Significant Clinical Indexes of Exercise-Induced Pulmonary Hypertension in Patients With Connective Tissue Disease

Pulmonary hypertension (PH) is an important cause of morbidity in patients with connective tissue disease (CTD), and an early stage of PH could present as exercise-induced PH (EIPH). This study investigated the significant clinical indexes of EIPH in patients with CTD. We enrolled 63 patients with CTD who did not have PH at rest. All patients underwent the 6-min walk test (6MWT), and systolic pulmonary artery pressure (SPAP) was evaluated on echocardiography before and after 6MWT. EIPH was defined as SPAP ≥40 mmHg after 6 WMT. Thirty-five patients had EIPH. On univariate logistic analysis, SPAP at rest, log brain natriuretic peptide (BNP), vital capacity (VC), and forced expiratory volume in 1 s (FEV1.0) were significantly correlated with EIPH. On multiple logistic analysis, SPAP at rest and VC were independent predictors of EIPH, whereas FEV1.0 and log BNP were not significantly associated with EIPH. The area under the receiver operating characteristics curve between EIPH and BNP, SPAP at rest, VC or FEV1.0 was 0.67, 0.76, 0.74, and 0.75, respectively. SPAP at rest and respiratory function, especially VC, could be independent predictors of EIPH in patients with CTD.