The prognostic value of vasoresponse to nitric oxide in patients with chronic thromboembolic pulmonary hypertension

Background

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by pulmonary artery obstructions due to organized chronic thrombotic material in major pulmonary arteries. In addition, about half of the patients suffer from a small vessel pulmonary arteriopathy that is a strong predictor of outcomes. Currently available treatment of CTEPH includes interventional strategies such as pulmonary endarterectomy (PEA) and balloon pulmonary angioplasty (BPA), and non-interventional strategies with PH-specific medications. A simple way of assessing small vessel disease is the degree of vasodilation (“vasoresponse”) in response to inhaled nitric oxide (iNO). In idiopathic pulmonary arterial hypertension vasoresponse serves as the best marker for good prognosis and treatment selection. In CTEPH, the prognostic value of vasoresponse remains unclear.

Purpose

We investigated the prognostic value of three definitions of vasoresponse to nitric oxide in patients with CTEPH.

Methods

We studied 325 CTEPH patients who underwent baseline diagnostic right heart catheterization (RHC) with 40ppm iNO testing at a general hospital (AKH) between 1995 and 2019. Cox regression models, adjusting for covariates including age, sex, comorbidities, and markers for disease severity at baseline, such as proBNP, GFR, NYHA functional class, were used to determine the risk of death or lung transplantation with respect to vasoresponse. We analysed three currently used definitions of vasoresponse to nitric oxide – the classical definition (CD) as a 10mmHg reduction in mPAP to a level below 40mmHg; an absolute definition (AD) as a 10mmHg reduction in mPAP regardless of resulting mPAP; and the percent definition (PD) as a 10% reduction in mPAP regardless of resulting mPAP.

Results

Patients had a median age of 62 (interquartile range [IQR]: 50, 71) at time of baseline right heart catheterization and 50% were female. During a median observation time of 5 years (IQR: 2.2, 9.0), the combined endpoint of death or lung transplantation occurred in 88 cases (27%). In the cox regression model PD vasoresponders, showed improved survival when undergoing PEA (p=0.0019). In PD vasoresponsive patients who were not given PEA surgery (n=66), PH medication therapy was associated with improved survival (p=0.0053), whereas BPA had no association with survival (p=0.58). In PD non-vasoresponsive patients who were not given PEA surgery (n=107) BPA improved survival (p<0.0001), whereas PH medication therapy did not improve survival (p=0.08).

Conclusion

The PD vasoresponse to iNO carries valuable prognostic information about freedom from death or lung transplantation in patients with CTEPH. In patients who are not eligible for PEA, PD vasoresponse can improve optimal therapy selection.

Funding Acknowledgement

Type of funding sources: None.

Response to anticoagulation in chronic thromboembolic pulmonary hypertension

Introduction

Chronic thromboembolic pulmonary hypertension (CTEPH) is caused by fibrotic thrombus in the pulmonary arteries, likely originating from pulmonary embolism. Inadequate anticoagulation is one of the suspected mechanisms of disease in CTEPH. The aim of our study was to assess phenprocoumon dosing and genetic polymorphisms of vitamin K epoxide reductase complex subunit 1 (VKORC 1) that are known to affect the dose required to reach therapeutic range.

Methods

The ratio of mean weekly phenprocoumon dose in relation to mean INR levels was assessed in CTEPH patients on phenoprocoumon oral anticoagulation for at least 6 months, compared with PAH patients. VKORC 1 (–1639, –3730) single nucleotide polymorphisms (SNPs) were determined by polymerase chain reaction (PCR).

Results

In 225 patients (167 CTEPH, 58 PAH) mean treatment duration was 51.7±44.7 months, and mean age was 62.9±13.87 years (49.7% female). Median weekly dose of phenprocoumon was 10.5 mg (IQR 9.0–16.5) for PAH vs. 14.25 mg (IQR 10.5–18.0) in the CTEPH cohort (p=0.016). Although median INR was not significantly different among the two groups (2.28 vs. 2.40 in the PAH vs. CTEPH, respectively, p=0.084), achieving the mentioned INR require significantly higher weekly doses in the CTEPH group. While distribution of VKORC1 variants was according to the Hardy Weinberg equilibrium, patients with CTEPH and VKORC1 –1639 GG homozygous wild type required significantly higher phenprocoumon doses compared with VKORC1 –1639 AA homozygous mutants (P<0.001).

Conclusion

CTEPH patients require more vitamin K antagonists in relation to INR levels than PAH patients. Unmet phenprocoumon dosing requirements may be one mechanism of disease in CTEPH.

Funding Acknowledgement

Type of funding sources: None.

Efficacy and safety of percutaneous pulmonary artery subtotal occlusion and CTO intervention in chronic thromboembolic pulmonary hypertension

Background

Balloon pulmonary angioplasty (BPA) is an emerging percutaneous therapy for patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH), and patients with mean pulmonary artery pressure (mPAP) ≤30mmHg have an excellent survival. Common vascular lesion types are ring-like stenoses (type A), web lesions (type B), subtotal occlusions (type C), chronic total occlusions (CTO, type D) and tortuous lesions (type E). Occlusive lesions (i.e. subtotal occlusions and CTOs) are most challenging. While the CTO intervention the coronary arteries remains controversial, risk and benefit of pulmonary artery occlusive lesion intervention in CTEPH has not been studied yet. We evaluated the impact of percutaneous pulmonary artery subtotal occlusion and CTO intervention on BPA treatment response.

Methods

120 patients underwent 712 BPA procedures between April 2014 and October 2019. Clinical features and hemodynamics were assessed at baseline and 6–12 months after the last BPA session.

Results

A total of 2542 lesions were targeted; 720 occlusions (28.3%; 352 CTOs and 368 subtotal occlusions) and 1822 non-occlusion lesions (71.7%). Complications occurred in 6.0% of all procedures (severe complications in 0.4% of all procedures). 45 patients completed BPA treatment after a median of 6 (4; 10) procedures per patient. In these patients, mPAP dropped from 40.1±10.8 to 25.6±5.1mmHg (p<0.001), without significant change in cardiac output (5.2±1.4 to 5.5±3.1L/min, p=0.409). In the overall cohort, success rate for recanalization of occlusions was 81% (subtotal occlusions (type C lesions): 98%; CTOs (type D lesions) 50%). Number of successfully treated lesions of any type (β −0.86 [−1.19; −0.53]; p<0.001), number of successfully treated occlusions (β −2.17 [−3.38; −0.97]; p=0.001) and number of successfully treated non-occlusion lesions (β −0.81 [−1.25; −0.37]; p<0.001) emerged as predictors of relative change in mPAP. The impact on relative change in mPAP was higher for CTOs (β −5.88 [−10.49; −1.26]; p=0.014) than for subtotal occlusions (β −2.51 [−4.18; −0.83]; p=0.004).

Conclusions

The number of successfully treated vascular lesions predicts treatment response to BPA. The number of successfully recanalized occlusions (particularly CTOs) appears to have the strongest impact on change in mPAP, highlighting the importance of advanced BPA technique.

Funding Acknowledgement

Type of funding sources: None. Visual overview

Lowering of mean pulmonary arterial pressure is a prognostic marker in pulmonary hypertension patients treated with subcutaneous treprostinil

Background

Treprostinil (TRE), a prostacyclin analog, is effective for the treatment of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension (CTEPH). We hypothesized that change of hemodynamics is of prognostic value. In our prospective registry we evaluated effects of first-line subcutaneous (sc) TRE in patients with severe pulmonary hypertension (PH) and analyzed the prognostic value of hemodynamic changes from baseline on long-term follow-up.

Methods

Data was collected from patients with pre-capillary PH in WHO functional class III or IV, mean right atrial pressure of ≥10mmHg, and/or cardiac index ≤2.2 liters/min/m2. Patients received first-line scTRE. Dose adjustments were performed individually according to clinical symptoms and side effects.

Results

Between 1999 and 2018 138 patients were treated. Of these, 18 (13%) patients underwent double lung transplantation, and 59 (42.8%) died of any cause. Overall survival rates at 1, 5, 10, and 15 years were 91%, 57%, 31% and 29%. The strongest predictor of outcome was change in mPAP after one year of scTRE. Change in mPAP (−18.4±7.9 mmHg) was associated with the best subsequent survival of 12.7±1.5 years.

Conclusion

The data suggest that patients benefit from aggressive lowering of mPAP in the first year of treatment.

Funding Acknowledgement

Type of funding source: None

The role of asymmetric dimethylarginine (ADMA) in the follow-up of patients with precapillary pulmonary hypertension (PH)

Introduction

Asymmetric dimethylarginine (ADMA) interferes with L-arginine in the production of nitric oxide, a key mediator of endothelial cell function. ADMA is elevated in pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) and is associated with unfavorable outcomes.

Aim

To assess the role of ADMA to monitor disease progression of PH patients treated with PAH-specific therapy.

Methods

ADMA was measured by competitive ELISA at baseline (BL) and follow-up (FU). Risk assessment including a clinical assessment, echocardiography, 6-minute walking test, NT-pro-BNP and hemodynamic assessment by right heart catheterization was performed accordingly. Risk was calculated according to the ESC/ERS 2015 guidelines by the SPHAR method.

Results

ADMA samples were collected from 113 patients treated at our institution between 2012 and 2019. 89 (79%) patients had PAH, 15 (13%) were diagnosed with CTEPH and 9 (8%) with group 3 – PH associated with lung disease. 69% were females. 15 (13.3%) patients had a low risk at baseline, 96 (85%) intermediate risk and 2 (1.8%) were high risk patients. 75% received oral medications, 31% received subcutaneous treprostinil. Median baseline ADMA was 0.738umol/l. At BL no significant difference of ADMA plasma levels was found among the different PH types (p=0.063), or between different risk categories (p=0.531).

Change in ADMA plasma levels correlated with change in risk (p=0.002, rs 0.291) and with change in mixed venous saturation (p=0.034, rs −0.205). Change in ADMA plasma levels also correlated with risk at FU (p=0.011, rs 0.240).

Patients categorized as low risk at FU had a median ADMA plasma level decrease of 22%, compared with −3 to 0% ADMA plasma level change in patients with moderate to high risk at FU (p=0.04). Patients who improved their risk category had a median decrease of ADMA plasma level of 23% vs. 2.3% in patients who did not improve (p=0.011). Decrease of ADMA plasma levels was a weak but significant discriminator for improvement of risk in ROC analysis (p=0.032, AUC 0.374).

Conclusion

ADMA plasma levels paralleled the hemodynamic and clinical benefit of PAH-specific treatments in patients with precapillary PH. ADMA could be used as a biomarker for monitoring treatment effects in precapillary PH.

Funding Acknowledgement

Type of funding source: None

In situ identification of mycobacteria in Crohn's disease patient tissue using confocal scanning laser microscopy

The diversity in the methodology employed to investigate Crohn's disease (CD) etiology has added significantly to the controversy of the mycobacterial role in this chronic inflammatory bowel disease. Mycobacterium avium subsp paratuberculosis (MAP), a proposed and suspected agent in many CD patients, is a fastidious and very slow grower bacillus, which causes Johne's disease (JD) in cattle. The methodology that has been widely and successfully used for isolation and identification of MAP from and in JD animals is not reliable and has proven to be unsuccessful in achieving the same objectives for CD diagnosis. In this study, a Confocal Scanning Laser Microscopy (CSLM) system has been employed in an attempt to detect MAP in CD patient. In situ hybridization was performed on full thickness tissue using rabbit anti-MAP polyclonal antibody that was adsorbed with E. coli protein extracts. Consequently, MAP was detected in the microvilli region in tissue specimens from CD patient and not in the controls. In the same CD tissue specimen, MAP was not detected when isotype normal rabbit sera was employed. The polyclonal antibody marker may be replaced with monoclonal antibodies, if available, or with MAP-specific-DNA or RNA probes. This technique adds an additional approach to investigate MAP role in CD etiology especially when the culture approach is long and inconsistent.

Open clinical trial of rifabutin and clarithromycin therapy in Crohn's disease

BACKGROUND

Crohn's disease, an inflammatory bowel disease in humans, has a suspected aetiology of Mycobacterium avium subsp. Paratuberculosis.

AIMS

To evaluate the role of rifabutin and clarithromycin anti-Mycobacterium avium subsp. Paratuberculosis treatment in Crohn's disease patients using an open clinical trial.

METHODS

. A total of 36 patients with acute presentations of Crohn's disease, whose sera tested positive against p35 and p36 antigens (two recombinant proteins of Mycobacterium avium subsp. Paratuberculosis), were selected for treatment with rifabutin and macrolide antibiotic therapy Rifabutin and macrolide antibiotic therapy medications included 250 mg 1 po bid clarithromycin and 150 mg 1 po bid Ri-fabutin accompanied with a probiotic. Crohn's disease patients' response to rifabutin and macrolide antibiotic therapy was monitored over a period ranging from 4 to 17 months.

RESULTS

Seven patients (19.4%) withdrew from the study since they were unable to tolerate medications. Of the remaining 29 patients, 21 (58.3%) reached a sustained state of improvement, traditionally defined as a decrease of 70 points between their entrance and exit Crohn's disease activity index scores together with the absence of the need of all other Crohn's medications, such as immunosuppressants and corticosteroids. Three Crohn's disease patients [8. 3%) noticed significant improvements, but required other Crohn's medications, concurrently with rifabutin and macrolide antibiotic therapy, to achieve and sustain improvement. Only 5 Crohn's disease patients (13.8%) were non-responders, noticing no marked improvement while on rifabutin and macrolide antibiotic therapy.

CONCLUSION

The data add further evidence to support the role of rifabutin and macrolide antibiotic therapy in the treatment of Crohn's disease specifically in those patients with evidence of Mycobacterium avium subsp. Paratuberculosis infection. A large multi-centre clinical trial is needed to further explore these findings.

Review article: Mycobacterium avium subsp. paratuberculosis as one cause of Crohn's disease

A number of theories regarding the aetiology of Crohn's disease have been proposed. Diet, infections, other unidentified environmental factors and immune disregulation, all working under the influence of a genetic predisposition, have been viewed with suspicion. Many now believe that Crohn's disease is a syndrome caused by several aetiologies. The two leading theories are the infectious and autoimmune theories. The leading infectious candidate is Mycobacterium avium subspecies paratuberculosis (Mycobacterium paratuberculosis), the causative agent of Johne's disease, an inflammatory bowel disease in a variety of mammals including cattle, sheep, deer, bison, monkeys and chimpanzees. The evidence to support M. paratuberculosis infection as a cause of Crohn's disease is mounting rapidly. Technical advances have allowed the identification and/or isolation of M. paratuberculosis from a significantly higher proportion of Crohn's disease tissues than from controls. These methodologies include: (i) improved culture techniques; (ii) development of M. paratuberculosis-specific polymerase chain reaction assays; (iii) development of a novel in situ hybridization method; (iv) efficacy of macrolide and anti-mycobacterial drug therapies; and (v) discovery of Crohn's disease-specific seroreactivity against two specific M. paratuberculosis recombinant antigens. The causal role for M. paratuberculosis in Crohn's disease and correlation of infection with specific stratification(s) of the disorder need to be investigated. The data implicating Crohn's as an autoimmune disorder may be viewed in a manner that supports the mycobacterial theory. The mycobacterial theory and the autoimmune theory are complementary; the first deals with the aetiology of the disorder, the second deals with its pathogenesis. Combined therapies directed against a mycobacterial aetiology and inflammation may be the optimal treatment of the disease.

Specific seroreactivity of Crohn's disease patients against p35 and p36 antigens of M. avium subsp. paratuberculosis

Crohn's disease (CD) is a chronic inflammatory bowel disease that is similar to Johne's disease in ruminants. Recent data have strengthened the association of M. avium subsp. paratuberculosis (M. paratuberculosis) with CD. To provide more evidence of an etiological association, antibody reactivities from CD patients were tested by immunoblotting against recombinant antigens that were identified previously from our M. paratuberculosis genomic library. Two clones (designated pMptb#40 (3.2-kb insert) and #48 (1.4-kb insert) expressing a 35K (p35)- and 36K(p36)-antigens showed specific reactivities with serum samples from CD patients. Serum samples from 75% of 53 CD patients, 14% of 35 normal individuals and 10% of 10 ulcerative colitis patients reacted to p35 antigen. Reactivities were also observed with serum samples from 89% of 89 CD patients, 14% of 50 normal controls and 15% of 29 ulcerative colitis patients reacted with p36 antigen. When the reactivity results from p35 and p36 were combined, the background from the controls was eliminated, i.e. only the CD patients reacted to both p35 and p36. The positive predictive value was 98% with specificity of 98% and the negative predictive value was 76% with sensitivity of 74% (39 positive out of 53). A statistical significance (p<0.0001) was observed when the results from CD serum samples reacting with either or both antigens were compared to the controls. The reactivity of anti-M. paratuberculosis (specifically against p35 and p36 antigens) antibodies in a significant proportion of CD patients would suggest a causal role for the organism in CD.

Use of short-term culture for identification of Mycobacterium avium subsp. paratuberculosis in tissue from Crohn's disease patients

OBJECTIVE

To investigate the role of Mycobacterium avium subsp. paratuberculosis (MAP) in Crohn's disease (CD), using short-term mycobacterial culture media.

METHODS

Sixty-three tissue specimens from 27 CD patients and 36 controls were processed and inoculated into a modified 7H9 broth base medium and incubated at 37 degrees C and 5% CO2 for up to 1 year. Acid-fast staining, determination of mycobactin dependency, PCR analysis using two IS900-derived oligonucleotides and hybridization with an internal probe were performed.

RESULTS

MAP was present in six of seven (86%) surgically resected tissue samples and in four of 20 (20%) biopsies, with an overall 37% from CD patients, as compared to two of 36 (5.6%) of control specimens. The presence of MAP in Mycobacterial Growth Indicator Tube (MGIT) cultures was detected within 10-12 weeks for surgically resected tissue and after 40 weeks for biopsy specimens, with no MAP growth detected in 12B* Bactec cultures.

CONCLUSIONS

Because MAP was present in 86% of resected tissue compared to 20% of biopsy specimens from CD patients, we speculate that MAP resides in the submucosal layer closer to the active part of the ulcer rather than on the surface of the mucosal cells. Thus, surgically resected tissue cultured in MGIT medium is a favorable protocol for rapid cultivation of MAP and for investigating its role in CD pathogenesis. The data support the mycobacterial role in CD pathogenesis.