Development and validation of a diagnostic nomogram in pulmonary hypertension due to left heart disease

BACKGROUND

Pulmonary hypertension (pH) due to left heart disease (pH-LHD) is the most common form of pH in clinical practice.

OBJECTIVES

The purpose of the study is to develop a diagnostic nomogram predictive model combining conventional noninvasive examination and detection indicators.

METHODS

Our study retrospectively included 361 patients with left heart disease (LHD) who underwent right heart catheterization between 2013 and 2020. All patients were randomly divided into a training cohort (253, 70 %) and a validation cohort (108, 30 %). pH was defined as resting mean pulmonary arterial pressure (mPAP) ≥25 mmHg measured by RHC examination. Data dimension reduction and feature selection were used by Lasso regression model. The nomogram was constructed based on multivariable logistic regression.

RESULTS

A total of 175 patients with LHD were diagnosed with pH during their hospitalization, representing 48.5 % of the cohort. The mean age of the overall group was 55.6 years, with 76.7 % being male patients. Excessive resting heart rate, elevated New York Heart Association functional class, increased red blood cell distribution width, right ventricular end-diastolic diameter, and pulmonary artery systolic pressure measured by echocardiography were independently associated with the prevalence of pH-LHD. The inclusion of these 5 variables in the nomogram showed good discrimination (AUC = 0.866 [95 % CI, 0.820-0.911]) and optimal calibration (Hosmer-Lemeshow test, P = 0.791) for the validation cohort.

CONCLUSIONS

The noninvasive nomogram of pH-LHD developed in this study has excellent diagnostic value and clinical applicability, and can more accurately evaluate the presence risk of pH in patients with LHD.

Emerging therapies: Potential roles of SGLT2 inhibitors in the management of pulmonary hypertension

Pulmonary hypertension (PH) is a pathophysiological disorder that may involve multiple clinical conditions and may be associated with a variety of cardiovascular and respiratory diseases. Pulmonary hypertension due to left heart disease (PH-LHD) currently lacks targeted therapies, while Pulmonary arterial hypertension (PAH), despite approved treatments, carries considerable residual risk. Metabolic dysfunction has been linked to the pathogenesis and prognosis of PH through various studies, with emerging metabolic agents offering a potential avenue for improving patient outcomes. Sodium-glucose cotransporter 2 inhibitor (SGLT-2i), a novel hypoglycemic agent, could ameliorate metabolic dysfunction and exert cardioprotective effects. Recent small-scale studies suggest SGLT-2i treatment may improve pulmonary artery pressure in patients with PH-LHD, and the PAH animal model shows that SGLT-2i can reduce pulmonary vascular remodeling and prevent progression in PAH, suggesting potential benefits for patients with PH-LHD and perhaps PAH. This review aims to succinctly review PH's pathophysiology, and the connection between metabolic dysfunction and PH, and investigate the prospective mechanisms of action of SGLT-2i in PH-LHD and PAH management.

Aldehyde Dehydrogenase 2 (ALDH2) rs671 Polymorphism is a Predictor of Pulmonary Hypertension Due to Left Heart Disease

AIM

Pulmonary hypertension due to left heart disease (PH-LHD) is commonly seen in patients with heart failure (HF), but there are limited treatment options. Recent studies have shown an association between aldehyde dehydrogenase 2 (ALDH2) rs671 polymorphisms and pulmonary hypertension (PH). Therefore, this study aimed to investigate the occurrence of ALDH2 rs671 polymorphisms, and the association between ALDH2 and risk of PH-LHD in patients with HF. It also investigated different ALDH2 genotypes and examined their association with cardiac structure and function in HF patients with PH-LHD.

METHODS

A total of 178 HF patients were consecutively enrolled in this study: 102 without PH-LHD and 76 with PH-LHD. Clinical data, parameters of echocardiography, and relevant biochemical indexes were recorded in both groups. Differences in data obtained between groups were compared, and the risk of variant ALDH2 polymorphisms with PH-LHD in HF patients was analysed using univariate and multivariate logistic regression.

RESULTS

The prevalence of ALDH2 rs671 GA/AA polymorphisms (variant ALDH2) was 24 of 102 patients (23.53%) in the HF without PH-LHD group, and 32 of 76 patients (42.10%) in the HF with PH-LHD group, with a statistically significant difference. Univariate and multivariate logistical regression showed that variant ALDH2 is an independent risk factor for HF combined with PH-LHD. A higher proportion of patients with variant ALDH2 in the HF with PH-LHD group had a tricuspid regurgitation velocity >2.8 m/s, and they had higher values of peak early diastolic velocity of the mitral orifice/peak velocity of the early diastolic wave of the mitral orifice, maximum frequency shift of pulmonary valve flow, and pulmonary artery stiffness.

CONCLUSIONS

Variant ALDH2 may be an independent risk factor for HF combined with PH-LHD. Variant ALDH2 may also be involved in pulmonary artery remodelling and is a potential new target for clinical treatment of PH-LHD.

A modified primary culture method of rat pulmonary vein smooth muscle cells

BACKGROUND

Although the pressure of pulmonary vein increases before pulmonary artery in pulmonary hypertension due to left heart disease (PH-LHD), only a few studies have assessed pulmonary vein smooth muscle cells (PVSMCs) because of the lack of a simple and feasible isolation method.

METHODS

In this study, we introduced a simple method to obtain PVSMCs. Primary pulmonary veins were removed by puncture needle cannula guidance. Then, PVSMCs were cultured by the tissue explant method and purified by the differential adhesion method. The cells were characterized by hematoxylin-eosin (HE) staining, immunohistochemistry, western blotting, and immunofluorescence to observe the morphology and verify the expression of alpha-smooth muscle actin (α-SMA).

RESULTS

The HE staining results showed that the pulmonary vein media was thinner than the pulmonary artery, the intima and adventitia of the pulmonary vein were removed by this method, and the obtained cells with good activity exhibited morphological characteristics of smooth muscle cells. In addition, higher α-SMA expression was observed in the cells obtained by our isolation method than in the traditional method.

CONCLUSION

This study established a simple and feasible method to isolate and culture PVSMCs that might facilitate the cytological experiments for PH-LHD.

Evaluation of Lung Glucose Uptake with Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/CT in Patients with Pulmonary Arterial Hypertension and Pulmonary Hypertension Due to Left Heart Disease

Aim: Previous studies have demonstrated increased glucose uptake by ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) in lung parenchyma in animal models or small pulmonary arterial hypertension (PAH) cohorts. However, it is not well known whether increased FDG uptake in the lung is a unique phenomenon in PAH or whether elevated pulmonary artery pressure (PAP) induces FDG uptake. Methods and results: Nineteen patients with PAH, 8 patients with pulmonary hypertension due to left heart disease (PH-LHD), and 14 age matched control subjects were included. All PH patients underwent right heart catheterization and FDG-PET. The mean standard uptake value (SUV g/mL) of FDG in each lung was obtained and average values of both lungs were calculated as mean lung FDG SUV. The correlation between hemodynamics and mean lung FDG SUV was also analyzed in PH patients. Mean PAP (mPAP) was not significantly different between PAH and PH-LHD (45±11 vs 43±5 mmHg, p=0.51). PAH patients demonstrated significantly increased mean lung FDG SUV compared with PH-LHD and controls (PAH: 0.76±0.26 vs PH-LHD: 0.51±0.12 vs controls: 0.53±0.16, p=0.0025). The mean lung FDG SUV did not correlate with mPAP either in PAH or PH-LHD. Conclusion: PAH is associated with increased lung FDG uptake indicating increased glucose utilization in the lung. This may represent metabolic shift to glycolysis and/or active inflammation in the remodeled pulmonary vasculature, and is observed to a greater extent in PAH than in patients with PH secondary to LHD and control subjects without PH.

Peak oxygen uptake is a strong prognostic predictor for pulmonary hypertension due to left heart disease

Background

Pulmonary hypertension in left heart disease (PH-LHD), which includes combined post- and precapillary PH (Cpc-PH) and isolated postcapillary PH (Ipc-PH), differs significantly in prognosis. We aimed to assess whether cardiopulmonary exercise testing (CPET) predicts the long-term survival of patients with PH-LHD.

Methods

A single-center observational cohort enrolled 89 patients with PH-LHD who had undergone right heart catherization and CPET (mean pulmonary arterial pressure > 20 mm Hg and pulmonary artery wedge pressure ≥ 15 mm Hg) between 2013 and 2021. A receiver operating characteristic curve was plotted to determine the cutoff value of all-cause death. Survival was estimated using the Kaplan–Meier method and analyzed using the log-rank test. The Cox proportional hazards model was performed to determine the association between CPET and all-cause death.

Results

Seventeen patients died within a mean of 2.2 ± 1.3 years. Compared with survivors, nonsurvivors displayed a significantly worse 6-min walk distance, workload, exercise time and peak oxygen consumption (VO₂)/kg with a trend of a lower oxygen uptake efficiency slope (OUES) adjusted by Bonferroni’s correction. Multivariate Cox regression revealed that the peak VO₂/kg was significantly associated with all-cause death after adjusting for Cpc-PH/Ipc-PH. Compared with Cpc-PH patients with a peak VO₂/kg ≥ 10.7 ml kg⁻¹ min⁻¹, Ipc-PH patients with a peak VO₂/kg < 10.7 ml kg⁻¹ min⁻¹ had a worse survival (P < 0.001).

Conclusions

The peak VO₂/kg is independently associated with all-cause death in patients with PH-LHD. The peak VO₂/kg can also be analyzed together with Cpc-PH/Ipc-PH to better indicate the prognosis of patients with PH-LHD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02574-0.

Data on plasma tumour and metabolism related proteins' potential in differentiation of HFpEF-PH from PAH and in prognosis of left heart failure patients with pulmonary hypertension

The data in the current paper constitutes supplementary material to our article entitled “Plasma tumour and metabolism related biomarkers AMBP, LPL and Glyoxalase I differentiate heart failure with preserved ejection fraction with pulmonary hypertension from pulmonary arterial hypertension” Ahmed et al. (2021). The study investigated 69 plasma tumour- and metabolism related proteins in healthy controls (n = 20) and in 115 patients of whom 48 had pulmonary arterial hypertension (PAH; n = 48) and 67 with left heart failure with pulmonary hypertension (LHF-PH) [heart failure with- preserved ejection fraction-PH (HFpEF-PH; n = 31) and reduced ejection fraction-PH (HFrEF-PH; n = 36)]. The haemodynamic data were obtained with right heart catheterization, and clinical data from medical records. The present article describe the plasma levels of tumour- and metabolism related proteins, analyzed with proximity extension assay, along with their uni- and multivariable diagnostic and prognostic potential. High sRAGE levels univariably emerged as a negative prognostic marker in LHF-PH.

Plasma tumour and metabolism related biomarkers AMBP, LPL and Glyoxalase I differentiate heart failure with preserved ejection fraction with pulmonary hypertension from pulmonary arterial hypertension

BACKGROUND

Discrimination of heart failure with preserved ejection fraction with pulmonary hypertension (HFpEF-PH) from pulmonary arterial hypertension (PAH) is crucial for clinical management but may be challenging due to similarities in clinical and comorbid characteristics. We aimed to investigate tumour and metabolism related proteins in differentiating HFpEF-PH from PAH.

METHODS

Sixty-nine tumour and metabolism plasma proteins were analysed with proximity extension assay in heathy controls (n = 20), patients with PAH (n = 48) and LHF-PH (n = 67) [HFpEF-PH (n = 31) and HF reduced EF-PH (n = 36)]. Haemodynamics were assessed with right heart catheterization.

RESULTS

The plasma levels of alpha-1-microglobulin/bikunin precursor (AMBP) and lipoprotein lipase (LPL), were higher in HFpEF-PH compared to healthy controls (p < 0.01), HFrEF-PH (p < 0.05), and PAH (p < 0.001). Glyoxalase I levels were higher in HFpEF-PH and HFrEF-PH compared to controls (p < 0.001) and PAH (p < 0.001). Each of plasma AMBP, LPL, and glyoxalase I, adjusted for age and sex in multivariable logistic regression models, could differentiate HFpEF-PH from PAH, with areas under the receiver operating characteristic curve (AUC) of 0.81, 0.84 and 0.79, respectively. The combination of AMBP, LPL and glyoxalse I yielded the largest AUC of 0.87 [95% confidence interval (0.79-0.95)] in discriminating HFpEF-PH from PAH, with a sensitivity of 87.1% and a specificity of 85.4%. In HFpEF-PH, the plasma levels of AMBP correlated with pulmonary arterial wedge pressure (r_s = -0.42, p = 0.018).

CONCLUSIONS

Plasma AMBP, LPL and glyoxalase I may facilitate the distinction of HFpEF-PH from PAH. Larger clinical studies are encouraged to confirm and validate our findings.

Mechanical stretching of the pulmonary vein mediates pulmonary hypertension due to left heart disease by regulating SAC/MAPK pathway and the expression of IL-6 and TNF-α

Background

This study aimed to explore whether the mechanical stretching-induced expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in pulmonary veins occurred through the stretch-activated channel (SAC)/ mitogen-activated protein kinases (MAPKs) pathway.

Methods

Sixty male Sprague-Dawley rats were divided into three sham groups and seven model groups. A metal clip was placed on the ascending aorta in the model group to establish PH-LHD rat model. The sham group received a similar operation without ascending aorta clamped. On day 25, pulmonary vein was given mechanical stretching with 0 g, 2.0 g tension in two model groups and two sham groups. Another four model groups were given 2.0 g tension after MAPKs pathway inhibitors soaked. The last sham group and model group rats’ pulmonary veins, pulmonary artery and lung tissues were obtained on day 35. Pulmonary vein, pulmonary artery and lung tissue were evaluated by echocardiography, HE staining, immunohistochemistry and western blotting respectively.

Results

On day 25, left heart weight, right ventricular pressure (35.339 cmH₂O) and left atrial pressure (13.657 cmH₂O) were increased in model group than those in sham group. Echocardiography showed left heart failure in the PH-LHD group (Interventrieular septum dimension 1.716 mm, left ventricular internal end diastolic dimension 4.888 mm, left ventricular posterior wall thickness in diastole 1.749 mm, ejection fraction 76.917%). But there was no difference in lung tissue between the sham group and PH-LHD group as showed by HE staining. Our results showed that the expression of IL-6 and TNF-α was highly expressed in PH-LHD rats’ serum and pulmonary vein, which were further increased after 2.0 g tension was given and were decreased after SAC/MAPKs inhibitors treatment. Meanwhile, on day 25, immunohistochemistry analysis showed the expression of IL-6 and TNF-α was higher in the PH-LHD rats’ pulmonary vein than that in pulmonary artery and lung tissue, and these expressions in pulmonary vein of PH-LHD group were also higher than that in sham group. However, on day 35, IL-6 and TNF-α were all increased in the pulmonary veins, arteries and lung tissues. Besides, our results uncovered that SAC/MAPKs pathway were upregulating in PH-LHD rats’ pulmonary vein.

Conclusion

In conclusion, pulmonary vein mechanical stretching exacerbated PH-LHD possibly through the SAC/MAPKs pathway and upregulating expression of IL-6 and TNF-α.

Imatinib relaxes the pulmonary venous bed of guinea pigs

Background

Recently, the IMPRES study revealed that systemic imatinib improves exercise capacity in patients with advanced pulmonary arterial hypertension. Imatinib blocks the tyrosine kinase activity of the platelet-derived growth factor (PDGF)-receptor (PDGFR), acts antiproliferative and relaxes pulmonary arteries. However so far, the relaxant effects of imatinib on pulmonary veins (PVs) and on the postcapillary resistance are unknown, although pulmonary hypertension (PH) due to left heart disease (LHD) is most common and primarily affects PVs. Next, it is unknown whether activation of PDGFR alters the pulmonary venous tone. Due to the reported adverse effects of systemic imatinib, we evaluated the effects of nebulized imatinib on the postcapillary resistance.

Methods

Precision-cut lung slices (PCLS) were prepared from guinea pigs. PVs were pre-constricted with Endothelin-1 (ET-1) and the imatinib-induced relaxation was studied by videomicroscopy; PDGF-BB-related vascular properties were evaluated as well. The effects of perfused/nebulized imatinib on the postcapillary resistance were studied in cavine isolated perfused lungs (IPL). Intracellular cAMP/cGMP was measured by ELISA in PVs.

Results

In PCLS, imatinib (100 μM) relaxed pre-constricted PVs (126%). In PVs, imatinib increased cAMP, but not cGMP and inhibition of adenyl cyclase or protein kinase A reduced the imatinib-induced relaxation. Further, inhibition of K_ATP-channels, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\mathrm{BK}}_{\mathrm{Ca}}^{2+} $$\end{document}BKCa2+-channels or K_v-channels diminished the imatinib-induced relaxation, whereas inhibition of NO-signaling was without effect. In the IPL, perfusion or nebulization of imatinib reduced the ET-1-induced increase of the postcapillary resistance. In PCLS, PDGF-BB contracted PVs, which was blocked by imatinib and by the PDGFR-β kinase inhibitor SU6668, whereas inhibition of PDGFR-α (ponatinib) had no significant effect. Conversely, PDGFR-β kinase inhibitors (SU6668/DMPQ) relaxed PVs pre-constricted with ET-1 comparable to imatinib, whereas the PDGFR-α kinase inhibitor ponatinib did not.

Conclusions

Imatinib-induced relaxation depends on cAMP and on the activation of K⁺-channels. Perfused or nebulized imatinib significantly reduces the postcapillary resistance in the pre-constricted (ET-1) pulmonary venous bed. Hence, nebulization of imatinib is feasible and might reduce systemic side effects. Conversely, PDGF-BB contracts PVs by activation of PDGFR-β suggesting that imatinib-induced relaxation depends on PDGFR-β-antagonism. Imatinib combines short-term relaxant and long-term antiproliferative effects. Thus, imatinib might be a promising therapy for PH due to LHD.