Evolution of randomized, controlled studies of medical therapy in chronic thromboembolic pulmonary hypertension

Prostacyclin pathway vasodilators in patients with chronic thromboembolic pulmonary hypertension (CTEPH): A systemic review and meta-analysis of randomized controlled trials

Although surgical and interventional therapy has emerged as the primary treatment for patients with chronic thromboembolic pulmonary hypertension (CTEPH), there remains a subset of patients who need medication therapy. This study aimed to evaluate the efficacy and safety outcomes of prostacyclin pathway vasodilators, providing further insight for clinical decision-making. A literature search was conducted in PubMed, Embase, and CENTRAL databases from inception to December 2023. Literature screening and quality assessment were carried out with the Cochrane Risk of Bias Tool. Data analysis was conducted using RevMan 5.4 software. We included 6 randomized controlled trials with 387 patients. Prostacyclin pathway vasodilators demonstrated a significant improvement in PVR (-125.26 dynes·sec·cm-5, 95%CI: -219.29 to -31.23, Z = 2.61, and p < 0.009), RAP (-0.78 mmHg, 95%CI: -1.52 to -0.04, Z = 2.06, and p = 0.04), cardiac index (0.62, 95%CI: 0.54 to 0.69, Z = 16.13, and p < 0.00001), and the number of patients showing improvement in WHO functional class (3.86, 95%CI: 1,92 to 7.77, Z = 3.79, and p = 0.0002) compared to controls, moreover, a trend towards improvement was observed in mPAP, 6MWD, and NT-proBNP. Regarding the safety endpoints, no significant difference was found in both groups in terms of serious adverse events and all-cause deaths. The prostacyclin pathway vasodilators present therapeutic potential for CTEPH patients with inoperable or persistent/recurrent PH after PEA/BPA primarily characterized by distal small-vessel and microvasculopathy. However, the current clinical evidence remains insufficient and controversial, necessitating further validation.

Pathogenesis, Diagnosis, and Management of Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is thought to occur as a sequelae of thromboembolic processes in the pulmonary vasculature. The pathophysiology of CTEPH is multifactorial, including impaired fibrinolysis, endothelial dysregulation, and hypoxic adaptations. The diagnosis of CTEPH is typically delayed considering the nonspecific nature of the symptoms, lack of screening, and relatively low incidence. Diagnostic tools include ventilation-perfusion testing, echocardiography, cardiac catheterization, and pulmonary angiography. The only potentially curative treatment for CTEPH is pulmonary endarterectomy However, approximately 40% of patients are inoperable. Currently, only Riociguat is Food and Drug Administration approved specifically for CTEPH, with additional drug trials underway.

Riociguat and balloon pulmonary angioplasty improve prognosis in patients with inoperable chronic thromboembolic pulmonary Hypertension

BACKGROUND

The combination of riociguat and interventional balloon pulmonary angioplasty (BPA) is currently used to treat patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH). The aim of the present study was to evaluate the impact of this combination therapy on the prognosis of inoperable CTEPH patients by comparing the long-term survival rates of patients undergoing combination therapy with riociguat and BPA with those of inoperable patients from the first international CTEPH registry who did not receive specific treatment.

METHODS

Between March 2014 and August 2019, 138 technically inoperable patients were included in the present prospective, observational cohort study when they were treated with riociguat and BPA at a single CTEPH referral center. Long-term survival of this cohort was compared using propensity score matching with that of inoperable patients recruited between 2007 and 2009 in the first international CTEPH registry. Kaplan-Meier methods were used to evaluate differences in outcomes.

RESULTS

Whereas the survival rate in the historical group was 84.6% in the first year, 76.6% in the second, 68.5% in the third, and 58.5% in the fifth year after diagnosis, implementation of riociguat/BPA led to survival rates of 100%, 96.7%, 92.9%, and 90% in the respective follow-up periods. In a comparison of 83 well-matched pairs from the 2 cohorts, survival was markedly better in the group treated with riociguat and BPA than in the historical cohort (HR = 0.145, 95% CI 0.05, 0.421).

CONCLUSION

The combination of riociguat and BPA for the treatment of inoperable CTEPH is associated with excellent 5-year survival rates.