Anticoagulation in patients with pulmonary arterial hypertension: An update on current knowledge

The role of anticoagulation on the long-term survival of patients with pulmonary arterial hypertension: A meta-analysis of 15 cohort studies

INTRODUCTION

Anticoagulation was once recommended for patients with pulmonary arterial hypertension (PAH). However, its survival benefit still remained controversial. We performed a meta-analysis to evaluate the effect of anticoagulation on the long-term survival of PAH patients.

METHODS

The PubMed, EMBASE, Web of Science, and WanFang electronic database were searched for eligible studies. Pooled hazard ratios (HRs) with 95 % confidence intervals (CIs) were calculated for effect estimate regarding anticoagulation on the survival of PAH patients.

RESULTS

Fifteen cohort studies involving 4266 PAH patients were included. Approximately 45.8 % patients received anticoagulation. The mean follow-up period ranged from 2.1 to 14 years. Anticoagulation had a tendency to, however, did not significantly reduce mortality of PAH patients (HR: 0.86, 95 % CI: 0.73-1.02). In subgroup analysis, anticoagulation decreased the mortality risk as analyzed from retrospective studies (HR: 0.80, 95 % CI: 0.65-0.98), but not prospective studies (HR: 0.95, 95 % CI: 0.70-1.29). For both idiopathic PAH (IPAH) and connective tissue disease associated PAH (CTD-PAH), anticoagulation therapy did not significantly improve the long-term survival rate (HR: 0.83, 95 % CI: 0.65-1.07, and HR: 1.05, 95 % CI: 0.77-1.42, respectively), and this result remained unchanged when pooling data from either retrospective or prospective studies. Further analysis showed that anticoagulation had no advantage in reducing mortality in patients with systemic sclerosis associated PAH, systemic erythematosus lupus related PAH (free of antiphospholipid syndrome), or CTD-PAH of non-specified etiology.

CONCLUSION

Anticoagulation may not reduce the long-term mortality of PAH patients, including those with IPAH and CTD-PAH. In the management of PAH, anticoagulants should be prescribed with caution before comprehensive risk to benefit evaluation. Larger and more vigorously designed controlled trials are warranted.

Pharmacological Gq inhibition induces strong pulmonary vasorelaxation and reverses pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening disease with limited survival. Herein, we propose the pharmacological inhibition of Gq proteins as a novel concept to counteract pulmonary vasoconstriction and proliferation/migration of pulmonary artery smooth muscle cells (PASMCs) in PAH. We demonstrate that the specific pan-Gq inhibitor FR900359 (FR) induced a strong vasorelaxation in large and small pulmonary arteries in mouse, pig, and human subjects ex vivo. Vasorelaxation by FR proved at least as potent as the currently used triple therapy. We also provide in vivo evidence that local pulmonary application of FR prevented right ventricular systolic pressure increase in healthy mice as well as in mice suffering from hypoxia (Hx)-induced pulmonary hypertension (PH). In addition, we demonstrate that chronic application of FR prevented and also reversed Sugen (Su)Hx-induced PH in mice. We also demonstrate that Gq inhibition reduces proliferation and migration of PASMCs in vitro. Thus, our work illustrates a dominant role of Gq proteins for pulmonary vasoconstriction as well as remodeling and proposes direct Gq inhibition as a powerful pharmacological strategy in PH.

Pulmonary Hypertension in Pregnancy: Challenges and Solutions

Pulmonary hypertension (PH) is a heterogeneous disease characterized by an elevated mean pulmonary artery pressure of 20 mm Hg or above. PH is a prevalent condition among women of reproductive age and is linked with poor prognosis during pregnancy. Pregnancy is a stressful event and complicates the management and prognosis in patients with PH. In this review, we discuss the pathogenesis, clinical presentation as well as therapeutic options for PH during pregnancy. We also highlight knowledge gaps to guide future research.

Pulmonary arterial hypertension patients display normal kinetics of clot formation using thrombelastography

Pulmonary arterial hypertension is characterized by endothelial dysfunction and microthrombi formation. The role of anticoagulation remains controversial, with studies demonstrating inconsistent effects on pulmonary arterial hypertension mortality. Clinical anticoagulation practices are currently heterogeneous, reflecting physician preference. This study uses thrombelastography and hematology markers to evaluate whether clot formation and fibrinolysis are abnormal in pulmonary arterial hypertension patients. Venous blood was collected from healthy volunteers (n = 20) and patients with pulmonary arterial hypertension (n = 20) on stable medical therapy for thrombelastography analysis. Individual thrombelastography parameters and a calculated coagulation index were used for comparison. In addition, hematologic markers, including fibrinogen, factor VIII activity, von Willebrand factor activity, von Willebrand factor antigen, and alpha2-antiplasmin, were measured in pulmonary arterial hypertension patients and compared to healthy volunteers. Between group differences were analyzed using t tests and linear mixed models, accounting for repeated measures when applicable. Although the degree of fibrinolysis (LY30) was significantly lower in pulmonary arterial hypertension patients compared to healthy volunteers (0.3% ± 0.6 versus 1.3% ± 1.1, p = 0.04), all values were within the normal reference range (0–8%). All other thrombelastography parameters were not significantly different between pulmonary arterial hypertension patients and healthy volunteers (p ≥ 0.15 for all). Similarly, alpha2-antiplasmin activity levels were higher in pulmonary arterial hypertension patients compared to healthy volunteers (103.7% ± 13.6 versus 82.6% ± 9.5, p < 0.0001), but all individual values were within the normal range (75–132%). There were no other significant differences in hematologic markers between pulmonary arterial hypertension patients and healthy volunteers (p ≥ 0.07 for all). Sub-group analysis comparing thrombelastography results in patients treated with or without prostacyclin pathway targeted therapies were also non-significant. In conclusion, treated pulmonary arterial hypertension patients do not demonstrate abnormal clotting kinetics or fibrinolysis by thrombelastography.

The Role of Antithrombotic Therapy in Heart Failure

Heart failure is a major contributor to global morbidity and mortality burden affecting approximately 1-2% of adults in developed countries, mounting to over 10% in individuals aged >70 years old. Heart failure is characterized by a prothrombotic state and increased rates of stroke and thromboembolism have been reported in heart failure patients compared with the general population. However, the impact of antithrombotic therapy on heart failure remains controversial. Administration of antiplatelet or anticoagulant therapy is the obvious (and well-established) choice in heart failure patients with cardiovascular comorbidity that necessitates their use, such as coronary artery disease or atrial fibrillation. In contrast, antithrombotic therapy has not demonstrated any clear benefit when administered for heart failure per se, i.e. with heart failure being the sole indication. Randomized studies have reported decreased stroke rates with warfarin use in patients with heart failure with reduced left ventricular ejection fraction, but at the expense of excessive bleeding. Non-vitamin K oral anticoagulants have shown a better safety profile in heart failure patients with atrial fibrillation compared with warfarin, however, current evidence about their role in heart failure with sinus rhythm is inconclusive and further research is needed. In the present review, we discuss the role of antithrombotic therapy in heart failure (beyond coronary artery disease), aiming to summarize evidence regarding the thrombotic risk and the role of antiplatelet and anticoagulant agents in patients with heart failure.

Newer approaches and novel drugs for inhalational therapy for pulmonary arterial hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by remodeling of small pulmonary arteries leading to increased pulmonary arterial pressure. Existing treatments acts to normalize vascular tone via three signaling pathways: the prostacyclin, the endothelin-1, and the nitric oxide. Although over the past 20 years, there has been considerable progress in terms of treatments for PAH, the disease still remains incurable with a disappointing prognosis.Areas covered: This review summarizes the pathophysiology of PAH, the advantages and disadvantages of the inhalation route, and assess the relative advantages various inhaled therapies for PAH. The recent studies concerning the development of controlled-release drug delivery systems loaded with available anti-PAH drugs have also been summarized.Expert opinion: The main obstacles of current pharmacotherapies of PAH are their short half-life, stability, and formulations, resulting in reducing the efficacy and increasing systemic side effects and unknown pathogenesis of PAH. The pulmonary route has been proposed for delivering anti-PAH drugs to overcome the shortcomings. However, the application of approved inhaled anti-PAH drugs is limited. Inhalational delivery of controlled-release nanoformulations can overcome these restrictions. Extensive studies are required to develop safe and effective drug delivery systems for PAH patients.

Anticoagulation in pulmonary arterial hypertension: a decision analysis

Systemic anticoagulation may be beneficial in pulmonary arterial hypertension, but there is no randomized clinical trial data to guide therapeutic decision making, and current guidelines do not account for patient preferences or quality of life. Decision analytic models to evaluate the potential risks and benefits of systemic anticoagulation in pulmonary arterial hypertension patients, focusing on the benefit in quality-adjusted life years, may be helpful in clarifying this uncertainty. We constructed a 31-state Markov decision analytic model to explore anticoagulation and no anticoagulation strategies. Modeled patient characteristics included gender, use of central catheter-based pulmonary arterial hypertension therapy, type of pulmonary arterial hypertension (idiopathic, idiopathic pulmonary arterial hypertension, or connective-tissue associated, connective tissue disease-pulmonary arterial hypertension), and use of oral contraceptive medication by females. Modeled events included mortality, thromboembolic complications, atrial fibrillation, stroke, and anticoagulation bleeding. Deterministic and probabilistic sensitivity analyses were performed. Anticoagulation was favored in all idiopathic pulmonary arterial hypertension cases, with a gain of 0.43-0.51 quality-adjusted life years, and detrimental in all connective tissue disease-pulmonary arterial hypertension cases, with a loss of 0.66-1.89 quality-adjusted life years. Anticoagulation would need to demonstrate a hazard ratio for pulmonary arterial hypertension mortality of 0.95 or better to be favored. In our model, idiopathic pulmonary arterial hypertension patients benefit from anticoagulation in terms of quality-adjusted life years, and connective tissue disease-pulmonary arterial hypertension patients were harmed, with a hazard ratio for pulmonary arterial hypertension mortality of 0.95 or better being required to favorably impact quality-adjusted life years. These results suggest that anticoagulation significantly improves quality adjusted life years and should be offered to all idiopathic pulmonary arterial hypertension patients. Shared decision models based on these results may help clarify therapeutic decision-making uncertainty in pulmonary arterial hypertension patients.

Mortality associated with cardiovascular drugs in patients with chronic obstructive pulmonary disease and right-sided heart failure - A danish nationwide registry-based study

BACKGROUND

The optimal medical treatment in patients with chronic obstructive pulmonary disease (COPD) and right-sided heart failure (RHF) is unknown. We aimed to estimate the risks of all-cause mortality associated with the current clinical use of various cardiovascular drugs in this patient-group.

METHODS

We followed all patients with registered COPD and RHF (defined as a diagnosis of pulmonary hypertension plus use of loop-diuretics) for the risk of all-cause mortality (Jan 1, 1995 to Dec 31, 2015) using the Danish nationwide administrative registries. The association between mortality and claimed prescriptions for cardiovascular drugs was assessed by multivariable Cox regression models.

RESULTS

5991 patients (mean age 74 ± standard deviation 10 years, 51% women) were included. Of these, 1440 (24%) used beta-blockers, 2149 (36%) renin-angiotensin system inhibitors [RASi], 1340 (22%) oral anticoagulants, 1376 (23%) calcium channel blockers, 1194 (20%) statins, 1824 (30%) spironolactone, and 2099 (35%) low-dose aspirin. During an average follow-up of 2.2 years (±standard deviation 2.8, min-max 0-19.6 years), 5071 (85%) died, corresponding to a mortality rate of 38 per 100 person-years (95% confidence interval 37-39). Compared to no use, beta-blockers were associated with adjusted hazards ratio 0.90 (95% confidence interval 0.84-0.98), RASi 0.92 (0.86-0.98), calcium channel blockers 0.86 (0.80-0.92), spironolactone 1.17 (1.10-1.24), statins 0.85 (0.78-0.92), oral anticoagulants 0.87 (0.79-0.95), and aspirin 0.99 (0.93-1.05). Propensity-score matched analyses and inverse-probability-weighted models yielded similar results.

CONCLUSION

Several cardiovascular drugs may be associated with lowered mortality in COPD and RHF. Given the grave prognosis, randomized clinical trials are warranted to test this hypothesis.

Critical Care of Patients After Pulmonary Thromboendarterectomy

Pulmonary thromboendarterectomy (PTE) remains the only curative surgery for patients with chronic thromboembolic pulmonary hypertension (CTEPH). Postoperative intensive care unit care challenges providers with unique disease physiology, operative sequelae, and the potential for detrimental complications. Central concerns in patients with CTEPH immediately after PTE relate to neurologic, pulmonary, hemodynamic, and hematologic aspects. Institutional experience in critical care for the CTEPH population, a multidisciplinary team approach, patient risk assessment, and integration of current concepts in critical care determine outcomes after PTE surgery. In this review, the authors will focus on specific aspects unique to this population, with integration of current available evidence and future directions. The goal of this review is to provide the cardiac anesthesiologist and intensivist with a comprehensive understanding of postoperative physiology, potential complications, and contemporary intensive care unit management immediately after pulmonary endarterectomy.

A case report of pulmonary arterial hypertension in pregnancy and complications of anticoagulation therapy

RATIONALE

Treprostinil, a potent vasodilator, is the treatment of choice for severe pulmonary arterial hypertension (PAH) during pregnancy. Its inhibition of platelet aggregation increases the risk of hemorrhage. In addition, anticoagulation therapy is widely used in pregnancy with PAH due to the hypercoagulable state. However, very little is known about the complications of anticoagulants' use in pregnancy with PAH.

PATIENT CONCERNS

A 27-year-old pregnant woman was admitted to the hospital at 32weeks with progressive dyspnea.

DIAGNOSES

The pregnant was diagnosed with ventricular septal defect 12 years prior to presentation. Combining clinical manifestation with results of right heart catheterization (RHC) and echocardiography, it was consistent with severe World Health Organization (WHO) group I PAH.

INTERVENTIONS

Supportive treatment included supplemental oxygen, intravenous treprostinil, sildenafil and prophylactic anticoagulation.

OUTCOMES

Gastrointestinal bleeding is occurred in our patient when dalteparin were used in conjunction with treprostinil. Her care was further complicated refractory to usual conservative measures before delivery.

LESSONS

This case report illustrates the complexities that arise when prostacyclin therapies are combined with necessary anticoagulation in patients with PAH during pregnancy. More intention should play to the complications of anticoagulant in pregnancy with PAH during treprostinil therapy.

Platelet and coagulation disorders in newly diagnosed patients with pulmonary arterial hypertension

There is a complex and not fully elucidated association between pulmonary arterial hypertension (PAH) and coagulation disorders. The goal of this study was to evaluate platelet function, coagulation and fibrinolysis in PAH patients at diagnosis, before PAH-specific treatment initiation. We enrolled 20 healthy controls and 30 PAH patients (20 with connective tissue disease (CTD-PAH) and 10 idiopathic (iPAH)). None of the participants was on any antiplatelet or anticoagulation therapy. Blood samples from PAH patients were collected during the initial right heart catheterization. All subjects were assessed with platelet function analyzer-100 (PFA-100), epinephrine (Epi) and ADP-induced light transmission aggregometry (LTA), thromboelastometry (ROTEM) and endogenous thrombin potential (ETP). Our results showed that Epi and ADP-LTA values were significantly lower in newly diagnosed PAH patients compared to controls. Disaggregation was present in 73% of patients, a characteristic not seen in healthy individuals. In ROTEM assay, CT and CFT measurements were significantly higher and a angle lower compared to controls. ETP testing revealed significantly reduced outcomes in AUC, Cmax and Tmax. When CTD-PAH and iPAH patient groups were compared, iPAH ADP-LTA values were significantly decreased compared to CTD-PAH. In conclusion, newly diagnosed PAH patients presented with decreased platelet aggregation, clot propagation and thrombin generation, along with delayed initiation of the coagulation process. These hemostatic deficits could indicate an "exhaustion" of the coagulation process that could be caused by endothelial dysfunction and chronic activation of the procoagulant pathways. Further studies are warranted to confirm these laboratory findings and assess their potential clinical significance.

Impact on survival of warfarin in patients with pulmonary arterial hypertension receiving subcutaneous treprostinil

INTRODUCTION

Anticoagulation is a common treatment modality in patients with pulmonary arterial hypertension (PAH). Further studies are needed to appropriately assess the risk/benefit ratio of anticoagulation, particularly in PAH patients receiving PAH-specific therapies.

AIMS

We use observational long-term data on PAH patients treated with subcutaneous (SQ) treprostinil from a large open-label study. Patients were followed for up to 4 years. The use of warfarin and bleeding events were recorded.

RESULTS

At total of 860 patients (age [mean±SD] 46±15 years, 76% female, 83% Caucasian, 49% idiopathic PAH, and 76% New York Heart Association [NYHA] functional class III) were included. All patients received SQ treprostinil (15% also other pulmonary hypertension [PH]-therapies) and 590 (69%) received warfarin during the study. The proportions of women, African American, and idiopathic pulmonary hypertension (IPAH) patients were higher in the group receiving warfarin. A higher proportion of patients with congenital heart disease and portopulmonary hypertension did not receive warfarin. There were no differences in unadjusted long-term survival between PAH patients receiving warfarin or not (log-rank test, P value=.69), even when only considering idiopathic PAH (P=.32). In addition, no difference was found in adjusted long-term survival both in PAH (P=.84) and idiopathic PAH patients (P=.44) based on the use of warfarin. Furthermore, no survival difference based on the use of warfarin were noted between propensity score-matched PAH patients (P=.37).

CONCLUSIONS

Long-term anticoagulation with warfarin was not associated with any significant effect on survival in PAH or idiopathic PAH patients treated with SQ treprostinil.

In Vitro Assessment of Pharmacokinetic Drug-Drug Interactions of Direct Oral Anticoagulants: Type 5-Phosphodiesterase Inhibitors Are Inhibitors of Rivaroxaban and Apixaban Efflux by P-Glycoprotein

Because of their lower bleeding risk and simplicity of use, direct oral anticoagulants (DOACs) could represent an interesting alternative to conventional anticoagulant treatment with vitamin K antagonists for patients with pulmonary arterial hypertension (PAH). P-glycoprotein (P-gp) plays a key role in DOAC pharmacokinetics. Type 5-phosphodiesterase inhibitors (PDE5is), a drug class commonly used in the treatment of PAH, have been shown to strongly inhibit P-gp. This work aimed to assess potential P-gp-mediated drug-drug interactions between PDE5is and DOACs using in vitro methods. A cellular model of drug transport assay, using P-gp-overexpressing Madin-Darby canine kidney cells (transfected with the human P-gp gene), was used to determine the bidirectional permeabilities of two DOACs (rivaroxaban and apixaban) in the absence and presence of increasing concentrations (0.5-100 µM) of three PDE5is (sildenafil, tadalafil, and vardenafil). Permeabilities and efflux ratios were calculated from DOAC concentrations, were measured with liquid chromatography coupled with mass spectrometry, and were subsequently used to determine the PDE5i percentage of inhibition and half maximal inhibitory concentration (IC₅₀ ). Rivaroxaban efflux was inhibited by 99%, 66%, and 100% with 100 µM sildenafil, tadalafil, and vardenafil, respectively. Similarly, apixaban efflux was inhibited by 97%, 74%, and 100%, respectively. The IC₅₀ values of the three PDE5is were 8, 28, and 5 µM for rivaroxaban and 23, 15, and 3 µM for apixaban, respectively. This study showed strong in vitro inhibition of DOAC efflux by PDE5is. In vivo studies are required to determine the clinical relevance of these interactions.

Features associated with pulmonary arterial hypertension in Chinese hospitalized systemic lupus erythematosus patients

Pulmonary arterial hypertension (PAH) is an increasingly recognized complication of systemic lupus erythematosus (SLE). This study aims to estimate the point prevalence of PAH and identify risk factors for PAH in a large cohort of hospitalized SLE patients. We have collected the medical records of patients hospitalized with SLE at the First Affiliated Hospital of Anhui Medical University and Anhui Provincial Hospital. Resting transthoracic echocardiography (TTE) was used to estimate pulmonary artery pressure (PAP) and PAH was defined as systolic PAP (PASP) > 30 mmHg. Patients with other connective tissue diseases, aPL syndrome, left heart disease, valvular heart disease, congenital heart disease, HIV, and portal hypertension were excluded because of diseases affecting the PAP. We assessed potential risk factors for PAH such as thrombogenic factors, SLE clinical manifestations, laboratory abnormalities and disease activity. Ninety-five were diagnosed with PAH of 1639 patients with SLE. The presence of high fibrinogen, serositis, and thrombocytopenia were significantly higher in patients with PAH than in those without PAH (all P < 0.05). Multivariate logistic regression found the associations between high fibrinogen (OR = 1.629), serositis (OR = 2.866), and thrombocytopenia (OR = 1.825) with PAH. The point prevalence of PAH was 5.8% in our cohort of patients with SLE. The significant association of high fibrinogen, serositis, and thrombocytopenia with PAH suggested that hypercoagulable state, organ damage, and hematological abnormality may all contribute to the development of PAH in SLE. This is important, as it is treatable.

Are statins beneficial for the treatment of pulmonary hypertension?

Pulmonary hypertension (PH) is a condition characterized by vasoconstriction and vascular remodeling with a poor prognosis. The current medical treatments available are supportive care therapy and pulmonary vascular-targeted therapy. Targeted treatments for PH include prostacyclin analogs, endothelin receptor antagonists, and phosphodiesterase type 5 inhibitors; however, these treatments cannot reverse pulmonary vascular remodeling. Recently, many novel treatment options involving drugs such as statins have been emerging. In this review, we attempt to summarize the current knowledge of the role of statins in PH treatment and their potential clinical effects. Many basic researches have proved that statins can be helpful for the treatment of PH both in vitro and in experimental models. The main mechanisms underlying the effects of statins are restoration of endothelial function, attenuation of pulmonary vascular remodeling, regulation of gene expression, regulation of intracellular signaling processes involved in PH, anti-inflammatory responses, and synergy with other targeted drugs. Nevertheless, clinical researches, especially randomized controlled trials for PH are rare. The current clinical researches show contrasting results on the clinical effects of statins in patients with PH. Carefully designed randomized, controlled trials are needed to test the safety and efficacy of statins for PH treatment.

Pulmonary Arterial Hypertension: Diagnosis and Treatment

Pulmonary arterial hypertension (PAH) is a specific, rare disease characterized by a well-described pattern of pulmonary vascular remodeling. The elevated pulmonary artery pressure in PAH results in increased right ventricular afterload, which, if untreated, leads rapidly to right ventricular failure and death. Recent marked expansion in knowledge about PAH has resulted in the development of effective therapies that improve quality of life and survival. However, delays in diagnosis and suboptimal treatment remain significant barriers to achieving optimal patient outcomes. Continued success in raising PAH awareness, earlier diagnosis, and the availability of new therapies mean a promising future for PAH patients.

A review of therapeutic agents for the management of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is an uncommon, progressive and life threatening disease characterized by a proliferative vasculopathy of the small muscular pulmonary arterioles resulting in elevated pulmonary vascular resistance and eventually right ventricular failure. An increasing understanding of the pathobiology of PAH and its natural history has led to the development of numerous targeted therapies. Despite these advances there is significant progression of disease and the survival rate remains low. This article reviews the agents currently available for the medical management of PAH.

Interstitial pneumonia and pulmonary hypertension associated with suspected ehrlichiosis in a dog

Background

In dogs with canine monocytic ehrlichiosis (CME), respiratory signs are uncommon and clinical and radiographic signs of interstitial pneumonia are poorly described. However, in human monocytic ehrlichiosis, respiratory signs are common and signs of interstitial pneumonia are well known. Pulmonary hypertension (PH) is classified based on the underlying disease and its treatment is aimed at reducing the clinical signs and, if possible, addressing the primary disease process. PH is often irreversible, but can be reversible if it is secondary to a treatable underlying etiology. CME is currently not generally recognized as one of the possible diseases leading to interstitial pneumonia and secondary PH in dogs. Only one case of PH associated with CME has been reported worldwide.

Case presentation

A seven-year-old, male intact, mixed breed dog was presented with 2 weeks history of lethargy and dyspnea. The dog previously lived in the Cape Verdean islands. Physical examination showed signs of right-sided congestive heart failure and poor peripheral perfusion. Thoracic radiography showed moderate right-sided cardiomegaly with dilation of the main pulmonary artery and a mild diffuse interstitial lung pattern with peribronchial cuffing. Echocardiography showed severe pulmonary hypertension with an estimated pressure gradient of 136 mm Hg. On arterial blood gas analysis, severe hypoxemia was found and complete blood count revealed moderate regenerative anemia and severe thrombocytopenia. A severe gamma hyperglobulinemia was also documented. Serology for Ehrlichia canis was highly positive. Treatment with oxygen supplementation, a typed packed red blood cell transfusion and medical therapy with doxycycline, pimobendan and sildenafil was initiated and the dog improved clinically. Approximately 2 weeks later, there was complete resolution of all clinical signs and marked improvement of the PH.

Conclusion

This report illustrates that CME might be associated with significant pulmonary disease and should be considered as a possible differential diagnosis in dogs presenting with dyspnea and secondary pulmonary hypertension, especially in dogs that have been in endemic areas. This is important because CME is a treatable disease and its secondary lung and cardiac manifestations may be completely reversible.

Where do we go from here? Reappraising the data on anticoagulation in pulmonary arterial hypertension

The use of anticoagulation as part of the treatment regimen in pulmonary arterial hypertension (PAH) remains a topic of debate. A recently published analysis of anticoagulation use in the Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL) study offers conflicting conclusions regarding the benefit of this therapeutic strategy. There remains no robust randomized trial in PAH weighing the risks versus benefits of including anticoagulation in treatment regimens, leaving clinicians to surmise value in individual patients. Reexamination of available data may help to provide guidance on this controversial topic in the absence of future dedicated investigations.