Usefulness of ventilatory gas analysis for the non-invasive evaluation of the severity of chronic thromboembolic pulmonary hypertension

Drug discovery focused on novel pathogenic proteins for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a fatal disease in which the wall thickening and narrowing of pulmonary microvessels progress due to complicated interactions among processes such as endothelial dysfunction, the proliferation of pulmonary artery smooth muscle cells (PASMCs) and adventitial fibrocytes, and inflammatory cell infiltration. Early diagnosis of patients with PAH is difficult and lung transplantation is the only last choice to save severely ill patients. However, the number of donors is limited. Many patients with PAH show rapid progression and a high degree of pulmonary arterial remodeling characterized by the abnormal proliferation of PASMCs, which makes treatment difficult even with multidrug therapy comprising pulmonary vasodilators. Thus, it is important to develop novel therapy targeting factors other than vasodilation, such as PASMC proliferation. In the development of PAH, inflammation and oxidative stress are deeply involved in its pathogenesis. Excessive proliferation and apoptosis resistance in PASMCs are key mechanisms underlying PAH. Based on those characteristics, we recently screened novel pathogenic proteins and have performed drug discovery targeting those proteins. To confirm the clinical significance of this, we used patient-derived blood samples to evaluate biomarker potential for diagnosis and prognosis. Moreover, we conducted high throughput screening and found several inhibitors of the pathogenic proteins. In this review, we introduce the recent progress on basic and clinical PAH research, focusing on the screening of pathogenic proteins and drug discovery.

Beneficial effects of riociguat on hemodynamic responses to exercise in CTEPH patients after balloon pulmonary angioplasty – A randomized controlled study

Background

Although balloon pulmonary angioplasty (BPA) improves symptoms and pulmonary hemodynamics in patients with chronic thromboembolic pulmonary hypertension (CTEPH), the effects of riociguat on hemodynamics and exercise capacity in patients after BPA remain to be elucidated.

Methods and Results

This study was a single-center, prospective, randomized, open-label trial. From November 2015 to November 2018, we prospectively examined 21 patients with CTEPH (65 ± 9 years old, M/F 2/19) who showed hemodynamic improvement with mean pulmonary arterial pressure (mPAP) < 30 mmHg after BPA without any vasodilators. We performed hemodynamic evaluation and expired gas analysis both at rest and during exercise in supine position using cycle ergometer. After right heart catheterization during exercise, they were randomly assigned to 2 groups with minimized method, using age, sex, and resting mPAP; riociguat (N = 10) and control (N = 11) groups. After 6 months, exercise capacity evaluated by 6-min walk distance and cardiopulmonary exercise testing, and resting hemodynamic parameters were comparable in both groups. However, cardiac output (CO) (6.0 ± 1.7–7.4 ± 1.6, P < 0.01) and pulmonary vascular resistance (4.8 ± 1.8–3.2 ± 0.7 Wood units, P = 0.02) at peak workload were significantly improved in the riociguat group as compared with the control group. The slope of linearized mPAP-CO relationship was significantly decreased in the riociguat group [14.5 (7.8, 14.7) to 6.41 (5.1, 11.4), P < 0.01] but not in the control group.

Conclusions

These results indicate that riociguat exerts beneficial effects on hemodynamic response to exercise in CTEPH patients even after hemodynamic improvement by BPA.