Reduced ventilatory efficiency during exercise predicts major vascular complications and mortality for interstitial lung disease in systemic sclerosis.

Objectives: Major vascular complication, such as digital ulcers (DUs), pulmonary arterial hypertension (PAH) and scleroderma renal crisis (SRC) are hallmarks of systemic sclerosis (SSc). Interstitial lung disease (ILD) is the major cause of mortality in SSc. The aim of study is to identify cardiopulmonary exercise testing (CPET) variables that predict MVC and mortality for ILD in SSc patients.
Methods: In this cohort study, 45 SSc patients underwent clinical evaluation, echocardiography, pulmonary function tests (PFTs), high resolution computerised tomography (HRCT) and CPET. PFTs and echocardiography were performed annually for a 5-year follow-up.
Results: 16 (35.6%) SSc patients had MVC: 14 new DUs (31.1%), 1 PAH (2.2%) and 1 SRC (2.2%). At univariate regression analysis, mRss [HR 1.099 (1.008-1.199), p<0.05], NVC patterns (active and late) [HR 0.032 (0.004-0.250), p<0.001], V'E/V'CO2 slope [HR 1.123 (1.052-1.198), p<0.001] were predictive of new onset of MVC. In multivariate analysis, NVC patterns (active and late) (HR 0.044 (0.004-0.486), p<0.05), V'E/V'CO2 (HR 1.094 (1.020-1.198), p<0.05) were predictive of new onset of MVC. The 5-year mortality for ILD is 8.9%. In univariate analysis, DLco [(HR 0.927(CI 0.874- 0.983), p<0.05], V'E/V'CO2 slope and lung parenchymal with radiological patterns of ILD [(1.2.02 (CI 1.018-1.419), p<0.05], represent risk factors for 5-year mortality for ILD [HR 1.142 (1.030-1.267), p<0.05]. In multivariate analysis, only V'E/V'CO2 slope [1.268 (CI 1.003-1.602), p<0.05] represents a risk factor for 5-year mortality for ILD.
Conclusions: V' E/V' CO2 slope is a prognostic marker of MVC and five-year mortality for ILD.