Reduction of maximal oxygen uptake in sarcoidosis: relationship with disease severity

Patients with sarcoidosis frequently exhibit exertional dyspnea. Although the functional limitation might be related to ventilatory problems, some patients exhibited exertional dyspnea without significant abnormalities of pulmonary function tests (PFT). Therefore, the mechanisms responsible for exercise intolerance remain unclear.

The aim of this retrospective study was to determine the mechanisms responsible for exercise intolerance.

Cardiopulmonary exercise testing (CPET) was performed in 157 dyspneic sarcoid patients (stage I: 29; stage II-III: 95; stage IV: 33) and VO2 peak was correlated with radiological stage and resting PFT.

VO2 peak was decreased in 73% patients, did not differ according to radiological stage and was correlated with VC, FVC, FEV1, TLC and DLCO. FVC was the major significant predictor of VO2 peak explaining 17% of VO2 variation. Among CPET variables, peak heart rate and VE/VO2 at ventilatory threshold explained 22% of VO2 alteration in stage I and stage II-III, and 9% in stage IV. In stage IV, V(D)/V(T) peak explained 41% of VO2 alteration.

In conclusion, in the lower stages circulatory impairment and impaired heart rate response to exercise are involved in the exercise capacity limitation, whereas in stage IV the ventilatory and gas exchange impairment may be more important. CPET must be performed to accurately characterize the mechanisms responsible for exercise limitation and help the clinician in the management of the disease.