Background Patients with CTD often complain of exertion dyspnea, due to lung diseases, heart diseases, musculoskeletal disorders and/or APAH. Although imaging and physiological tests could reveal pathophysiology, some of them remain unknown. Especially APAH is rarely diagnosed in WHO functional class I or II, because pulmonary vasculopathy (PV) cannot be detected until two-thirds of pulmonary blood vessels deteriorated, ¹ with cardiac ultrasonography (UCG) or right heart catheterization (RHC) at rest. Pathophysiological considerations suggest that the haemodynamic/metabolic impairment in APAH may be observed during exercise before the disease becomes evident at rest.^2–3 We evaluated exertion dyspnea of unknown to find out early APAH with CPET.

Objectives We performed CPET in patients who complained of exertion dyspnea and tried to detect early PV.

Methods From June 13th in 2015 to October 28th in 2016, we performed CPET and evaluate their clinical state in 28 patients, 17–80 years 2 males/26 females, 5 mixed connective tissue disease (MCTD), 15 SSc, 3 SLE, 2 Sjögren's syndrome, 3 dermatomyositis. They underwent UCG, pulmonary function testing (PFT), 6-minutes walk test, and nailfold capillaroscopy by Cutolo's method.⁴

Results Twenty cases presented decreased peak VO2. VE/VCO₂ ratio, which represent increased ventilation-perfusion mismatch, elevated in 12 cases. 8 cases, with decreased peak VO2 but normal VE/VCO_2, were regarded that muscle weakness mainly induced exertion dyspnea, and advised exercise. Twelve cases with decreased peak VO2 and elevated VE/VCO₂ were estimated to have APAH or/and interstitial lung disease (ILD). Seven of them underwent RHC and 1 case diagnosed as definite APAH, and another 1 case as post capillary PH.

A 34 years MCTD woman without ILD showed an active capillaroscopic pattern, her peak VO2 decreased (13.9ml/kg/min.) and nadir VE/VCO₂ elevated (39). Although her mean PAP was normal, we suspected she had early PV and administered PDE5 inhibitor to her and her dyspnea had gone soon and CPET parameters improved.

CPET was also useful for early detections of therapeutic gains in APAH. A SSc woman, diagnosed as APAH by RHC, was performed CPET only 9 days after administration of PDE5 inhibitor. Her peak VO2 elavated (13.3 to 15.4 ml/kg/min.) and nadir VE/VCO₂ decreased (43.4 to 38.9) promptly.

Thirteen patients showed an early capillaroscopic pattern, 7 an active pattern and 3 a late pattern. Median values of minimum VE/VCO₂ ratio significantly differed (p<0.05) in the three capillaroscopic groups, being progressively worse from early to late capillaroscopic pattern.

Conclusions We performed CPET in every patient safely. Although more research is required, CPET may provide valuable information notably in APAH patients.

References

1. Hachulla E, et al. French PAH-SSc Network. PAH with SSc in patients with functional class? dyspnea; mild symptoms but severe outcome. Rheumatology 2010;49:940–4.

2. Grunig E, et al. Non-invasive diagnosis of pulmonary hypertension: ESC/ERS Guidelines with Updated Commentary of the Cologne Consensus Conference 2011. Int J Cardiol 2011;154:53.

3. Domitrescu C, et al. Developing PV in SSc, detected with non-invasive CPET. PLoS ONE 2010;5e14293.

4. Cutolo M, et al. Nailfold videocapillaroscopy assessment of microvascular damage in SSc. J Rheumatol. 2000 Jan;27(1):155–60.

References

Disclosure of Interest None declared