AB1160 IMPACT OF COVID-19 TREATMENTS ON PERIPHERAL CAPILLARY DENSITY EVALUATED BY NAILFOLD VIDEOCAPILLAROSCOPY

Abstract

BackgroundHuman SARS-CoV-2 infection can induce a wide spectrum of organ dysfunctions, including microvascular impairment [1]. S1 subunit of viral receptor-binding domain binds to the angiotensin-converting enzyme 2 receptor on endothelium and S2 subunit allows the virus to enter endothelial cells. The resulting breakdown of barrier integrity drives a cascade of inflammatory and thrombotic events, that aggravate the course of COVID-19 together with other risk factors [2-4]. Up to date, a lower capillary density has been reported in several distinct body districts, using sublingual video microscopy, ocular optical coherence tomography angiography, skin functional laser Doppler perfusion imaging and nailfold videocapillaroscopy (NVC) [5-8]. NVC examination has been performed in adult COVID-19 patients, however, without a control group [8].ObjectivesTo confirm the statistical significance of the reduction in capillary density per linear millimeter evaluated by NVC in comparison with primary Raynaud’s phenomenon (PRP) patients and control subjects (CNT) and to evaluate the impact of an aggressive therapy against COVID-19 on the sparing in the number of capillaries.MethodsSixty-one COVID-19 survivors, thirty-one PRP patients and thirty CNT age and sex-matched underwent NVC analysis. Demographic and clinical data of COVID-19 survivors were collected with special regard to concomitant therapies, that included antivirals, antibiotics, anticoagulants and anti-inflammatory/immunomodulant drugs (glucocorticoids, hydroxychloroquine, IL-6 receptor antagonist). COVID-19 survivors were divided in two subgroups according to the severity of the active infection: thirty-four survivors with past mild-moderate disease (either unneedy for oxygen supplementation or need for Venturi mask) and twenty-seven survivors with past severe disease (need for Continuous Positive Airways Pressure and/or mechanical ventilation). The same Rheumatologist performed NVC evaluations in all patients and controls, using an optical probe, equipped with a 200x magnification lens and connected to a picture analysis software (Videocap, DS Medica, Milan, Italy). Absolute capillary number per linear millimeter was counted.ResultsCOVID-19 survivors underwent NVC examination after a mean period of 126±53 days from the disease onset. Multivariate analysis showed differences in absolute capillary number per linear millimeter (p<0.001) after adjusting for age, sex, body mass index, comorbidities and concomitant drugs. The mean (± standard deviation) absolute nailfold capillary number per linear millimeter was significantly lower in severe (8.2±1.15) and mild-moderate (8.4±0.75) COVID-19 survivors than in both PRP (8.7±0.68) and CNT subjects (9.3±0.53) (p<0.001). The analysis of the impact of treatments on capillary density in the severe COVID-19 patients showed a positive trend (preservation of the capillary number) with antivirals (no: 7.8±1.53; yes: 8.5±0.64; p=0.35) and anti-IL-6 receptor antagonist administration (no: 7.8±1.36; yes: 8.6±0.74; p=0.16), while none of the other drugs was shown to be effective (glucocorticoids p = 0.46; antibiotics = 0.52; anticoagulants not evaluable as they were used in all COVID-19 patients).ConclusionSARS-CoV-2 infection seems associated to a significant capillary loss as distinctive NVC feature and data concerning the comparison of capillary density pre COVID-19 and post COVID-19 are desirable to reinforce this observation. The positive trend in saving the number of capillaries induced by aggressive anti-inflammatory therapies in COVID-19 survivors needs larger cohorts of patients.