Sex-specific cardiopulmonary exercise testing indices to estimate the severity of inoperable chronic thromboembolic pulmonary hypertension

Respiratory Diseases in Women

Respiratory diseases exhibit diverse patterns in prevalence, clinical presentations, and outcomes between men and women. Historically, certain conditions were more prevalent in men, but trends have shifted, highlighting the need to understand sex disparities in respiratory health. Social, environmental, and healthcare changes have reshaped the landscape of respiratory diseases, complicating diagnosis and treatment. Moreover, the underrepresentation of women in clinical trials has limited our understanding of their specific needs. In this review, we explore the sex differences in the prevalence, clinical characteristics, and presentation of respiratory diseases, emphasizing the importance of tailored approaches to diagnosis and management. By recognizing and addressing these disparities, we can advance toward more equitable and effective respiratory healthcare for all individuals.

Performance-based outcome measures for assessing physical capacity in patients with pulmonary embolism: A scoping review

INTRODUCTION

Up to 50 % of patients surviving a pulmonary embolism (PE) report persisting shortness of breath, reduced physical capacity and psychological distress. As the PE population is heterogeneous compared to other cardiovascular patient groups, outcome measures for assessing physical capacity traditionally used in cardiac populations may not be reliable for the PE population as a whole. This scoping review aims to 1) map performance-based outcome measures (PBOMs) used for assessing physical capacity in PE research, and 2) to report the psychometric properties of the identified PBOMs in a PE population.

METHODS

The review was conducted according to the Joanna Briggs Institute framework for scoping reviews and reported according to the PRISMA-Extension for Scoping Reviews guideline.

RESULTS

The systematic search of five databases identified 4585 studies, of which 243 studies met the inclusion criteria. Of these, 185 studies focused on a subgroup of patients with chronic thromboembolic pulmonary hypertension. Ten different PBOMs were identified in the included studies. The 6-minute walk test (6MWT) and cardiopulmonary exercise test (CPET) were the most commonly used, followed by the (Modified) Bruce protocol and Incremental Shuttle Walk test. No studies reported psychometric properties of any of the identified PBOMs in a PE population.

CONCLUSIONS

Publication of studies measuring physical capacity within PE populations has increased significantly over the past 5-10 years. Still, not one study was identified, reporting the validity, reliability, or responsiveness for any of the identified PBOMs in a PE population. This should be a priority for future research in the field.

Gender differences in the incidence of chronic thromboembolic pulmonary hypertension after acute pulmonary embolism: A meta-analysis

BACKGROUND

To explore the role of gender in the incidence of chronic thromboembolic pulmonary hypertension after acute pulmonary embolism.

METHODS

Two researchers search the PubMed Database, Embase Database and Cochrane Library Database from their establishment to October 2022, using Endnote software for document management and RevMan5.3 software for the meta-analysis of the included literature. A total of 11 studies are selected, including 5788 acute pulmonary embolism events and 391 patients (179 males and 212 females) with chronic thromboembolic pulmonary hypertension (CTEPH) under the stated conditions. The results show that there is no statistically significant difference in the incidence of CTEPH between males and females after PE (P = .28), with combined OR of 0.89 and 95% CI 0.72-1.10.

RESULTS AND CONCLUSIONS

Gender is found to be absent as a factor in the incidence of CTEPH after acute pulmonary embolism. This may indicate that gender is not a risk factor for CTEPH and that female patients are not necessarily more likely to have a higher incidence than male patients. As such, accurate judgments should be made on the possible complications of all patients after acute pulmonary embolism, which will be conducive to early detection and intervention in the treatment of CTEPH.

The Role of Strain by Cardiac Magnetic Resonance Imaging in Predicting the Prognosis of Patients with Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by thrombotic obstruction of the pulmonary arteries, and right ventricular (RV) dysfunction is a major cause of death. Cardiac magnetic resonance (CMR) is the gold standard for assessing heart wall deformation; therefore, we aimed to determine the prognostic value of CMR strain in patients with CTEPH. Strain derived by CMR was measured at the time of diagnosis in 45 patients with CTEPH, and the relationship between RV strain and prognosis was determined through follow-up. The value of RV strain in the prognostic model was compared with that of pulmonary arterial hypertension (PAH) risk stratification. The RV global peak longitudinal strain (GLS) and global peak circumferential strain (GCS) in CTEPH patients were lower than the normal references of RV strain in the control group. GLS and longitudinal strain in the basal segment were independent risk factors for adverse events (P < .050). Adding CMR parameters to PAH risk stratification improved its predictive power in patients with CTEPH. GLS and GCS scores were impaired in patients with chronic RV overload. RV strain derived by CMR imaging is a promising noninvasive tool for the follow-up of patients with CTEPH.

Sex-specific differences in sleep-disordered breathing and nocturnal hypoxemia in chronic thromboembolic pulmonary hypertension and chronic thromboembolic pulmonary disease

Objective

Although chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic pulmonary disease (CTEPD) are known to be accompanied by symptoms associated with sleep-disordered breathing (SDB) and nocturnal hypoxemia, the sex-specific differences of SDB and nocturnal hypoxemia in patients with CTEPH and CTEPD remain unknown.

Methods

Between July 2020 and August 2022, data were retrieved from 57 males and 63 female patients with CTEPH and CTEPD who underwent sleep study at Shanghai Pulmonary Hospital. Nocturnal mean SpO₂ (mean SpO₂) < 90% was defined as nocturnal hypoxemia. Logistic and linear regression analysis was performed to assess the predictive value of sleep study indices to hemodynamic parameters. Receiver operating characteristic (ROC) curve was applied to analyze the specific parameters to predict the risk of CTEPH.

Results

SDB was similarly present in males and females, and both sexes predominantly had obstructive sleep apnea (OSA); more women were diagnosed with nocturnal hypoxemia (32 vs. 7%, p = 0.002). SaO₂ was negatively associated with mean pulmonary arterial pressure (mPAP) in men (p < 0.001), whereas the ratio of nocturnal SpO₂ < 90% of the total monitoring time (T90%) was positively correlated with mPAP. Mean SpO₂ was an independent predictor for pulmonary vascular resistance and cardiac output in women (p = 0.001, p < 0.001, p = 0.001, respectively). T90%, SaO₂, and minimal SpO₂ were combined to develop a new composite parameter: hypoxemia scoring index (HSI). ROC curve analysis indicated that HSI levels of 0.55 could discriminate CTEPH from CTEPD with a sensitivity of 92.3% and specificity of 87.5% in female patients (an area under the curve, 0.937; 95% CI: 0.879–0.995, p < 0.001).

Conclusion

Sex-specific nocturnal hypoxemia was present in patients with CTEPH or CTEPD. In female patients, the HSI showed high capacity for predicting the risk of CTEPH.

Clinical trials registration

Registry: chictr.org.cn; Identifier: ChiCTR-DDD-16009406.

Pulmonary Embolism in Women: A Systematic Review of the Current Literature

Cardiovascular disease is the leading cause of death in women. Pulmonary embolism (PE) is the third most-common cause of cardiovascular death, after myocardial infarction (MI) and stroke. We aimed to evaluate the attributes and outcomes of PE specifically in women and explore sex-based differences. We conducted a systematic review of the literature using electronic databases PubMed and Embase up to 1 April 2022 to identify studies investigating PE in women. Of the studies found, 93 studies met the eligibility criteria and were included. The risk of PE in older women (especially >40 years of age) superseded that of age-matched men, although the overall age- and sex-adjusted incidence of PE was found to be lower in women. Risk factors for PE in women included age, rheumatologic disorders, hormone replacement therapy or oral contraceptive pills, pregnancy and postpartum period, recent surgery, immobilization, trauma, increased body mass index, obesity, and heart failure. Regarding pregnancy, a relatively higher incidence of PE has been observed in the immediate postpartum period compared to the antenatal period. Women with PE tended to be older, presented more often with dyspnea, and were found to have higher NT-proBNP levels compared to men. No sex-based differences in in-hospital mortality and 30-day all-cause mortality were found. However, PE-related mortality was higher in women, particularly in hemodynamically stable patients. These differences form the basis of future research and outlets for reducing the incidence, morbidity, and mortality of PE in women.

Sex Differences in Pulmonary Hypertension

Pulmonary hypertension (PH) includes multiple diseases that share as common characteristic an elevated pulmonary artery pressure and right ventricular involvement. Sex differences are observed in practically all causes of PH. The most studied type is pulmonary arterial hypertension (PAH) which presents a gender bias regarding its prevalence, prognosis, and response to treatment. Although this disease is more frequent in women, once affected they present a better prognosis compared to men. Even if estrogens seem to be the key to understand these differences, animal models have shown contradictory results leading to the birth of the estrogen paradox. In this review we will summarize the evidence regarding sex differences in experimental animal models and, very specially, in patients suffering from PAH or PH from other etiologies.

Sex and survival following pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension: a Scandinavian observational cohort study

Studies have suggested sex-related survival differences in chronic thromboembolic pulmonary hypertension (CTEPH). Whether long-term prognosis differs between men and women following pulmonary endarterectomy for CTEPH remains unclear. We investigated sex-specific survival after pulmonary endarterectomy for CTEPH. We included all patients who underwent pulmonary endarterectomy for CTEPH at two Scandinavian centers and obtained baseline characteristics and vital statuses from patient charts and national health-data registers. Propensity scores and weighting were used to account for baseline differences. Flexible parametric survival models were employed to estimate the association between sex and all-cause mortality and the absolute survival differences. The expected survival in an age-, sex-, and year of surgery matched general population was obtained from the Human Mortality Database, and the relative survival was used to estimate cause-specific mortality. A total of 444 patients were included, comprising 260 (59%) men and 184 (41%) women. Unadjusted 30-day mortality was 4.2% in men versus 9.8% in women (p = 0.020). In weighted analyses, long-term survival did not differ significantly in women compared with men (hazard ratio: 1.36; 95% confidence interval: 0.89–2.06). Relative survival at 15 years conditional on 30-day survival was 94% (79%–107%) in men versus 75% (59%–88%) in women. In patients who underwent pulmonary endarterectomy for CTEPH, early mortality was higher in women compared with men. After adjustment for differences in baseline characteristics, female sex was not associated with long-term survival. However, relative survival analyses suggested that the observed survival in men was close to the expected survival in the matched general population, whereas survival in women deviated notably from the matched general population.

PeakPETCO2 combined with FEV1/FVC predicts vasodilator-responsive patients with idiopathic pulmonary arterial hypertension

Cardiopulmonary exercise testing and pulmonary function test are important methods for detecting human cardio-pulmonary function. Whether they could screen vasoresponsiveness in idiopathic pulmonary artery hypertension (IPAH) patients remains undefined. One hundred thirty-two IPAH patients with complete data were retrospectively enrolled. Patients were classified as vasodilator-responsive (VR) group and vasodilator-nonresponsive (VNR) group on the basis of the acute vasodilator test. Pulmonary function test and cardiopulmonary exercise testing were assessed subsequently and all patients were confirmed by right heart catheterization. We analyzed cardiopulmonary exercise testing and pulmonary function test data and derived a prediction rule to screen vasodilator-responsive patients in IPAH. Nineteen of VR-IPAH and 113 of VNR-IPAH patients were retrospectively enrolled. Compared with VNR-IPAH patients, VR-IPAH patients had less severe hemodynamic effects (lower RAP, m PAP, PAWP, and PVR). And VR-IPAH patients had higher anaerobic threshold (AT), peak partial pressure of end-tidal carbon dioxide (PETCO2), oxygen uptake efficiency (OUEP), and FEV1/FVC (P all <0.05), while lower peak partial pressure of end-tidal oxygen (PETO2) and minute ventilation (VE)/carbon dioxide output (VCO2) slope (P all <0.05). FEV1/FVC (Odds Ratio [OR]: 1.14, 95% confidence interval [CI]: 1.02-1.26, P = 0.02) and PeakPETCO2 (OR: 1.13, 95% CI: 1.01-1.26, P = 0.04) were independent predictors of VR adjusted for age, sex, and body mass index. A novel formula (=-16.17 + 0.123 × PeakPETCO2 + 0.127×FEV1/FVC) reached a high area under the curve value of 0.8 (P = 0.003). Combined with these parameters, the optimal cutoff value of this model for detection of VR is -1.06, with a specificity of 91% and sensitivity of 67%. Compared with VNR-IPAH patients, VR-IPAH patients had less severe hemodynamic effects. Higher FEV1/FVC and higher peak PETCO2 were associated with increased odds for vasoresponsiveness. A novel score combining PeakPETCO2 and FEV1/FVC provides high specificity to predict VR patients among IPAH.

Sex Differences in Right Ventricular Dysfunction: Insights From the Bench to Bedside

There are inherent distinctions in right ventricular (RV) performance based on sex as females have better RV function than males. These differences are magnified and have very important prognostic implications in two RV-centric diseases, pulmonary hypertension (PH), and arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). In both PH and ARVC/D, RV dysfunction results in poor patient outcomes. However, there are no currently approved therapies specifically targeting the failing RV, an important unmet need for these two life-threatening disorders. In this review, we highlight human data demonstrating divergent RV phenotypes in healthy, PH, and ARVC/D patients based on sex. Furthermore, we discuss the links between estrogen (the female predominant sex hormone), testosterone (the male predominant sex hormone), and dehydroepiandrosterone (a precursor hormone for multiple sex hormones in males and females) and RV function in both disorders. To provide potential mechanistic insights into sex differences in RV function, we review data that investigate how sex hormones combat or contribute to pathophysiological changes in the RV. Finally, we highlight the ongoing clinical trials in pulmonary arterial hypertension targeting estrogen and dehydroepiandrosterone signaling. Hopefully, a greater understanding of the factors that promote superior RV function in females will lead to novel therapeutic approaches to combat RV dysfunction in PH and ARVC/D.

Changed hemodynamics in acute vasoreactivity testing: prognostic predictors in chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is similar to pulmonary arterial hypertension (PAH) in its pathogenesis. Changed hemodynamic parameters in acute vasoreactivity testing (AVT) have proved to be prognostic predictors of PAH. We wanted to determine whether these changed indices also impacted the prognosis of CTEPH. Data was retrieved for 86 CTEPH patients who underwent right heart catheterization (RHC) with AVT at Shanghai Pulmonary Hospital from 2009 to 2018 and following up for 20 ± 15 months for event. Cox proportional hazards models were performed to determine the predictors of independent event-free survival. Receiver operating characteristic curve was plotted to determine the cut-off value of independent parameters in CTEPH. Kaplan-Meier method and log-rank test were used to perform the Survival analyses. Forty seven patients had an event. Many hemodynamic indices improved after AVT. The event-free group had better mean right atrial pressure, mean pulmonary arterial pressure, pulmonary vascular resistance (PVR) and oxygen saturation of mixed venous blood (SvO2) both at baseline and after AVT. The event-free group also showed higher cardiac output (CO) and cardiac index (CI) after AVT. Among the changed hemodynamic parameters during the AVT, ΔCO, ΔCO/baseline CO, ΔCI, ΔCI/baseline CI and ΔPVR/baseline PVR were significantly higher in the event-free group. Foremost, ΔPVR/baseline PVR, PVR after AVT and baseline SvO2 were independent predictors for event-free survival. Patients with SvO2 ≥ 61.65% at baseline or PVR < 8.09 WU after AVT or ΔPVR/baseline PVR ≥ 0.054 had significantly better survival. Hemodynamic indices both at baseline and after AVT as well as the changes in these indices reflected the severity of CTEPH. Baseline SvO2, PVR after AVT, and ΔPVR/baseline PVR could be used as independent predictors to estimate the outcomes of CTEPH patients.

Sex differences of hemodynamics during acute vasoreactivity testing to predict the outcomes of chronic thromboembolic pulmonary hypertension

BACKGROUND

Acute vasoreactivity testing (AVT) which reflects the compliance of the pulmonary vascular bed has been proven to be of prognostic value. The purpose of the present study is to explore the sex differences of hemodynamics during the AVT and their impact on event-free survival in patients with chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

Eighty-six patients underwent a right heart catheterization and AVT at Shanghai Pulmonary Hospital from February 2009 to February 2018. Univariate and multiple stepwise regression analysis were performed to determine the predictors of independent event-free survival, and receiver operating characteristic curve was plotted to determine the cut-off value of independent parameters in CTEPH.

RESULTS

There were no significant differences in both demographics and hemodynamics between male and female patients with CTEPH. Except ΔPVR/PVR showed a significantly higher difference in female than male patients (P = 0.034). Male patients had higher mRAP of pre- and post-AVT than female patients in the event-free subgroup, while, female patients showed higher PVR of pre-AVT than male patients in the event subgroup (P < 0.05). The mRAP and SvO₂ were independent predictors of event-free survival in female patients both before and after the AVT, whereas ΔSvO₂ was an independent predictor of event-free survival in male patients.

CONCLUSION

Hemodynamics during the AVT varied between male and female patients with CTEPH. Both sexes displayed unique hemodynamic responses that were independently able to predict event-free survival. Therefore, better estimates of prognosis in CTEPH can be made when sex differences are also taken into consideration.

Sex-specific differences in chronic thromboembolic pulmonary hypertension. Results from the European CTEPH registry

BACKGROUND

Women are more susceptible than men to several forms of pulmonary hypertension, but have better survival. Sparse data are available on chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

We investigated sex-specific differences in the clinical presentation of CTEPH, performance of pulmonary endarterectomy (PEA), and survival.

RESULTS

Women constituted one-half of the study population of the European CTEPH registry (N = 679) and were characterized by a lower prevalence of some cardiovascular risk factors, including prior acute coronary syndrome, smoking habit, and chronic obstructive pulmonary disease, but more prevalent obesity, cancer, and thyroid diseases. The median age was 62 (interquartile ratio, 50-73) years in women and 63 (interquartile ratio, 53-70) in men. Women underwent PEA less often than men (54% vs 65%), especially at low-volume centers (48% vs 61%), and were exposed to fewer additional cardiac procedures, notably coronary artery bypass graft surgery (0.5% vs 9.5%). The prevalence of specific reasons for not being operated, including patient's refusal and the proportion of proximal vs distal lesions, did not differ between sexes. A total of 57 (17.0%) deaths in women and 70 (20.7%) in men were recorded over long-term follow-up. Female sex was positively associated with long-term survival (adjusted hazard ratio, 0.66; 95% confidence interval, 0.46-0.94). Short-term mortality was identical in the two groups.

CONCLUSIONS

Women with CTEPH underwent PEA less frequently than men, especially at low-volume centers. Furthermore, they had a lower prevalence of cardiovascular risk factors and were less often exposed to additional cardiac surgery procedures. Women had better long-term survival.

Cardiac remodelling in a swine model of chronic thromboembolic pulmonary hypertension: comparison of right vs. left ventricle

KEY POINTS

Right ventricle (RV) function is the most important determinant of survival and quality of life in patients with chronic thromboembolic pulmonary hypertension (CTEPH). The changes in right and left ventricle gene expression that contribute to ventricular remodelling are incompletely investigated. RV remodelling in our CTEPH swine model is associated with increased expression of the genes involved in inflammation (TGFβ), oxidative stress (ROCK2, NOX1 and NOX4), and apoptosis (BCL2 and caspase-3). Alterations in ROCK2 expression correlated inversely with RV contractile reserve during exercise. Since ROCK2 has been shown to be involved in hypertrophy, oxidative stress, fibrosis and endothelial dysfunction, ROCK2 inhibition may present a viable therapeutic target in CTEPH.

ABSTRACT

Right ventricle (RV) function is the most important determinant of survival and quality of life in patients with chronic thromboembolic pulmonary hypertension (CTEPH). The present study investigated whether the increased cardiac afterload is associated with (i) cardiac remodelling and hypertrophic signalling; (ii) changes in angiogenic factors and capillary density; and (iii) inflammatory changes associated with oxidative stress and interstitial fibrosis. CTEPH was induced in eight chronically instrumented swine by chronic nitric oxide synthase inhibition and up to five weekly pulmonary embolizations. Nine healthy swine served as a control. After 9 weeks, RV function was assessed by single beat analysis of RV-pulmonary artery (PA) coupling at rest and during exercise, as well as by cardiac magnetic resonance imaging. Subsequently, the heart was excised and RV and left ventricle (LV) tissues were processed for molecular and histological analyses. Swine with CTEPH exhibited significant RV hypertrophy in response to the elevated PA pressure. RV-PA coupling was significantly reduced, correlated inversely with pulmonary vascular resistance and did not increase during exercise in CTEPH swine. Expression of genes associated with hypertrophy (BNP), inflammation (TGFβ), oxidative stress (ROCK2, NOX1 and NOX4), apoptosis (BCL2 and caspase-3) and angiogenesis (VEGFA) were increased in the RV of CTEPH swine and correlated inversely with RV-PA coupling during exercise. In the LV, only significant changes in ROCK2 gene-expression occurred. In conclusion, RV remodelling in our CTEPH swine model is associated with increased expression of genes involved in inflammation and oxidative stress, suggesting that these processes contribute to RV remodelling and dysfunction in CTEPH and hence represent potential therapeutic targets.