Chronic thromboembolic disease among patients undergoing surgical pulmonary embolectomy for acute pulmonary embolism.

BACKGROUND: This study aimed to assess the prevalence of chronic thromboembolic lesions in the pulmonary arteries among patients undergoing pulmonary embolectomy for acute pulmonary embolism and their impact on treatment outcomes. METHODS: We conducted a retrospective, single-center analysis of consecutive patients undergoing emergency pulmonary embolectomy for acute pulmonary embolism between 2013 and August 2021. According to European Society of Cardiology guidelines, the diagnosis was based on clinical presentation, imaging studies and laboratory tests. Surgery was selected as the optimal treatment modality within the Pulmonary Embolism Response Team. Based on the intraoperatively identified chronic lesions patients were divided into two groups: acute only and acute/chronic. The analysis comprised history, laboratory and imaging studies, early and long-term mortality, and postoperative complications. We determined predictive factors for chronic thromboembolic lesions and risk factors for death. RESULTS: The analysis included 33 patients. Intraoperatively, 42% (14) of patients had chronic lesions. Predictive factors for these lesions are the duration of symptoms >1 week (OR=13.75), pulmonary artery dilatation >3.15 cm (OR=39.00) and right ventricle systolic pressure >52 mmHg (OR=29.33). No hospital deaths occurred in the acute only group and two in the acute/chronic group (0% vs. 14.3%; P=0.172). Risk factors for death are the duration of symptoms >3 weeks (HR=7.35) and postoperative use of extracorporeal membrane oxygenation (HR=7.04). CONCLUSIONS: Acute thromboembolic disease overlapping chronic clots is relatively common among patients undergoing pulmonary artery embolectomy. A detailed evaluation of the patient's medical history and imaging studies can identify these patients, as they require special attention when making treatment decisions. Surgical treatment in a center of expertise in pulmonary endarterectomy seems reasonable.

Role of Oxygen Starvation in Right Ventricular Decompensation and Failure in Pulmonary Arterial Hypertension.

Right ventricular (RV) function and eventually failure determine outcome in patients with pulmonary arterial hypertension (PAH). Initially, RV responds to an increased load caused by PAH with adaptive hypertrophy; however, eventually RV failure ensues. Unfortunately, it is unclear what causes the transition from compensated RV hypertrophy to decompensated RV failure. Moreover, at present, there are no therapies for RV failure; those for left ventricular (LV) failure are ineffective, and no therapies specifically targeting RV are available. Thus there is a clear need for understanding the biology of RV failure and differences in physiology and pathophysiology between RV and LV that can ultimately lead to development of such therapies. In this paper, we discuss RV adaptation and maladaptation in PAH, with a particular focus of oxygen delivery and hypoxia as the principal drivers of RV hypertrophy and failure, and attempt to pinpoint potential sites for therapy.

The Utility of a Resting Electrocardiogram (ECG-PH Index) in Evaluating the Efficacy of Pulmonary Endarterectomy in Chronic Thromboembolic Pulmonary Hypertension.

BACKGROUND: The ECG-PH index (PH-ECG score) has been proposed as a valuable ECG-derived method of evaluating the effectiveness of balloon pulmonary angioplasty (BPA) in chronic thromboembolic pulmonary hypertension (CTEPH). Pulmonary endarterectomy (PEA) is the main form of therapy for CTEPH with a proximal clot location. The objective of this study was to assess the clinical utility of a resting electrocardiogram (ECG-PH index) in assessing the effectiveness of PEA in CTEPH patients. METHODS: The retrospective analysis included 73 patients who underwent PEA. Their ECG-PH index values were calculated using four ECG parameters: R-wave amplitude V1 + S-wave amplitude V5/V6 > 10.5 mm, QRS-wave axis > 110 degrees, R-wave amplitude V1 > S-wave amplitude V1, and SIQIII pattern. PH-ECG scores were assessed after a median time of 13 months (IQR: 8-31 months) had passed since the PEA procedures. RESULTS: The current analysis documented that ECG-PH index = 0 is a good reflection of mPAP < 25mmHg (sensitivity 76.1%; specificity 66.7%; positive predictive value 79.5%; negative predictive value 62.1%) or mPAP ≤ 20 mmHg (sensitivity 69.6%; specificity 70.6%; positive predictive value 88.6%; negative predictive value 41.4%) after PEA. The values of the area under the ROC curve for ECG-PH index were 0.772 (95% CI: 0.676-0.867) and 0.743 (95% CI: 0.637-0.849) for the mPAP < 25 mmHg and mPAP ≤ 20 mmHg patient groups, respectively. CONCLUSION: The ECG-PH index may be useful for monitoring the haemodynamic effect of PEA in CTEPH patients.

Emerging Role of Balloon Pulmonary Angioplasty in Chronic Thromboembolic Pulmonary Disease-Insights from the 2022 ESC Guidelines.

In this article, we discuss the topic of chronic thromboembolic pulmonary disease (CTEPD) and the growing role of balloon pulmonary angioplasty (BPA) in its treatment. We present the pathophysiology of CTEPD which arises from an incomplete resolution of thrombi in the pulmonary arteries and leads to stenosis and occlusion of the vessels. The article focuses mainly on the chronic thromboembolic pulmonary hypertension (CTEPH) subpopulation for which prognosis is very poor when left untreated. We describe a multimodal approach to treating CTEPH, including pulmonary endarterectomy (PEA), BPA, and pharmacological therapies. Additionally, the benefits of pharmacological pre-treatment before BPA and the technical aspects of the procedure itself are outlined. It is emphasized that BPA does not replace PEA but serves as a complementary treatment option for eligible patients. We summarized efficacy and treatment goals including an improvement in functional and biochemical parameters before and after BPA. Patients who received pre-treatment with riociguat prior to BPA exhibited a notable reduction in the occurrence of less severe complications. However, elderly patients are still perceived as an especially vulnerable group. It is shown that the prognosis of patients undergoing BPA is similar to PEA in the first years after the procedure but the long-term prognosis of BPA still remains unclear. The 2022 ESC/ERS guidelines highlight the significant role of BPA in the multimodal treatment of CTEPH, emphasizing its effectiveness and recommending its consideration as a therapeutic option for patients with CTEPD, both with and without pulmonary hypertension. This review summarizes the available evidence for BPA, patient selection, procedural details, and prognosis and discusses the potential future role of BPA in the management of CTEPH.

Case report: Transected Hickman catheter and its thrombotic occlusion in a patient with idiopathic pulmonary arterial hypertension-can a catheter replacement be avoided?

A 25-year-old female with idiopathic pulmonary arterial hypertension (PAH), who had a Hickman catheter implanted for continuous intravenous epoprostenol infusion, was admitted to the clinic after inadvertently cutting the catheter with nail scissors during a routine dressing change. Approximately 7 cm of the external segment of the Hickman catheter remained intact, with the distal end knotted by paramedics. A decision was made to repair the damaged Hickman catheter. However, it was discovered that its lumen was completely occluded by thrombosis. Therefore, catheter patency was mechanically restored using a 0.035-inch stiff guidewire in a sterile operating theatre setting, under fluoroscopy guidance. Successful aspiration and catheter flushing were achieved. Continuity of the Hickman catheter was then restored using a repair kit (Bard Access Systems) as per the manufacturer's instructions, with no visible leakage thereafter. Epoprostenol infusion through the Hickman catheter was resumed 24 h later, and the patient was discharged in good general condition two days afterward.

Impact of diabetes mellitus on disease severity and patient survival in idiopathic pulmonary arterial hypertension: data from the Polish multicentre registry (BNP-PL).

BACKGROUND: Recent studies revealed that alterations in glucose and lipid metabolism in idiopathic pulmonary arterial hypertension (IPAH) are associated with disease severity and poor survival. However, data regarding the impact of diabetes mellitus (DM) on the prognosis of patients with IPAH remain scarce. The aim of our study was to determine that impact using data from a national multicentre prospective pulmonary hypertension registry. METHODS: We analysed data of adult patients with IPAH from the Database of Pulmonary Hypertension in the Polish population (BNP­PL) between March 1, 2018 and August 31, 2020. Upon admission, clinical, echocardiographic, and haemodynamic data were collected at 21 Polish IPAH reference centres. The all-cause mortality was assessed during a 30-month follow-up period. To adjust for differences in age, body mass index (BMI), and comorbidities between patients with and without DM, a 2-group propensity score matching was performed using a 1:1 pairing algorithm. RESULTS: A total of 532 patients with IPAH were included in the study and 25.6% were diagnosed with DM. Further matched analysis was performed in 136 patients with DM and 136 without DM. DM was associated with older age, higher BMI, more advanced exertional dyspnea, increased levels of N-terminal pro-brain natriuretic peptide, larger right atrial area, increased mean right atrial pressure, mean pulmonary artery pressure, pulmonary vascular resistance, and all-cause mortality compared with no DM. CONCLUSIONS: Patients with IPAH and DM present with more advanced pulmonary vascular disease and worse survival than counterparts without DM independently of age, BMI, and cardiovascular comorbidities.

Treatment of high- and intermediate-high-risk pulmonary embolism by the Pulmonary Embolism Response Team: Focus on catheter-directed therapies.

BACKGROUND: Multidisciplinary Pulmonary Embolism Response Teams (PERTs) were established to individualize the treatment of high-risk (HR) and intermediate-high-risk (IHR) pulmonary embolism (PE) patients, which pose a challenge in clinical practice. METHODS: We retrospectively collected the data of all HR and IHR acute PE patients consulted by PERT CELZAT between September 2017 and October 2022. The patient population was divided into four different treatment methods: anticoagulation alone (AC), systemic thrombolysis (ST), surgical embolectomy (SE), and catheter-directed therapies (CDTx). Baseline clinical characteristics, risk stratification, PE severity parameters, and treatment outcomes were compared between the four groups. RESULTS: Of the 110 patients with HR and IHR PE, 67 (61%) patients were treated with AC only, 11 (10%) with ST, 15 (14%) underwent SE, and 17 (15%) were treated with CTDx. The most common treatment option in the HR group was reperfusion therapy, used in 20/24 (83%) cases, including ST in 7 (29%) patients, SE in 5 (21%) patients, and CTDx in 8 (33%) patients. In contrast, IHR patients were treated with AC alone in 63/86 (73%) cases. The in-hospital mortality rate was 9/24 (37.5%) in the HR group and 4/86 (4.7%) in the IHR group. CONCLUSIONS: The number of advanced procedures aimed at reperfusion was substantially higher in the HR group than in the IHR PE group. Despite the common use of advanced reperfusion techniques in the HR group, patient mortality remained high. There is a need further to optimize the treatment of patients with HR PE to improve outcomes.

Balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension: a clinical consensus statement of the ESC working group on pulmonary circulation and right ventricular function.

The current treatment algorithm for chronic thromboembolic pulmonary hypertension (CTEPH) as depicted in the 2022 European Society of Cardiology (ESC)/European Respiratory Society (ERS) guidelines on the diagnosis and treatment of pulmonary hypertension (PH) includes a multimodal approach of combinations of pulmonary endarterectomy (PEA), balloon pulmonary angioplasty (BPA) and medical therapies to target major vessel pulmonary vascular lesions, and microvasculopathy. Today, BPA of >1700 patients has been reported in the literature from centers in Asia, the US, and also Europe; many more patients have been treated outside literature reports. As BPA becomes part of routine care of patients with CTEPH, benchmarks for safe and effective care delivery become increasingly important. In light of this development, the ESC Working Group on Pulmonary Circulation and Right Ventricular Function has decided to publish a document that helps standardize BPA to meet the need of uniformity in patient selection, procedural planning, technical approach, materials and devices, treatment goals, complications including their management, and patient follow-up, thus complementing the guidelines. Delphi methodology was utilized for statements that were not evidence based. First, an anatomical nomenclature and a description of vascular lesions are provided. Second, treatment goals and definitions of complete BPA are outlined. Third, definitions of complications are presented which may be the basis for a standardized reporting in studies involving BPA. The document is intended to serve as a companion to the official ESC/ERS guidelines.

The Diagnostic Approach to Pulmonary Hypertension.

The clinical presentation of pulmonary hypertension (PH) is nonspecific, resulting in significant delays in its detection. In the majority of cases, PH is a marker of the severity of other cardiopulmonary diseases. Differential diagnosis aimed at the early identification of patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) who do require specific and complex therapies is as important as PH detection itself. Despite all efforts aimed at the noninvasive assessment of pulmonary arterial pressure, the formal confirmation of PH still requires catheterization of the right heart and pulmonary artery. The current document will give an overview of strategies aimed at the early diagnosis of PAH and CTEPH, while avoiding their overdiagnosis. It is not intended to be a replica of the recently published European Society of Cardiology (ESC) and European Respiratory Society (ERS) Guidelines on Diagnosis and Treatment of Pulmonary Hypertension, freely available at the Web sites of both societies. While promoting guidelines' recommendations, including those on new definitions of PH, we will try to bring them closer to everyday clinical practice, benefiting from our personal experience in managing patients with suspected PH.

Long COVID syndrome after SARS-CoV-2 survival in patients with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension.

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) patients have a more severe COVID-19 course than the general population. Many patients report different persistent symptoms after SARS-CoV-2 infection. The aim of our study is to analyze the prevalence of long COVID-19 symptoms and assess if COVID-19 affects pulmonary hypertension (PH) prognosis. PAH/CTEPH patients who survived COVID-19 for at least 3 months before visiting the PH centers were included in the study. The patients were assessed for symptoms in acute phase of SARS-CoV-2 infection and persisting in follow-up visit, WHO functional class, 6-min walk distance, NT-proBNP concentration. The COMPERA 2.0 model was used to calculate 1-year risk of death due to PH at baseline and at follow-up. Sixty-nine patients-54 (77.3%) with PAH and 15 (21.7%) with CTEPH, 68% women, with a median age of 47.5 years (IQR 37-68)-were enrolled in the study. About 17.1% of patients were hospitalized due to COVID-19 but none in an ICU. At follow-up (median: 155 days after onset of SARS-CoV-2 symptoms), 62% of patients reported at least 1 COVID-19-related symptom and 20% at least 5 symptoms. The most frequently reported symptoms were: fatigue (30%), joint pain (23%), muscle pain (17%), nasal congestion (17%), anosmia (13%), insomnia (13%), and dyspnea (12%). Seventy-two percent of PH patients had a low or intermediate-low risk of 1-year death due to PH at baseline, and 68% after COVID-19 at follow-up. Over 60% of PAH/CTEPH patients who survived COVID-19 suffered from long COVID-19 syndrome, but the calculated 1-year risk of death due to PH did not change significantly after surviving mild or moderate COVID-19.

Catheter-directed mechanical aspiration thrombectomy in a real-world pulmonary embolism population: a multicenter registry.

AIMS: High- (HR) and intermediate-high risk (IHR) pulmonary embolisms (PEs) are related to high early mortality and long-term sequelae. We aimed to describe clinical outcomes and adverse events in IHR and HR pulmonary embolism (PE) treated with catheter-directed mechanical thrombectomy (CDMT) in a real-world population. METHODS AND RESULTS: This study is a multicenter, prospective registry enrolling 110 PE patients treated with CDMT between 2019 and 2022. The CDMT was performed using the 8F Indigo (Penumbra, Alameda, CA, USA) system bilaterally in pulmonary arteries (PAs). The primary safety endpoints included device or PE-related death during the 48-h after CDMT, procedure-related major bleeding, or other major adverse events. Secondary safety outcomes were all-cause mortality during hospitalization or the follow-up. The primary efficacy outcomes were the reduction of PA pressures and change in the right-to-left ventricular (RV/L) ratio assessed in the imaging 24-48 h after the CDMT.71.8% of patients had IHR PE and 28.2% HR PE. 11.8% of patients had a failure and 34.5% had contraindications to thrombolysis, and 2.7% had polytrauma. There was 0.9% intraprocedural death related to RV failure and 5.5% deaths within the first 48 h. CDMT was complicated by major bleeding in 1.8%, pulmonary artery injury in 1.8%, and ischaemic stroke in 0.9%. Immediate haemodynamic improvements included a 10.4 ± 7.8 mmHg (19.7%) drop in systolic PAP (P < 0.0001), a 6.1 ± 4.2 mmHg (18.8%) drop in mean PAP, and 0.48 ± 0.4 (36%) drop in RV/LV ratio (P < 0.0001). CONCLUSION: These observational findings suggest that CDMT may improve hemodynamics with an acceptable safety profile in patients with IHR and HR PE.

Role of catheter-directed therapies in the treatment of acute pulmonary embolism. Expert opinion of the Polish PERT Initiative, Working Group on Pulmonary Circulation, Association of Cardiovascular Interventions, and Association of Intensive Cardiac Care of the Polish Cardiac Society.

Thanks to advances in interventional cardiology technologies, catheter-directed treatment has become recently a viable therapeutic option in the treatment of patients with acute pulmonary embolism at high risk of early mortality. Current transcatheter techniques allow for local fibrinolysis or embolectomy with minimal risk of complications. Therefore, these procedures can be considered in high-risk patients as an alternative to surgical pulmonary embolectomy when systemic thrombolysis is contraindicated or ineffective. They are also considered in patients with intermediate-high-risk pulmonary embolism who do not improve or deteriorate clinically despite anticoagulation. The purpose of this article is to present the role of transcatheter techniques in the treatment of patients with acute pulmonary embolism. We describe current knowledge and expert opinions in this field. Interventional treatment is described in the broader context of patient care organization and therapeutic modalities. We present the organization and responsibilities of pulmonary embolism response team, role of pre-procedural imaging, periprocedural anticoagulation, patient selection, timing of intervention, and intensive care support. Currently available catheter-directed therapies are discussed in detail including standardized protocols and definitions of procedural success and failure. This expert opinion has been developed in collaboration with experts from various Polish scientific societies, which highlights the role of teamwork in caring for patients with acute pulmonary embolism.

Cancer-associated thrombosis: comparison of characteristics, treatment, and outcomes in oncologic and nononcologic patients followed by a pulmonary embolism response team.

INTRODUCTION: The risk of venous thromboembolism (VTE) in patients with cancer is currently 12 times higher than in the general population, and even 23 times higher when they receive chemotherapy. The main goal of the pulmonary embolism response team at the Center for the Management of Pulmonary Embolism (PERT­CELZAT) is to improve prognosis through interdisciplinary care, with a particular focus on patients with contraindications to standard pharmacologic treatment, requiring individual decision­making, including a wider use of interventional therapeutic methods. OBJECTIVES: The objectives of the study were to report and compare the characteristics and outcomes of pulmonary embolism (PE) in patients with and without cancer treated by the PERT­CELZAT. PATIENTS AND METHODS: The analysis included 235 patients diagnosed with VTE who were consulted by local PERT between September 2017 and December 2021. The study group was divided into 2 cohorts: oncologic patients (OP) and nononcologic patients (NOP). There were 81 patients in the OP group (mean [SD] age, 66.2 [14.1] years) and 154 patients in the NOP group (mean age, 57.4 [17.4] years). RESULTS: The OPs were older and more frequently diagnosed with incidental PE. In­hospital mortality for all patients reached 6.4% (15/235), 3.7% in the OP and 7.8% in the NOP group (P = 0.27). In­hospital events, such as major bleeding, minor bleeding, recurrent PE, and deep venous thrombosis occurred with similar frequency in both groups. Posthospital mortality up to 12 months after the PE diagnosis was 12.8% (10/78) in the OP and 4.2% (6/142) in the NOP group (P = 0.03). In a long­term survival analysis, cancer was associated with increased risk of mortality (hazard ratio, 2.44 [95% CI, 1.51-3.95]; P <0.001) when adjusted for age. CONCLUSIONS: The multidisciplinary therapeutic approach may provide the OPs with VTE an in­hospital survival rate noninferior to that of the NOPs. The OPs died more often in the following months, because of their underlying neoplastic disease.

Acute pulmonary embolism with coexisting right heart thrombi in transit-surgical treatment of 20 consecutive patients.

OBJECTIVES: The presence of right heart thrombi in transit (RHTiT) in the setting of acute pulmonary embolism (PE) is associated with high mortality. The optimal management in such cases is inconclusive. We present the results of surgical treatment of 20 consecutive patients diagnosed with high- or intermediate-high-risk PE with coexisting RHTiT. METHODS: A retrospective analysis was performed of all consecutive patients undergoing surgical treatment in the Medicover Hospital between 2013 and 2021 for acute PE with coexisting thrombi in-transit in right heart cavities. The diagnosis was based on echocardiography, computed tomography pulmonary angiography and laboratory tests. Eligibility criteria for surgical treatment were acute PE with RHTiT, right ventricular overload on imaging studies and significantly elevated levels of cardiac troponin and NTproBNP. All patients were operated on with extracorporeal circulation using deep hypothermia and total circulatory arrest. The primary end point was hospital all-cause mortality; secondary end points were perioperative complications and long-term mortality. RESULTS: The analysis included 20 patients. There was no in-hospital death. Nearly one-third of patients required temporal hemofiltration for postoperative renal failure, but this did not involve the need for dialysis at discharge. No neurological complications occurred in any patient. The mean follow-up was 46 months (range 13-98). There was 1 death in the long-term follow-up, not related to PE. CONCLUSIONS: Surgical treatment of patients with acute PE and coexisting RHTiT can provide favourable results.

Outcomes of COVID-19 in patients vaccinated and unvaccinated against SARS-CoV-2 and suffering from pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension.

INTRODUCTION: Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) lead to progressive right heart failure. The mortality rates in PAH and CTEPH patients due to COVID­19 are high, and vaccination against COVID­19 is recommended in this group. OBJECTIVES: We analyzed the incidence and outcomes of COVID­19in the PAH/CTEPH patients for 2 years of the pandemic, as well as the predictors of worse outcomes of COVID­19 in this group. PATIENTS AND METHODS: PAH/CTEPH patient data for this observational, cohort study were obtained from 3 pulmonary hypertension centers between March 11, 2020 and March 11, 2022. RESULTS: A total of 364 consecutive patients with PAH/CTEPH (248/122; 232 women [64%]; median [interquartile range] age, 61 years [18-92]) were included in the study. All the patients had advanced pulmonary hypertension at baseline. Eighty­five patients (23%) suffered from COVID­19. Seven of them (8%), all of whom were unvaccinated, died of COVID­19. The unvaccinated patients suffered from COVID­19 more often than the vaccinated ones (46% vs 9%; P <0.001). As many as 31% of the PAH/CTEPH patients with COVID­19 needed hospitalization, in 8% of cases in the intensive care unit. Age equal to or above 65 years and severe pulmonary hypertension defined as a World Health Organization functional class 3 or 4 were associated with severe COVID­19 in the PAH/CTEPH patients. CONCLUSIONS: The vaccinated PAH/CTEPH patients suffered from COVID­19 less frequently than the unvaccinated ones. The mortality rate and hospitalization due to COVID­19 were higher in the PAH/CTEPH patients than in the general population. All efforts should be made to convince the PAH/CTEPH patients to vaccinate against COVID­19.

Catheter-directed therapy to treat intermediateand high-risk pulmonary embolism: Personal experience and review of the literature.

Pulmonary embolism (PE) is the third leading cause of cardiovascular death in the western world. Prompt recognition, risk stratification, and individualized treatment are crucial to improve outcomes in patients with PE. Anticoagulation alone is a sufficient therapeutic option in low-risk patients, whereas primary reperfusion with systemic thrombolysis (ST) is usually chosen in high-risk patients. The choice of treatment in intermediate-risk patients is complex and depends on the clinical presentation. Catheter-directed therapy (CDTh) includes all therapies delivered via a catheter placed in the branches of the pulmonary arteries directly into the thrombus. Because ST bears a high risk of major bleeding and numerous patients have contraindications to ST, CDTh is an alternative to ST in intermediate- and high-risk PE patients. CDTh includes local thrombolysis using low-dose alteplase, ultrasound-assisted thrombolysis, and mechanical fragmentation and aspiration of the thrombi, as well as their combinations. In this review article, we have summarized devices and technical details for CDTh, discussed the efficacy and safety of CDTh in comparison to ST in previous clinical trials, and outlined future research directions regarding CDTh, both based on the literature and our personal experience from the local PE Response Team of the Center for the Management of Pulmonary Embolism (CELZAT) in Warsaw.

Biomarker-based approach to determine etiology and severity of pulmonary hypertension: Focus on microRNA.

Pulmonary arterial hypertension (PAH) is characterized by remodeling of the pulmonary arteries, and defined by elevated pulmonary arterial pressure, measured during right heart catheterization. There are three main challenges to the diagnostic and therapeutic process of patients with PAH. First, it is difficult to differentiate particular PAH etiology. Second, invasive diagnostic is required to precisely determine the severity of PAH, and thus to qualify patients for an appropriate treatment. Third, the results of treatment of PAH are unpredictable and remain unsatisfactory. MicroRNAs (miRNAs) are small non-coding RNAs that regulate post transcriptional gene-expression. Their role as a prognostic, and diagnostic biomarkers in many different diseases have been studied in recent years. MiRNAs are promising novel biomarkers in PAH due to their activity in various molecular pathways and processes underlying PAH. Lack of biomarkers to differentiate between particular PAH etiology and evaluate the severity of PAH, as well as paucity of therapeutic targets in PAH open a new field for the possibility to use miRNAs in these applications. In our article, we discuss the potential of miRNAs use as diagnostic tools, prognostic biomarkers and therapeutic targets in PAH.