Ab0239 Thermographic Assessment of Digital Vasculopathy in Idiopathic Inflammatory Myopathies

Background: Idiopathic inflammatory myopathies (IIMs) are a group of heterogeneous autoimmune rheumatic diseases divided in subtypes: dermatomyositis (DM), polymyositis (PM), immune-mediated necrotizing myopathy (IMNM), inclusion body myositis (IBM), anti-synthetase syndrome (ASyS) and overlap myositis (OL). Nailfold capillaroscopy examines capillaries next to the nailbed using high-magnification optical imaging, whereas thermography uses an infrared camera to measure the temperature of the skin, which is representative of underlying blood flow (and larger vessel function). Both techniques are used in the assessment of patients with systemic sclerosis (SSc) which has a vasculopathic component to its pathogenesis, help to differentiate primary Raynaud's phenomenon (RP) from RP secondary to SSc, and can predict SSc disease severity. Nailfold capillaroscopy abnormalities have been described in IIMs, more frequently in DM and ASyS, suggesting an underlying vasculopathic pathogenesis akin to SSc. However thermographic assessment has not been specifically studied in IIMs. Objectives: We aimed to report thermography findings in patients with IIM and the relationship with structural abnormalities of the microvasculature. Methods: We retrospectively reviewed patients with a clinical diagnosis of IIM seen in a national tertiary referral service who also had been assessed by thermography and also nailfold capillaroscopy. Results: The study included 20 patients (80% female, mean ±SD age at diagnosis 50 ±16 years) with DM (50%), ASyS (35%), OL (5%) and unclear diagnosis (10%), where 15 patients had thermography performed. 11 of 15 had normal rewarming after cold challenge (distal dorsal difference DDD at 23°C normal) and 4 were abnormal. Considering the abnormal thermography patients, 3 of them had normal rewarming after heat challenge (DDD at 30°C normal). The majority had abnormal nailfold capillaroscopy (n=15) where the most frequent findings were enlarged capillaries and decreased density. Considering those with abnormal capillaroscopy, 10 also had thermography performed, where most exhibited normal rewarming after cold challenge. 5 of 18 had RP (2 missing data), most of them with abnormal nailfold capillaroscopy but normal rewarming after cold challenge. Conclusion: Most patients had normal thermography findings and microvascular structural alterations were not obviously correlated with functional abnormalities. RP was infrequent. Such findings differ from those reported in SSc and need to be studied further to clarify underlying vasculopathic pathogenesis and differences that may exist in different subtypes. The added role of thermography as a biomarker to aid diagnosis and management in this group of patients is yet to be defined. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.