Riociguat: an upcoming therapy in chronic thromboembolic pulmonary hypertension?

Principles of pharmacological correction of pulmonary arterial hypertension

Definition and classification: Pulmonary hypertension (PH) is a group of life-threatening progressive diseases of various genesis, characterized by a progressive increase in arterial pressure (AP) in the pulmonary artery (PA), the remodeling of pulmonary vessels, which leads to an increase in pulmonary vascular resistance and pulmonary arterial pressure and more often leads to right ventricular heart failure and premature death. Pulmonary hypertension is clinically divided into five groups: patients in the first group have idiopathic pulmonary arterial hypertension (IPAH), whereas in patients of other groups secondary PH associated with cardiopulmonary or other systemic diseases is observed. The development of secondary LH is caused by congenital heart defects, collagenoses, presence of thrombus in the pulmonary artery, prolonged high pressure in the left atrium, hypoxemia, chronic obstructive pulmonary diseases (COPDs). In case of secondary PH, thrombosis and other changes in the pulmonary veins occur.

Ways of pharmacological correction of pulmonary hypertension: Over the last decade pharmacotherapy of PH has been developing rapidly, and the introduction of modern methods of treatment, especially for primary PAH, has led to positive results. However, despite the progress in treatment, the functional limitations and survival of patients remain unsatisfactory. Currently, there are two levels of treatment for pulmonary hypertension: primary and specific pathogenetic therapies. Primary therapy is aimed at the main cause of PH. It also includes supportive therapy. Pathogenetic therapy includes prostanoids, endothelin receptor antagonists, and phosphodiesterase-5 inhibitors. Tactics of therapy can be established on the basis of either clinical classification, or functional class. Prostanoids are a promising group of drugs for the treatment of pulmonary arterial hypertension (PAH), since they possess not only vasodilating, but also antiplatelet and antiproliferative actions. Therefore, it seems logical to use prostacyclin and its analogs to treat patients with various forms of PAH.

Monitoring for Pulmonary Hypertension Following Pulmonary Embolism: The INFORM Study

BACKGROUND

Pulmonary hypertension and chronic thromboembolic pulmonary hypertension may develop after a pulmonary embolism event. A ventilation-perfusion scan is recommended as a first-line modality for suspected chronic thromboembolic pulmonary hypertension. In this study, we determined the prevalence of pulmonary hypertension following incident pulmonary embolism and the disease-monitoring patterns in this population.

METHODS

We conducted a retrospective claims database analysis of incident pulmonary embolism cases (July 1, 2010 to September 30, 2011) and extracted data for 1 year prior to and 2 years after the incident pulmonary embolism event. Data were analyzed for diagnoses and symptoms related to pulmonary hypertension, claims consistent with other heart or lung diseases, diagnostic imaging tests, and time to first diagnostic imaging test post pulmonary embolism.

RESULTS

Of the 7068 incident pulmonary embolism patients that met eligibility criteria, 87% had a claim for a pulmonary hypertension-related symptom and 7.6% had a claim for pulmonary hypertension during follow-up. Only 55% of all pulmonary embolism patients had diagnostic procedural claim(s) post pulmonary embolism: echocardiogram, 47%; computed tomographic angiography, 20%; ventilation-perfusion scan, 6%; and right heart catheterization or pulmonary angiography, <1%. The mean time from pulmonary embolism diagnosis to first screening test was 131 days.

CONCLUSIONS

Despite exhibiting pulmonary hypertension-related symptoms, many pulmonary embolism patients did not undergo imaging tests that could diagnose pulmonary hypertension or chronic thromboembolic pulmonary hypertension. This study suggests that physician education about the risk of pulmonary hypertension and chronic thromboembolic pulmonary hypertension after pulmonary embolism may need to be improved.

Budgetary Impact of Adding Riociguat to a US Health Plan for the Treatment of Patients with Pulmonary Arterial Hypertension or Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are chronic, debilitating, and life-threatening conditions. Riociguat is the first and only pharmacotherapy approved by the US Food and Drug Administration (FDA) for the treatment of PAH and for CTEPH in patients who are either inoperable or have persistent pulmonary hypertension after surgery.

OBJECTIVE

To estimate the budgetary impact of adding riociguat to a US health plan's formulary for the treatment of patients with PAH or CTEPH using a budget impact analytic model.

METHODS

A customizable, Microsoft Excel-based decision analytic tool was developed to estimate the impact of riociguat on per-member per-month (PMPM) and per-member per-year (PMPY) bases in Medicare and non-Medicare health plans. The economic impact was calculated based on 1 million insured lives, published prevalence estimates of PAH and CTEPH, pharmacotherapy-eligible patients with PAH or CTEPH, administration costs, and monitoring costs related to pharmacotherapy. The drug costs were based on wholesale acquisition costs, and the medical costs were derived from Truven Health MarketScan claims data and the Medicare 2013 Clinical Diagnostic Laboratory Fee Schedule and Physician Fee Schedule. The market share for approved treatments was based on a tracking study of physicians treating patients with PAH or CTEPH. A sensitivity analysis was used to test the model's robustness.

RESULTS

In a hypothetical plan population of 1 million members, the model estimated that 7 patients with PAH and 2 patients with CTEPH would be suitable for pharmacotherapy. Overall, 3 patients (1 with PAH and 2 with CTEPH) were receiving riociguat in a health plan consisting of patients with commercial and with Medicare insurance coverage. The incremental PMPY and PMPM costs for providing insurance coverage for riociguat were $0.27 and $0.02, respectively, for non-Medicare and Medicare health plans. Sensitivity analyses indicated that the budget impact increased by $0.01 PMPM, with a 25% increase in base-case parameter values.

CONCLUSION

Riociguat is a first-in-class and the only FDA-approved treatment for patients with PAH or CTEPH-2 debilitating, chronic, and life-threatening conditions with poor prognosis. This drug offers health plans an effective and safe treatment option, with a minimal economic impact. The financial impact to a health plan of providing coverage for riociguat in the first year of treatment was as low as $0.02 PMPM. The real-world budget impact of riociguat needs to be measured using real-world evidence to validate our results.

Chronic thromboembolic pulmonary hypertension: Medical treatment

Chronic thromboembolic pulmonary hypertension (CTEPH) is responsible for significant levels of morbidity and mortality. The estimated cumulative incidence of CTEPH is 2-4% among patients presenting with acute pulmonary thromboembolism. Currently, at the time of CTEPH diagnosis, 37.9% of the patients in an international registry were receiving at least one pulmonary arterial hypertension (PAH)-targeted therapy. Advanced medical therapy is considered in patients with inoperable disease, as a bridge to pulmonary endarterectomy or in those with persistent or recurrent pulmonary hypertension. PAH-specific medical therapies include endothelin receptor antagonists, phosphodiesterase inhibitors, and prostacyclin analogues. The present article will focus on recent developments in the pharmacological treatment of CTEPH.

Pulmonary edema predictive scoring index (PEPSI), a new index to predict risk of reperfusion pulmonary edema and improvement of hemodynamics in percutaneous transluminal pulmonary angioplasty

OBJECTIVES

This study sought to identify useful predictors for hemodynamic improvement and risk of reperfusion pulmonary edema (RPE), a major complication of this procedure.

BACKGROUND

Percutaneous transluminal pulmonary angioplasty (PTPA) has been reported to be effective for the treatment of chronic thromboembolic pulmonary hypertension (CTEPH). PTPA has not been widespread because RPE has not been well predicted.

METHODS

We included 140 consecutive procedures in 54 patients with CTEPH. The flow appearance of the target vessels was graded into 4 groups (Pulmonary Flow Grade), and we proposed PEPSI (Pulmonary Edema Predictive Scoring Index) = (sum total change of Pulmonary Flow Grade scores) × (baseline pulmonary vascular resistance). Correlations between occurrence of RPE and 11 variables, including hemodynamic parameters, number of target vessels, and PEPSI, were analyzed.

RESULTS

Hemodynamic parameters significantly improved after median observation period of 6.4 months, and the sum total changes in Pulmonary Flow Grade scores were significantly correlated with the improvement in hemodynamics. Multivariate analysis revealed that PEPSI was the strongest factor correlated with the occurrence of RPE (p < 0.0001). Receiver-operating characteristic curve analysis demonstrated PEPSI to be a useful marker of the risk of RPE (cutoff value 35.4, negative predictive value 92.3%).

CONCLUSIONS

Pulmonary Flow Grade score is useful in determining therapeutic efficacy, and PEPSI is highly supportive to reduce the risk of RPE after PTPA. Using these 2 indexes, PTPA could become a safe and common therapeutic strategy for CTEPH.

Soluble guanylate cyclase stimulation prevents fibrotic tissue remodeling and improves survival in salt-sensitive Dahl rats

BACKGROUND

A direct pharmacological stimulation of soluble guanylate cyclase (sGC) is an emerging therapeutic approach to the management of various cardiovascular disorders associated with endothelial dysfunction. Novel sGC stimulators, including riociguat (BAY 63-2521), have a dual mode of action: They sensitize sGC to endogenously produced nitric oxide (NO) and also directly stimulate sGC independently of NO. Little is known about their effects on tissue remodeling and degeneration and survival in experimental malignant hypertension.

METHODS AND RESULTS

Mortality, hemodynamics and biomarkers of tissue remodeling and degeneration were assessed in Dahl salt-sensitive rats maintained on a high salt diet and treated with riociguat (3 or 10 mg/kg/d) for 14 weeks. Riociguat markedly attenuated systemic hypertension, improved systolic heart function and increased survival from 33% to 85%. Histological examination of the heart and kidneys revealed that riociguat significantly ameliorated fibrotic tissue remodeling and degeneration. Correspondingly, mRNA expression of the pro-fibrotic biomarkers osteopontin (OPN), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) and plasminogen activator inhibitor-1 (PAI-1) in the myocardium and the renal cortex was attenuated by riociguat. In addition, riociguat reduced plasma and urinary levels of OPN, TIMP-1, and PAI-1.

CONCLUSIONS

Stimulation of sGC by riociguat markedly improves survival and attenuates systemic hypertension and systolic dysfunction, as well as fibrotic tissue remodeling in the myocardium and the renal cortex in a rodent model of pressure and volume overload. These findings suggest a therapeutic potential of sGC stimulators in diseases associated with impaired cardiovascular and renal functions.

Recent advances in chronic thromboembolic pulmonary hypertension

Surgical excellence in pulmonary thromboendarterectomy (PTE) for chronic thromboembolic pulmonary hypertension (CTEPH) has begun to spread around the world. The perioperative mortality for this procedure is typically under 10%. The maximal benefit from PTE is derived in those patients who have a high proximal clot burden that is surgically accessible, as outlined by the Jamieson classification. Residual pulmonary hypertension after successful PTE is common and increasingly is managed with maintenance oral pulmonary vasodilator therapy such as endothelin antagonists, phosphodiesterase inhibitors, and/or prostaglandins. The role of pulmonary vasodilator therapy in CTEPH before PTE is limited and should not delay definitive surgical therapy. Although plain deep hypothermic circulatory arrest (DHCA) is the classic technique for CTEPH, alternatives such as DHCA with antegrade cerebral perfusion are feasible as well. Prolonged mechanical ventilation after PTE remains common in part because of reperfusion pulmonary edema. Careful perioperative management can reduce the incidence of this syndrome. Because ventilator-associated pneumonia is also a common complication after PTE, it represents a major opportunity for outcome improvement, particularly because there are multiple modalities for its prevention and prompt diagnosis.

Therapeutic strategies in pulmonary hypertension

Pulmonary hypertension (PH) is a life-threatening condition characterized by elevated pulmonary arterial pressure. It is clinically classified into five groups: patients in the first group are considered to have pulmonary arterial hypertension (PAH) whereas patients of the other groups have PH that is due to cardiopulmonary or other systemic diseases. The management of patients with PH has advanced rapidly over the last decade and the introduction of specific treatments especially for PAH has lead to an improved outcome. However, despite the progress in the treatment, the functional limitation and the survival of these patients remain unsatisfactory and there is no cure for PAH. Therefore the search for an “ideal” therapy still goes on. At present, two levels of treatment can be identified: primary and specific therapy. Primary therapy is directed at the underlying cause of the PH. It also includes a supportive therapy consisting in oxygen supplementation, diuretics, and anticoagulation which should be considered in all patients with PH. Specific therapy is directed at the PH itself and includes treatment with vasodilatators such as calcium channel blockers and with vasodilatator and pathogenetic drugs such as prostanoids, endothelin receptor antagonists and phosphodiesterase type-5 inhibitors. These drugs act in several pathogenetic mechanisms of the PH and are specific for PAH although they might be used also in the other groups of PH. Finally, atrial septostomy and lung transplantation are reserved for patients refractory to medical therapy. Different therapeutic approaches can be considered in the management of patients with PH. Therapy can be established on the basis of both the clinical classification and the functional class. It is also possible to adopt a goal-oriented therapy in which the timing of treatment escalation is determined by inadequate response to known prognostic indicators.