Multiparametric Monitoring of Disease Progression in Contemporary Patients with Wild-Type Transthyretin Amyloid Cardiomyopathy Initiating Tafamidis Treatment.

BACKGROUND: Recently, a disease modifying therapy has become available for transthyretin amyloid cardiomyopathy (ATTR-CM). A validated monitoring concept of treatment is lacking, but a current expert consensus recommends three clinical domains (clinical, biomarker and ECG/imaging) assessed by several measurable features to define disease progression. METHODS: We retrospectively analyzed data of wild-type ATTR-CM patients initiating tafamidis therapy assessed within our local routine protocol at baseline and 6-months follow-up with respect to the frequency of values beyond the proposed thresholds defining disease progression. Additionally, associations of cardiac magnetic resonance (CMR) tomography with clinical domains were examined within a subgroup. RESULTS: Sixty-two ATTR-CM patients were included (88.7% male, mean age 79 years). In total, 16.1% of patients had progress in the clinical and functional domain, 33.9% in the biomarker domain and 43.5% in the imaging/electrocardiography (ECG) domain, with the latter driven by deterioration of the diastolic dysfunction grade and global longitudinal strain. In total, 35.5% of patients showed progress in none, 35.5% in one, 29.0% in two and no patient in three domains, the latter indicating overall disease progression. A subgroup analysis of twenty-two patients with available baseline and follow-up CMR data revealed an increase in CMR-based extracellular volume by more than 5% in 18.2% of patients, with no significant correlation with progress in one of the clinical domains. CONCLUSIONS: We provide first frequency estimates of the markers of disease progression according to a recent expert consensus statement, which might help refine the multiparametric monitoring concept in patients with ATTR-CM.

Impact of rapid sequential combination therapy on distinct haemodynamic measures in newly diagnosed pulmonary arterial hypertension.

AIMS: In pulmonary arterial hypertension (PAH), upfront combination therapy with ERA and PDE5i is associated with a reduction in morbidity and mortality events and improves standard haemodynamics, but data remain limited. Aims of this study were (i) to capture detailed haemodynamic effects of rapid sequential dual combination therapy in patients with newly diagnosed PAH; (ii) to monitor the impact of treatment initiation on clinical variables and patients' risk status, and (iii) to compare the treatment effect in patients with 'classical PAH' and 'PAH with co-morbidities'. METHODS: Fifty patients (median age 57 [42-71] years, 66% female) with newly diagnosed PAH (76% idiopathic) were treated with a PD5i/sGC-S or ERA, followed by addition of the respective other drug class within 4 weeks. All patients underwent repeat right heart catheterization (RHC) during early follow-up. RESULTS: At early repeat RHC (7 ± 2 months), there were substantial reductions in mean pulmonary artery pressure (mPAP: 52.2 ± 13.5 to 39.0 ± 10.6 mmHg; -25.3%), and pulmonary vascular resistance (PVR: 12.1 ± 5.7 to 5.8 ± 3.1 WU; -52.1%), and an increase in cardiac index (2.1 ± 0.4 to 2.7 ± 0.7 mL/min/m2; +32.2%) (all P < 0.05). Haemodynamic improvements correlated with improved clinical parameters including 6-min walking distance (336 ± 315 to 389 ± 120 m), NTproBNP levels (1.712 ± 2.024 to 506 ± 550 ng/L, both P < 0.05) and WHO-FC at 12 months, resulting in improved risk status, and were found in patients with few (n = 37) or multiple cardiovascular co-morbidities (BMI > 30 kg/m2, hypertension, diabetes, coronary artery disease [≥3]; n = 13), albeit baseline PVR in PAH patients with multiple co-morbidities was lower (9.3 ± 4.4 vs. 13.1 ± 5.9 WU) and PVR reduction less pronounced compared with those with few co-morbidities (-42.7% vs. -54.7%). However, comprehensive haemodynamic assessment considering further variables of prognostic relevance such as stroke volume index and pulmonary artery compliance showed similar improvements among the two groups (SVI: +50.0% vs. +49.2%; PAC: 91.7% vs. 100.0%). Finally, the 4-strata risk assessment approach was better able to capture treatment response as compared with other approaches, particularly in patients with co-morbidities. CONCLUSIONS: Rapid sequential combination therapy with PDE5i/sGC-S and ERA substantially ameliorates cardiopulmonary haemodynamics at early follow-up in patients without, and to a lesser extent, with cardiovascular co-morbidities. This occurs in line with improvements of clinical parameters and risk status.

Compressed SENSE accelerated 3D single-breath-hold late gadolinium enhancement cardiovascular magnetic resonance with isotropic resolution: clinical evaluation.

Aim: The purpose of this study was to investigate the clinical application of Compressed SENSE accelerated single-breath-hold LGE with 3D isotropic resolution compared to conventional LGE imaging acquired in multiple breath-holds. Material & Methods: This was a retrospective, single-center study including 105 examinations of 101 patients (48.2 ± 16.8 years, 47 females). All patients underwent conventional breath-hold and 3D single-breath-hold (0.96 × 0.96 × 1.1 mm3 reconstructed voxel size, Compressed SENSE factor 6.5) LGE sequences at 1.5 T in clinical routine for the evaluation of ischemic or non-ischemic cardiomyopathies. Two radiologists independently evaluated the left ventricle (LV) for the presence of hyperenhancing lesions in each sequence, including localization and transmural extent, while assessing their scar edge sharpness (SES). Confidence of LGE assessment, image quality (IQ), and artifacts were also rated. The impact of LV ejection fraction (LVEF), heart rate, body mass index (BMI), and gender as possible confounders on IQ, artifacts, and confidence of LGE assessment was evaluated employing ordinal logistic regression analysis. Results: Using 3D single-breath-hold LGE readers detected more hyperenhancing lesions compared to conventional breath-hold LGE (n = 246 vs. n = 216 of 1,785 analyzed segments, 13.8% vs. 12.1%; p < 0.0001), pronounced at subendocardial, midmyocardial, and subepicardial localizations and for 1%-50% of transmural extent. SES was rated superior in 3D single-breath-hold LGE (4.1 ± 0.8 vs. 3.3 ± 0.8; p < 0.001). 3D single-breath-hold LGE yielded more artifacts (3.8 ± 1.0 vs. 4.0 ± 3.8; p = 0.002) whereas IQ (4.1 ± 1.0 vs. 4.2 ± 0.9; p = 0.122) and confidence of LGE assessment (4.3 ± 0.9 vs. 4.3 ± 0.8; p = 0.374) were comparable between both techniques. Female gender negatively influenced artifacts in 3D single-breath-hold LGE (p = 0.0028) while increased heart rate led to decreased IQ in conventional breath-hold LGE (p = 0.0029). Conclusions: In clinical routine, Compressed SENSE accelerated 3D single-breath-hold LGE yields image quality and confidence of LGE assessment comparable to conventional breath-hold LGE while providing improved delineation of smaller LGE lesions with superior scar edge sharpness. Given the fast acquisition of 3D single-breath-hold LGE, the technique holds potential to drastically reduce the examination time of CMR.

Thoracic aorta diameters in Marfan patients: Intraindividual comparison of 3D modified relaxation-enhanced angiography without contrast and triggering (REACT) with transthoracic echocardiography.

OBJECTIVE: To compare the measurement of aortic diameters using a novel flow-independent MR-Angiography (3D modified Relaxation-Enhanced Angiography without Contrast and Triggering (modified REACT)) and transthoracic echocardiography (TTE) in Marfan syndrome (MFS) patients. MATERIAL AND METHODS: This retrospective, single-center analysis included 46 examinations of 32 MFS patients (mean age 37.5 ± 11.3 years, 17 women, no prior aortic surgery) who received TTE and 3D modified REACT (ECG- and respiratory-triggering, Compressed SENSE factor 9 for acceleration of image acquisition) of the thoracic aorta. Aortic diameters (sinus of Valsalva (SV), sinotubular junction (STJ), and ascending aorta (AoA)) were independently measured by two cardiologists in TTE (leading-edge) and two radiologists in modified REACT (inner-edge, using multiplanar reconstruction). Intraclass correlation coefficient, Bland-Altman analyses, and Pearson's correlation (r) were used to assess agreement between observers and methods. RESULTS: Interobserver correlation at the SV, STJ, and AoA were excellent for both, TTE (ICC = 0.95-0.98) and modified REACT (ICC = 0.99-1.00). There was no significant difference between TTE and modified REACT for diameters measured at the SV (39.24 ± 3.24 mm vs. 39.63 ± 3.76 mm; p = 0.26; r = 0.78) and the STJ (35.16 ± 4.47 mm vs. 35.37 ± 4.74 mm; p = 0.552; r = 0.87). AoA diameters determined by TTE were larger than in modified REACT (34.29 ± 5.31 mm vs. 30.65 ± 5.64 mm; p < 0.01; r = 0.74). The mean scan time of modified REACT was 05:06 min ± 02:47 min, depending on the patient's breathing frequency and heart rate. CONCLUSIONS: Both TTE and modified REACT showed a strong correlation for all aortic levels; however, at the AoA, diameters were larger using TTE, mostly due to the limited field of view of the latter with measurements being closer to the aortic valve. Given the excellent interobserver correlation and the strong agreement with TTE, modified REACT represents an attractive method to depict the thoracic aorta in MFS patients.

Prevalence of left ventricular thrombus formation after mitral valve edge-to-edge repair.

The prevalence of left ventricular (LV) thrombus formation following percutaneous mitral valve edge-to-edge repair (TMVR) with the MitraClip system is unclear. Decreased total stroke volume and perfusion of the LV apex after mitral valve repair may facilitate thrombus formation especially in the context of reduced LV function. LV thrombus may cause disabling stroke or other thromboembolic events in this elderly and multimorbid patient cohort. Analyses of the prevalence of and risk factors for left ventricular thrombus formation in patients treated with the MitraClip system due to severe mitral valve regurgitation. All discharge and follow-up transthoracic echocardiographic examinations up to 6 months of 453 consecutive patients treated with the MitraClip system were screened for the presence of LV thrombus. Prevalence of LV thrombus formation was 1.1% (5/453). Importantly, LV thrombi were exclusively found in patients with severely depressed left ventricular systolic function (LV-EF < 30%), comprising a prevalence of 4.4% in this subgroup (5/113). Importantly, two of these patients were under active DOAC therapy with Rivaroxaban and Apixaban, respectively. Apart from LV-EF, we did not identify other factors that might have facilitated LV thrombus formation. LV thrombus formation following percutaneous mitral valve repair occurred exclusively in patients with severely depressed LV-EF. As two patients developed LV thrombus despite of DOAC therapy, anticoagulation with a Vitamin K antagonist should be considered in patients with an indication for oral anticoagulation following TMVR.

Coagulation-independent effects of thrombin and Factor Xa: role of protease-activated receptors in pulmonary hypertension.

AIMS: Pulmonary arterial hypertension (PAH) is a devastating disease with limited therapeutic options. Vascular remodelling of pulmonary arteries, characterized by increased proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), is a hallmark of PAH. Here, we aimed to systematically characterize coagulation-independent effects of key coagulation proteases thrombin and Factor Xa (FXa) and their designated receptors, protease-activated receptor (PAR)-1 and -2, on PASMCs in vitro and experimental PAH in vivo. METHODS AND RESULTS: In human and murine PASMCs, both thrombin and FXa were identified as potent mitogens, and chemoattractants. FXa mediated its responses via PAR-1 and PAR-2, whereas thrombin signalled through PAR-1. Extracellular-signal regulated kinases 1/2, protein kinase B (AKT), and sphingosine kinase 1 were identified as downstream mediators of PAR-1 and PAR-2. Inhibition of FXa or thrombin blunted cellular responses in vitro, but unexpectedly failed to protect against hypoxia-induced PAH in vivo. However, pharmacological inhibition as well as genetic deficiency of both PAR-1 and PAR-2 significantly reduced vascular muscularization of small pulmonary arteries, diminished right ventricular systolic pressure, and right ventricular hypertrophy upon chronic hypoxia compared to wild-type controls. CONCLUSION: Our findings indicate a coagulation-independent pathogenic potential of thrombin and FXa for pulmonary vascular remodelling via acting through PAR-1 and PAR-2, respectively. While inhibition of single coagulation proteases was ineffective in preventing experimental PAH, our results propose a crucial role for PAR-1 and PAR-2 in its pathobiology, thus identifying PARs but not their dedicated activators FXa and thrombin as suitable targets for the treatment of PAH.

Ferric carboxymaltose in patients with pulmonary arterial hypertension and iron deficiency: a long-term study.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a progressive disease with limited survival. Iron deficiency (ID) correlates with disease severity and mortality. While oral iron supplementation was shown to be insufficient in such patients, the potential impact of parenteral iron on clinical measures warrants further investigation. METHODS: We retrospectively analysed the long-term effects of intravenous ferric carboxymaltose (FCM) on iron status and clinical measures in patients with PAH and ID [ferritin < 100 µg/L or ferritin 100-300 µg/L and transferrin saturation (TSAT) < 20%] who were on stable targeted PAH therapy, compared with matched controls without ID. Patients with ID received a single infusion of FCM (500 to 1000 mg). Clinical measures monitored included exercise capacity, World Health Organization (WHO) functional class, ESC/ERS risk status, and hospitalizations. The observation period was up to 18 months. RESULTS: One hundred and seventeen patients (mean age 60.9 ± 16.1 years; 64.1% females) with confirmed PAH and on stable targeted therapy for ≥3 months were included (58 with and 59 patients without ID who did not receive FCM). In patients with ID, iron supplementation with FCM resulted in an immediate and sustained improvement of iron status for up to 18 months (serum iron, ferritin, TSAT, all P < 0.01). Fourteen patients in the FCM group received a second FCM infusion after 9.6 ± 4.8 months due to recurrent ID. At 6 and 18 months after FCM infusion, 6 min walk distance improved from 377.5 ± 15.9 at baseline to 412.5 ± 15.1 and 400.8 ± 14.5 m, respectively (both P < 0.05). WHO functional class (P < 0.05) and ESC/ERS risk status also improved, and there was a reduction of hospitalizations for worsening PAH in the 12 months post vs. prior to iron repletion (P = 0.029). No significant changes were observed in the control group. FCM was well tolerated in all patients, with no severe adverse events. CONCLUSIONS: In addition to targeted therapy, correction of ID by parenteral iron supplementation with FCM appears feasible and safe, has sustained effects on iron status, and may improve the clinical status and hospitalization rates in patients with PAH. Larger controlled studies are required to confirm this finding.

Risk Stratification of Patients Undergoing Percutaneous Repair of Mitral and Tricuspid Valves Using a Multidimensional Geriatric Assessment.

BACKGROUND: Given their advanced age and high comorbidity, individual risk assessment is crucial in patients undergoing transcatheter mitral and tricuspid valve repair. Therefore, we evaluated the use of a comprehensive geriatric assessment score, the multidimensional prognostic index (MPI), for risk stratification in these patients. METHODS: We conducted a prospective, observational single-center study, including 226 patients undergoing percutaneous repair for mitral or tricuspid regurgitation. The MPI was calculated preprocedural and covers 8 domains (activities of daily living, instrumental activities of daily living, mental status, nutrition, risk of pressure ulcers, comorbidity, medication, and marital/cohabitation status). We sought to identify an association of MPI score with procedural outcomes and 6-month mortality. RESULTS: A total of 53.1% of patients were stratified as low risk according to MPI (MPI-1 group), 44.2% as medium risk (MPI-2 group), and 2.7% as high risk (MPI-3 group). Procedural efficacy and safety were similar between groups. The estimated survival rate at 6 months was 97±2% in MPI-1 group, 79±4% in MPI-2 group (hazard ratio, 6.90 [95% CI, 2.36-12.2]; P≤0.001) and 50±20% in MPI-3 group (hazard ratio, 20.3 [95% CI, 4.51-91.3]; P<0.001). An increase in 1 SD of the MPI score (0.14 points, possible range of MPI score 0-1) was associated with a hazard ratio of 2.13 (95% CI, 1.58-2.73; P≤0.001) for death after 6 months. The risk association of the MPI with mortality remained significant in multivariate analysis including risk factors, such as peripheral artery disease and NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels. CONCLUSIONS: A comprehensive geriatric assessment with the MPI score provides additional information on mortality risk beyond established cardiovascular risk factors.

The six-transmembrane protein Stamp2 ameliorates pulmonary vascular remodeling and pulmonary hypertension in mice.

Six-transmembrane protein of prostate (Stamp2) protects from diabetes and atherosclerosis in mice via anti-inflammatory mechanisms. As chronic inflammation is a hallmark of pulmonary arterial hypertension (PAH), we investigated the role of Stamp2. Stamp2 expression was substantially reduced in the lung of humans with idiopathic PAH, as well as in experimental PAH. In Stamp2-deficient mice, hypoxia modestly aggravated pulmonary vascular remodeling and right ventricular pressure compared to WT. As endothelial cell (EC) and pulmonary arterial smooth muscle cell (PASMC) phenotypes drive remodeling in PAH, we explored the role of Stamp2. Knock-down of Stamp2 in human EC neither affected apoptosis, viability, nor release of IL-6. Moreover, Stamp2 deficiency in primary PASMC did not alter mitogenic or migratory properties. As Stamp2 deficiency augmented expression of inflammatory cytokines and numbers of CD68-positive cells in the lung, actions of Stamp2 in macrophages may drive vascular remodeling. Thus, PASMC responses were assessed following treatment with conditioned media of primary Stamp2-/- or WT macrophages. Stamp2-/- supernatants induced PASMC proliferation and migration stronger compared to WT. A cytokine array revealed CXCL12, MCP-1 and IL-6 as most relevant candidates. Experiments with neutralizing antibodies confirmed the role of these cytokines in driving Stamp2's responses. In conclusion, Stamp2 deficiency aggravates pulmonary vascular remodeling via cross-talk between macrophages and PASMC. Despite a substantial pro-inflammatory response, the hemodynamic effect of Stamp2 deficiency is modest suggesting that additional mechanisms apart from inflammation are necessary to induce severe PAH.

Prognosis of persistent mitral regurgitation in patients undergoing transcatheter aortic valve replacement.

OBJECTIVE: The objective of this study was to assess imaging predictors of mitral regurgitation (MR) improvement and to evaluate the impact of MR regression on long-term outcome in patients undergoing transcatheter aortic valve replacement (TAVR). BACKGROUND: Concomitant MR is a frequent finding in patients with severe aortic stenosis but usually left untreated at the time of TAVR. METHODS: Mitral regurgitation was graded by transthoracic echocardiography before and after TAVR in 677 consecutive patients with severe aortic stenosis. 2-year mortality was related to the degree of baseline and discharge MR. Morphological echo analysis was performed to determine predictors of MR improvement. RESULTS: 15.2% of patients presented with baseline MR ≥ 3 +, which was associated with a significantly decreased 2-year survival (57.7% vs. 74.4%, P < 0.001). MR improved in 50% of patients following TAVR, with 44% regressing to MR ≤ 2 +. MR improvement to ≤ 2 + was associated with significantly better survival compared to patients with persistent MR ≥ 3 +. Baseline parameters including non-severe baseline MR, the extent of mitral annular calcification and large annular dimension (≥ 32 mm) predicted the likelihood of an improvement to MR ≤ 2 +. A score based on these parameters selected groups with differing probability of MR ≤ 2 + post TAVR ranging from 10.5 to 94.4% (AUC 0.816; P < 0.001), and was predictive for 2-year mortality. CONCLUSION: Unresolved severe MR is a critical determinant of long term mortality following TAVR. Persistence of severe MR following TAVR can be predicted using selected parameters derived from TTE-imaging. These data call for close follow up and additional mitral valve treatment in this subgroup. Factors associated with MR persistence or regression after TAVR.

Therapeutic potential of phosphodiesterase type 5 inhibitors in heart failure with preserved ejection fraction and combined post- and pre-capillary pulmonary hypertension.

OBJECTIVE: Heart failure with preserved ejection fraction (HFpEF) is frequently associated with pulmonary hypertension (PH), which substantially impacts survival. Based on pulmonary vascular resistance (PVR) and the diastolic pressure gradient (DPG), current guidelines distinguish between isolated post-capillary PH (IpcPH) and combined post- and pre-capillary PH (CpcPH). However, the therapeutic consequences of this sub-classification remain entirely unclear. We specifically investigated the efficacy and safety of PDE5i in patients with HFpEF and CpcPH. METHODS: In 40 hemodynamically precisely characterized patients with HFpEF and Cpc-PH who were treated with a PDE5i for at least 12 months, the therapeutic effect on 6-minute walk distance (6MWD), WHO functional class (FC), NTproBNP levels, right ventricular function, and hospitalization rates was evaluated. RESULTS: Patients' mean age was 73 ±â€¯9 years, and comorbidities were frequent (78% hypertension, 58% atrial fibrillation, 35% diabetes). Initially, 38 patients (95%) were in WHO-FC III and 2 patients (5%) in WHO-FC II. Prior to PDE5i initiation, mean PAPm was 46.2 ±â€¯10.3 mmHg, PAWP 21.2 ±â€¯4.7 mmHg, DPG 5.5 ±â€¯7.2 mmHg, and PVR 6.2 ±â€¯3.0 WU. After 12 months of PDE5i therapy, the 6MWD increased from initially 277 ±â€¯17 to 340 ±â€¯18 m (p < 0.001), and the proportion of patients in WHO-FC I/II increased from 5% to 37.5%. NTproBNP levels decreased by 33% (p = 0.004), and TAPSE improved from 16.8 ±â€¯0.7 mm at baseline to 18.2 ±â€¯0.6 mm (p = 0.01). The rate of HF-associated hospitalizations was substantially lower in the 12 months post PDE5i initiation compared to the prior 12 months. The DPG had no impact on the response to therapy. No deaths occurred, and typical side effects of PDE5i were observed. CONCLUSION: These data indicate that at least a subset of precisely characterized patients with HFpEF and CpcPH who tolerate PDE5i may benefit from targeted therapy. A randomized study in this particular sub-population is warranted.

Risk stratification strategy and assessment of disease progression in patients with pulmonary arterial hypertension: Updated Recommendations from the Cologne Consensus Conference 2018.

In the summer of 2016, delegates from the German Respiratory Society, the German Society of Cardiology and the German Society of Pediatric Cardiology met in Cologne, Germany, to define consensus-based practice recommendations for the management of patients with pulmonary arterial hypertension (PAH). These recommendations were built on the 2015 European Pulmonary Hypertension guidelines and included new evidence, where available, and were last updated in the spring of 2018. This article focusses on the proposed risk stratification and assessment of disease progression in patients with pulmonary arterial hypertension (PAH), covering 3 parts: In part 1, methods and markers that are recommended to assess severity and progression of PAH are discussed and commented. These updated comments incorporate most recent data as well as challenges arising from the variability of phenotypes of PAH patients with increasing cardiopulmonary comorbidities. In part 2, the proposed ESC/ERS risk stratification strategy is discussed, together with a review of the recent validation studies from different European registries. Finally, in part 3, the working group of the Cologne Consensus Conference provides recommendations on how risk assessment may be implemented in routine clinical practice and may serve clinical decision making.

End-Tidal CO2 Predicts Reduction in Mitral Regurgitation in Patients Undergoing Percutaneous Mitral Valve Edge-to-Edge Repair.

OBJECTIVES: We evaluated end-tidal CO2 (etCO2), which has been proposed to assess acute hemodynamic changes, to guide percutaneous edge-to-edge mitral valve repair (PMVR) with the MitraClip system. METHODS: Thirty-nine patients (aged 78 ± 14 years) undergoing PMVR for moderate-to-severe mitral regurgitation (MR) of primary and secondary etiology were included. General anesthesia was maintained with sevoflurane and constant ventilation parameters to ensure stable etCO2 tension. MR grade was determined semiquantitatively by transesophageal echocardiography by 2 experienced operators blinded to etCO2 measurements. etCO2 levels were measured 3, 5, 10, and 15 min after final MitraClip placement. RESULTS: Overall, etCO2 increased from 32.2 ± 1.7 before to 35.4 ± 3.0, 34.6 ± 2.6, and 34.2 ± 2.4 mm Hg 3, 5, and 10 min after implantation. A significant correlation was noted between the echocardiographic reduction in MR grade and the increase in etCO2. ANOVA for repeated measures confirmed a significant increase in etCO2 after clip implantation (corrected F = 20.0; p < 0.001) and revealed a significantly greater increase in etCO2 in patients with MR reduction ≥2 grades as compared to lesser MR reductions (F = 6.47; p = 0.015). Blood pressure changes did not correlate with the degree of MR reduction. CONCLUSIONS: We observed a close correlation between the reduction in MR grade during PMVR and etCO2, which might evolve as a useful parameter to complement treatment guidance during PMVR.

Pioglitazone alleviates cardiac and vascular remodelling and improves survival in monocrotaline induced pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a fatal disease with limited therapeutic options. Pathophysiological changes comprise obliterative vascular remodelling of small pulmonary arteries, elevated mean pulmonary arterial systolic pressure (PASP) due to elevated resistance of pulmonary vasculature, adverse right ventricular remodelling, and heart failure. Recent findings also indicate a role of increased inflammation and insulin resistance underlying the development of PAH. We hypothesized that treatment of this condition with the peroxisome proliferator-activated receptor-γ (PPARγ) activator pioglitazone, known to regulate the expression of different genes addressing insulin resistance, inflammatory changes, and vascular remodelling, could be a beneficial approach. PAH was induced in adult rats by a single subcutaneous injection of monocrotaline (MCT). Pioglitazone was administered for 2 weeks starting 3 weeks after MCT-injection. At day 35, hemodynamics, organ weights, and -indices were measured. We performed morphological and molecular characterization of the pulmonary vasculature, including analysis of the degree of muscularization, proliferation rates, and medial wall thickness of the small pulmonary arteries. Furthermore, markers of cardiac injury, collagen content, and cardiomyocyte size were analyzed. Survival rates were monitored throughout the experimental period. Pioglitazone treatment improved survival, reduced PASP, muscularization of small pulmonary arteries, and medial wall thickness. Further, MCT-induced right ventricular hypertrophy and fibrosis were attenuated. This was accompanied with reduced cardiac expression of brain natriuretic peptide, as well as decreased cardiomyocyte size. Finally, pulmonary macrophage content and osteopontin gene expression were attenuated. Based on the beneficial impact of pioglitazone, activation of PPARγ might be a promising treatment option in PAH.

Class IA Phosphatidylinositol 3-Kinase Isoform p110α Mediates Vascular Remodeling.

OBJECTIVE: Neointima formation after vascular injury remains a significant problem in clinical cardiology, and current preventive strategies are suboptimal. Phosphatidylinositol 3'-kinase is a central downstream mediator of growth factor signaling, but the role of phosphatidylinositol 3'-kinase isoforms in vascular remodeling remains elusive. We sought to systematically characterize the precise role of catalytic class IA phosphatidylinositol 3'-kinase isoforms (p110α, p110ß, p110δ), which signal downstream of receptor tyrosine kinases, for vascular remodeling in vivo. APPROACH AND RESULTS: Western blot analyses revealed that all 3 isoforms are abundantly expressed in smooth muscle cells. To analyze their significance for receptor tyrosine kinases-dependent cellular responses, we used targeted gene knockdown and isoform-specific small molecule inhibitors of p110α (PIK-75), p110ß (TGX-221), and p110δ (IC-87114), respectively. We identified p110α to be crucial for receptor tyrosine kinases signaling, thus affecting proliferation, migration, and survival of rat, murine, and human smooth muscle cells, whereas p110ß and p110δ activities were dispensable. Surprisingly, p110δ exerted noncatalytic functions in smooth muscle cell proliferation, but had no effect on migration. Based on these results, we generated a mouse model of smooth muscle cell-specific p110α deficiency (sm-p110α(-/-)). Targeted deletion of p110α in sm-p110α(-/-) mice blunted growth factor-induced cellular responses and abolished neointima formation after balloon injury of the carotid artery in mice. In contrast, p110δ deficiency did not affect vascular remodeling in vivo. CONCLUSIONS: Receptor tyrosine kinases-induced phosphatidylinositol 3'-kinase signaling via the p110α isoform plays a central role for vascular remodeling in vivo. Thus, p110α represents a selective target for the prevention of neointima formation after vascular injury, whereas p110ß and p110δ expression and activity do not play a significant role.

Genetic Ablation of PDGF-Dependent Signaling Pathways Abolishes Vascular Remodeling and Experimental Pulmonary Hypertension.

OBJECTIVE: Despite modern therapies, pulmonary arterial hypertension (PAH) harbors a high mortality. Vascular remodeling is a hallmark of the disease. Recent clinical studies revealed that antiremodeling approaches with tyrosine-kinase inhibitors such as imatinib are effective, but its applicability is limited by significant side effects. Although imatinib has multiple targets, expression analyses support a role for platelet-derived growth factor (PDGF) in the pathobiology of the disease. However, its precise role and downstream signaling events have not been established. APPROACH AND RESULTS: Patients with PAH exhibit enhanced expression and phosphorylation of ß PDGF receptor (ßPDGFR) in remodeled pulmonary arterioles, particularly at the binding sites for phophatidyl-inositol-3-kinase and PLCγ at tyrosine residues 751 and 1021, respectively. These signaling molecules were identified as critical downstream mediators of ßPDGFR-mediated proliferation and migration of pulmonary arterial smooth muscle cells. We, therefore, investigated mice expressing a mutated ßPDGFR that is unable to recruit phophatidyl-inositol-3-kinase and PLCγ (ßPDGFR(F3/F3)). PDGF-dependent Erk1/2 and Akt phosphorylation, cyclin D1 induction, and proliferation, migration, and protection against apoptosis were abolished in ßPDGFR(F3/F3) pulmonary arterial smooth muscle cells. On exposure to chronic hypoxia, vascular remodeling of pulmonary arteries was blunted in ßPDGFR(F3/F3) mice compared with wild-type littermates. These alterations led to protection from hypoxia-induced PAH and right ventricular hypertrophy. CONCLUSIONS: By means of a genetic approach, our data provide definite evidence that the activated ßPDGFR is a key contributor to pulmonary vascular remodeling and PAH. Selective disruption of PDGF-dependent phophatidyl-inositol-3-kinase and PLCγ activity is sufficient to abolish these pathogenic responses in vivo, identifying these signaling events as valuable targets for antiremodeling strategies in PAH.