Predictors of Improvement in Exercise Tolerance After Balloon Pulmonary Angioplasty for Chronic Thromboembolic Pulmonary Hypertension

Background Balloon pulmonary angioplasty (BPA) improves exercise tolerance and hemodynamic parameters in patients with chronic thromboembolic pulmonary hypertension. However, it is still unclear which patient characteristics contribute to the improvement in exercise tolerance after BPA in chronic thromboembolic pulmonary hypertension. Methods and Results We retrospectively analyzed 126 patients with chronic thromboembolic pulmonary hypertension (aged 63±14 years; female, 65%) who underwent BPA without concomitant programmed exercise rehabilitation at Keio University between November 2012 and April 2018. Hemodynamic data and 6‐minute walk distance (6MWD), as a measure of exercise tolerance, were evaluated before and 1 year after BPA. The clinical characteristics that contributed to improvement in exercise tolerance were elucidated. The 6MWD significantly increased from 372.0 m (256.5–431.3) to 462.0 m (378.8–537.0) 1 year after BPA (P<0.001). The improvement rate in the 6MWD after BPA exhibited a good correlation with age, height, mean pulmonary artery pressure, and 6MWD at baseline (Spearman rank correlation coefficients=−0.28, 0.24, −0.40, and 0.44, respectively). Additional multivariable linear regression analysis revealed that young age, tall height, high mean pulmonary artery pressure, short 6MWD at baseline, and high lung capacity at baseline were significant predictors of the improvement in 6MWD by BPA (standardized partial regression coefficient −0.39, 0.22, 0.19, −0.62, and 0.25, P<0.001, 0.007, 0.011, <0.001, and <0.001, respectively). Conclusions BPA without concomitant programmed exercise rehabilitation significantly improves exercise tolerance. This was particularly true in young patients with high stature, high mean pulmonary artery pressure, short 6MWD, and lung capacity at the time of diagnosis

Anaerobic threshold using sweat lactate sensor under hypoxia

Abstract We aimed to investigate the reliability and validity of sweat lactate threshold (sLT) measurement based on the real-time monitoring of the transition in sweat lactate levels (sLA) under hypoxic exercise. In this cross-sectional study, 20 healthy participants who underwent exercise tests using respiratory gas analysis under hypoxia (fraction of inspired oxygen [FiO2], 15.4 ± 0.8%) in addition to normoxia (FiO2, 20.9%) were included; we simultaneously monitored sLA transition using a wearable lactate sensor. The initial significant elevation in sLA over the baseline was defined as sLT. Under hypoxia, real-time dynamic changes in sLA were successfully visualized, including a rapid, continual rise until volitionary exhaustion and a progressive reduction in the recovery phase. High intra- and inter-evaluator reliability was demonstrated for sLT’s repeat determinations (0.782 [0.607–0.898] and 0.933 [0.841–0.973]) as intraclass correlation coefficients [95% confidence interval]. sLT correlated with ventilatory threshold (VT) (r = 0.70, p < 0.01). A strong agreement was found in the Bland–Altman plot (mean difference/mean average time: − 15.5/550.8 s) under hypoxia. Our wearable device enabled continuous and real-time lactate assessment in sweat under hypoxic conditions in healthy participants with high reliability and validity, providing additional information to detect anaerobic thresholds in hypoxic conditions