Citations

ABSTRACT In normal health, the liver and lungs enjoy a close anatomic, physiologic, and functional relationship. In the context of pulmonary vascular disease, however, there is accumulating evidence that the interplay between the gut microbiome, hepatic system, and pulmonary vasculature (so‐called “gut‐liver‐lung” axis) plays an important role in driving disease pathogenesis and determining clinical outcomes. Despite recognizing the importance of the gut‐liver‐lung axis in pulmonary vascular disease however, little is known about the clinical characteristics, circulating factors, and physiologic pathways that mediate this important axis of communication. In this clinical and translationally focused review, we provide an overview of liver‐lung communication in normal physiology, and contrast this with gut‐liver‐lung derangements in pulmonary arterial hypertension, portopulmonary hypertension, and hepatopulmonary syndrome. We conclude with identifying key gaps in knowledge that will need to be addressed in order to manipulate the gut‐liver‐lung axis to prevent worsening pulmonary vascular disease, develop novel therapeutics, and improve patient outcomes.

ABSTRACTLung transplantation is indicated for selected patients with advanced pulmonary arterial hypertension (PAH). We used a modified Delphi process to develop recommendations on care of patients with PAH undergoing lung transplantation. This Delphi panel was recruited from the Pulmonary Vascular Research Institute's Innovative Drug Discovery Initiative ‐ Lung Transplantation Workstream, consisting of clinical and research experts in PAH and lung transplantation. In this process, 29 panelists were given open‐ended questions, querying topics related to lung transplantation in PAH. A steering group converted the responses into discrete statements. Panelists then rated agreement using a Likert scale in two further survey rounds: −5 (strongly disagree) to 5 (strongly agree). Consensus was defined as mean ≥ 2.5 or ≤ −2.5, with a standard deviation not crossing zero. Consensus was reached on 141 of 223 statements. Notable areas of consensus were for early discussions about transplantation, and agreement with previously published referral and listing criteria. There was agreement that lung transplantation could be offered in sick candidates, including those with concurrent renal or hepatic insufficiency. Bilateral lung transplantation was considered the procedure of choice for most patients, with rare indications for heart‐lung transplantation. Consensus on bridging strategies included use of veno‐arterial extracorporeal membrane oxygenation and preemptive awake cannulation in those with severe right ventricular dysfunction. Consensus was also achieved on intraoperative use of invasive hemodynamic monitoring, and prolonged postoperative circulatory support guided by hemodynamic response and echocardiography. Patients with PAH undergoing transplantation require specialized management, which differs somewhat from other candidates.

Abstract Rationale Pulmonary arterial hypertension (PAH) is associated with significant morbidity and mortality. The extent of medication nonadherence in PAH is uncertain and may be linked to adverse outcomes. There has been a lack of multicenter, registry-based studies assessing medication nonadherence and patient-centered outcomes in PAH. Objectives To determine the prevalence of self-reported nonadherence in Pulmonary Hypertension Association Registry (PHAR) participants with PAH or chronic thromboembolic pulmonary hypertension and the relationship of nonadherence with several patient-centered outcomes (mortality, hospitalization rates, emergency department visits, and health-related quality of life). Methods Self-reported PAH medication nonadherence was captured at PHAR enrollment and during follow-up visits. Predictors of nonadherence were modeled using generalized estimating equations assuming a binary distribution. Outcomes associated with nonadherence were modeled using generalized estimating equations with a Poisson distribution. Results A total of 1,543 patients were included, of whom 1,092 (70.8%) were female and 1,340 (86.8%) had PAH. The overall rate of any self-reported nonadherence was 6.1% (95% confidence interval [CI], 5.3–6.9). Predictors of nonadherence included self-reported male sex at birth (odds ratio [OR], 1.4; 95% CI, 1.0–1.9; P = 0.02), poverty (OR, 1.6; 95% CI, 1.2–2.3; P = 0.01), not being married or partnered (OR, 1.5; 95% CI, 1.1–1.9; P = 0.01), having Medicaid or no health insurance (OR, 2.1; 95% CI, 1.5–2.9; P < 0.001), and having completed high school but not having a college degree (OR, 1.7; 95% CI, 1.1–2.9; P < 0.001). PHAR participants who reported any nonadherence had 50.0% more emergency department visits (P < 0.001), 13.3% more hospital admissions (P = 0.03), and 61.9% more days hospitalized (P = 0.01). No relationship was observed between nonadherence and the type or number of PAH therapies or all-cause mortality. Participants reporting nonadherence had worse mean Short Form-12 scores (P < 0.001) and worse emPHasis-10 scores (P = 0.02). Conclusions The rate of self-reported nonadherence in PHAR registrants was low but was associated with male sex and several social determinants of health. Although the complexity or type of PAH regimen did not appear to influence nonadherence, nonadherence was associated with numerous adverse patient-centered outcomes, including greater healthcare use and worse health-related quality of life. Because of limitations in the structure of the gathered data, relationships between exposure and outcomes were not temporally definitive; these observations warrant additional prospective studies.

Abstract Rationale Inhibition of aromatase with anastrozole reduces pulmonary hypertension in experimental models. Objectives We aimed to determine whether anastrozole improved the 6-minute-walk distance (6MWD) at 6 months in pulmonary arterial hypertension (PAH). Methods We performed a randomized, double-blind, placebo-controlled phase II clinical trial of anastrozole in subjects with PAH at seven centers. Eighty-four postmenopausal women with PAH and men with PAH were randomized in a 1:1 ratio to receive anastrozole 1 mg or placebo by mouth daily, stratified by sex using permuted blocks of variable sizes. All subjects and study staff were masked. The primary outcome was the change from baseline in 6MWD at 6 months. By intention-to-treat analysis, we estimated the treatment effect of anastrozole using linear regression models adjusted for sex and baseline 6MWD. Assuming 10% loss to follow-up, we anticipated having 80% power to detect a difference in the change in 6MWD of 22 meters. Measurements and Main Results Forty-one subjects were randomized to placebo and 43 to anastrozole, and all received the allocated treatment. Three subjects in the placebo group and two in the anastrozole group discontinued the study drug. There was no significant difference in the change in 6MWD at 6 months (placebo-corrected treatment effect, −7.9 m; 95% confidence interval, −32.7 to 16.9; P = 0.53). There was no difference in adverse events between the groups. Conclusions Anastrozole did not show a significant effect on 6MWD compared with placebo in postmenopausal women with PAH and in men with PAH. Anastrozole was safe and did not have adverse effects. Clinical trial registered with www.clincialtrials.gov (NCT03229499).

A 6-minute walk test is a simple tool for assessing submaximal exercise capacity. We sought to determine whether a 6-minute walk distance (6MWD) predicts outcomes in patients with cirrhosis. The Pulmonary Vascular Complications of Liver Disease 2 study is a multicenter, prospective cohort study that enrolled adults with portal hypertension during liver transplantation evaluation. We excluded subjects with an incident or prevalent portopulmonary hypertension. The 6-minute walk test was performed using standardized methods. Cox proportional hazards modeling and multivariable linear regression analysis were performed to determine the relationship between baseline 6MWD and outcomes. The study sample included 352 subjects. The mean 6MWD was 391±101 m. For each 50-meter decrease in 6MWD, there was a 25% increase in the risk of death (HR 1.25, 95% CI [1.11, 1.41], p < 0.001) after adjustment for age, gender, body mass index, MELD-Na, and liver transplant as a time-varying covariate. In a multistate model, each 50-meter decrease in 6MWD was associated with an increased risk of death before the liver transplant ( p < 0.001) but not after the transplant. 6MWD was similar to MELD-Na in discriminating mortality. Each 50-meter decrease in 6MWD was associated with an increase in all-cause ( p < 0.001) and transplant-free hospitalizations ( p < 0.001) in multivariable models for time-to-recurrent events. Shorter 6MWD was associated with worse Short Form-36 physical ( p < 0.001) and mental component scores ( p = 0.05). In conclusion, shorter 6MWD is associated with an increased risk of death, hospitalizations, and worse quality of life in patients evaluated for liver transplantation. The 6-minute walk distance may be a useful adjunct for risk assessment in patients undergoing liver transplant evaluation.