Background Juvenile dermatomyositis (JDM) is a systemic autoimmune disease of unknown etiology, characterized primarily by weakness in proximal muscles and pathognomonic skin rashes. Other organ systems may also be affected, such as the respiratory and cardiovascular systems.[1-2] Impaired autonomic control has been described in rheumatic diseases,[3-5] however, heart rate variability (HRV) is scarcely investigated in childhood rheumatic diseases.
Objectives Low HRV is a well-established predictor of cardiac death. We investigated arrhythmias and HRV, furthermore, the association between HRV and inflammatory markers, echocardiographic measurements and disease parameters in patients with JDM.
Methods Fifty-five patients with JDM were examined 2–34 years (median 13.5 years) after disease onset, and compared with 55 age and sex matched controls. Holter ECG monitoring and echocardiography were analysed blinded to patient information. Arrhythmia and HRV (6 internationally accepted parameters; cSDNN, SDANN, rMSSD, pNN50, LF, HF) were analysed by standard software, finally adjudicated by an experienced cardiologist. Markers of inflammation (ESR, hsCRP) and cytokines were analysed. Disease activity and organ damage were assessed by clinical examination at follow-up and retrospectively by chart review.
Results In 2/6 HRV parameters, JDM patients had lower values than controls. No difference in arrhythmias was found between the groups. In patients, but not in controls, there were significant negative correlations between 5/6 HRV parameters, and ESR and hsCRP (rsp -0.306 to -0.470, p's 0.023-<0.001). Also, in patients, correlation was found between 3/6 HRV parameters and systolic and diastolic function. Active disease and low HRV were associated. Patients with hsCRP in the highest quartile (Q4) had lower HRV in all parameters compared to those in pooled Q1-3 (p's <0.001) (Figure).
Conclusions JDM patients had reduced HRV, which was associated with elevated inflammatory markers, active disease and reduced myocardial function. This suggests reduced vagal control of the heart; further studies are needed to determine if this is also associated with cardiac morbidity or mortality.
Schwartz, T., et al., In juvenile dermatomyositis, cardiac systolic dysfunction is present after long-term follow-up and is predicted by sustained early skin activity. Ann Rheum Dis, 2014. 73(10): p. 1805-10.
Schwartz, T., et al., Cardiac dysfunction in juvenile dermatomyositis: a case-control study. Ann.Rheum.Dis., 2011. 70(5): p. 766-771.
Di, F.M., et al., Autonomic dysfunction and microvascular damage in systemic sclerosis. Clin.Rheumatol., 2007. 26(8): p. 1278-1283.
Evrengul, H., et al., Heart rate variability in patients with rheumatoid arthritis. Rheumatol.Int., 2004. 24(4): p. 198-202.
Stein, K.S., et al., Heart rate variability in patients with systemic lupus erythematosus. Lupus, 1996. 5(1): p. 44-48.
Wozniak, J., et al., Evaluation of heart rhythm variability and arrhythmia in children with systemic and localized scleroderma. J.Rheumatol., 2009. 36(1): p. 191-196.
Disclosure of Interest None declared