In juvenile dermatomyositis, heart rate variability is reduced, and associated with both cardiac dysfunction and markers of inflammation: a cross-sectional study median 13.5 years after symptom onset.

Objectives: Low heart rate variability (HRV) is a well-established predictor of cardiac death. The aim of this study was to investigate arrhythmias and HRV in patients with JDM, and associations between HRV and inflammatory markers, echocardiographic measurements and disease parameters.

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 (six parameters) were analysed by standard software, finally adjudicated by an experienced cardiologist. Markers of inflammation (ESR, high sensitivity (hs)CRP and cytokines) were analysed. Disease activity and organ damage were assessed by clinical examination at follow-up and retrospectively by chart review.

Results: In two out of six 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 five out of six HRV parameters, and ESR and hsCRP (Spearman correlation coefficient, -0.306 to -0.470; P, 0.023 to <0.001). Also, in patients, negative correlations were found between three out of six 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 with those in pooled Q1-3 (P < 0.001).

Conclusion: 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 whether this is also associated with cardiac morbidity or mortality.