A simple non-invasive diagnostic algorithm for ruling out chronic thromboembolic pulmonary hypertension in patients after acute pulmonary embolism

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.

The Early Detection of Pulmonary Hypertension

BACKGROUND

Up to 1% of the world population and 10% of all persons over age 65 suffer from pulmonary hypertension (PH). The latency from the first symptom to the diagnosis is more than one year on average, and more than three years in 20% of patients. 40% seek help from more than four different physicians until their condition is finally diagnosed.

METHODS

This review is based on publications retrieved by a selective literature search on pulmonary hypertension.

RESULTS

The most common causes of pulmonary hypertension are left heart diseases and lung diseases. Its cardinal symptom is exertional dyspnea that worsens as the disease progresses. Additional symptoms of right heart failure are seen in advanced stages. Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are rare, difficult to diagnose, and of particular clinical relevance because specific treatments are available. For this reason, strategies for the early detection of PAH and CTEPH have been developed. The clinical suspicion of PH arises in a patient who has nonspecific symptoms, electrocardiographic changes, and an abnormal (NT-pro-)BNP concentration. Once the suspicion of PH has been confirmed by echocardiography and, if necessary, differential-diagnostic evaluation with a cardiopulmonary stress test, and after the exclusion of a primary left heart disease or lung disease, the patient should be referred to a PH center for further diagnostic assessment, classification, and treatment.

CONCLUSION

If both the (NT-pro-)BNP and the ECG are normal, PH is unlikely. Knowledge of the characteristic clinical manifestations and test results of PH is needed so that patients can be properly selected for referral to specialists and experts in PH.

[Diagnostic Algorithm and Screening of Pulmonary Hypertension]

The new guidelines for the diagnosis and treatment of pulmonary hypertension include a new diagnostic algorithm and provide specific recommendations for the required diagnostic procedures, including screening methods. These recommendations are commented on by national experts under the auspices of the DACH. These comments provide additional decision support and background information, serving as a further guide for the complex diagnosis of pulmonary hypertension.

External validation of the InShape II study algorithm for exclusion of chronic thromboembolic pulmonary hypertension in patients with pulmonary thromboembolism

BACKGROUND AND AIM

The most severe long-term complication of pulmonary embolism (PE) is chronic thromboembolic pulmonary hypertension (CTEPH), and its early diagnosis often requires numerous diagnostic tests. The InShape II study proposes an early screening algorithm that aims to reduce the number of echocardiographic studies. The objective of our study is to validate this algorithm in our patient cohort.

MATERIALS AND METHODS

We retrospectively analyzed patients admitted to Hospital Rey Juan Carlos between November 2017 and February 2020, who were diagnosed with PE based on computed tomography angiography (CTA). Patients were followed for at least one year, and clinical, laboratory, and complementary test data were collected at three months and one year. The InShape II algorithm was applied to these patients to validate its results.

RESULTS

During the study period, 236 patients were diagnosed with PE, of which 137 were excluded. The algorithm was validated in 99 patients. Applying the InShape II score, 19 echocardiograms would have been performed (three of them with intermediate-high probability of CTEPH), while 80 echocardiograms would have been avoided (two of them with intermediate-high probability). This yielded a sensitivity of 60% and a specificity of 83% for the score, with an area under the curve (AUC) of 0.715 (95% CI: 0.472-0.958).

CONCLUSIONS

Our results support the notion that the InShape II algorithm could be a useful tool for initial screening of CTEPH in low-incidence settings, as it would avoid unnecessary echocardiograms that do not provide additional value.

Post-Pulmonary Embolism Syndrome and Functional Outcomes after Acute Pulmonary Embolism

Survivors of acute pulmonary embolism (PE) are at risk of developing persistent, sometimes disabling symptoms of dyspnea and/or functional limitations despite adequate anticoagulant treatment, fulfilling the criteria of the post-PE syndrome (PPES). PPES includes chronic thromboembolic pulmonary hypertension (CTEPH), chronic thromboembolic pulmonary disease, post-PE cardiac impairment (characterized as persistent right ventricle impairment after PE), and post-PE functional impairment. To improve the overall health outcomes of patients with acute PE, adequate measures to diagnose PPES and strategies to prevent and treat PPES are essential. Patient-reported outcome measures are very helpful to identify patients with persistent symptoms and functional impairment. The primary concern is to identify and adequately treat patients with CTEPH as early as possible. After CTEPH is ruled out, additional diagnostic tests including cardiopulmonary exercise tests, echocardiography, and imaging of the pulmonary vasculature may be helpful to rule out non-PE-related comorbidities and confirm the ultimate diagnosis. Most PPES patients will show signs of physical deconditioning as main explanation for their clinical presentation. Therefore, cardiopulmonary rehabilitation provides a good potential treatment option for this patient category, which warrants testing in adequately designed and executed randomized trials. In this review, we describe the definition and characteristics of PPES and its diagnosis and management.

Long-term sequelae following acute pulmonary embolism: A nationwide follow-up study regarding the incidence of CTEPH, dyspnea, echocardiographic and V/Q scan abnormalities

We aimed to follow a nationwide cohort of patients with pulmonary embolism (PE) without any exclusions to generate information regarding long-term symptoms, investigational findings and to determine the prevalence of chronic thromboembolic pulmonary hypertension (CTEPH). We hypothesized that this approach would yield generalizable estimates of CTEPH prevalence and incidence. All individuals diagnosed with acute PE in Sweden in 2005 were identified using the National Patient Register. In 2007, survivors were asked to complete a questionnaire regarding current symptoms. Those with dyspnea were referred for further examinations with laboratory tests, electrocardiogram (ECG), and a ventilation/perfusion scan (V/Q scan). If CTEPH was suspected, a referral to the nearest pulmonary arterial hypertension-center was recommended. Of 5793 unique individuals with PE diagnosis in 2005, 3510 were alive at the beginning of 2007. Altogether 53% reported dyspnea at some degree whereof a large proportion had V/Q scans indicating mismatched defects. Further investigation revealed 6 cases of CTEPH and in parallel 18 cases were diagnosed outside this study. The overall prevalence of CTEPH was 0.4% (95% confidence interval [CI]: 0.2%-0.6%) and 0.7% (95% CI: 0.4%-1.0%) among the survivors. The cumulative incidence of CTEPH in the group of patients who underwent a V/Q scan was 1.1% (95% CI: 0.2%-2.0%). There was a high mortality following an acute PE, a high proportion of persistent dyspnea among survivors, whereof several had pathological findings on V/Q scans and echocardiography. Only a minority developed CTEPH, indicating that CTEPH is the tip of the iceberg of post-PE disturbances.

Chronic thromboembolic pulmonary hypertension and the post-pulmonary embolism (PE) syndrome

Over a third of patients surviving acute pulmonary embolism (PE) will experience long-term cardiopulmonary limitations. Persistent thrombi, impaired gas exchange, and altered hemodynamics account for aspects of the postpulmonary embolism syndrome that spans mild functional limitations to debilitating chronic thromboembolic pulmonary hypertension (CTEPH), the most worrisome long-term consequence. Though pulmonary endarterectomy is potentially curative for the latter, less is understood surrounding chronic thromboembolic disease (CTED) and post-PE dyspnea. Advances in pulmonary vasodilator therapies and growing expertise in balloon pulmonary angioplasty provide options for a large group of patients ineligible for surgery, or those with persistent postoperative pulmonary hypertension. In this clinical review, we discuss epidemiology and pathophysiology as well as advances in diagnostics and therapeutics surrounding the spectrum of disease that may follow months after acute PE.

Biomarkers of collagen turnover and wound healing in chronic thromboembolic pulmonary hypertension patients before and after pulmonary endarterectomy

BACKGROUND

In chronic thromboembolic pulmonary hypertension (CTEPH), fibrotic remodeling of tissue and thrombi contributes to disease progression. Removal of the thromboembolic mass by pulmonary endarterectomy (PEA) improves hemodynamics and right ventricular function, but the roles of different collagens before as well as after PEA are not well understood.

METHODS

In this study, hemodynamics and 15 different biomarkers of collagen turnover and wound healing were evaluated in 40 CTEPH patients at diagnosis (baseline) and 6 and 18 months after PEA. Baseline biomarker levels were compared with a historical cohort of 40 healthy subjects.

RESULTS

Biomarkers of collagen turnover and wound healing were increased in CTEPH patients compared with healthy controls, including a 35-fold increase in the PRO-C4 marker of type IV collagen formation and a 55-fold increase in the C3M marker of type III collagen degradation. PEA reduced pulmonary pressures to almost normal levels 6 months after the procedure, with no further improvement at 18 months. There were no changes in any of the measured biomarkers after PEA.

CONCLUSIONS

Biomarkers of collagen formation and degradation are increased in CTEPH suggesting a high collagen turnover. While PEA effectively reduces pulmonary pressures, collagen turnover is not significantly modified by surgical PEA.

Electrocardiogram in patients with pulmonary hypertension

INTRODUCTION

Pulmonary hypertension (PH) is a potentially life-threatening cardiovascular disease defined by a mean pulmonary arterial pressure (mPAP) > 20 mmHg. Due to non-specific symptoms, PH is often diagnosed late and at advanced stage. In addition to other diagnostic modalities, the electrocardiogram (ECG) can help in establishing the diagnosis. Knowledge of typical ECG signs could help to detect PH earlier.

METHODS

A non-systematic literature review on the typical electrocardiographic patterns of PH was performed.

RESULTS

Characteristic signs of PH include right axis deviation, SIQIIITIII and SISIISIII patterns, P pulmonale, right bundle branch block, deep R waves in V1 and V2, deep S waves in V5 and V6, and right ventricular hypertrophy (R in V1 + S in V5, V6 > 1,05 mV). Repolarisation abnormalities such as ST segment depressions or T wave inversions in leads II, III, aVF, and V1 to V3 are common as well. Furthermore, a prolonged QT/QTc interval, an increased heart rate, or supraventricular tachyarrhythmias can be observed. Some parameters may even provide information about the patient's prognosis.

CONCLUSION

Not every PH patient shows electrocardiographic PH signs, especially in mild PH. Thus, the ECG is not useful to completely rule out PH, but provides important clues to PH when symptoms are present. The combination of typical ECG signs and the co-occurrence of electrocardiographic signs with clinical symptoms and elevated BNP levels are particularly suspicious. Diagnosing PH earlier could prevent further right heart strain and improve patient prognosis.

Clinical controversies in the management of acute pulmonary embolism: evaluation of four important but controversial aspects of acute pulmonary embolism management that are still subject of debate and research

INTRODUCTION

Acute pulmonary embolism (PE) is a disease with a broad spectrum of clinical presentations. While some patients can be treated at home or may even be left untreated, other patients require an aggressive approach with reperfusion treatment.

AREAS COVERED

(1) Advanced reperfusion treatment in hemodynamically stable acute PE patients considered to be at high risk of decompensation and death, (2) the treatment of subsegmental pulmonary embolism, (3) outpatient treatment for hemodynamically stable PE patients with signs of right ventricle (RV) dysfunction, and (4) the optimal approach to identify and treatpost-PE syndrome.

EXPERT OPINION

Outside clinical trials, hemodynamically stable acute PE patients should not be treated with primary reperfusion therapy. Thrombolysis and/or catheter-directed therapy are only to be considered as rescue treatment. Subsegmental PE can be left untreated in selected low-risk patients, after proximal deep vein thrombosis has been ruled out. Patients with an sPESI or Hestia score of 0 criteria can be treated at home, independent of the presence of RV overload. Finally, health-care providers should be aware of post-PE syndrome and diagnose chronic thromboembolic pulmonary disease (CTEPD) as early as possible. Persistently symptomatic patients without CTEPD benefit from exercise training and cardiopulmonary rehabilitation.

From acute pulmonary embolism to post-pulmonary embolism sequelae

Aim of this narrative review is to summarize the functional and hemodynamic implications of acute PE and PE sequelae, namely the post-PE syndrome. Briefly, we will first describe the epidemiology, diagnostic procedures, and therapeutic approaches of acute PE. Then, we will provide a definition of the post-PE syndrome and present the so far accumulated evidence regarding its epidemiology and the implications that arise for further diagnosis and treatment. Lastly, we will explore the most devastating long-term complication of PE, namely chronic thromboembolic pulmonary hypertension (CTEPH), and recent advances in its management.

CTEPH: A Kaiser Permanente Northern California Experience

INTRODUCTION

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare and life-threatening form of pulmonary hypertension and the only potentially curable form of the World Health Organization Pulmonary Hypertension classes. Thus, the prompt and accurate diagnosis of this condition is imperative. Despite widespread chronic symptoms following acute pulmonary embolism (PE), the condition is rarely considered, and an externally validated inexpensive diagnostic algorithm is lacking.

METHODS

A long-term, retrospective cohort study was conducted to assess the incidence of CTEPH following acute PE in a real-world study population. Additional data were collected regarding the practice patterns of diagnostic testing and imaging, particularly in patients with persistent or recurrent symptoms. Amongst diagnosed CTEPH patients, previously established risk factors were evaluated for degree of risk and commonly used diagnostic tests (electrocardiogram [ECG] right ventricular hypertrophy [RVH] pattern, B-type natriuretic peptide [BNP] elevations) employed during this period were evaluated and assessed for feasibility as screening tests. The study population was obtained from the MAPLE study cohort, comprised of patients presenting with acute PE in 21 community medical centers across the Kaiser Permanente Northern California system from January 2013 to April 2015. Diagnosis of CTEPH was confirmed via pulmonary vascular imaging (ventilation/perfusion [V/Q] scanning, computed tomography angiography, pulmonary angiography) and diagnostic right heart catheterization (RHC). Probable diagnoses were defined as a combination of suggestive echocardiographic and RHC findings. Additional inclusion criteria included age (≥18 years) with at least 2 years follow up and no previous diagnosis of CTEPH or PE during the prior 30 days.

RESULTS

There were 1973 patients who met inclusion criteria (mean age 62.4 years). Despite 75 % of patients developing symptoms consistent with CTEPH >3 months following acute PE, only 5.6 % of these symptomatic patients underwent V/Q scanning. There was overall a very low cumulative incidence of CTEPH (2.3 %), which was significantly higher amongst patients with symptoms compared to those without symptoms. When controlled for confounding in the multivariate analysis, only recurrent PE (HR 19.3, P < 0.001) and pulmonary artery systolic pressure >50 mmHg (HR 10.4, P < 0.001) were statistically significant predictors of CTEPH. Of the non-invasive diagnostic tests, ECG criteria for RVH were found to be poorly sensitive (2.6 %), but very specific (98.8 %) for CTEPH. Elevated levels of BNP alone were more sensitive than RVH ECG criteria (76.3 %) but poorly specific (44.4 %).

CONCLUSIONS

The diagnosis of CTEPH is uncommonly made following acute PE. Despite the frequency of persistent symptoms consistent with CTEPH following acute PE, the appropriate diagnostic work-up is rarely undertaken as evidenced in this cohort. This suggests that CTEPH is underappreciated and rarely considered, likely underestimating the true incidence in this cohort. Future studies are needed to elucidate the true prevalence of CTEPH and further investigate both the optimal diagnostic tools and timing of appropriate screening. These discoveries may help guide future development of diagnostic algorithms that can effectively rule out and accurately identify this potentially curable disease in a timely manner.

[Pulmonary Endarterectomy and Treatment for Chronic Thromboembolic Pulmonary Hypertension]

Pulmonary Endarterectomy and Treatment for Chronic Thromboembolic Pulmonary Hypertension Abstract. Chronic thromboembolic pulmonary hypertension is a relatively rare disease which mostly evolves as a complication of acute pulmonary embolism resulting from the fibrotic organization of residual thrombotic material despite adequate anticoagulation leading to precapillary pulmonary hypertension and persistence of its symptoms. The elevated pulmonary vascular resistance leads to right ventricular heart failure, its symptoms and reduced prognosis. The therapy of choice is the pulmonary endarterectomy, which leads to a reduction of symptoms, optimization of the hemodynamics and improved prognosis. Misdiagnosis and delayed referral often lead to disease progression along with poor surgical outcome. In case of more distal, surgically non-accessible disease, treatment consists of balloon pulmonary angioplasty and pulmonary vasodilator drugs.

Diagnostic efficacy of ECG-derived ventricular gradient for the detection of chronic thromboembolic pulmonary hypertension in patients with acute pulmonary embolism

INTRODUCTION

Application of the chronic thromboembolic pulmonary hypertension (CTEPH) rule out criteria (manual electrocardiogram [ECG] reading and N-terminal pro-brain natriuretic peptide [NTproBNP] test) can rule out CTEPH in pulmonary embolism (PE) patients with persistent dyspnea (InShape II algorithm). Increased pulmonary pressure may also be identified using automated ECG-derived ventricular gradient optimized for right ventricular pressure overload (VG-RVPO).

METHOD

A predefined analysis of the InShape II study was performed. The diagnostic performance of the VG-RVPO for the detection of CTEPH and the incremental diagnostic value of the VG-RVPO as new rule-out criteria in the InShape II algorithm were evaluated.

RESULTS

60 patients were included; 5 (8.3%) were ultimately diagnosed with CTEPH. The mean baseline VG-RVPO (at time of PE diagnosis) was -18.12 mV·ms for CTEPH patients and - 21.57 mV·ms for non-CTEPH patients (mean difference 3.46 mV·ms [95%CI -29.03 to 35.94]). The VG-RVPO (after 3-6 months follow-up) normalized in patients with and without CTEPH, without a clear between-group difference (mean Δ VG-RVPO of -8.68 and - 8.42 mV·ms respectively; mean difference of -0.25 mV·ms, [95%CI -12.94 to 12.44]). The overall predictive accuracy of baseline VG-RVPO, follow-up RVPO and Δ VG-RVPO for CTEPH was moderate to poor (ROC AUC 0.611, 0.514 and 0.539, respectively). Up to 76% of the required echocardiograms could have been avoided with VG-RVPO criteria replacing the InShape II rule-out criteria, however at cost of missing up to 80% of the CTEPH diagnoses.

CONCLUSION

We could not demonstrate (additional) diagnostic value of VG-RVPO as standalone test or as on top of the InShape II algorithm.

Pulmonary thromboembolic events in COVID‐19 – a systematic literature review

Pulmonary thromboembolic events have been linked to coronavirus disease 2019 (COVID‐19), but their incidence and long‐term sequelae remain unclear. We performed a systematic literature review to investigate the incidence of pulmonary embolism (PE), microthrombi, thrombosis in situ (thromboinflammatory disease), and chronic thromboembolic pulmonary hypertension (CTEPH) during and after COVID‐19. PubMed and the World Health Organization Global Research Database were searched on May 7, 2021. Hospital cohort and database studies reporting data for ≥1000 patients and autopsy studies reporting data for ≥20 patients were included. Results were summarized descriptively. We screened 1438 records and included 41 references (32 hospital/database studies and 9 autopsy studies). The hospital/database studies reported the incidence of PE but not CTEPH, microthrombi, or thromboinflammatory disease. PE incidence varied widely (0%–1.1% of outpatients, 0.9%–8.2% of hospitalized patients, and 1.8%–18.9% of patients in intensive care). One study reported PE events occurring within 45 days after hospital discharge (incidence in discharged patients: 0.2%). Segmental arteries were generally the most common location for PE. In autopsy studies, PE, thromboinflammatory disease, and microthrombi were reported in 6%–23%, 43%–100%, and 45%–84% of deceased patients, respectively. Overall, the included studies mostly focused on PE during the acute phase of COVID‐19. The results demonstrate the challenges of identifying and characterizing vascular abnormalities using current protocols (e.g., visual computed tomography reads). Further research is needed to detect subtle pulmonary vascular abnormalities, distinguish thromboinflammatory disease from PE, optimize treatment, and assess the incidence of long‐term sequelae after COVID‐19.

Isoprostane-8 and GDF-15 as novel markers of post-PE syndrome: Relation with prothrombotic factors

BACKGROUND

Post-pulmonary embolism (PE) syndrome occurs in up to 50% of PE patients. The pathophysiology of this syndrome is obscure.

OBJECTIVE

We investigated whether enhanced oxidative stress and prothrombotic state may be involved in post-PE syndrome.

METHODS

We studied 101 normotensive noncancer PE patients (aged 56.5 ± 13.9 years) on admission, after 5-7 days and after a 3-month anticoagulation, mostly with rivaroxaban. A marker of oxidative stress, 8-isoprostane, endogenous thrombin potential, fibrinolysis proteins, clot lysis time (CLT) and fibrin clot permeability (K_s ), along with PE biomarkers, were determined.

RESULTS

Patients who developed the post-PE syndrome (n = 31, 30.7%) had at baseline 77.6% higher N-terminal brain natriuretic propeptide and 46.8% higher growth differentiation factor 15, along with 14.1% longer CLT associated with 34.4% higher plasminogen activator inhibitor-1 as compared to subjects without post-PE syndrome (all P < .05). After 5-7 days, only hypofibrinolysis was noted in post-PE syndrome patients. When measured at 3 months, prolonged CLT and reduced K_s were observed in post-PE syndrome patients, accompanied by 23.8% higher growth differentiation factor 15 and 35.8% higher plasminogen activator inhibitor-1 (all P < .05). 8-isoprostane levels ≥108 pg/ml (odds ratio=4.36; 95% confidence interval 1.63-12.27) and growth differentiation factor 15 ≥ 1529 pg/ml (odds ratio=3.89; 95% confidence interval 1.29-12.16) measured at 3 months were associated with higher risk of developing post-PE syndrome.

CONCLUSIONS

Enhanced oxidative stress and prothrombotic fibrin clot properties could be involved in the pathogenesis of the post-PE syndrome. Elevated growth differentiation factor 15 assessed at 3 months might be a new biomarker of this syndrome.

Prediction of chronic thromboembolic pulmonary hypertension with standardised evaluation of initial computed tomography pulmonary angiography performed for suspected acute pulmonary embolism

Objectives

Closer reading of computed tomography pulmonary angiography (CTPA) scans of patients presenting with acute pulmonary embolism (PE) may identify those at high risk of developing chronic thromboembolic pulmonary hypertension (CTEPH). We aimed to validate the predictive value of six radiological predictors that were previously proposed.

Methods

Three hundred forty-one patients with acute PE were prospectively followed for development of CTEPH in six European hospitals. Index CTPAs were analysed post hoc by expert chest radiologists blinded to the final diagnosis. The accuracy of the predictors using a predefined threshold for ‘high risk’ (≥ 3 predictors) and the expert overall judgment on the presence of CTEPH were assessed.

Results

CTEPH was confirmed in nine patients (2.6%) during 2-year follow-up. Any sign of chronic thrombi was already present in 74/341 patients (22%) on the index CTPA, which was associated with CTEPH (OR 7.8, 95%CI 1.9–32); 37 patients (11%) had ≥ 3 of 6 radiological predictors, of whom 4 (11%) were diagnosed with CTEPH (sensitivity 44%, 95%CI 14–79; specificity 90%, 95%CI 86–93). Expert judgment raised suspicion of CTEPH in 27 patients, which was confirmed in 8 (30%; sensitivity 89%, 95%CI 52–100; specificity 94%, 95%CI 91–97).

Conclusions

The presence of ≥ 3 of 6 predefined radiological predictors was highly specific for a future CTEPH diagnosis, comparable to overall expert judgment, while the latter was associated with higher sensitivity. Dedicated CTPA reading for signs of CTEPH may therefore help in early detection of CTEPH after PE, although in our cohort this strategy would not have detected all cases.

Key Points

• Three expert chest radiologists re-assessed CTPA scans performed at the moment of acute pulmonary embolism diagnosis and observed a high prevalence of chronic thrombi and signs of pulmonary hypertension.

• On these index scans, the presence of ≥ 3 of 6 predefined radiological predictors was highly specific for a future diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH), comparable to overall expert judgment.

• Dedicated CTPA reading for signs of CTEPH may help in early detection of CTEPH after acute pulmonary embolism.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08364-0.

Identification of chronic thromboembolic pulmonary hypertension on CTPAs performed for diagnosing acute pulmonary embolism depending on level of expertise

BACKGROUND

Expert reading often reveals radiological signs of chronic thromboembolic pulmonary hypertension (CTEPH) or chronic PE on computed tomography pulmonary angiography (CTPA) performed at the time of acute pulmonary embolism (PE) presentation preceding CTEPH. Little is known about the accuracy and reproducibility of CTPA reading by radiologists in training in this setting.

OBJECTIVES

To evaluate 1) whether signs of CTEPH or chronic PE are routinely reported on CTPA for suspected PE; and 2) whether CTEPH-non-expert readers achieve comparable predictive accuracy to CTEPH-expert radiologists after dedicated instruction.

METHODS

Original reports of CTPAs demonstrating acute PE in 50 patients whom ultimately developed CTEPH, and those of 50 PE who did not, were screened for documented signs of CTEPH. All scans were re-assessed by three CTEPH-expert readers and two CTEPH-non-expert readers (blinded and independently) for predefined signs and overall presence of CTEPH.

RESULTS

Signs of chronic PE were mentioned in the original reports of 14/50 cases (28%), while CTEPH-expert radiologists had recognized 44/50 (88%). Using a standardized definition (≥3 predefined radiological signs), moderate-to-good agreement was reached between CTEPH-non-expert readers and the experts' consensus (k-statistics 0.46; 0.61) at slightly lower sensitivities. The CTEPH-non-expert readers had moderate agreement on the presence of CTEPH (κ-statistic 0.38), but both correctly identified most cases (80% and 88%, respectively).

CONCLUSIONS

Concomitant signs of CTEPH were poorly documented in daily practice, while most CTEPH patients were identified by CTEPH-non-expert readers after dedicated instruction. These findings underline the feasibility of achieving earlier CTEPH diagnosis by assessing CTPAs more attentively.

Chronic thromboembolic pulmonary hypertension anno 2021

PURPOSE OF REVIEW

In the past decades, the diagnostic and therapeutic management of chronic thromboembolic pulmonary hypertension (CTEPH) has been revolutionized.

RECENT FINDINGS

Advances in epidemiological knowledge and follow-up studies of pulmonary embolism patients have provided more insight in the incidence and prevalence. Improved diagnostic imaging techniques allow accurate assessment of the location and extend of the thromboembolic burden in the pulmonary artery tree, which is important for the determination of the optimal treatment strategy. Next to the pulmonary endarterectomy, the newly introduced technique percutaneous pulmonary balloon angioplasty and/or P(A)H-targeted medical therapy has been shown to be beneficial in selected patients with CTEPH and might also be of importance in patients with chronic thromboembolic pulmonary vascular disease.

SUMMARY

In this era of a comprehensive approach to CTEPH with different treatment modalities, a multidisciplinary approach guides management decisions leading to optimal treatment and follow-up of patients with CTEPH.

Biomarkers in premature calves with and without respiratory distress syndrome

BACKGROUND

Approaches to the evaluation of pulmonary arterial hypertension (PAH) in premature calves by using lung-specific epithelial and endothelial biomarkers are needed.

OBJECTIVE

To investigate the evaluation of PAH in premature calves with and without respiratory distress syndrome (RDS) by using lung-specific epithelial and endothelial biomarkers and determine the prognostic value of these markers in premature calves.

ANIMALS

Fifty premature calves with RDS, 20 non-RDS premature calves, and 10 healthy term calves.

METHODS

Hypoxia, hypercapnia, and tachypnea were considered criteria for RDS. Arterial blood gases (PaO2 , PaCO2 , oxygen saturation [SO2 ], base excess [BE], and serum lactate concentration) were measured to assess hypoxia. Serum concentrations of lung-specific growth differentiation factor-15 (GDF-15), asymmetric dimethylarginine (ADMA), endothelin-1 (ET-1), vascular endothelial growth factor (VEGF), and surfactant protein D (SP-D) were measured to assess PAH.

RESULTS

Arterial blood pH, PaO2 , SO2 , and BE of premature calves with RDS were significantly lower and PaCO2 and lactate concentrations higher compared to non-RDS premature and healthy calves. The ADMA and SP-D concentrations of premature calves with RDS were lower and serum ET-1 concentrations higher than those of non-RDS premature and healthy calves. No statistical differences for GDF-15 and VEGF were found among groups.

CONCLUSIONS AND CLINICAL IMPORTANCE

Significant increases in serum ET-1 concentrations and decreases in ADMA and SP-D concentrations highlight the utility of these markers in the diagnosis of PAH in premature calves with RDS. Also, we found that ET-1 was a reliable diagnostic and prognostic biomarker for PAH and predicting mortality in premature calves.

Evaluation and management of patients with chronic thromboembolic pulmonary hypertension - consensus statement from the ISHLT

ISHLT members have recognized the importance of a consensus statement on the evaluation and management of patients with chronic thromboembolic pulmonary hypertension. The creation of this document required multiple steps, including the engagement of the ISHLT councils, approval by the Standards and Guidelines Committee, identification and selection of experts in the field, and the development of 6 working groups. Each working group provided a separate section based on an extensive literature search. These sections were then coalesced into a single document that was circulated to all members of the working groups. Key points were summarized at the end of each section. Due to the limited number of comparative trials in this field, the document was written as a literature review with expert opinion rather than based on level of evidence.

Raising the bar to ultradisciplinary collaborations in management of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension is an underdiagnosed and potentially fatal subgroup of pulmonary hypertension, if left untreated. Clinical signs include exertional dyspnea and non-specific symptoms. Diagnosis requires multimodality imaging and heart catheterization. Pulmonary endarterectomy, an open heart surgery, is the gold standard treatment of choice in selected patients in specialized centers. Targeted medical therapy and balloon pulmonary angioplasty can be effective in high-risk patients with significant comorbidities, distal pulmonary vascular obstructions, or recurrent/persistent pulmonary hypertension after pulmonary endarterectomy. Currently, there is a limited number of data regarding novel coronavirus-2019 infection in patients with chronic thromboembolic pulmonary hypertension and the changing spectrum of the disease during the pandemic. Challenging times during this outbreak due to healthcare crisis and relatively higher case-fatality rates require convergence; that is an ultradisciplinary collaboration, which crosses disciplinary and sectorial boundaries to develop integrated knowledge and new paradigms. Management strategies for the "new normal" such as virtual care, preparedness for further threats, redesigned standards and working conditions, reevaluation of specific recommendations, and online collaborations for optimal decisions for chronic thromboembolic pulmonary hypertension patients may change the poor outcomes.

Non-invasive early exclusion of chronic thromboembolic pulmonary hypertension after acute pulmonary embolism: the InShape II study

BACKGROUND

The current diagnostic delay of chronic thromboembolic pulmonary hypertension (CTEPH) after pulmonary embolism (PE) is unacceptably long, causing loss of quality-adjusted life years and excess mortality. Validated screening strategies for early CTEPH diagnosis are lacking. Echocardiographic screening among all PE survivors is associated with overdiagnosis and cost-ineffectiveness. We aimed to validate a simple screening strategy for excluding CTEPH early after acute PE, limiting the number of performed echocardiograms.

METHODS

In this prospective, international, multicentre management study, consecutive patients were managed according to a screening algorithm starting 3 months after acute PE to determine whether echocardiographic evaluation of pulmonary hypertension (PH) was indicated. If the 'CTEPH prediction score' indicated high pretest probability or matching symptoms were present, the 'CTEPH rule-out criteria' were applied, consisting of ECG reading and N-terminalpro-brain natriuretic peptide. Only if these results could not rule out possible PH, the patients were referred for echocardiography.

RESULTS

424 patients were included. Based on the algorithm, CTEPH was considered absent in 343 (81%) patients, leaving 81 patients (19%) referred for echocardiography. During 2-year follow-up, one patient in whom echocardiography was deemed unnecessary by the algorithm was diagnosed with CTEPH, reflecting an algorithm failure rate of 0.29% (95% CI 0% to 1.6%). Overall CTEPH incidence was 3.1% (13/424), of whom 10 patients were diagnosed within 4 months after the PE presentation.

CONCLUSIONS

The InShape II algorithm accurately excluded CTEPH, without the need for echocardiography in the overall majority of patients. CTEPH was identified early after acute PE, resulting in a substantially shorter diagnostic delay than in current practice.

Chronic thromboembolic pulmonary hypertension risk score evaluation and validation (CTEPH Solution): proposal of a study protocol aimed to realize a validated risk score for early diagnosis

BACKGROUND

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) is the most serious long-term complication of acute pulmonary embolism (PE) though it is the only potentially reversible form of Pulmonary Hypertension (PH). Its incidence is mainly limited to the first 2 years following the embolic event, however it is often underdiagnosed or misdiagnosed.

METHODS

This is a multicenter observational cross-sectional and prospective study. Patients with a prior diagnosis of PE will be enrolled and undergo baseline evaluation for prevalent PH detection through a clinical examination and an echocardiogram as first screening exam. All cases of intermediate-high echocardiographic probability of PH will be confirmed by right heart catheterization and then identified as CTEPH through appropriate imaging and functional examinations in order to exclude other causes of PH. A CTEPH Risk Score will be created using retrospective data from this prevalent cohort of patients and will be then validated on an incident cohort of patients with acute PE.

RESULTS

1000 retrospective and 218 prospective patients are expected to be enrolled and the study is expected to be completed by the end of 2021. Up to now 841 patients (620 retrospective and 221 prospective) have been enrolled.

CONCLUSIONS

This study is the first large prospective study for the prediction of CTEPH development in patients with PE. It aims to create a comprehensive scoring tool that includes echocardiographic data which may allow early detection of CTEPH and the application of targeted follow up screening programs in patients with PE.

Caging the dragon: Research approach to COVID-19-related thrombosis

The incidence of venous thrombosis, mostly pulmonary embolism (PE), ranging from local immunothrombosis to central emboli, but also deep vein thrombosis (DVT) in people with coronavirus disease 2019 (COVID-19) is reported to be remarkably high. The relevance of better understanding, predicting, treating, and preventing COVID-19-associated venous thrombosis meets broad support, as can be concluded from the high number of research, review, and guideline papers that have been published on this topic. The Dutch COVID & Thrombosis Coalition (DCTC) is a multidisciplinary team involving a large number of Dutch experts in the broad area of venous thrombosis and hemostasis research, combined with experts on virology, critically ill patients, pulmonary diseases, and community medicine, across all university hospitals and many community hospitals in the Netherlands. Within the consortium, clinical data of at least 5000 admitted COVID-19-infected individuals are available, including substantial collections of biobanked materials in an estimated 3000 people. In addition to considerable experience in preclinical and clinical thrombosis research, the consortium embeds virology-hemostasis research models within unique biosafety facilities to address fundamental questions on the interaction of virus with epithelial and vascular cells, in relation to the coagulation and inflammatory system. The DCTC has initiated a comprehensive research program to answer many of the current questions on the pathophysiology and best anticoagulant treatment of COVID-19-associated thrombotic complications. The research program was funded by grants of the Netherlands Thrombosis Foundation and the Netherlands Organization for Health Research and Development. Here, we summarize the design and main aims of the research program.

Chronic Thromboembolic Disease and Chronic Thromboembolic Pulmonary Hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic pulmonary vascular disease (CTED) are rare manifestations of venous thromboembolism. Presumably, CTEPH and CTED are variants of the same pathophysiological mechanism. CTEPH and CTED can be near-cured by pulmonary endarterectomy, balloon pulmonary angioplasty, and medical treatment with Riociguat or subcutaneous treprostinil, which are the approved drugs.

Why, Whom, and How to Screen for Chronic Thromboembolic Pulmonary Hypertension after Acute Pulmonary Embolism

Chronic thromboembolic pulmonary hypertension (CTEPH) is considered a long-term complication of acute pulmonary embolism (PE). Diagnosing CTEPH is challenging, as demonstrated by a considerable diagnostic delay exceeding 1 year, which has a negative impact on the patient's prognosis. Dedicated screening CTEPH strategies in PE survivors could potentially help diagnosing CTEPH earlier, although the optimal strategy is unknown. Recently published updated principles for screening in medicine outline the conditions that must be considered before implementation of a population-based screening program. Following these extensive principles, we discuss the pros and cons of CTEPH screening, touching on the epidemiology of CTEPH, the prognosis of CTEPH in the perspective of emerging treatment possibilities, and potentially useful tests and test combinations for screening. This review provides a modern perspective on CTEPH screening including a novel approach using a simple noninvasive algorithm of sequential diagnostic tests applied to all PE survivors.

Galectin-3, GDF-15, and sST2 for the assessment of disease severity and therapy response in patients suffering from inoperable chronic thromboembolic pulmonary hypertension

PURPOSE

This study examined sST2, GDF-15, and galectin-3 as indicators of disease severity and therapy response in chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

This study included 57 inoperable CTEPH patients who underwent balloon pulmonary angioplasty and 25 controls without cardiovascular disease. Biomarker levels were examined in relation to advanced hemodynamic impairment [tertile with worst right atrial pressure (RAP) and cardiac index], hemodynamic therapy response [normalized hemodynamics (meanPAP ≤25 mmHg, PVR ≤3 WU and RAP ≤6 mmHg) or a reduction of meanPAP ≥25%; PVR ≥ 35%, RAP ≥25%].

RESULTS

GDF-15 [820 (556-1315) pg/ml vs. 370 (314-516) pg/ml; p < 0.001] and sST2 [53.7 (45.3-74.1) ng/ml vs. 48.7 (35.5-57.0) ng/ml; p = 0.02] were higher in CTEPH patients than in controls. At baseline, a GDF-15 level ≥1443 pg/ml (AUC 0.88; OR 31.4) and a sST2 level ≥65 ng/ml (AUC 0.80; OR 10.9) were associated with advanced hemodynamic impairment. At follow-up GDF-15 ≤ 958 pg/ml (AUC = 0.74, OR 18) identified patients with optimal hemodynamic therapy response and ≤760 pg/ml (AUC = 0.79, OR 14).

CONCLUSION

GDF-15 and sST2 levels are higher in CTEPH and identified patients with advanced hemodynamic impairment. Further, decreased GDF-15 levels at follow-up were associated with hemodynamic therapy response. The diagnostic strength was not superior to NT-proBNP.

Essential aspects of the follow-up after acute pulmonary embolism: An illustrated review

Care for patients with acute pulmonary embolism (PE) involves more than determination of the duration of anticoagulant therapy. After choosing the optimal initial management strategy based on modern risk stratification schemes, patients require focused attention aimed at prevention of major bleeding, identification of underlying (malignant) disease, prevention of cardiovascular disease, and monitoring for long-term complications. The most frequent complication of PE is the so-called "post-PE syndrome," a phenomenon of permanent functional limitations after PE occurring in up to 50% of patients. The post-PE syndrome is caused by persistent deconditioning, anxiety, and/or ventilatory or circulatory impairment as a result of acute PE. The most severe and most feared presentation of the post-PE syndrome is chronic thromboembolic pulmonary hypertension (CTEPH), a deadly disease if it remains untreated. While CTEPH may be successfully treated with pulmonary endarterectomy, balloon pulmonary angioplasty, and/or pulmonary hypertension drugs, the major challenge is to diagnose CTEPH at an early stage. Poor awareness for the post-PE syndrome and in particular for CTEPH, high prevalence of persistent symptoms after PE and inefficient application of diagnostic tests in clinical practice all contribute to an unacceptable diagnostic delay and underdiagnosis. Its consequences are dire: increased mortality in patients with CTEPH, and excess health care costs, higher prevalence of depression, more unemployment and poorer quality of life in patients with post-PE syndrome in general. In this review, we provide an overview of the incidence and impact of the post-PE syndrome, and illustrate the clinical presentation, optimal diagnostic strategy as well as therapeutic options.

Diagnosis of chronic thromboembolic pulmonary hypertension after acute pulmonary embolism

Chronic thromboembolic pulmonary hypertension (CTEPH) is the most severe long-term complication of acute pulmonary embolism (PE). Untreated CTEPH is fatal, but, if diagnosed in time, successful surgical (pulmonary endarterectomy), medical (pulmonary hypertension drugs) and/or interventional (balloon pulmonary angioplasty) therapies have been shown to improve clinical outcomes, especially in case of successful pulmonary endarterectomy. Early diagnosis has however been demonstrated to be challenging. Poor awareness of the disease by patients and physicians, high prevalence of the post-PE syndrome (i.e. persistent dyspnoea, functional limitations and/or decreased quality of life following an acute PE diagnosis), lack of clear guideline recommendations as well as inefficient application of diagnostic tests in clinical practice lead to a reported staggering diagnostic delay >1 year. Hence, there is a great need to improve current clinical practice and diagnose CTEPH earlier. In this review, we will focus on the clinical presentation of and risk factors for CTEPH, and provide best practices for PE follow-up programmes from expert centres, based on a clinical case.

Prediction Score for persisting perfusion defects after pulmonary embolism

AIMS

Long-term persistence of perfusion defect after pulmonaryembolism (PE) may lead to the development of chronic thromboembolic pulmonary hypertension. Identification of patients at risk of such a complication using a scoring system would be beneficial in clinical practice. Here, we aimed to derive a score for predicting persistence of perfusion defects after PE.

METHODS

83 patients after PE were re-examined 6, 12 and 24 months after the PE episode. Data collected at the time of PE and perfusion status during follow-ups were used for modelling perfusion defects persistence using the Cox proportional hazards model and validated using bootstrap method.

RESULTS

A simple scoring system utilizing two variables (hemoglobin levels and age at the time of PE) was developed. Patients with hemoglobin levels over 140 g/L who were older than 65 years were at the highest risk of perfusion defects; in patients with the same hemoglobin levels and age <65 years, the risk was reduced by 79%, and by 89% in patients with hemoglobin <140 g/L.

CONCLUSION

The proposed scoring system may be useful in clinical practice for identifying patients with high risk of persisting perfusion defects, flagging them for closer follow up, thus improving the effectiveness of long-term treatment of patients after PE.

Growth differentiation factor-15 as candidate predictor for mortality in adults with pulmonary hypertension

Objective

Despite its predictive value for mortality in various diseases, the relevance of growth differentiation factor-15 (GDF-15) as prognostic biomarker in pulmonary hypertension (PH) remains unclear. This study investigated the association between GDF-15 and outcomes in adults with PH.

Methods

This is a single-centre prospective observational cohort study. All adults with PH were included at the day of their diagnostic right heart catheterisation between 2012 and 2016. PH due to left heart disease was excluded. Venous blood sampling was performed and included GDF-15 and N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurements. Kaplan-Meier curves and Cox regression analysis were used to investigate the association between GDF-15 and a composite endpoint of death or lung transplantation. We adjusted for age and NT-proBNP in multivariable analysis. Reference values were established by GDF-15 measurements in healthy controls.

Results

GDF-15 was measured in 103 patients (median age 59.2 years, 65% women, 51% pulmonary arterial hypertension). GDF-15 was elevated in 76 patients (74%). After a median follow-up of 3.4 (IQR 2.3–4.6) years, 32 patients (31.1%) reached the primary endpoint. Event-free survival 2 years after diagnosis was 100% in patients with normal GDF-15 versus 72.4% in patients with elevated GDF-15 (p=0.007). A significant association was found between GDF-15 and the primary endpoint (HR per twofold higher value 1.77, 95% CI 1.39 to 2.27, p<0.001), also after adjustment for age and NT-proBNP (HR 1.41, 95% CI 1.02 to 1.94, p=0.038).

Conclusions

High GDF-15 levels are associated with an increased risk of death or transplant in adults with PH, independent of age and NT-proBNP. As non-specific biomarker, GDF-15 could particularly be useful to detect low-risk patients.

Circulating biomarkers in chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a serious condition characterized with chronic organized thrombi that obstruct the pulmonary vessels, leading to pulmonary hypertension (PH) and ultimately right heart failure. Although CTEPH is the only form of PH that can be cured with surgical intervention, not all patients with CTEPH will be deemed operable. Some CTEPH patients still have a poor prognosis. Therefore, the determination of diagnostic and prognostic biomarkers of CTEPH is of great importance for the early intervention to improve prognosis of patients with CTEPH. Several markers related to multiple mechanisms of CTEPH have been recently identified as circulating diagnostic and prognostic biomarkers in these patients. However, the existing literature review of biomarkers of CTEPH is relatively sparse. In this article, we review recent advances in circulating biomarkers of CTEPH and describe future applications of these biomarkers in the management of CTEPH.

2018 TSOC guideline focused update on diagnosis and treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized as a progressive and sustained increase in pulmonary vascular resistance, which may induce right ventricular failure. In 2014, the Working Group on Pulmonary Hypertension of the Taiwan Society of Cardiology (TSOC) conducted a review of data and developed a guideline for the management of PAH.⁴ In recent years, several advancements in diagnosis and treatment of PAH has occurred. Therefore, the Working Group on Pulmonary Hypertension of TSOC decided to come up with a focused update that addresses clinically important advances in PAH diagnosis and treatment. This 2018 focused update deals with: (1) the role of echocardiography in PAH; (2) new diagnostic algorithm for the evaluation of PAH; (3) comprehensive prognostic evaluation and risk assessment; (4) treatment goals and follow-up strategy; (5) updated PAH targeted therapy; (6) combination therapy and goal-orientated therapy; (7) updated treatment for PAH associated with congenital heart disease; (8) updated treatment for PAH associated with connective tissue disease; and (9) updated treatment for chronic thromboembolic pulmonary hypertension.

The problem of under-diagnosis and over-diagnosis of pulmonary embolism

Pulmonary embolism (PE) is an increasingly recognised condition which is associated with significant morbidity and mortality. Despite the better awareness of this serious condition, the diagnosis is still overlooked in many cases with sometimes fatal consequences. Under-diagnosis may be due to several reasons including reliance on non-specific 'classic' symptoms, belief that bedside measurements will likely be abnormal in the setting of acute PE, and confounding factors like co-existent cardiorespiratory diseases or being in an intensive care unit, where the diagnosis may not be considered. At the same time, incidental diagnosis of PE is occurring more often due to frequent use of imaging investigations alongside advancements in CT technology, and dilemma exists as to whether the chance finding of PE requires anticoagulation, especially when identified only at the subsegmental level. This article reviews these two issues of under-diagnosis and over-diagnosis of PE in the current era.

Predictive Capability of Cardiopulmonary and Exercise Parameters From Day 1 to 6 Months After Acute Pulmonary Embolism

We hypothesized that the slope of relation ventilation to carbon dioxide output (V'E/V'CO2-slope) could be predictive already during the very first days after submassive pulmonary embolism (PE) to right ventricular systolic pressure (RVsys by echocardiography) after 6 months. We evaluated 21 hemodynamically stable patients at admittance, at days 3, 7, 90, and 180 by cardiopulmonary exercise testing and echocardiography. V'E/V'CO2-slope (48.4 ± 10.8) decreased within the first week (43.0 ± 9.8 at day 7) and normalized until follow-up at 6 months (35.0 ± 11.3; P < 10-4), p(a-ET)CO2 remained abnormal between days 1 and 3 (5.0 ± 3.9 to 6.7 ± 5.3 mmHg). RVsys declined from 41.7 ± 14.3 to 26.3±13.1 mmHg (P < 10-4) at 6 months. V'E/V'CO2-slope (r²= 0.27; P < .02) and RVsys (r² = 0.28; P = .03) at day 7 correlated with RVsys at 6 months. p(a-ET)CO2, p(a-ET)O2, V'D/V'T were not related to RVsys after 6 months. RVsys 6 months after acute PE is positively correlated with the V'E/V'CO2-slope at day 7.

Chronic thromboembolic pulmonary hypertension from the perspective of patients with pulmonary embolism

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare but feared long-term complication of acute pulmonary embolism (PE), although CTEPH may occur in patients with no history of symptomatic venous thromboembolism. It represents the most severe presentation of the so-called 'post-PE syndrome', a phenomenon of permanent functional limitations after PE caused by deconditioning after PE or ventilatory or circulatory impairment as a result of unresolved pulmonary artery thrombi. Because the post-PE syndrome may occur in up to 50% of PE survivors, and CTEPH tends to have an insidious and non-specific clinical presentation, CTEPH is often not diagnosed or diagnosed after a very long delay. Once the diagnosis is confirmed, the treatment of choice is pulmonary endarterectomy which effectively lowers the pulmonary vascular resistance and normalizes resting pulmonary artery pressures, leading to recovery of the right ventricle. When pulmonary endarterectomy is not technically feasible, balloon pulmonary angioplasty may be a potential acceptable alternative. Also, medical treatment may help to improve patient's symptoms and hemodynamics. Current studies are focusing on strategies for earlier CTEPH diagnosis after acute PE, as well as the most optimal treatment of inoperable patients. This review will focus on the epidemiology, risk factors, diagnosis and treatment of CTEPH from the perspective of the PE patient.

Pulmonary embolism

Pulmonary embolism (PE) is caused by emboli, which have originated from venous thrombi, travelling to and occluding the arteries of the lung. PE is the most dangerous form of venous thromboembolism, and undiagnosed or untreated PE can be fatal. Acute PE is associated with right ventricular dysfunction, which can lead to arrhythmia, haemodynamic collapse and shock. Furthermore, individuals who survive PE can develop post-PE syndrome, which is characterized by chronic thrombotic remains in the pulmonary arteries, persistent right ventricular dysfunction, decreased quality of life and/or chronic functional limitations. Several important improvements have been made in the diagnostic and therapeutic management of acute PE in recent years, such as the introduction of a simplified diagnostic algorithm for suspected PE as well as phase III trials demonstrating the value of direct oral anticoagulants in acute and extended treatment of venous thromboembolism. Future research should aim to address novel treatment options (for example, fibrinolysis enhancers) and improved methods for predicting long-term complications and defining optimal anticoagulant therapy parameters in individual patients, and to gain a greater understanding of post-PE syndrome.

Sensitivity of a Simple Noninvasive Screening Algorithm for Chronic Thromboembolic Pulmonary Hypertension after Acute Pulmonary Embolism

Background  Recently, we constructed a noninvasive screening algorithm aiming at earlier chronic thromboembolic pulmonary hypertension (CTEPH) detection after acute pulmonary embolism (PE), consisting of a prediction score and combined electrocardiography (ECG)/N-terminal pro-brain natriuretic peptide (NT-proBNP) assessment. The aim of this study was to confirm the algorithm's sensitivity for CTEPH detection and to evaluate the reproducibility of its individual items. Methods  Two independent researchers calculated the prediction score in 54 consecutive patients with a history of acute PE and proven CTEPH based on clinical characteristics at PE diagnosis, and evaluated the ECG and NT-proBNP level assessed at the moment of CTEPH diagnosis. Interobserver agreement for the assessment of the prediction score, right-to-left ventricle (RV/LV) ratio measurement on computed tomography pulmonary angiography, as well as ECG reading was evaluated by calculating Cohen's kappa statistics. Results  Median time between PE diagnosis and presentation with CTEPH was 9 months (interquartile range: 5-15). The sensitivity of the algorithm was found to be 91% (95% confidence interval [CI]: 79-97%), indicating that 27 of 30 cases of CTEPH would have been detected when applying the screening algorithm to 1,000 random PE survivors with a 3% CTEPH incidence (projected negative predictive value: 99.7%; 95% CI: 99.1-99.9%). The interobserver agreement for calculating the prediction score, RV/LV ratio measurement, and ECG reading was excellent with a kappa of 0.96, 0.95, and 0.89, respectively. Conclusion  The algorithm had a high sensitivity of 91% and was highly reproducible. Prospective validation of the algorithm in consecutive PE patients is required before it can be used in clinical practice.

Diagnostic Evaluation of Chronic Thromboembolic Pulmonary Hypertension

Pulmonary hypertension is defined by a mean pulmonary artery pressure greater than 25 mm Hg. Chronic thromboembolic pulmonary hypertension (CTEPH) is defined as pulmonary hypertension in the presence of an organized thrombus within the pulmonary vascular bed that persists at least 3 months after the onset of anticoagulant therapy. Because CTEPH is potentially curable by surgical endarterectomy, correct identification of patients with this form of pulmonary hypertension and an accurate assessment of surgical candidacy are essential to provide optimal care. Patients most commonly present with symptoms of exertional dyspnea and otherwise unexplained decline in exercise capacity. Atypical chest pain, a nonproductive cough, and episodic hemoptysis are observed less frequently. With more advanced disease, patients often develop symptoms suggestive of right ventricular compromise. Physical examination findings are minimal early in the course of this disease, but as pulmonary hypertension progresses, may include nonspecific finding of right ventricular failure, such as a tricuspid regurgitation murmur, pedal edema, and jugular venous distention. Chest radiographs may suggest pulmonary hypertension, but are neither sensitive nor specific for the diagnosis. Radioisotopic ventilation-perfusion scanning is sensitive for detecting CTEPH, making it a valuable screening study. Conventional catheter-based pulmonary angiography retains an important role in establishing the presence and extent of chronic thromboembolic disease. However, computed tomographic and magnetic resonance imaging are playing a growing diagnostic role. Innovative technologies such as dual-energy computed tomography, dynamic contrast-enhanced magnetic resonance imaging, and optical coherence tomography show promise for contributing diagnostic information and assisting in the preoperative characterization of patients with CTEPH.

Non-invasive algorithms for the diagnosis of pulmonary hypertension

Precapillary pulmonary hypertension (PH) is diagnosed when mean pulmonary arterial pressure (mPAP) equals or exceeds 25 mmHg and the pulmonary capillary wedge pressure (PCWP) is equal or lower than 15 mmHg. Because both parameters can only be derived from invasive hemodynamic assessment, right heart catheter (RHC) is still a gold standard for the diagnosis of PH. Severe precapillary PH corresponds to pulmonary vascular disease and carries a poor prognosis. Unfortunately, due to a generally low specificity of non-invasive estimates of systolic pulmonary pressure, at least 50% of patients with suspicion of PH need to undergo invasive RHC for exclusion of precapillary PH. Therefore, and also in order to manage the growing number of postcapillary PH due to heart and lung disease in the general population, pulmonary and cardiologic diagnostic algorithms combining multiple parameters have been developed. Recent disease scores are reviewed, and an outlook is given on emerging evidence from the DETECT clinical study holding the promise to non-invasively predict precapillary PH in vulnerable patients. These diagnostic trees help limit unnecessary procedures and help differentiate the current categories of PH. However, one has to keep in mind that the diagnosis of PH is still made by hemodynamic assessment.

Incidence of chronic thromboembolic pulmonary hypertension after acute pulmonary embolism: a contemporary view of the published literature

The incidence of chronic thromboembolic pulmonary hypertension (CTEPH) after pulmonary embolism (PE) is relevant for management decisions but is currently unknown.We performed a meta-analysis of studies including consecutive PE patients followed for CTEPH. Study cohorts were predefined as "all comers", "survivors" or "survivors without major comorbidities". CTEPH incidences were calculated using random effects models.We selected 16 studies totalling 4047 PE patients who were mostly followed up for >2-years. In 1186 all comers (two studies), the pooled CTEPH incidence was 0.56% (95% CI 0.1-1.0). In 999 survivors (four studies) CTEPH incidence was 3.2% (95% CI 2.0-4.4). In 1775 survivors without major comorbidities (nine studies), CTEPH incidence was 2.8% (95% CI 1.5-4.1). Both recurrent venous thromboembolism and unprovoked PE were significantly associated with a higher risk of CTEPH, with odds ratios of 3.2 (95% CI 1.7-5.9) and 4.1 (95% CI 2.1-8.2) respectively. The pooled CTEPH incidence in 12 studies that did not use right heart catheterisation as the diagnostic standard was 6.3% (95% CI 4.1-8.4).The 0.56% incidence in the all-comer group probably provides the best reflection of the incidence of CTEPH after PE on the population level. The ∼3% incidences in the survivor categories may be more relevant for daily clinical practice. Studies that assessed CTEPH diagnosis by tests other than right heart catheterisation provide overestimated CTEPH incidences.