Martis N, Queyrel-Moranne V, Launay D, Neviere R, Fuzibet JG, Marquette CH, Leroy S

J Rheumatol. 2018 Jan;45(1):95-102. doi: 10.3899/jrheum.161349. Epub 2017 Nov 1.

OBJECTIVE: Exercise limitation in patients with systemic sclerosis (SSc) is often
multifactorial and related to complications such as interstitial lung disease
(ILD), pulmonary vasculopathy (PV), left ventricular dysfunction (LVD), and/or
peripheral/muscular limitation (PML). We hypothesized that cardiopulmonary
exercise testing (CPET) could not only suggest and rank competing etiologies, but
also highlight peripheral impairment.
METHODS: Clinical, resting pulmonary function testing, and CPET data from
patients with SSc referred for exercise limitation between October 2009 and
November 2015 were retrospectively analyzed in this bi-center study. Patients
were categorized as having ILD, PV, LVD, and/or PML based on CPET response
patterns and the diagnoses were matched with results from the reference
investigations. The latter consisted of transthoracic echocardiography, chest
computed tomography scan, and right heart catheterization (RHC).
RESULTS: Twenty-seven patients presented with CPET profiles consistent with ILD
(n = 16), PV (n = 15), LVD (n = 5), and PML (n = 19). None of the subjects had a
normal CPET profile. There was a statistically significant negative correlation
between resting DLCO, on the one hand, and dead space to tidal volume ratio and
alveolar-arterial gradient [P(Ai-a)O2] on the other (p < 0.005). CPET identified
90% of patients with a mean pulmonary arterial pressure at rest ≥ 21 mmHg
measured by RHC (n = 10). Peak P(Ai-a)O2, taken independently from other
variables, was crucial in distinguishing subjects with ILD from those without ILD
(p < 0.05).
CONCLUSION: CPET is useful for the characterization of multifactorial exercise
limitation in patients with SSc and in identifying SSc-related complications such
as ILD and PV. This study also identifies PML as an underestimated cause of
exercise limitation.