Abstract
Background:
People with rheumatoid arthritis (RA) are at high risk for cardiovascular diseases (CVD) and CVD mortality. Reduced Chronotropic response (CR), which produces exercise intolerance, is known as a contributing factor to CVD and mortality. Studies have shown that people with RA have reduced CR. However, knowledge about the factors associated with CR in people with RA is limited.
Objectives:
To explore the factors associated with CR including CVD risk factors, inflammatory markers and cardiorespiratory fitness (VO
2
peak).
Methods:
106 people with RA completed a treadmill exercise tolerance test while heart rate (HR) was monitored via 12 leads ECG. CR was defined as the percentage of [(achieved peak HR minus resting HR) divided by (age-predicted maximum HR minus resting HR)]. Serological CVD risk factors and inflammatory markers including lipids profile, markers of insulin resistance and sensitivity (HOMA, QUICKi), high sensitivity C-reactive protein (hsCRP), erythrocyte sedimentation rate (ESR), fibrinogen and white blood cells (WBC) were examined via a fasted blood sample. VO
2
peak was assessed via breath-by-breath gas analysis.
Results:
34% had reduced CR based on the cut-off value (≤ 80%) and the average CR was 86.2 ± 21%. Body mass index (r=-0.33, p=.001), HOMA (r=-0.26, p=.009), hsCRP (r=-0.23, p=.02), ESR (r=-0.21, p=.04), fibrinogen (r=-0.2, p=.05), WBC (r=-0.21, p=.04) were inversely associated with CR, whereas, high density lipoprotein (HDL) (r=0.43, p<.001), QUICKi (r=0.31, p=.002), and VO
2
peak (r=0.4, p<.001) were positively associated with CR. When all the variables were entered into a stepwise linear regression, HDL (p<.001) and VO
2
peak (p=.009) were independently associated with CR.
Conclusion:
The current findings suggest that CR in RA was associated with many CVD risk factors, inflammatory markers, and cardiorespiratory fitness. Among all the varibales, HDL and cardiorespiratory fitness were moderately and independently associated with CR. Future studies should investigate the effect of improving these associated variables on CR in people with RA via exercise training programes.
Acknowledgements:
Thanks to physical activity in Rheumatoid arthritis research team and Research department in Dudley Hospital. Sincere appreciation and gratitude to Dr Jet Veldhuizen van Zanten, Prof. Joan Duda, and Prof. George Kitas from the University of Birmingham and Prof. George Metsios from the University of Wolverhampton.
Disclosure of Interests:
None declared