Long-term outcome of patients with persistent vascular obstruction on computed tomography pulmonary angiography 6 months after acute pulmonary embolism

Pulmonary perfusion defects or residual vascular obstruction and persistent symptoms after pulmonary embolism: a systematic review and meta-analysis

Introduction

Up to 50% of pulmonary embolism (PE) patients have perfusion defects or residual vascular obstruction during follow-up despite adequate anticoagulant treatment, and a similar percentage experience chronic functional limitations and/or dyspnoea post-PE. We aimed to evaluate the association between pulmonary perfusion defects or residual vascular obstruction and functional recovery after PE.

Methods

We performed a systematic review and meta-analysis including studies assessing both the presence of perfusion defects or residual vascular obstruction and functional recovery (i.e. persistent symptoms, quality of life, exercise endurance). An odds ratio was pooled for perfusion defects or residual vascular obstruction and persistent symptoms using a random-effect model.

Results

12 studies were included totalling 1888 PE patients; at a median of 6 months after PE (range 2-72 months), 34% had perfusion defects or residual vascular obstruction and 37% reported persistent symptoms. Among patients with perfusion defects or residual vascular obstruction, 48% (95% CI 37-60%, I2=82%) remained symptomatic during follow-up, compared to 34% (95% CI 20-51%, I2=96%) of patients without such defects. Presence of perfusion defects or residual vascular obstruction was associated with persistent symptoms (OR 2.15, 95% CI 1.66-2.78; I2=0%, τ=0). Notably, there was no association between these defects and quality of life or cardiopulmonary exercise test parameters.

Conclusion

While the odds of having persistent symptoms was higher in patients with perfusion defects or residual vascular obstruction after acute PE, a significant proportion of these patients reported no limitations. A possible causality between perfusion defects or residual vascular obstruction and residual functional limitation therefore remains to be proven.

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.

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.

Clinical and imaging risk factors for the persistence of thromboembolism following acute pulmonary embolism

Background

Predicting the progression of acute pulmonary embolism to chronic pulmonary thromboembolism (CPTE) disease is essential to monitoring and improving the long-term prognosis of pulmonary embolism. We explored the risk factors for chronic persistence of thromboembolism after acute pulmonary embolism.

Methods

Cases with newly onset acute pulmonary embolism in the China-Japan Friendship Hospital from November 2016 to November 2019 were retrospectively analyzed. The clinical characteristics, serological examination results, and treatment strategies of acute pulmonary embolism patients were obtained through the electronic medical record system (Goodwill E-Health Info Co., Ltd.). Imaging parameters on computed tomography pulmonary angiography (CTPA) images at the onset of the acute pulmonary embolism were measured and counted. Notably, we propose a new parameter based on CTPA images: the ratio of S_d (sum of residual segmental pulmonary artery diameter) to MPA_d (the main pulmonary artery diameter) (S_d/MPA_d). After 3 months of regular treatment for acute pulmonary embolism, patients were classified into a CPTE group or a non-CPTE group based on the presence of residual embolus. All data were compared between the CPTE group and non-CPTE group. Furthermore, logistic regression analysis was used to investigate risk factors for the progression of acute pulmonary embolism to CPTE.

Results

A total of 77 cases (male:female = 1:1.26) were included in the study. There were 43 cases (55.84%) in the CPTE group and 34 cases in the non-CPTE group (44.16%). The results of univariate analysis showed that there were statistically significant differences between the 2 groups in risk stratification (χ²=8.043; P=0.005), protein S activity (χ²=5.551; P=0.018), the ratio of sum of residual segmental pulmonary artery diameter to the main pulmonary artery diameter (S_d/MPA_d; t=–2.103; P=0.039), Mastora score (U=362.500; P<0.001), and embolus location (χ²=16.969; P<0.001). However, there were no statistically significant differences between the 2 groups in treatment options (P=0.381). According to multivariate logistic-regression analysis, protein S activity <55% (P=0.025), S_d/MPA_d ≥1.97 (P=0.011), and an embolus being located in the central pulmonary artery (P<0.001) were independent risk factors for chronic persistence of thromboembolism following acute pulmonary embolism.

Conclusions

The protein S activity, location of the embolus, and S_d/MPA_d on CTPA at the onset of acute pulmonary embolism may suggest the progression of acute pulmonary embolism to CPTE.

Dyspnea after pulmonary embolism: a nation-wide population-based case-control study

Dyspnea is common after a pulmonary embolism. Often, but not always, the dyspnea can be explained by pre-existing comorbidities, and only rarely by chronic thromboembolic pulmonary hypertension (CTEPH). CTEPH is probably the extreme manifestation of a far more common condition, called the post-pulmonary embolism syndrome. The purpose of this retrospective study was to investigate the prevalence and predictors of dyspnea among Swedish patients that survived a pulmonary embolism, compared to the general population. All Swedish patients diagnosed with an acute pulmonary embolism in 2005 (n = 5793) were identified via the Swedish National Patient Registry. Patients that lived until 2007 (n = 3510) were invited to participate. Of these, 2105 patients responded to a questionnaire about dyspnea and comorbidities. Data from the general population (n = 1905) were acquired from the multinational MONItoring of trends and determinants in CArdiovascular disease health survey, conducted in 2004. Patients with pulmonary embolism had substantially higher prevalences of both exertional dyspnea (53.0% vs. 17.3%, odds ratio (OR): 5.40, 95% confidence intervals (CI): 4.61-6.32) and wake-up dyspnea (12.0% vs. 1.7%, OR: 7.7, 95% CI: 5.28-11.23) compared to control subjects. These differences remained after adjustments and were most pronounced among younger patients. The increased risk for exertional dyspnea and wake-up dyspnea remained after propensity score matching (OR (95% CI): 4.11 (3.14-5.38) and 3.44 (1.95-6.06), respectively). This population-based, nation-wide study demonstrated that self-reported dyspnea was common among patients with previous pulmonary embolism. This finding suggested that a post-pulmonary embolism syndrome might be present, which merits further investigation.

Prognostic factors of clot resolution on follow-up computed tomography angiography and recurrence after a first acute pulmonary embolism

BACKGROUND

Recent studies seem to confirm the relationship between residual pulmonary obstruction (RPO) in pulmonary embolism (PE) and risk of recurrent thrombosis and chronic thromboembolic pulmonary hypertension (CTEPH). However, the prognostic factors associated with PE resolution on follow-up computed tomography angiography (CTA) are not clear.

OBJECTIVES

To determine the prognostic factors of resolution of PE diagnosed and monitored by CTA and the impact of RPO on late complications.

METHODS

We retrospectively analyzed 241 patients with PE who had undergone a 12-month follow-up and CT scan evaluation at 6 months. Factors related to resolution and the impact of RPO on the outcome were analyzed.

RESULTS

Resolution was achieved in 74.3% of all cases after 6 months of treatment. Absence of chronic obstructive pulmonary disease (COPD) (OR, 3.22 [1.35-7.71]; p = 0.009), provoked PE (OR, 2.02 [1.08-3.79]; p = 0.028), early initiation of treatment (<7 days) (OR, 2.42 [1.22-4.78]; p = 0.011), and degree of obstruction caused by the initial PE as indicated by a Qanadli score lower than 16 (OR, 2.12 [1.03-4.37]; p = 0.043) were associated with complete resolution. RPO was associated with recurrent PE as well as the combined endpoint consisting of recurrent VTE and/or CTEPH (4.67 [95% CI, 1.26-17.26]; p = 0.02) and (OR 6.4 [95% CI, 1.9-21.2]; p < 0.005), respectively.

CONCLUSIONS

Resolution of PE is associated with a lower risk of recurrent thrombosis. Earlier initiation of treatment improves prognosis as measured by resolution on follow-up CTA.

Predicting the Risk of Recurrent Venous Thromboembolism: Current Challenges and Future Opportunities

Acute venous thromboembolism (VTE) is a commonly diagnosed condition and requires treatment with anticoagulation to reduce the risk of embolisation as well as recurrent venous thrombotic events. In many cases, cessation of anticoagulation is associated with an unacceptably high risk of recurrent VTE, precipitating the use of indefinite anticoagulation. In contrast, however, continuing anticoagulation is associated with increased major bleeding events. As a consequence, it is essential to accurately predict the subgroup of patients who have the highest probability of experiencing recurrent VTE, so that treatment can be appropriately tailored to each individual. To this end, the development of clinical prediction models has aided in calculating the risk of recurrent thrombotic events; however, there are several limitations with regards to routine use for all patients with acute VTE. More recently, focus has shifted towards the utility of novel biomarkers in the understanding of disease pathogenesis as well as their application in predicting recurrent VTE. Below, we review the current strategies used to predict the development of recurrent VTE, with emphasis on the application of several promising novel biomarkers in this field.

Risk of recurrent venous thromboembolism after acute pulmonary embolism: Role of residual pulmonary obstruction and persistent right ventricular dysfunction. A meta-analysis

Essentials Debated is the role of residual pulmonary obstruction (RPO) in predicting venous thromboembolism. Whether right ventricular dysfunction (RVD) predicts recurrent venous thromboembolism is unknown. 15 studies on RPO and 4 on RVD and venous thromboembolism were included in this meta-analysis. RPO is a predictor of recurrent venous thromboembolism when assessed by perfusion lung scan. RVD after acute pulmonary embolism is not associated with recurrent venous thromboembolism.

BACKGROUND

There is conflicting evidence regarding the role of residual pulmonary obstruction (RPO) or persistent right ventricular dysfunction (RVD) after pulmonary embolism (PE) as a predictor of recurrent venous thromboembolism (VTE). The aim of this study was to assess whether RPO or persistent RVD after PE is associated with recurrent VTE.

METHODS

MEDLINE and EMBASE were searched through December 2018. Studies reporting on (a) RPO either on computed tomography (CT) angiography or perfusion lung scan, or RVD on echocardiography or CT angiography, after therapeutic anticoagulation for the acute PE, and (b) recurrent VTE, were included in this meta-analysis.

RESULTS

RPO was associated with an increased risk of recurrent VTE (16 studies; 3472 patients; odds ratio [OR] 2.22; 95% confidence interval [CI] 1.61-3.05; I2  = 26%); the association was statistically significant for lung scan-detected RPO (11 studies; 2916 patients; OR 2.21; 95% CI 1.63-3.01) but not for CT angiography-detected RPO (five studies; 556 patients; OR 2.56; 95% CI 0.82-7.94). No significant association was found between persistent RVD and recurrent VTE (four studies; 852 patients; OR 1.62; 95% CI 0.63-4.17).

CONCLUSIONS

RPO is a predictor of recurrent VTE after a first acute PE, mainly when assessed by perfusion lung scan.

Efficacy evaluation of reteplase in a novel canine acute pulmonary thromboembolism model developed by minimally invasive surgery and digital subtraction angiography

Purpose

In order to evaluate the thrombolytic effects of reteplase in pulmonary thromboembolism (PTE), we developed a novel canine PTE model. The efficacy of reteplase against PTE in comparison to alteplase was clarified for the first time, and this PTE model could be further applied to studies of novel thrombolytic therapies.

Patients and methods

Twenty-four dogs were divided into four groups: sham operation, vehicle, alteplase, and reteplase. Autologous thrombi/saline were injected into the pulmonary artery, and thrombolytic agents were administrated. Thrombus formation and dissolution were monitored by real-time digital subtraction angiography (DSA), and pulmonary pressures were measured simultaneously. Blood coagulation, blood gas, hematology, and histopathologic examinations were used as subsidiary methods.

Results

The canine PTE model was established with a significant decrease of blood flow and ~75% blocking area. Administration of reteplase (0.6 mg/kg) resulted in effective thrombus dissolution with a recovery of over 80% blood flow, as effective as alteplase (1.6 mg/kg). Correspondingly, the elevated pulmonary systolic, diastolic, and mean arterial pressures declined to the normal level. Blood coagulation was changed by reteplase, with a dramatic elongation of prothrombin time, activated partial thromboplastin time, and thrombin time, even longer than alteplase. In contrast to the vehicle group, no obvious pathological changes were found in the two thrombolytic groups. Hematological, blood biochemical, and blood gas results also indicated that reteplase had no adverse reactions in this PTE model.

Conclusion

Reteplase proved to be an effective and safe therapy for PTE for the first time, and a small dosage of reteplase exerted an efficacy comparable to the routine dosage of alteplase. Our findings indicated the potential of reteplase as clinical treatment against PTE. This technically innovative, stability- and validity-proved canine PTE model developed by minimally invasive surgery and DSA resembled major clinical features. This may further facilitate our understanding of thrombotic disorders and development of prophylactic and therapeutic approaches.

The secondary prevention of venous thromboembolism: Towards an individual therapeutic strategy

After the anticoagulant withdrawal, a substantial proportion of patients with venous thromboembolism will develop recurrent events. Whether to consider an extended treatment depends on the risk of recurrence and bleeding risk. The assessment of the individual risk profile remains a difficult task. Several basal and post-basal factors modulate the risk of recurrence and may help clinicians to select patients who can benefit from the extended therapy. During the year 2017, new evidence regarding the post-basal factors was provided by the Morgagni and Scope studies. Another interesting novelty was the VTE-BLEED score, the first bleeding risk score that obtained the external validation in venous thromboembolism setting. In secondary prevention, the use of direct oral anticoagulants is growing instead of vitamin K antagonist. Even at lower doses, direct oral anticoagulants showed to be effective and safe, to reduce all-cause mortality and seemed to be superior to placebo for the composite outcome of fatal bleeding and fatal recurrence. After the recently published Einstein-Choice trial, the role of aspirin has become truly marginal as rivaroxaban 10 mg showed a bleeding risk similar to aspirin 100 mg but a greater effectiveness reducing the relative risk of recurrence by about 70%. Another option for secondary prevention could be sulodexide, with a lower protective effect than direct oral anticoagulants but an interesting safety profile. In conclusion, in our opinion, an individual strategy taking into account the risk of recurrence, bleeding risk, therapeutic options and patient preferences is the most appropriate approach to secondary prevention of venous thromboembolism.

Optimal duration of anticoagulation

Once anticoagulation is stopped, the risk of recurrent venous thromboembolism (VTE) over years after a first episode is consistently around 30%. This risk is higher in patients with unprovoked than in those with (transient) provoked VTE, and among the latter in patients with medical than in those with surgical risk factors. Baseline parameters that have been found to be related to the risk of recurrent VTE are the proximal location of deep-vein thrombosis, obesity, old age, male sex and non-0 blood group, whereas the role of inherited thrombophilia is controversial. The persistence of residual vein thrombosis at ultrasound assessment has consistently been shown to increase the risk, as do persistently high values of D-dimer and the early development of the post-thrombotic syndrome. Although the latest international guidelines suggest indefinite anticoagulation for most patients with the first episode of unprovoked VTE, strategies that incorporate the assessment of residual vein thrombosis and D-dimer have the potential to identify subjects in whom anticoagulation can be safely discontinued. Moreover, new opportunities are offered by a few emerging anti-Xa and anti-IIa oral compounds, which are likely to induce fewer haemorrhagic complications than vitamin K antagonists while preserving the same effectiveness; and by low-dose aspirin, which has the potential to prevent the occurrence of both venous and arterial thrombotic events.

Impact of residual pulmonary obstruction on the long-term outcome of patients with pulmonary embolism

The impact of residual pulmonary obstruction on the outcome of patients with pulmonary embolism is uncertain.We recruited 647 consecutive symptomatic patients with a first episode of pulmonary embolism, with or without concomitant deep venous thrombosis. They received conventional anticoagulation, were assessed for residual pulmonary obstruction through perfusion lung scanning after 6 months and then were followed up for up to 3 years. Recurrent venous thromboembolism and chronic thromboembolic pulmonary hypertension were assessed according to widely accepted criteria.Residual pulmonary obstruction was detected in 324 patients (50.1%, 95% CI 46.2-54.0%). Patients with residual pulmonary obstruction were more likely to be older and to have an unprovoked episode. After a 3-year follow-up, recurrent venous thromboembolism and/or chronic thromboembolic pulmonary hypertension developed in 34 out of the 324 patients (10.5%) with residual pulmonary obstruction and in 15 out of the 323 patients (4.6%) without residual pulmonary obstruction, leading to an adjusted hazard ratio of 2.26 (95% CI 1.23-4.16).Residual pulmonary obstruction, as detected with perfusion lung scanning at 6 months after a first episode of pulmonary embolism, is an independent predictor of recurrent venous thromboembolism and/or chronic thromboembolic pulmonary hypertension.

The risk of recurrent thromboembolic disorders in patients with unprovoked venous thromboembolism: new scenarios and opportunities

The risk of recurrent thromboembolic disorders in the 10-year period following an episode of unprovoked venous thromboembolism (VTE) ranges between 30 and 50%, the rate being higher in patients with primary deep venous thrombosis (DVT) than in those with primary pulmonary embolism (PE). The clinical presentation with primary PE increases by more than three times the risk of a new PE episode over that with isolated DVT. Baseline parameters that increase this risk are the proximal location of DVT, obesity, old age and male sex, whereas the role of thrombophilia is controversial. An increasing role is played by post-baseline parameters such as the ultrasound assessment of residual vein thrombosis and the determination of D-dimer. While the latest international guidelines suggest indefinite anticoagulation for most patients with the first episode of unprovoked VTE, new scenarios are being offered by the identification of risk stratification models and by strategies that have the potential to help identify patients in whom anticoagulation can be safely discontinued, such as those that incorporate the assessment of D-dimer and residual vein thrombosis. New opportunities are being offered by low-dose aspirin, which has recently been reported to decrease by more than 30% the risk of recurrent events without increasing the bleeding risk; and especially by a few emerging anti-Xa and anti-IIa oral compounds, which are likely to induce fewer haemorrhagic complications than vitamin K antagonists while preserving at least the same effectiveness, do not require laboratory monitoring, and can be used immediately after the thrombotic episode.