chapter, a cross-sectional study compared HRR between age-and sex-matched RA (N=43) and diabetes mellitus (N=26) patients as well as inflammatory markers, CVD risk factors, and measures of wellbeing. There was no difference in HRR or inflammation between the two groups. A sub-analysis found that cardiorespiratory fitness was an independent predictor of HRR. These findings suggest that parasympathetic activity in RA associate with several CVD risk factors, and cardiorespiratory fitness is an important factor associated with it.