Bosentan-based, treat-to-target therapy in patients with pulmonary arterial hypertension: results from the COMPASS-3 study

Contribution of pressure and flow changes to resistance reduction after pulmonary arterial hypertension treatment: a meta-analysis of 3898 patients

Background

Pulmonary arterial hypertension (PAH)-targeted therapies exert significant haemodynamic changes; however, systematic synthesis is currently lacking.

Methods

We searched PubMed, CENTRAL and Web of Science for studies evaluating mean pulmonary artery pressure (mPAP), cardiac index/cardiac output (CI/CO) and pulmonary vascular resistance (PVR) of PAH-targeted therapies either in monotherapy or combinations as assessed by right heart catheterisation in treatment-naïve PAH patients. We performed a random-effects meta-analysis with meta-regression.

Results

We included 68 studies (90 treatment groups) with 3898 patients (age 47.4±13.2 years, 74% women). In studies with small PVR reduction (<4 WU), CI/CO increase (R2=62%) and not mPAP reduction (R2=24%) was decisive for the PVR reduction (p<0.001 and p=0.36, respectively, in the multivariable meta-regression model); however, in studies with large PVR reduction (>4 WU), both CI/CO increase (R2=72%) and mPAP reduction (R2=35%) contributed significantly to the PVR reduction (p<0.001 and p=0.01, respectively). PVR reduction as a percentage of the pre-treatment value was more pronounced in the oral+prostanoid intravenous/subcutaneous combination therapy (mean difference -50.0%, 95% CI -60.8- -39.2%), compared to oral combination therapy (-41.7%, -47.6- -35.8%), prostanoid i.v./s.c. monotherapy (-31.8%, -37.6- -25.9%) and oral monotherapy (-21.6%, -25.4- -17.8%). Changes in haemodynamic parameters were significantly associated with changes in functional capacity of patients with PAH as expressed by the 6-min walking distance.

Conclusion

Combination therapies, especially with the inclusion of parenteral prostanoids, lead to remarkable haemodynamic improvement in treatment-naïve PAH patients and may unmask the contribution of mPAP reduction to the overall PVR reduction in addition to the increase in CO.

Is low-risk status a surrogate outcome in pulmonary arterial hypertension? An analysis of three randomised trials

BACKGROUND

Targeting short-term improvements in multicomponent risk scores for mortality in patients with pulmonary arterial hypertension (PAH) could result in improved long-term outcomes. We aimed to determine whether PAH risk scores were adequate surrogates for clinical worsening or mortality outcomes in PAH randomised clinical trials (RCTs).

METHODS

We performed an individual participant data meta-analysis of RCTs selected from PAH trials provided by the US Food and Drug Administration (FDA). We calculated predicted risk using the COMPERA, COMPERA 2.0, non-invasive FPHR, REVEAL 2.0, and REVEAL Lite 2 risk scores. The primary outcome of interest was time to clinical worsening, a composite endpoint composed of any of the following events: all-cause death, hospitalisation for worsening PAH, lung transplantation, atrial septostomy, discontinuation of study treatment (or study withdrawal) for worsening PAH, initiation of parenteral prostacyclin analogue therapy, or decrease of at least 15% in 6-min walk distance from baseline, combined with either worsening of WHO functional class from baseline or the addition of an approved PAH treatment. The secondary outcome of interest was time to all-cause mortality. We assessed the surrogacy of these risk scores, parameterised as attainment of low-risk status by 16 weeks, for improvement in long-term clinical worsening and survival using mediation and meta-analysis frameworks.

FINDINGS

Of 28 trials received from the FDA, three RCTs (AMBITION, GRIPHON, and SERAPHIN; n=2508) had the data necessary to assess long-term surrogacy. The mean age was 49 years (SD 16), 1956 (78%) participants were women, 1704 (68%) were classified as White, and 280 (11%) were Hispanic or Latino. 1388 (55%) of 2503 participants with available data had idiopathic PAH and 776 (31%) of 2503 had PAH associated with connective tissue disease. In a mediation analysis, the proportions of treatment effects explained by attainment of low-risk status ranged only from 7% to 13%. In a meta-analysis of trial-regions, the treatment effects on low-risk status were not predictive of the treatment effects on time to clinical worsening (R2 values 0·01-0·19) nor the treatment effects on time to all-cause mortality (R2 values 0-0·2). A leave-one-out analysis suggested that the use of these risk scores as surrogates might lead to biased inferences regarding the effect of therapies on clinical outcomes in PAH RCTs. Results were similar when using absolute risk scores at 16 weeks as the potential surrogates.

INTERPRETATION

Multicomponent risk scores have utility for the prediction of outcomes in patients with PAH. Clinical surrogacy for long-term outcomes cannot be inferred from observational studies of outcomes. Our analyses of three PAH trials with long-term follow-up suggest that further study is necessary before using these or other scores as surrogate outcomes in PAH RCTs or clinical care.

FUNDING

Cardiovascular Medical Research and Education Fund, US National Institutes of Health.

Establishing minimally important differences for cardiac MRI end-points in pulmonary arterial hypertension

BACKGROUND

Cardiac magnetic resonance (CMR) is the gold standard technique to assess biventricular volumes and function, and is increasingly being considered as an end-point in clinical studies. Currently, with the exception of right ventricular (RV) stroke volume and RV end-diastolic volume, there is only limited data on minimally important differences (MIDs) reported for CMR metrics. Our study aimed to identify MIDs for CMR metrics based on US Food and Drug Administration recommendations for a clinical outcome measure that should reflect how a patient "feels, functions or survives".

METHODS

Consecutive treatment-naïve patients with pulmonary arterial hypertension (PAH) between 2010 and 2022 who had two CMR scans (at baseline prior to treatment and 12 months following treatment) were identified from the ASPIRE registry. All patients were followed up for 1 additional year after the second scan. For both scans, cardiac measurements were obtained from a validated fully automated segmentation tool. The MID in CMR metrics was determined using two distribution-based (0.5sd and minimal detectable change) and two anchor-based (change difference and generalised linear model regression) methods benchmarked to how a patient "feels" (emPHasis-10 quality of life questionnaire), "functions" (incremental shuttle walk test) or "survives" for 1-year mortality to changes in CMR measurements.

RESULTS

254 patients with PAH were included (mean±sd age 53±16 years, 79% female and 66% categorised as intermediate risk based on the 2022 European Society of Cardiology/European Respiratory Society risk score). We identified a 5% absolute increase in RV ejection fraction and a 17 mL decrease in RV end-diastolic or end-systolic volumes as the MIDs for improvement. Conversely, a 5% decrease in RV ejection fraction and a 10 mL increase in RV volumes were associated with worsening.

CONCLUSIONS

This study establishes clinically relevant CMR MIDs for how a patient "feels, functions or survives" in response to PAH treatment. These findings provide further support for the use of CMR as a clinically relevant clinical outcome measure and will aid trial size calculations for studies using CMR.

Therapy for Pulmonary Arterial Hypertension: Glance on Nitric Oxide Pathway

Pulmonary arterial hypertension (PAH) is a severe disease with a resultant increase of the mean pulmonary arterial pressure, right ventricular hypertrophy and eventual death. Research in recent years has produced various therapeutic options for its clinical management but the high mortality even under treatment remains a big challenge attributed to the complex pathophysiology. Studies from clinical and non-clinical experiments have revealed that the nitric oxide (NO) pathway is one of the key pathways underlying the pathophysiology of PAH. Many of the essential drugs used in the management of PAH act on this pathway highlighting its significant role in PAH. Meanwhile, several novel compounds targeting on NO pathway exhibits great potential to become future therapy medications. Furthermore, the NO pathway is found to interact with other crucial pathways. Understanding such interactions could be helpful in the discovery of new drug that provide better clinical outcomes.

The REPAIR Study: Effects of Macitentan on RV Structure and Function in Pulmonary Arterial Hypertension

OBJECTIVES

The REPAIR (Right vEntricular remodeling in Pulmonary ArterIal hypeRtension) study evaluated the effect of macitentan on right ventricular (RV) and hemodynamic outcomes in patients with pulmonary arterial hypertension (PAH), using cardiac magnetic resonance (CMR) and right heart catheterization (RHC).

BACKGROUND

RV failure is the primary cause of death in PAH. CMR is regarded as the most accurate noninvasive method for assessing RV function and remodeling and CMR measures of RV function and structure are strongly prognostic for survival in patients with PAH. Despite this, CMR is not routinely used in PAH clinical trials.

METHODS

REPAIR was a 52-week, open-label, single-arm, multicenter, phase 4 study evaluating the effect of macitentan 10 mg, with or without phosphodiesterase type-5 inhibition, on RV remodeling and function and cardiopulmonary hemodynamics. Primary endpoints were change from baseline to week 26 in RV stroke volume, determined by CMR; and pulmonary vascular resistance, determined by RHC. Efficacy measures were assessed for all patients with baseline and week 26 data for both primary endpoints.

RESULTS

At a prespecified interim analysis in 42 patients, both primary endpoints were met, enrollment was stopped, and the study was declared positive. At final analysis (n = 71), RV stroke volume increased by 12 mL (96% confidence level: 8.4-15.6 mL; P < 0.0001) and pulmonary vascular resistance decreased by 38% (99% confidence level: 31%-44%; P < 0.0001) at week 26. Significant positive changes were also observed in secondary and exploratory CMR (RV and left ventricular), hemodynamic, and functional endpoints at week 26. Improvements in CMR RV and left ventricular variables and functional parameters were maintained at week 52. Safety (n = 87) was consistent with previous clinical trials.

CONCLUSIONS

In the context of this study, macitentan treatment in patients with PAH resulted in significant and clinically-relevant improvements in RV function and structure and cardiopulmonary hemodynamics. At 52 weeks, improvements in RV function and structure were sustained. (REPAIR: Right vEntricular remodeling in Pulmonary ArterIal hypeRtension [REPAIR]; NCT02310672).

The Use of Risk Assessment Tools and Prognostic Scores in Managing Patients with Pulmonary Arterial Hypertension

PURPOSE OF REVIEW

Pulmonary arterial hypertension (PAH) is a chronic, progressive, and incurable disease with significant morbidity and mortality. Despite increasingly available treatment options, PAH patients continue to experience disease progression and increased rates of hospitalizations due to right heart failure. Physician's ability to comprehensively assess PAH patients, determine prognosis, and monitor disease progression and response to treatment remains critical in optimizing outcomes.

RECENT FINDINGS

Risk assessment in PAH should include a range of clinical, hemodynamic, and exercise parameters, performed in a serial fashion over the course of treatment. Approaches to risk assessment in PAH patients include the use of risk variables, scores, and equations that stratify the impact of both modifiable (e.g., 6-min walk distance, functional class, brain natriuretic peptide), and non-modifiable (e.g., age, gender, PAH etiology) risk factors. Such tools allow physicians to better determine prognosis, allocate treatment resources, and enhance the consistency of treatment approaches across providers. Comprehensive and accurate risk prediction is essential to make individualized treatment decisions and optimizing outcomes in PAH.

Phosphodiesterase 5 inhibitors for pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) comprises a group of complex and heterogenous conditions, characterised by elevated pulmonary artery pressure, and which left untreated leads to right-heart failure and death. PH includes World Health Organisation (WHO) Group 1 pulmonary arterial hypertension (PAH); Group 2 consists of PH due to left-heart disease (PH-LHD); Group 3 comprises PH as a result of lung diseases or hypoxia, or both; Group 4 includes PH due to chronic thromboembolic occlusion of pulmonary vasculature (CTEPH), and Group 5 consists of cases of PH due to unclear and/or multifactorial mechanisms including haematological, systemic, or metabolic disorders. Phosphodiesterase type 5 (PDE5) inhibitors increase vasodilation and inhibit proliferation.

OBJECTIVES

To determine the efficacy of PDE5 inhibitors for pulmonary hypertension in adults and children.

SEARCH METHODS

We performed searches of CENTRAL, MEDLINE, Embase, CINAHL, and Web of Science up to 26 September 2018. We handsearched review articles, clinical trial registries, and reference lists of retrieved articles.

SELECTION CRITERIA

We included randomised controlled trials that compared any PDE5 inhibitor versus placebo, or any other PAH disease-specific therapies, for at least 12 weeks. We include separate analyses for each PH group.

DATA COLLECTION AND ANALYSIS

We imported studies identified by the search into a reference manager database. We retrieved the full-text versions of relevant studies, and two review authors independently extracted data. Primary outcomes were: change in WHO functional class, six-minute walk distance (6MWD), and mortality. Secondary outcomes were haemodynamic parameters, quality of life/health status, dyspnoea, clinical worsening (hospitalisation/intervention), and adverse events. When appropriate, we performed meta-analyses and subgroup analyses by severity of lung function, connective tissue disease diagnosis, and radiological pattern of fibrosis. We assessed the evidence using the GRADE approach and created 'Summary of findings' tables.

MAIN RESULTS

We included 36 studies with 2999 participants (with pulmonary hypertension from all causes) in the final review. Trials were conducted for 14 weeks on average, with some as long as 12 months. Two trials specifically included children.Nineteen trials included group 1 PAH participants. PAH participants treated with PDE5 inhibitors were more likely to improve their WHO functional class (odds ratio (OR) 8.59, 95% confidence interval (CI) 3.95 to 18.72; 4 trials, 282 participants), to walk 48 metres further in 6MWD (95% CI 40 to 56; 8 trials, 880 participants), and were 22% less likely to die over a mean duration of 14 weeks (95% CI 0.07 to 0.68; 8 trials, 1119 participants) compared to placebo (high-certainty evidence). The number needed to treat to prevent one additional death was 32 participants. There was an increased risk of adverse events with PDE5 inhibitors, especially headache (OR 1.97, 95% CI 1.33 to 2.92; 5 trials, 848 participants), gastrointestinal upset (OR 1.63, 95% CI 1.07 to 2.48; 5 trials, 848 participants), flushing (OR 4.12, 95% CI 1.83 to 9.26; 3 trials, 748 participants), and muscle aches and joint pains (OR 2.52, 95% CI 1.59 to 3.99; 4 trials, 792 participants).Data comparing PDE5 inhibitors to placebo whilst on other PAH-specific therapy were limited by the small number of included trials. Those PAH participants on PDE5 inhibitors plus combination therapy walked 19.66 metres further in six minutes (95% CI 9 to 30; 4 trials, 509 participants) compared to placebo (moderate-certainty evidence). There were limited trials comparing PDE5 inhibitors directly with other PAH-specific therapy (endothelin receptor antagonists (ERAs)). Those on PDE5 inhibitors walked 49 metres further than on ERAs (95% CI 4 to 95; 2 trials, 36 participants) (low-certainty evidence). There was no evidence of a difference in WHO functional class or mortality across both treatments.Five trials compared PDE5 inhibitors to placebo in PH secondary to left-heart disease (PH-LHD). The quality of data were low due to imprecision and inconsistency across trials. In those with PH-LHD there were reduced odds of an improvement in WHO functional class using PDE5 inhibitors compared to placebo (OR 0.53, 95% CI 0.32 to 0.87; 3 trials, 285 participants), and those using PDE5 inhibitors walked 34 metres further compared to placebo (95% CI 23 to 46; 3 trials, 284 participants). There was no evidence of a difference in mortality. Five trials compared PDE5 inhibitors to placebo in PH secondary to lung disease/hypoxia, mostly in COPD. Data were of low quality due to imprecision of effect and inconsistency across trials. There was a small improvement of 27 metres in 6MWD using PDE5 inhibitors compared to placebo in those with PH due to lung disease. There was no evidence of worsening hypoxia using PDE5 inhibitors, although data were limited. Three studies compared PDE5 inhibitors to placebo or other PAH-specific therapy in chronic thromboembolic disease. There was no significant difference in any outcomes. Data quality was low due to imprecision of effect and heterogeneity across trials.

AUTHORS' CONCLUSIONS

PDE5 inhibitors appear to have clear beneficial effects in group 1 PAH. Sildenafil, tadalafil and vardenafil are all efficacious in this clinical setting, and clinicians should consider the side-effect profile for each individual when choosing which PDE5 inhibitor to prescribe.While there appears to be some benefit for the use of PDE5 inhibitors in PH-left-heart disease, it is not clear based on the mostly small, short-term studies, which type of left-heart disease stands to benefit. These data suggest possible harm in valvular heart disease. There is no clear benefit for PDE5 inhibitors in pulmonary hypertension secondary to lung disease or chronic thromboembolic disease. Further research is required into the mechanisms of pulmonary hypertension secondary to left-heart disease, and cautious consideration of which subset of these patients may benefit from PDE5 inhibitors. Future trials in PH-LHD should be sufficiently powered, with long-term follow-up, and should include invasive haemodynamic data, WHO functional class, six-minute walk distance, and clinical worsening.

Risk Assessment in Pulmonary Arterial Hypertension Patients: The Long and Short of it

Pulmonary arterial hypertension (PAH) is a chronic and rapidly progressive disease that is characterized by extensive narrowing of the pulmonary vasculature, leading to increases in pulmonary vascular resistance, subsequent right ventricular dysfunction, and eventual death. There are currently multiple approved drugs—developed as single or combination therapies in the last few years—that have improved outcome and functionality in PAH. However, despite improvement in short-term survival with these new effective therapies, PAH remains an incurable disease with a median survival of 7 years (Figure 1).1 This chronic disease state may be characterized by morbid events such as hospitalizations that herald rapid disease progression and account for a significant disease burden (Figure 2).23 Physician ability to predict PAH disease progression is critical for determining optimal care of patients. Accurate risk assessment allows clinicians to determine the patient's prognosis, identify treatment goals, and monitor disease progression and the patient's response to treatment. Risk assessment for PAH patients should include a range of clinical, hemodynamic, and exercise parameters, performed in a serial fashion over the treatment course. Patient risk stratification can also help physicians better allocate treatment resources in settings where they are scarce. If widely adopted, risk prediction can enhance the consistency of treatment approaches across PAH practitioners and improve the timeliness of referral for lung transplantation. Hence, along with advancing PAH treatment options, comprehensive risk prediction is essential to make individualized treatment decisions in the current treatment era.

Several tools are currently available for assessing risk in PAH (Figure 3). These include the 2015 European Society of Cardiology/European Respiratory Society pulmonary hypertension guidelines' risk variables,4 the French registry equation,5 the National Institutes of Health risk equation,6 or a risk score such as the one derived from the Registry to Evaluate Early And Long-term PAH Disease Management.1 These registries and evaluations of clinical trial sets have provided important insights into the importance of both modifiable (eg, 6-minute walk distance, functional class, brain natriuretic peptide, and nonmodifiable (eg, age, gender, PAH etiology) risk factors that predict survival. The following review explores commonly cited risk factors, both modifiable and nonmodifiable, and their implications for patient outcomes.