Quantitative videocapillaroscopy correlates with functional respiratory parameters: a clue for vasculopathy as a pathogenic mechanism for lung injury in systemic sclerosis.

BACKGROUND

To determine whether lung involvement is related to microvascular perturbations, nailfold videocapillaroscopy (NVC) was performed in patients with systemic sclerosis (SSc).

METHODS

A cross-sectional study was consecutively accomplished in 152 SSc patients. NVC, a pulmonary function test and echocardiography were undergone within a 3-month period. Finally, 134 patients with at least eight NVC (200× magnification) images were selected for quantitative and qualitative examinations.

RESULTS

Patients with interstitial lung disease presented lower median capillary density (4.86/mm vs 5.88/mm, p = 0.005) and higher median of neoangiogenesis (0.56/mm vs 0.31/mm, p = 0.005). A higher quantity of neoangiogenesis capillaries was found in patients with pulmonary arterial hypertension (0.70/mm vs 0.33/mm, p = 0.008). Multivariate linear regression analysis established a correlation between neoangiogenesis and decreased forced vital capacity (FVC) (p < 0.001): for each capillary with neoangiogenesis visualized on average per 1 mm, FVC was 7.3% reduced. In qualitative NVC, a late pattern as defined by Cutolo was also associated with lower FVC (p = 0.018). The number of giant capillaries was associated with reduced diffusion capacity of the lung for carbon monoxide (DLCO) (p = 0.016); for each giant capillary per 1 mm, DLCO was 11.8% diminished.

CONCLUSIONS

A good correlation was observed between distinctive quantitative and qualitative NVC features with lung functional parameters such as FVC and DLCO. It is suggested that vasculopathy could play a role in SSc lung involvement.