Endpoints in pulmonary arterial hypertension: the role of clinical worsening

Hospitalisation Is Prognostic of Survival in Chronic Thromboembolic Pulmonary Hypertension

This analysis investigated the prognostic value of hospitalisation in chronic thromboembolic pulmonary hypertension (CTEPH) using data from the Czech Republic, wherein pulmonary endarterectomy (PEA) was the only targeted treatment option until 2015. Using a landmark method, this analysis quantified the association between a first CTEPH-related hospitalisation event occurring before 3-, 6-, 9-, and 12-month landmark timepoints and subsequent all-cause mortality in adult CTEPH patients diagnosed between 2003 and 2016 in the Czech Republic. Patients were stratified into operable and inoperable, according to PEA eligibility. CTEPH-related hospitalisations were defined as non-elective. Hospitalisations related to CTEPH diagnosis, PEA, balloon pulmonary angioplasty, or clinical trial participation were excluded. Of 436 patients who survived to ≥3 months post diagnosis, 309 were operable, and 127 were inoperable. Sex- and age-adjusted hazard ratios (HRs) showed CTEPH-related hospitalisation was a statistically significant prognostic indicator of mortality at 3, 9, and 12 months in inoperable patients, with an approximately 2-fold increased risk of death in the hospitalisation group (HRs [95% CI] ranging from 1.98 [1.06-3.70] to 2.17 [1.01-4.63]). There was also a trend of worse survival probabilities in the hospitalisation groups for operable patients, with the difference most pronounced at 3 months, with a 76% increased risk of death (adjusted HR [95% CI] 1.76 [1.15-2.68]). This first analysis on the prognostic value of CTEPH-related hospitalisations demonstrates that a first CTEPH-related hospitalisation is prognostic of mortality in CTEPH, particularly for inoperable patients. These patients may benefit from medical and/or interventional therapy.

Dynamics of 6-Minute Walk Distance as a Predictor of Efficiency Specific Pulmonary Vasodilators

Pulmonary hypertension is a severe and often rapidly progressive disease with a fatal outcome. Approved specific therapy with five classes of drugs – prostanoids, endothelin receptor antagonists, phosphodiesterase-5 inhibitors, soluble guanylate cyclase stimulators and prostacyclin receptor agonists has significantly improved the prognosis of patients. An accessible and reproducible criterion of exercise tolerance – a distance walked in six-minute walk test (6MXD) – occupies one of the central places among the performance indicators (clinical, echocardiographic and hemodynamic) of specific pulmonary vasodilators. Reflecting the clinical severity of pulmonary hypertension and, according to some data, its long-term prognosis, the dynamics of 6MXD is an integral component of the combined primary endpoints of randomized controlled trials. In the CHEST-2019 recommendations, the dynamics of the 6MXD was used to standardize the randomized controlled trials. The 6MXD is indispensable for dynamic observation and decisionmaking on further treatment tactics 

Ventricular Diastolic Pressure Ratio as a Marker of Treatment Response in Pulmonary Hypertension

BACKGROUND

Pulmonary hypertension (PH) is diagnosed and classified through right-sided heart catheterization, with a number of hemodynamic markers used to help guide treatment decisions. These markers may not reflect the complex remodeling of the right ventricle or the interplay between ventricles and struggle to predict treatment response. This study investigates the use of a novel marker: the ratio of left ventricular end-diastolic pressure to right ventricular end-diastolic pressure (LVEDP/RVEDP) in predicting treatment outcomes in a cohort of patients with PH.

METHODS

We performed a retrospective analysis of patients with PH at INOVA Fairfax Hospital's advanced lung disease program with simultaneous left-sided and right-sided heart catheterization. The primary end point was the time to clinical improvement, defined by an improvement in distance walked on the 6-min walk test (6MWT) of > 35 m in a year without interceding hospitalization for worsening PH or the need for additional PH therapy.

RESULTS

A total of 51 patients were included in the final analysis, 21 of whom (41.2%) had a salutary treatment effect with a mean improvement in the 6MWT of 75 m. Treatment responders were more likely to have a lower LVEDP/RVEDP ratio (1.08 vs 1.62; P = .051). This association persisted in the final multivariate regression model after adjustment for age and sex and controlling for severity of PH (OR, 0.17; 95% CI, 0.03-0.65; P = .024).

CONCLUSIONS

The LVEDP/RVEDP ratio is a novel marker for therapeutic response in patients with PH treated with pulmonary vasodilator medications and may offer robust predictive value independent of existing markers of disease severity.

Six-Minute Walk Test in Evaluation of Children with Pulmonary Arterial Hypertension

Six-minute walk test (6MWT) is a submaximal exercise test applied for evaluation of adults with pulmonary arterial hypertension (PAH). It was widely used as an endpoint in the clinical trials. The aim of the study was to assess the usefulness of 6MWT in management of children with PAH and to establish correlations with other clinical features. 164 6MWT were performed in 15 children between 5 and 18 years with PAH confirmed by right heart catheterization (102 in patients with shunt, 62 without shunt). Distance in 6MWT (6MWD)-% of predicted for age and gender, desaturation at the maximum effort, peak heart rate (HR)-% of maximal HR, were compared to the level of NTproBNP, WHO-FC, echocardiography parameters, and events of PAH treatment intensification. 6MWD had low negative correlation with peak HR (τ -0.1 p = 0,03), negative correlation with NTproBNP (τ -0.17 p = 0.002), and no dependence on echocardiography parameters. The presence of shunt was associated with lower 6MWD, lower blood saturation at rest, and higher desaturation after effort. Patients in III/IV WHO-FC achieved higher rest HR and maximal HR in comparison to patients in I/II WHO-FC (63.1 vs. 55.2% p < 0.01) and lower 6MWD (64.3 vs. 77.5% p < 0.01). In 14 out of 20 6MWT performed after treatment intensification, increase of distance was observed. The results of 6MWT were consistent with clinical status (WHO-FC, NTproBNP) but not with echocardiography parameters. 6MWT may be the source of additional information in management of children with PAH.

A simple hemodynamic parameter to predict clinical worsening in pulmonary arterial hypertension

BACKGROUND

Predicting prognosis is a cornerstone in management of pulmonary arterial hypertension. Hemodynamic parameters are among the robust indicators of right ventricular function and prognosis. In this study we have investigated the association of a simple hemodynamic parameter with clinical worsening in pulmonary arterial hypertension.

METHODS AND PATIENTS

120 patients were enrolled in a single center prospective cohort study after confirmation of precapillary pulmonary hypertension and were followed for an average of 36months on guideline recommended treatment protocols. cSvO₂ was calculated as the ratio of right atrial pressure over Mixed Venous Oxygen Saturation. Independent predictors of clinical worsening were identified using multivariable Cox regression models.

RESULTS

By the end of the follow up a total of 21 patients died and 63 were hospitalized for pulmonary hypertension. Time-to-event Cox regression model showed a strong association between cSvO₂ and time to clinical worsening (HR: 250.13, CI: (38.56-1622.34) &p-value: <0.0001).

CONCLUSION

The index of cSvO₂ includes both parameters of cardiac output and right ventricular filling pressure and might be beneficial in predicting clinical worsening in patients with pulmonary arterial hypertension.

Combination Therapy for Pulmonary Arterial Hypertension: A Systematic Review and Meta-analysis

BACKGROUND

Combination therapy (CT) for patients with pulmonary arterial hypertension (PAH) has been recommended for many years, despite weak evidence of efficacy over monotherapy (MT). A previous meta-analysis comparing CT vs MT with pulmonary vasodilators failed to demonstrate a clear reduction in clinical worsening events.

METHODS

We searched for relevant articles in PubMed, EMBASE, the Cochrane Database, and clinicaltrials.gov; we also manually searched review articles and conference abstracts from 1980-December 2015. Target articles were double-blinded studies of 2 or more pulmonary vasodilators given in combination vs monotherapy for treatment of patients with PAH. The principal outcome of interest was "combined clinical worsening" (CCW) events (including but not limited to death or hospitalization). Data on physiological outcomes were also explored. Meta-analysis was performed using the DerSimonian and Laird random-effects model.

RESULTS

We extracted data from 18 randomized controlled trials (RCTs) (N = 4162). CT was associated with a significant 38% reduction of risk of CCW (15 RCTs: n = 3906; risk ratio [RR], 0.62; 95% confidence interval [CI], 0.50-0.77). This reduction in risk was driven by a reduction in nonfatal end points (12 RCTs: n = 2611; RR, 0.56; 95% CI, 0.40-0.78) and not by a reduction of mortality (12 RCTs: n = 2717; RR, 0.79; 95% CI, 0.53-1.17). CT was also associated with improvement in 6-minute walking distance (10 RCTs: n = 1553; weighted mean difference [WMD], +23.0 m; 95% CI, 15.9-30.1), improved functional class (9 RCTs: n = 1737; RR, 1.26; 95% CI, 1.05-1.51), and beneficial effects on pulmonary hemodynamics such as cardiac index (WMD, +0.35 L/min/m; 95% CI, 0.14-0.56).

CONCLUSIONS

In this highly comprehensive meta-analysis, CT reduces the risk of CCW events in patients with PAH and brings physiological improvement.

Clinical Worsening as Composite Study End Point in Pediatric Pulmonary Arterial Hypertension

BACKGROUND

Clinical worsening (CW), an increasingly used composite end point in adult pulmonary arterial hypertension (PAH), has not yet been evaluated in pediatric PAH. This study aims to evaluate the usefulness of CW in pediatric PAH by assessing the event incidence and prognostic value of each separate component of CW and of the composite CW end point.

METHODS

Seventy pediatric patients with PAH from the Dutch National Network for Pediatric Pulmonary Hypertension, who started PAH-targeted therapy between January 2000 and January 2014, were included in the study and underwent standardized follow-up. The following CW components were prospectively registered: death, lung transplantation (LTx), PAH-related hospitalizations, initiation of IV prostanoids, and functional deterioration (World Health Organization functional-class deterioration, ≥ 15% decrease in 6-min walk distance, or both). The longitudinal event incidence and prognostic value were assessed for each separate component and their combination.

RESULTS

The end-point components of death, LTx, hospitalizations, initiation of IV prostanoids, and functional deterioration occurred with a longitudinal event rate of 10.1, 2.5, 21.4, 9.4 and 48.1 events per 100 person-years, respectively. The composite CW end point occurred 91.5 times per 100 person-years. The occurrences of either hospitalization, initiation of IV prostanoids, or functional deterioration were predictive of death or LTx (P < .001 for each component). In this cohort, 1-, 3-, and 5-year transplant-free survival was 76%, 64%, and 56%, respectively. Freedom from CW at 1, 3, and 5 years was 43%, 22%, and 17%, respectively.

CONCLUSIONS

CW occurred with a high event incidence and each of the soft end-point components was predictive of death or LTx. This supports the usefulness of CW as a study end point in clinical trials in pediatric PAH.

Development of macitentan for the treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a serious, chronic condition that, without early recognition and treatment, leads to progressive right heart failure and death. The dual endothelin receptor antagonist macitentan was designed through a deliberate discovery process to maximize endothelin-axis blockade while improving adverse-effect profiles compared with previous compounds. Macitentan's efficacy was demonstrated in an event-driven morbidity and mortality study of treatment-naive and background PAH therapy-treated symptomatic patients. Compared to placebo, 10 mg of macitentan significantly reduced the relative risk of morbidity and mortality by 45%, primarily by delaying PAH worsening, most prominently in World Health Organization (WHO) functional class II and III PAH patients. Macitentan reduced the incidence of the composite end point of PAH-related hospitalizations and mortality and improved WHO FC and exercise capacity (6-min walk distance). Furthermore, it significantly improved cardiopulmonary hemodynamics and quality of life, and had a favorable safety and tolerability profile. To date, this was the largest and longest prospective trial for PAH. Macitentan, currently the only approved oral PAH treatment shown to be safe and effective in delaying long-term progression and reducing PAH-related hospitalizations, has changed treatment paradigms from goal-directed to long-term outcome-oriented therapy.

Functional exercise capacity, physical activity, and respiratory and peripheral muscle strength in pulmonary hypertension according to disease severity

[Purpose] This study investigated functional capacity, physical activity, and respiratory and peripheral muscle strength in different functional classes of pulmonary arterial hypertension (PAH) compared with healthy subjects. [Subjects and Methods] This study included 31 patients with class II (n = 16) or class III (n = 15) PAH, classified according to the World Health Organization. Fifteen healthy subjects served as controls. Functional capacity was assessed using the 6-minute walk test (6MWT). Physical activity was determined using the International Physical Activity Questionnaire Short Form (IPAQ-SF). Respiratory muscle strength was measured using a mouth pressure device. Peripheral muscle strength was evaluated using a dynamometer. [Results] The 3 groups had similar demographic variables (p > 0.05). There were significant differences in 6MWT distance, maximal inspiratory pressure, and IPAQ categorical classification between the 3 groups (p < 0.05). Maximal expiratory pressure; total IPAQ score; and knee extensor, shoulder abductor, and hand grip strength were significantly lower in PAH patients (classes II and III) than in healthy subjects (p < 0.05). [Conclusion] As PAH progresses, respiratory muscle strength, functional exercise capacity, and physical activity decrease. Functional class should be taken into consideration when planning rehabilitation programs for this patient group.

An update on medical therapy for pulmonary arterial hypertension

Over the past 20 years, great progress has been made in the treatment of pulmonary arterial hypertension (PAH). Available therapies target one of three principal pathways: the endothelin (ET), nitric oxide (NO) or the prostacyclin (PGI2) pathway. Evidence shows that current drugs, used either as monotherapy or in different combinations, can improve exercise capacity, clinical symptoms, hemodynamics and even survival in PAH. Unfortunately, the disease remains incurable and the prognosis of the disease is still poor. However, existing and novel potent antiproliferative therapies are being explored, and new agents targeting different and/or additional pathways are likely to become available to clinicians in the near future. Promising candidates include tyrosine kinase antagonists (e.g. imatinib); soluble guanylate cyclase stimulators (riociguat); an oral analog of prostacyclin (selexipag); and a tissue targeting endothelin receptor antagonist (macitentan). Phase II or III trials have either been completed or are underway to evaluate the safety and efficacy of these various therapies.

Endpoints in PAH clinical trials in the era of combination therapy: how do we decide whether something is working without going bankrupt?

There has been substantial progress in the treatment of pulmonary arterial hypertension using specific disease-targeted therapies. As the number of agents available grows, and as new treatment strategies emerge, it is essential that the endpoints we use to assess efficacy are sufficiently meaningful and sensitive enough to detect changes that are often subtle. Although the six-minute walk has been the traditional primary endpoint in clinical trials, there is now a move towards more patient-centred composite endpoints such as time to clinical worsening. These endpoints need to be more clearly defined and universally applied so as to make direct comparison between new drugs and new combinations possible.

Efficacy and safety of sildenafil treatment in pulmonary arterial hypertension: a systematic review

BACKGROUND

To evaluate the safety and efficacy of using sildenafil for ≥ 12 weeks to treat pulmonary arterial hypertension (PAH).

METHODS

Randomized controlled trials (RCTs) of sildenafil therapy in patients with PAH published through May 2013 were identified by searching PubMed, the Cochrane Library, Embase, relevant websites, and reference lists of relevant studies. Two reviewers independently assessed the quality of the trials and extracted information.

RESULTS

Meta-analysis was carried out with subsets of 4 trials involving 545 patients. Sildenafil therapy significantly reduced clinical worsening of PAH compared to placebo (RR 0.39, 95% CI 0.21-0.69) and improved the 6-min walk distance (MD 31.3 m, 95% CI 18.01-44.67), WHO functional class, hemodynamic variables and health-related quality of life (HRQoL). Sildenafil did not, however, improve all-cause mortality (RR 0.29, 95% CI 0.02-4.94) or Borg dyspnea score relative to placebo, nor did it significantly affect the incidence of serious adverse events. In fact, sildenafil was associated with higher total incidence of adverse events, but these additional events were mild to moderate in severity and were tolerable.

CONCLUSIONS

Sildenafil therapy lasting ≥ 12 weeks improves multiple clinical and hemodynamic outcomes in patients with PAH, but it appears to have no effect on mortality or serious adverse events. The long-term efficacy and safety of sildenafil therapy in PAH requires further study based on large and well-designed RCTs.

Combination therapy improves exercise capacity and reduces risk of clinical worsening in patients with pulmonary arterial hypertension: a meta-analysis

BACKGROUND

Clinical studies on combination therapy in patients with pulmonary arterial hypertension (PAH) revealed mixed results.

AIMS

The aim of the present meta-analysis was to evaluate the effect of combination therapy on exercise capacity [measured with 6-minute walk distance (6MWD)] and clinical worsening in PAH patients.

METHODS

We identified trials of importance from the Cochrane Library, EMBASE, and PUBMED databases, reviews, and reference lists of relevant articles. We calculated risk ratios for dichotomous data and weighted mean differences, with 95% confidence intervals (CIs), for net changes in 6MWD.

RESULTS

Seven trials with a total of 768 patients (386 patients in the combination treatment group and 382 patients in the monotherapy group) were included in the meta-analysis. Compared with the monotherapy group, combination therapy increased 6MWD by 21.59 meters (weighted mean difference 21.59 m, 95% CI of 13.25-29.93; P < 0.001) and reduced the risk of clinical worsening (risk ratio: 0.43, 95% CI: 0.26-0.72, P = 0.001). For both outcomes, no significant heterogeneity and publication bias were found.

CONCLUSION

Compared with monotherapy, combination therapy improves exercise capacity and reduces the risk of clinical worsening in PAH patients. In future studies, more large randomized controlled trials should be designed to adequately assess the efficacy and safety of combination therapy.

A pulmonary hypertension gas exchange severity (PH-GXS) score to assist with the assessment and monitoring of pulmonary arterial hypertension

Submaximal exercise gas analysis may be a useful method to assess and track pulmonary arterial hypertension (PAH) severity. The aim of the present study was to develop an algorithm, using exercise gas exchange data, to assess and monitor PAH severity. Forty patients with PAH participated in the study, completing a range of clinical tests and a novel submaximal exercise step test, which lasted 6 minutes and incorporated rest (2 minutes), exercise (3 minutes), and recovery (1 minute) ventilatory gas analysis. Using gas exchange data, including breathing efficiency, end-tidal carbon dioxide, oxygen saturation, and oxygen pulse, a pulmonary hypertension gas exchange severity (PH-GXS) score was developed. Patients were retested after about 6 months. There was significant separation between healthy controls and patients with moderate PAH (World Health Organization [WHO] class I/II) and those with more severe PAH (WHO class III/IV) for breathing efficiency, end-tidal carbon dioxide, oxygen saturation, and oxygen pulse. The PH-GXS score was significantly correlated with WHO class (r = 0.51), 6-minute walking distance (r = -0.59), right ventricular systolic pressure (r = 0.49), log N-terminal pro-B-type natriuretic peptide (r = 0.54), and pulmonary vascular resistance (r = 0.71). The PH-GXS score remained unchanged in 22 patients retested (1.50 ± 0.92 vs 1.48 ± 0.94), as did WHO class (2.3 ± 0.8 vs 2.3 ± 0.8) and 6-minute walking distance (455 ± 120 vs 456 ± 103 m). Small individual changes were observed in the PH-GXS score, with 8 patients improving and 8 deteriorating. In conclusion, the PH-GXS score differentiated between patients with PAH and was correlated with traditional clinical measures. The PH-GXS score was unchanged in our cohort after 6 months, consistent with traditional clinical metrics, but individual differences were evident. A PH-GXS score may be a useful way to track patient responses to therapy.

End tidal CO(2) tension: pulmonary arterial hypertension vs pulmonary venous hypertension and response to treatment

BACKGROUND

CO(2) excretion is impaired in pulmonary arterial hypertension (PAH) due to underlying vascular obstruction and increased dead space. Our aim was to determine whether resting end tidal CO(2) (Etco(2)) could differentiate patients with PAH from those with pulmonary venous hypertension (PVH) or patients without pulmonary hypertension (PH) and whether successful treatment of PAH resulted in higher Etco(2) values.

METHODS

We performed Etco(2) measurements for five breaths at rest and after a 6-min walk test (6MWT) in patients seen at our pulmonary vascular center. Mean Etco(2) values were correlated with 6-min walk distance and right-sided heart catheterization data.

RESULTS

We enrolled 84 patients with PAH, 17 with PVH without left ventricular systolic dysfunction, and seven with no PH and no severe alterations in pulmonary function testing. Etco(2) was significantly lower in patients with PAH than in those with no PH and PVH (P < .0001 PAH vs both groups). Etco(2) correlated with the pulmonary artery diastolic pressure-to-pulmonary artery occlusion pressure gradient (r = -0.50, P = .0002) and pulmonary vascular resistance (r = -0.44, P = .002). Etco(2) after 6MWT correlated with walk distance (r = 0.34, P = .003). In patients with prostaglandin therapy escalation, Etco(2) increased in those who had clinical improvement, whereas in patients who did not improve clinically, Etco(2) failed to rise (P = .04).

CONCLUSIONS

Etco(2) is a promising tool to differentiate patients with PAH from those with PVH or no PH, correlates with diagnostic and prognostic hemodynamic indicators, and may increase with successful treatment of PAH.