The Association Between Nailfold Capillary Density and Pulmonary and Cardiac Involvement in Medium- to Long-standing Juvenile Dermatomyositis.

OBJECTIVE: To explore the associations between microvascular abnormalities assessed by nailfold capillaroscopy (NFC) and pulmonary and cardiac involvement in patients with juvenile dermatomyositis (DM) assessed after medium- to long-term follow-up.

METHODS: Fifty-eight juvenile DM patients were examined mean 17.0 (SD 10.6) years after symptom onset. Nailfold capillary density (NCD) and neovascular pattern (defined as scleroderma active or late pattern) were analysed blinded to clinical data. Pulmonary involvement was assessed by pulmonary function tests (PFT) including spirometry, diffusion capacity for carbon monoxide (DLCO) and body plethysmography; also high-resolution computed tomography (HRCT) was performed. Cardiac involvement was assessed by electrocardiography, Holter monitoring (heart rate variability) and echocardiography.

RESULTS: Patients with low NCD (<6 capillaries/mm) (n=21), compared to patients with normal NCD (≥ 6 capillaries/mm) (n=37), presented lower forced vital capacity (89.7 vs 98.5% of predicted), total lung capacity (87.8 vs 94.5% of predicted) and more often low DLCO (15/21 (71%) vs 14/37 (38%)); all p's<0.05. HRCT assessed airways disease was more frequent in the low NCD group (6/21 (30%) vs 3/37 (8%); p=0.034). No associations were found between i) NCD and cardiac parameters or ii) neovascular pattern and pulmonary or cardiac parameters.

CONCLUSION: In juvenile DM patients, low NCD was associated with lung involvement, which was mostly subclinical. No significant associations with cardiac involvement were found. These results shed light on possible mechanisms underlying organ involvement, but further and preferably larger studies are needed to identify NCD as a potential biomarker for lung and cardiac involvement in juvenile DM. This article is protected by copyright. All rights reserved.