Characteristics of patients with a relatively greater minimum VE/VCO2 against peak VO2% and impaired exercise tolerance

Efficacy and Safety of Balloon Pulmonary Angioplasty for Patients With Chronic Thromboembolic Pulmonary Hypertension and Comorbid Chronic Obstructive Pulmonary Disease

Background Balloon pulmonary angioplasty (BPA) is a promising treatment modality for nonoperable chronic thromboembolic pulmonary hypertension (CTEPH). However, BPA for atypical CTEPH with concurrent chronic obstructive pulmonary disease (COPD) remains controversial owing to the risk of exacerbation of ventilation-perfusion mismatch. We aimed to evaluate the efficacy and safety of BPA for CTEPH with moderate or severe COPD. Methods and Results Data from 149 patients with CTEPH, who underwent BPA from March 2011 to June 2021, were retrospectively analyzed. Patients were divided based on COPD comorbidity: the COPD group (n=32, defined as forced expiratory volume in 1 second/forced vital capacity <70% and forced expiratory volume in 1 second <80% predicted) and the non-COPD group (n=101); patients with mild COPD (n=16) were excluded. Hemodynamic and respiratory parameters were compared between the groups. Hemodynamics improved similarly in both groups (reduction in pulmonary vascular resistance): -55.6±29.0% (COPD group) and -58.9±21.4% (non-COPD group); P=nonsignificant. Respiratory function and oxygenation improved in the COPD group (forced expiratory volume in 1 second/forced vital capacity [61.8±7.0% to 66.5±10.2%, P=0.02] and arterial oxygen partial pressure [60.9±10.6 mm Hg to 69.3±13.6 mm Hg, P<0.01]). Higher vital capacity (P=0.024) and higher diffusing capacity for lung carbon monoxide (P=0.028) at baseline were associated with greater improvement in oxygenation in the multivariable linear analysis. Lung injury per BPA session was 1.6% in the COPD group. Conclusions The efficacy and safety of BPA for nonoperable CTEPH in patients with comorbid COPD were similar to those in patients without COPD. Oxygenation and forced expiratory volume in 1 second/forced vital capacity improved in patients with COPD. BPA should be considered in patients with CTEPH with concurrent COPD.

Microvasculopathy Evaluated by Dual-Energy Computed Tomography in Patients with Chronic Thromboembolic Pulmonary Hypertension and Pulmonary Arterial Hypertension

Background: Poor subpleural perfusion (PSP) on dual-energy computed tomography (DE-CT) suggests microvasculopathy in chronic thromboembolic pulmonary hypertension (CTEPH). However, whether the microvasculopathy findings are equivalent to those in pulmonary arterial hypertension (PAH) remains unclear. The aim of this study was to elucidate the characteristics of microvasculopathy in CTEPH compared to those of that in PAH. Methods: We retrospectively reviewed subpleural perfusion on DE-CT and the hemodynamics of 23 patients with PAH and 113 with inoperable CTEPH. Subpleural perfusion on DE-CT was classified as poor (subpleural spaces in all segments with little or no perfusion) or normal. Results: PSP was observed in 51% of patients with CTEPH and in 4% of those with PAH (p < 0.01). CTEPH patients with PSP had poorer baseline hemodynamics and lower diffusing capacity for carbon monoxide divided by the alveolar volume (DLCO/VA) than those with CTEPH with normal perfusion (pulmonary vascular resistance [PVR]: 768 ± 445 dynes-sec/cm5 vs. 463 ± 284 dynes-sec/cm5, p < 0.01; DLCO/VA, 60.4 ± 16.8% vs. 75.9 ± 15.7%, p < 0.001). Despite the existence of PSP, hemodynamics improved to nearly normal in both groups after balloon pulmonary angioplasty. Conclusions: PSP on DE-CT, which is one of the specific imaging findings in CTEPH, might suggest a different mechanism of microvasculopathy from that in PAH.

Assessment of oxygenation after balloon pulmonary angioplasty for patients with inoperable chronic thromboembolic pulmonary hypertension

BACKGROUND

The efficacy of balloon pulmonary angioplasty (BPA) in patients with inoperable chronic thromboembolic pulmonary hypertension would be promising. However, some patients showed residual dyspnea or symptoms, despite normalized hemodynamics. We aimed to clarify the clinical impact of oxygenation parameters on BPA outcome.

METHOD

Ninety-nine consecutive patients who underwent BPA from September 2011 to December 2019 were enrolled. We evaluated hemodynamics with right heart catheterization, arterial blood gas examination, New York Heart Association functional class (NYHA-FC), respiratory function tests, nocturnal oximetry, and exercise capacity (6-min walk test and cardiopulmonary exercise testing) at baseline and after BPA.

RESULT

Nearly normal hemodynamics was achieved after BPA (mean pulmonary artery pressure (PAP): 37.5 ± 10.0 to 20.6 ± 4.9 mmHg, p < 0.01). Oxygenation slightly improved (partial pressure of arterial oxygen; 61.5 ± 12.3 to 67.7 ± 12.7 mmHg, p < 0.01). Exertional desaturation remained unchanged (-8.1 ± 4.8 to -7.8 ± 5.1, p = 0.59), and this was associated with residual symptom (NYHA-FC ≥ 2) after BPA (OR 0.591, 95% CI 0.416-0.840, p = 0.003) in multivariate regression analyses. Lower vital capacity (r² = 0.03, p = 0.01), higher mean PAP (r² = 0.08, p = 0.02), and higher minute ventilation/carbon dioxide production (VE/VCO₂) slope (r² = 0.18, p < 0.01), the marker of ventilatory inefficiency, were correlated with exertional desaturation after BPA in multivariate linear analyses.

CONCLUSION

Although hemodynamics nearly normalized, oxygenation did not. Moreover, exertional desaturation remained unchanged. This might cause residual symptom after BPA. Residual pulmonary hypertension suggesting incurable arteriopathy, and higher VE/VCO₂ slope suggesting ventilation-perfusion mismatch might be related to exertional desaturation. Domiciliary oxygen therapy should be continued, if necessary.