Consequences of Using Post- or Prebronchodilator Reference Values in Interpreting Spirometry.

Rationale: Postbronchodilator spirometry is used for the diagnosis of chronic obstructive pulmonary disease. However, prebronchodilator reference values are used for spirometry interpretation. Objectives: To compare the resulting prevalence rates of abnormal spirometry and study the consequences of using pre- or postbronchodilator reference values generated within SCAPIS (Swedish CArdioPulmonary bioImage Study) when interpreting postbronchodilator spirometry in a general population. Methods: SCAPIS reference values for postbronchodilator and prebronchodilator spirometry were based on 10,156 and 1,498 never-smoking, healthy participants, respectively. We studied the associations of abnormal spirometry, defined by using pre- or postbronchodilator reference values, with respiratory burden in the SCAPIS general population (28,851 individuals). Measurements and Main Results: Bronchodilation resulted in higher predicted medians and lower limits of normal (LLNs) for FEV1/FVC ratios. The prevalence of postbronchodilator FEV1/FVC ratio lower than the prebronchodilator LLN was 4.8%, and that of postbronchodilator FEV1/FVC lower than the postbronchodilator LLN was 9.9%, for the general population. An additional 5.1% were identified as having an abnormal postbronchodilator FEV1/FVC ratio, and this group had more respiratory symptoms, emphysema (13.5% vs. 4.1%; P < 0.001), and self-reported physician-diagnosed chronic obstructive pulmonary disease (2.8% vs. 0.5%, P < 0.001) than subjects with a postbronchodilator FEV1/FVC ratio greater than the LLN for both pre- and postbronchodilation. Conclusions: Pre- and postbronchodilator spirometry reference values differ with regard to FEV1/FVC ratio. Use of postbronchodilator reference values doubled the population prevalence of airflow obstruction; this was related to a higher respiratory burden. Using postbronchodilator reference values when interpreting postbronchodilator spirometry might enable the identification of individuals with mild disease and be clinically relevant.

Prevalence of atherosclerosis in individuals with prediabetes and diabetes compared to normoglycaemic individuals-a Swedish population-based study.

BACKGROUND: Patients with type 2 diabetes have an increased risk of death and cardiovascular events and people with diabetes or prediabetes have been found to have increased atherosclerotic burden in the coronary and carotid arteries. This study will estimate the cross-sectional prevalence of atherosclerosis in the coronary and carotid arteries in individuals with prediabetes and diabetes, compared with normoglycaemic individuals in a large population-based cohort. METHODS: The 30,154 study participants, 50-64 years, were categorized according to their fasting glycaemic status or self-reported data as normoglycaemic, prediabetes, and previously undetected or known diabetes. Prevalence of affected coronary artery segments, severity of stenosis and coronary artery calcium score (CACS) were determined by coronary computed tomography angiography. Total atherosclerotic burden was assessed in the 11 clinically most relevant segments using the Segment Involvement Score and as the presence of any coronary atherosclerosis. The presence of atherosclerotic plaque in the carotid arteries was determined by ultrasound examination. RESULTS: Study participants with prediabetes (n = 4804, 16.0%) or diabetes (n = 2282, 7.6%) had greater coronary artery plaque burden, more coronary stenosis and higher CACS than normoglycaemic participants (all, p < 0.01). Among male participants with diabetes 35.3% had CACS ≥ 100 compared to 16.1% among normoglycaemic participants. For women, the corresponding figures were 8.9% vs 6.1%. The prevalence of atherosclerosis in the coronary arteries was higher in participants with previously undetected diabetes than prediabetes, but lower than in patients with known diabetes. The prevalence of any plaque in the carotid arteries was higher in participants with prediabetes or diabetes than in normoglycaemic participants. CONCLUSIONS: In this large population-based cohort of currently asymptomatic people, the atherosclerotic burden in the coronary and carotid arteries increased with increasing degree of dysglycaemia. The finding that the atherosclerotic burden in the coronary arteries in the undetected diabetes category was midway between the prediabetes category and patients with known diabetes may have implications for screening strategies and tailored prevention interventions for people with dysglycaemia in the future.

Risk stratification in chronic thromboembolic pulmonary hypertension predicts survival.

OBJECTIVES: To investigate if the pulmonary arterial hypertension (PAH) risk assessment tool presented in the 2015 ESC/ERS guidelines is valid for patients with chronic thromboembolic pulmonary hypertension (CTEPH) when taking pulmonary endarterectomy (PEA) into account. Design. Incident CTEPH patients registered in the Swedish PAH Registry (SPAHR) between 2008 and 2016 were included. Risk stratification performed at baseline and follow-up classified the patients as low-, intermediate-, or high-risk using the proposed ESC/ERS risk algorithm. Results. There were 250 CTEPH patients with median age (interquartile range) 70 (14) years, and 53% were male. Thirty-two percent underwent PEA within 5 (6) months. In a multivariable model adjusting for age, sex, and pharmacological treatment, patients with intermediate-risk or high-risk profiles at baseline displayed an increased mortality risk (Hazard Ratio [95% confidence interval]: 1.64 [0.69-3.90] and 5.39 [2.13-13.59], respectively) compared to those with a low-risk profile, whereas PEA was associated with better survival (0.38 [0.18-0.82]). Similar impact of risk profile and PEA was seen at follow-up. Conclusion. The ESC/ERS risk assessment tool identifies CTEPH patients with reduced survival. Furthermore, PEA improves survival markedly independently of risk group and age. Take home message: The ESC/ERS risk stratification for PAH predicts survival also in CTEPH patients, even when taking PEA into account.

A comprehensive risk stratification at early follow-up determines prognosis in pulmonary arterial hypertension.

Aims: Guidelines recommend a goal-oriented treatment approach in pulmonary arterial hypertension (PAH). The aim is to reach a low-risk profile, as determined by a risk assessment instrument. This strategy is incompletely validated. We aimed to investigate the bearing of such risk assessment and the benefit of reaching a low-risk profile. Methods and results: Five hundred and thirty PAH patients were included. Follow-up assessments performed after a median of 4 (interquartile range 3-5) months were available for 383 subjects. Patients were classified as 'Low', 'Intermediate', or 'High risk' and the benefit of reaching the 'Low risk' group was estimated. Survival differed (P < 0.001) between the risk groups at baseline and at follow-up. Survival was similar for patients who remained in or improved to the 'Low risk' group. Survival was similar for patients who remained in or worsened to the 'Intermediate risk' or 'High risk' groups. Irrespective of follow-up risk group, survival was better (P < 0.001) for patients with a higher proportion of variables at low risk. Results were unchanged after excluding patients with idiopathic PAH >65 years at diagnosis, and when patients with idiopathic or connective tissue disease-associated PAH were analysed separately. Patients in the 'Low risk' group at follow-up exhibited a reduced mortality risk (hazard ratio 0.2, 95% confidence interval 0.1-0.4 in multivariable analysis adjusted for age, sex and PAH subset), as compared to patients in the 'Intermediate risk' or 'High risk' groups. Conclusion: These findings suggest that comprehensive risk assessments and the aim of reaching a low-risk profile are valid in PAH.

Impact of age and comorbidity on risk stratification in idiopathic pulmonary arterial hypertension.

Recent reports from worldwide pulmonary hypertension registries show a new demographic picture for patients with idiopathic pulmonary arterial hypertension (IPAH), with an increasing prevalence among the elderly.We aimed to investigate the effects of age and comorbidity on risk stratification and outcome of patients with incident IPAH.The study population (n=264) was categorised into four age groups: 18-45, 46-64, 65-74 and ≥75 years. Individual risk profiles were determined according to a risk assessment instrument, based on the European Society of Cardiology and the European Respiratory Society guidelines. The change in risk group from baseline to follow-up (median 5 months) and survival were compared across age groups. In the two youngest age groups, a significant number of patients improved (18-45 years, Z= -4.613, p<0.001; 46-64 years, Z= -2.125, p=0.034), but no significant improvement was found in the older patient groups. 5-year survival was highest in patients aged 18-45 years (88%), while the survival rates were 63%, 56% and 36% for patients in the groups 46-64, 65-74 and ≥75 years, respectively (p<0.001). Ischaemic heart disease and kidney dysfunction independently predicted survival.These findings highlight the importance of age and specific comorbidities as prognostic markers of outcome in addition to established risk assessment algorithms.

Plasma L-arginine levels distinguish pulmonary arterial hypertension from left ventricular systolic dysfunction.

Pulmonary arterial hypertension (PAH) is a life-threatening condition, characterized by an imbalance of vasoactive substances and remodeling of pulmonary vasculature. Nitric oxide, formed from L-arginine, is essential for homeostasis and smooth muscle cell relaxation in PAH. Our aim was to compare plasma concentrations of L-arginine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) in PAH compared to left ventricular systolic dysfunction (LVSD) and healthy subjects. This was an observational, multicenter study comparing 21 patients with PAH to 14 patients with LVSD and 27 healthy subjects. Physical examinations were obtained and blood samples were collected. Plasma levels of ADMA, SDMA, L-arginine, L-ornithine, and L-citrulline were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Plasma levels of ADMA and SDMA were higher, whereas L-arginine and L-arginine/ADMA ratio were lower in PAH patients compared to healthy subjects (p < 0.001). Patients with PAH also had lower levels of L-arginine than patients with LVSD (p < 0.05). L-Arginine correlated to 6 min walking distance (6MWD) (r s = 0.58, p = 0.006) and L-arginine/ADMA correlated to WHO functional class (r s = -0.46, p = 0.043) in PAH. In conclusion, L-arginine levels were significantly lower in treatment naïve PAH patients compared to patients with LVSD. Furthermore, L-arginine correlated with 6MWD in PAH. L-arginine may provide useful information in differentiating PAH from LVSD.

Prognosis and response to first-line single and combination therapy in pulmonary arterial hypertension.

OBJECTIVES: To investigate survival, treatment escalation, effects of first-line single- and first-line combination therapy and prognostic markers in idiopathic- (IPAH), hereditary- (HPAH) and connective tissue disease-associated (CTD-PAH) pulmonary arterial hypertension (PAH). DESIGN: Retrospective analysis of medical journals from PAH patients at Skåne University Hospital 2000-2011. RESULTS: 1-, 2- and 3-year survival was 87%, 67%, and 54%, respectively, for the entire population, but worse (p = 0.003) in CTD-PAH than IPAH/HPAH. After 1, 2 and 3 years, 58%, 41% and 24% of patients starting on single therapy were alive on single therapy. 37.5% of patients on first-line single therapy received escalated treatment at first follow-up. First-line combination therapy more greatly decreased pulmonary vascular resistance index (PVRI, p = 0.017) than first-line single therapy. Only first-line combination therapy improved (p = 0.042) cardiac index (CI). Higher mean right atrial pressure (MRAP, p = 0.018), MRAP/CI (p = 0.021) and WHO functional class (p < 0.001) and lower 6-min walking distance (6MWD, p = 0.001) at baseline, and higher PVRI (p = 0.008) and lower 6MWD (p = 0.004) at follow-up were associated with worse outcome. CONCLUSIONS: We confirm improved survival with PAH-targeted therapies. Survival is still poor and early treatment escalation frequently needed. First-line combination therapy may more potently improve haemodynamics. MRAP/CI may represent a new prognostic marker in PAH.

P2Y1 and P2Y12 receptors in hypoxia- and adenosine diphosphate-induced pulmonary vasoconstriction in vivo in the pig.

PURPOSE: To investigate the role of P2Y1 and P2Y12 receptors in hypoxia- and adenosine diphosphate (ADP)-induced pulmonary vasoconstriction. METHODS: 19 anaesthetized, mechanically ventilated pigs (31.3 ± 0.7 kg) were evaluated in normoxia and hypoxia, without (n = 6) or with P2Y1 receptor antagonist MRS2500 (n = 7) or P2Y12 receptor antagonist cangrelor (n = 6) treatment. 12 pigs (29.3 ± 0.4 kg) were evaluated before and during ADP infusion, without and with MRS2500 (n = 6) or cangrelor (n = 6) pre-treatment. RESULTS: Hypoxia increased (p < 0.05) mean pulmonary artery pressure (MPAP) by 14.2 ± 1.1 mmHg and pulmonary vascular resistance (PVR) by 2.7 ± 0.4 WU. Without treatment MPAP and PVR remained unaltered (p = ns) for 90 min hypoxia. During hypoxia MRS2500 decreased (p < 0.013) MPAP by 4.3 ± 1.2 mmHg within 15 min. Cangrelor decreased (p < 0.036) MPAP to be 3.3 ± 0.4 and 3.6 ± 0.6 mmHg lower than hypoxia baseline after 10 and 30 min. PVR was, however, unaltered (p = ns) by MRS2500 or cangrelor during hypoxia. ADP increased (p < 0.001) MPAP and PVR to stabilize 11.1 ± 1.3 mmHg and 2.7 ± 0.3 WU higher than baseline. MRS2500 or cangrelor pre-treatment totally abolished the sustained MPAP- and PVR-increases to ADP. CONCLUSIONS: ADP elicits pulmonary vasoconstriction through P2Y1 and P2Y12 receptor activation. ADP is not a mandatory modulator, but may still contribute to pulmonary vascular tone during acute hypoxia. Further investigations into the mechanisms behind ADP-induced pulmonary vasoconstriction and the role of ADP as a modulator of pulmonary vascular tone during hypoxia are warranted.

Levosimendan attenuates hypoxia-induced pulmonary hypertension in a porcine model.

BACKGROUND: Levosimendan was hypothesized to attenuate hypoxic pulmonary vasoconstriction (HPV). METHODS: Fourteen anaesthetized pigs (30.9 ± 1.0 kg) were studied in normoxia (FiO2∼0.21) and hypoxia (FiO2∼0.10), before and 10-90 minutes after infusion of placebo (n = 7) or levosimendan (n = 7). RESULTS: Compared with normoxia, hypoxia baseline at FiO2∼0.10 (n = 14) increased pulmonary vascular resistance (PVR) by 1.9 ± 0.4 Wood Units (WU) (P < 0.001), mean pulmonary artery pressure (MPAP) by 14.3 ± 0.9 mm Hg (P < 0.001), mean right atrial pressure (MRAP) by 2.1 ± 0.4 mm Hg (P < 0.001), pulmonary capillary wedge pressure (PCWP) by 1.5 ± 0.3 mm Hg (P < 0.001), cardiac output (CO) by 1.3 ± 0.2 L/minute (P < 0.001) and heart rate (HR) by 19.9 ± 5.5 beats·per minute (P < 0.001). Systemic vascular resistance (SVR) decreased by 7.2 ± 1.0 WU (P < 0.001), MAP and stroke volume (SV) remained unaltered (P = ns). Compared with hypoxia baseline, levosimendan decreased MPAP and PVR (P < 0.05), by approximately 9% and 19%, respectively, plateauing between 10 and 90 minutes. SV increased (P < 0.05) by approximately 22%, plateauing after 60 minutes. MRAP, PCWP, HR, CO, MAP, SVR, and blood-O2 consumption remained unaltered (P = ns). Compared with hypoxia baseline, with placebo, MPAP remained stable (P = ns), PVR increased (P < 0.05) and CO decreased (P < 0.05) by approximately 20% and 11% after 60-90 and 30-90 minutes, respectively. SV decreased (P < 0.05) by approximately 8%, plateauing after 60-90 minutes. PCWP and MRAP decreased (P < 0.05) by approximately 12%, plateauing after 10-60 and 10-90 minutes, respectively. MPAP, HR, MAP, SVR, and blood-O2 consumption remained unchanged (P = ns), except at 60 minutes where MAP decreased (P < 0.05) by approximately 4%. CONCLUSIONS: Levosimendan attenuated HPV and the cardiodepressive effect of sustained hypoxia.

Predicting mortality during long-term follow-up in pulmonary arterial hypertension.

The European Society of Cardiology (ESC) and European Respiratory Society (ERS) guideline recommendation of comprehensive risk assessments, which classify patients with pulmonary arterial hypertension (PAH) as having low, intermediate or high mortality risk, has not been evaluated during long-term follow-up in a "real-life" clinical setting. We therefore aimed to investigate the utility of risk assessment in a clinical setting for up to 5 years post diagnosis. 386 patients with PAH from the Swedish PAH Registry were included. Risk group (low/intermediate/high) and proportion of low-risk variables were investigated at 3-, 4- and 5-year follow-ups after time of diagnosis. In an exploratory analysis, survival rates of patients with low-intermediate or high-intermediate risk scores were compared. A low-risk profile was in multivariate Cox proportional hazards regressions found to be a strong, independent predictor of longer transplant-free survival (p<0.001) at the 3-, 4- and 5-year follow-ups. Also, for the 3-, 4- and 5-year follow-ups, survival rates significantly differed (p<0.001) between the three risk groups. Patients with a greater proportion of low-risk variables had better (p<0.001) survival rates. Patients with a high-intermediate risk score had worse survival rates (p<0.001) than those with a low-intermediate risk score. Results were similar when excluding patients with ≥3 risk factors for heart failure with preserved ejection fraction, atrial fibrillation and/or age >75 years at diagnosis. Our findings suggest that the ESC/ERS guideline strategy for comprehensive risk assessments in PAH is valid also during long-term follow-up in a "real-life" clinical setting.

Early risk prediction in idiopathic versus connective tissue disease-associated pulmonary arterial hypertension: call for a refined assessment.

Despite systematic screening and improved treatment strategies, the prognosis remains worse in patients with connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH) compared to patients with idiopathic/hereditary pulmonary arterial hypertension (IPAH). We aimed to investigate differences in clinical characteristics, outcome and performance of the European Society of Cardiology (ESC)/ European Respiratory Society (ERS) risk stratification tool in these patient groups. This retrospective analysis included incident patients with CTD-PAH (n=197, of which 64 had interstitial lung disease, ILD) or IPAH (n=305) enrolled in the Swedish PAH Register (SPAHR) 2008-2019. Patients were classified as low, intermediate or high risk at baseline, according to the "SPAHR-equation". One-year survival, stratified by type of PAH, was investigated by Cox proportional regression. At baseline, CTD-PAH patients had lower diffusing capacity for carbon monoxide and lower haemoglobin but, at the same time, lower N-terminal prohormone-brain natriuretic peptide, longer 6 min walk distance, better haemodynamics and more often a low-risk profile. No difference in age, World Health Organisation functional class (WHO-FC) or renal function between groups was found. One-year survival rates were 75, 82 and 83% in patients with CTD-PAH with ILD, CTD-PAH without ILD and IPAH, respectively. The 1-year mortality rates for low-, intermediate- and high-risk groups in the whole cohort were 0, 18 and 34% (p<0.001), respectively. Corresponding percentages for CTD-PAH with ILD, CTD-PAH without ILD and IPAH patients were: 0, 26, 67% (p=0.008); 0, 19, 39% (p=0.004); and 0, 16, 29% (p=0.001), respectively. The ESC/ERS risk assessment tool accurately identified low-risk patients but underestimated the 1-year mortality rate of CTD-PAH and IPAH patients assessed as having intermediate risk at diagnosis.

The ratio FEV1 /FVC and its association to respiratory symptoms-A Swedish general population study.

Chronic airflow limitation (CAL) can be defined as fixed ratio of forced expiratory volume in 1 s (FEV1 )/forced vital capacity (FVC) < 0.70 after bronchodilation. It is unclear which is the most optimal ratio in relation to respiratory morbidity. The aim was to investigate to what extent different ratios of FEV1 /FVC were associated with any respiratory symptom. In a cross-sectional general population study, 15,128 adults (50-64 years of age), 7,120 never-smokers and 8,008 ever-smokers completed a respiratory questionnaire and performed FEV1 and FVC after bronchodilation. We calculated different ratios of FEV1 /FVC from 0.40 to 1.0 using 0.70 as reference category. We analysed odds ratios (OR) between different ratios and any respiratory symptom using adjusted multivariable logistic regression. Among all subjects, regardless of smoking habits, the lowest odds for any respiratory symptom was at FEV1 /FVC = 0.82, OR 0.48 (95% CI 0.41-0.56). Among never-smokers, the lowest odds for any respiratory symptom was at FEV1 /FVC = 0.81, OR 0.53 (95% CI 0.41-0.70). Among ever-smokers, the odds for any respiratory symptom was lowest at FEV1 /FVC = 0.81, OR 0.43 (95% CI 0.16-1.19), although the rate of inclining in odds was small in the upper part, that is FEV1 /FVC = 0.85 showed similar odds, OR 0.45 (95% CI 0.38-0.55). We concluded that the odds for any respiratory symptoms continuously decreased with higher FEV1 /FVC ratios and reached a minimum around 0.80-0.85, with similar results among never-smokers. These results indicate that the optimal threshold associated with respiratory symptoms may be higher than 0.70 and this should be further investigated in prospective longitudinal studies.

Chronic airflow limitation and its relation to respiratory symptoms among ever-smokers and never-smokers: a cross-sectional study.

BACKGROUND: The diagnosis of chronic obstructive pulmonary disease is based on the presence of persistent respiratory symptoms and chronic airflow limitation (CAL). CAL is based on the ratio of forced expiratory volume in 1 s to forced vital capacity (FEV1:FVC) after bronchodilation, and FEV1:FVC less than the fifth percentile is often used as a cut-off for CAL. The aim was to investigate if increasing percentiles of FEV1:FVC were associated with any respiratory symptom (cough with phlegm, dyspnoea or wheezing) in a general population sample of never-smokers and ever-smokers. METHODS: In a cross-sectional study comprising 15 128 adults (50-64 years), 7120 never-smokers and 8008 ever-smokers completed a respiratory questionnaire and performed FEV1 and FVC after bronchodilation. We calculated their z-scores for FEV1:FVC and defined the fifth percentile using the Global Lung Function Initiative (GLI) reference value, GLI5 and increasing percentiles up to GLI25. We analysed the associations between different strata of percentiles and prevalence of any respiratory symptom using multivariable logistic regression for estimation of OR. RESULTS: Among all subjects, regardless of smoking habits, the odds of any respiratory symptom were elevated up to the GLI15-20 strata. Among never-smokers, the odds of any respiratory symptom were elevated at GLI<5 (OR 3.57, 95% CI 2.43 to 5.23) and at GLI5-10 (OR 2.57, 95% CI 1.69 to 3.91), but not at higher percentiles. Among ever-smokers, the odds of any respiratory symptom were elevated from GLI<5 (OR 4.64, 95% CI 3.79 to 5.68) up to GLI≥25 (OR 1.33, 95% CI 1.00 to 1.75). CONCLUSIONS: The association between percentages of FEV1:FVC and respiratory symptoms differed depending on smoking history. Our results support a higher percentile cut-off for FEV1:FVC for never-smokers and, in particular, for ever-smokers.

Sex-specific differences and survival in patients with idiopathic pulmonary arterial hypertension 2008-2016.

BACKGROUND: Women with idiopathic pulmonary arterial hypertension (IPAH) have been found to have a worse haemodynamic status at diagnosis, but better survival than men. Over the past decade, demographics have changed and new treatments have become available. The objective of this study was to investigate sex differences in an incident IPAH population diagnosed between 2008 and 2016. METHODS: Differences in clinical characteristics of patients included in the Swedish Pulmonary Arterial Hypertension Register (SPAHR) were analysed at the time of diagnosis. Survival by sex was investigated using Cox proportional hazard regression and Kaplan-Meier curves. RESULTS: The study included 271 patients diagnosed with IPAH, median age was 68 (1st-3rd quartiles 54-74) years and 56% were women. At diagnosis, women were younger, had lower pulmonary vascular resistance and fewer comorbidities and more often received a combination of PAH-targeted therapies than men. Men had worse survival rates than women (hazard ratio 1.49; CI 1.02-2.18; p=0.038), but this difference did not remain after adjustment for age (hazard ratio 1.30; CI 0.89-1.90; p=0.178). CONCLUSIONS: Men with incident IPAH have worse crude survival than women. This is due to women being younger with a less pronounced comorbidity burden than men at the time of diagnosis.

[Pulmonary hypertension due to lung diseases]. / Pulmonell hypertension vanligt vid kronisk lungsjukdom - Europeiska riktlinjer kring utredning och behandling.

Pulmonary hypertension due to lung diseases In 2015 the European Society of Cardiology and European Respiratory Society published new guidelines on the diagnosis and treatment of pulmonary hypertension (PH). PH due to lung diseases and/or hypoxia was classified as a separate entity. PH is common in lung diseases, but seldom severe. Nevertheless, the presence of PH in a patient with lung disease is associated with worse outcome. If there is clinical suspicion of PH in a patient with lung disease, echocardiography is recommended, and if there are signs of severe PH and/or severe right ventricular dysfunction the patient should be referred to a PH expert centre. Patients may have lung disease and e.g. pulmonary arterial hypertension or chronic thromboembolic PH simultaneously, and targeted treatments are available in such cases. PH-targeted drugs should, however, not be used to treat PH due to lung diseases, since there are no robust data speaking for their benefit and a risk of impaired arterial oxygenation due to inhibition of hypoxic pulmonary vasoconstriction. Instead, the underlying lung disease should be optimally treated, including long-term oxygen therapy in case of chronic hypoxemia.