Overdiagnosis of pulmonary embolism: definition, causes and implications

Epidemiology, Etiology, and Pathophysiology of Pulmonary Embolism

Over the last 20 years, there has been a progressive increase in the incidence of pulmonary embolism (PE) diagnosis in the United States, Europe, and Australia. Increased use of computed tomography pulmonary angiography has likely contributed in part to this rising incidence. However, it is pertinent to note that the burden of comorbidities associated with PE, such as malignancy, obesity, and advanced age, has also increased over the past 20 years. Time-trend analysis in North American, European, and Asian populations suggests that mortality rates associated with PE have been declining. The reported improved survival rates in PE over the past 20 years are likely, at least in part, to be the result of better adherence to guidelines, improved risk stratification, and enhanced treatment. Factors contributing to the development of venous thromboembolism (VTE) include stasis of blood, hypercoagulability, endothelial injury, and inflammation. In 70 to 80% of cases of PE, the thrombi embolizes from the proximal deep veins of the lower extremities and pelvis. Strong risk factors for VTE include lower extremity fractures and surgeries, major trauma, and hospitalization within the previous 3 months for acute myocardial infarction or heart failure with atrial fibrillation. Acute PE causes several pathophysiological responses including hypoxemia and right ventricle (RV) failure. The latter is a result of pulmonary artery occlusion and associated vasoconstriction. Hemodynamic compromise from RV failure is the principal cause of poor outcome in patients with acute PE.

Computed tomography pulmonary angiogram ordering, adherence to decision rules and yield in the emergency department: An observational study

OBJECTIVE

Pulmonary embolism (PE) frequently requires diagnosis through CT pulmonary angiogram (CTPA). Appropriate application of evidence-based clinical decision tools can reduce unnecessary CTPAs. This study assessed adherence to and the efficacy of various aspects of the Queensland Health suspected PE diagnostic pathway, including Wells score, PE rule out criteria (PERC) and age-adjusted D-dimer interpretation.

METHODS

Retrospective study of CTPAs ordered from 1 January to 30 April 2023 in a tertiary and urban ED in Southeast Queensland. Data on clinical variables, D-dimer and CTPA results were collected through medical record and radiology database review. Descriptive analyses were used to determine adherence to Queensland guidelines and performance of D-dimer interpretation tools (including comparison of age-adjusted PE with a new pre-test probability [PTP]-based model using D-dimer cut-off <1000 ng/mL for Wells score ≤4 and 500 ng/mL for Wells score 4.5-6).

RESULTS

A total of 573 CTPAs were available for analysis with a 12.4% (95% confidence interval 10.0-15.4) diagnostic yield. Stratification by Wells score showed yields of 4.0%, 18.5% and 41% for low-, moderate- and high-risk patients, respectively. Twenty-five patients with low-PTP who received CTPA could have been excluded with the PERC rule. Age-adjusted D-dimer interpretation may have prevented 26 CTPAs with no false negatives, whereas PTP approach may have prevented 128 CTPAs with four false negatives.

CONCLUSION

Guideline adherence can be improved, and adherence to existing clinical decision tools may reduce unnecessary CTPA ordering and increase diagnostic yield. The use of the age-adjusted D-dimer had good sensitivity, whereas the new PTP approach will require further prospective research.

POCUS for Thrombus: Emphasizing the Importance of Initial Point-of-Care Ultrasound in the Management of Pulmonary Thromboembolism

Pulmonary embolism (PE) constitutes a substantial health burden among individuals in the United States. It ranks as the third most common cause of cardiovascular death aside from stroke and myocardial infarction. Diagnostic errors are common with PE as patients can present with non-specific symptoms or could be completely asymptomatic with PE being an incidental finding. Diagnostic errors can result in missed or late diagnosis of PE, which, in turn, increases health care costs, morbidity, and mortality rates. Hence, early diagnosis is crucial. Computed tomography pulmonary angiography (CTPA) remains the gold standard in PE diagnosis, despite exposure to high doses of radiation. Point-of-care ultrasound (POCUS) is an underutilized, non-invasive technique that aids in the early diagnosis of PE and can safely reduce the radiation from CTPA in cases where contraindication exists. POCUS has been shown to have a high sensitivity and specificity for early diagnosis of PE.

How to recognize pulmonary embolism in syncope patients: A simple rule

BACKGROUND

Syncope can be the presenting symptom of Pulmonary Embolism (PE). It is not known wether using a standardized algorithm to rule-out PE in all patients with syncope admitted to the Emergency Departments (ED) is of value or can lead to overdiagnosis and overtreatment.

METHODS

We tested if simple anamnestic and clinical parameters could be used as a rule to identify patients with syncope and PE in a multicenter observational study. The rule's sensitivity was tested on a cohort of patients that presented to the ED for syncopal episodes caused by PE. The clinical impact of the rule was assessed on a population of consecutive patients admitted for syncope in the ED.

RESULTS

Patients were considered rule-positive in the presence of any of the following: hypotension, tachycardia, peripheral oxygen saturation ≤ 93 % (SpO2), chest pain, dyspnea, recent history of prolonged bed rest, clinical signs of deep vein thrombosis, history of previous venous thrombo-embolism and active neoplastic disease. The sensitivity of the rule was 90.3 % (95 % CI: 74.3 % to 98.0 %). The application of the rule to a population of 217 patients with syncope would have led to a 70 % reduction in the number of subjects needing additional diagnostic tests to exclude PE.

CONCLUSIONS

Most patients with syncope due to PE present with anamnestic and clinical features indicative of PE diagnosis. A clinical decision rule can be used to identify patients who would benefit from further diagnostic tests to exclude PE, while reducing unnecessary exams that could lead to over-testing and over-diagnosis.

Short- and Long-Term Mortality for Patients With and Without a Cancer Diagnosis Following Pulmonary Embolism in Denmark, 2000 to 2020: A Nationwide Study

BACKGROUND

New treatment regimens have been introduced in the past 20 years, which may influence the short- and long-term prognosis for patients with and without a cancer diagnosis following pulmonary embolism. However, newer studies investigating these trends are lacking. Therefore, we aimed to investigate the 30- and 31- to 365-day mortality following pulmonary embolism.

METHODS AND RESULTS

Using the Danish nationwide registries, patients with a diagnosis of pulmonary embolism between 2000 and 2020 were included. Age- and sex-standardized 30- and 31- to 365-day mortality was calculated and stratified by cancer status. In total, 60 614 patients (29.6% with recent cancer; mean age, 68.2 years) were included. The 30-day mortality for patients with no recent cancer decreased from 19.1% (95% CI, 17.9%-20.4%) in 2000 to 7.3% (95% CI, 6.7%-8.0%) in 2018 to 2020 (hazard ratio [HR], 0.36 [95% CI, 0.32-0.40]; P<0.001). The 30-day mortality for patients with recent cancer decreased from 32.2% (95% CI, 28.8%-36.6%) to 14.1% (95% CI, 12.7%-15.5%) (HR, 0.38 [95% CI, 0.33-0.44]; P<0.001). The 31- to 365-day mortality for patients with no recent cancer decreased from 12.5% (95% CI, 11.4%-13.6%) to 9.4% (95% CI, 8.6%-10.2%) (HR, 0.73 [95% CI, 0.64-0.83]; P<0.001).The 31- to 365-day mortality for patients with recent cancer remained stable: 39.4% (95% CI, 35.1%-43.7%) to 38.3% (95% CI, 35.9%-40.6%) (HR, 0.97 [95% CI, 0.84-1.12]; P=0.69).

CONCLUSIONS

From 2000 to 2020, improvements were observed in 30-day mortality following pulmonary embolism regardless of cancer status. For patients with recent cancer, 31- to 365-day mortality did not improve, whereas a minor improvement was observed for patients without recent cancer.

How to Combat Over-Testing for Patients Suspected of Pulmonary Embolism: A Narrative Review

The diagnosis of PE remains difficult in 2023 because the signs and symptoms are not sensible nor specific. The consequences of potential diagnostic errors can be dramatic, whether by default or by excess. Furthermore, the achievement of a simple diagnostic strategy, based on clinical probability assessment, D-dimer measurement and computed tomography pulmonary angiography (CTPA) leads to a new challenge for PE diagnosis: over-testing. Indeed, since the 2000s, the wide availability of CTPA resulted in a major increase in investigations with a mod I confirm erate increase in PE diagnosis, without any notable improvement in patient outcomes. Quite the contrary, the complications of anticoagulation for PE increased significantly, and the long-term consequences of imaging diagnostic radiation is an important concern, especially the risk of breast cancer for young women. As a result, several strategies have been proposed to fight over-testing. They are mostly based on defining a subgroup of patients for whom no specific exam should be required to rule-out PE and adjusting the D-dimer cutoff to allow the exclusion of PE without performing CTPA. This narrative review presents the advantages and limitations of these different strategies as well as the perspective in PE diagnosis.

Artificial Intelligence Tool for Detection and Worklist Prioritization Reduces Time to Diagnosis of Incidental Pulmonary Embolism at CT

Purpose

To evaluate the diagnostic efficacy of artificial intelligence (AI) software in detecting incidental pulmonary embolism (IPE) at CT and shorten the time to diagnosis with use of radiologist reading worklist prioritization.

Materials and Methods

In this study with historical controls and prospective evaluation, regulatory-cleared AI software was evaluated to prioritize IPE on routine chest CT scans with intravenous contrast agent in adult oncology patients. Diagnostic accuracy metrics were calculated, and temporal end points, including detection and notification times (DNTs), were assessed during three time periods (April 2019 to September 2020): routine workflow without AI, human triage without AI, and worklist prioritization with AI.

Results

In total, 11 736 CT scans in 6447 oncology patients (mean age, 63 years ± 12 [SD]; 3367 men) were included. Prevalence of IPE was 1.3% (51 of 3837 scans), 1.4% (54 of 3920 scans), and 1.0% (38 of 3979 scans) for the respective time periods. The AI software detected 131 true-positive, 12 false-negative, 31 false-positive, and 11 559 true-negative results, achieving 91.6% sensitivity, 99.7% specificity, 99.9% negative predictive value, and 80.9% positive predictive value. During prospective evaluation, AI-based worklist prioritization reduced the median DNT for IPE-positive examinations to 87 minutes (vs routine workflow of 7714 minutes and human triage of 4973 minutes). Radiologists' missed rate of IPE was significantly reduced from 44.8% (47 of 105 scans) without AI to 2.6% (one of 38 scans) when assisted by the AI tool (P < .001).

Conclusion

AI-assisted workflow prioritization of IPE on routine CT scans in oncology patients showed high diagnostic accuracy and significantly shortened the time to diagnosis in a setting with a backlog of examinations.Keywords: CT, Computer Applications, Detection, Diagnosis, Embolism, Thorax, ThrombosisSupplemental material is available for this article.© RSNA, 2023See also the commentary by Elicker in this issue.

Raising the D-dimer threshold for ruling out pulmonary embolism: A single-site, observational study with a historical comparison

OBJECTIVE

The objective of this study was to assess the impact of introduction of a new pulmonary embolism (PE) diagnostic guideline with a raised D-dimer threshold.

METHODS

This is a single-site, observational, cohort study with a historical comparison. The new guideline raised the D-dimer threshold to 1000 ng/mL for most patients with a Wells' score of 4 or less. Patients investigated for PE with a D-dimer level and/or definitive imaging in 6-month periods before and after the introduction of the guideline were eligible. Patients with D-dimers of 500-1000 ng/mL were prospectively followed up at 3 months for missed PE.

RESULTS

During the pre-intervention period, 688 patients were investigated for PE, 366 (53.2%) received definitive imaging and 39 PE were diagnosed (5.7% overall, 10.7% of those imaged). For the 121 patients with D-dimers ≥500 and <1000 ng/mL, 87 (71.9%) were imaged with 7 (5.8%) having a PE diagnosed. Post intervention there were 930 patients, of which 426 (45.8%) received definitive chest imaging and there were 50 patients with PE diagnosed (5.4% overall, 11.7% of those imaged). For the 185 patients with D-dimers ≥500 and <1000 ng/mL, 60 (32.4%) were imaged with 5 (2.7%) having PE diagnosed. No cases of missed PE were identified at 3 months.

CONCLUSION

The introduction of the new guideline was associated with a reduction in overall imaging rates without evidence of missed PE. Further evaluation in other settings is recommended.

Diagnostic test accuracy of imaging modalities for adults with acute pulmonary embolism: A systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis aimed to evaluate the current literature on diagnostic test accuracy (DTA) of imaging modalities for adults with acute pulmonary embolism (APE).

BACKGROUND

Medical imaging plays an integral role in evaluating and managing those with APE. Guidance for imaging modality use for APE diagnosis varies due to a lack of clinical standardisation. Despite this, CTPA remains the first-line imaging modality used by clinicians.

METHODS

A literature search of PubMed, EMBASE, Trove and Mednar databases (2012-2020; English language) was performed. Studies assessing the DTA of imaging modalities for APE diagnosis were included. DTA studies methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2 tool). Results of eligible studies were pooled using random or fixed effects modelling the calculate the pooled DTA of explored imaging modalities for APE. The Higgins I² test were performed to assess between study heterogeneity.

RESULTS

10 Studies, involving 998 participants, were enrolled and pooled using the random effects model. Of the explored modalities, magnetic resonance imaging (MRI), specifically pulmonary MRI and magnetic resonance pulmonary angiography (MRPA) exhibited the highest pooled DTA. Sensitivity, specificity, negative likelihood ratio, positive likelihood ratio and diagnostic odds ratio for MRPA were 0.952 (95% CI, 0.881 to 0.987), 0.857 (95% CI, 0.637 to 0.97), 5.631 (95% CI, 2.163 to 14.659), 0.06 (95% CI, 0.007 to 0.537) and 80.310 (95% CI, 15.607 to 413.25) respectively. Based on the QUADAS-2 criteria, most studies presented low to moderate risk of bias and concern regarding applicability.

CONCLUSION

The explored ultrasound and MRI protocols which exhibit a lower radiation burden when compared to the current gold standard computed tomography pulmonary angiography (CTPA), have acceptable diagnostic accuracy for APE and can be useful in certain situations.

Ventilation Scintigraphy With Radiolabeled Carbon Nanoparticulate Aerosol (Technegas): State-of-the-Art Review and Diagnostic Applications to Pulmonary Embolism During COVID-19 Pandemic

ABSTRACT

Invented and first approved for clinical use in Australia 36 years ago, Technegas is the technology that enabled ventilation scintigraphy with 99m Tc-labeled carbon nanoparticles ( 99m Tc-CNP). The US Food and Drug Administration (FDA) has considered this technology for more than 30 years but only now is getting close to approving it. Meanwhile, more than 4.4 million patients benefited from this technology in 64 countries worldwide. The primary application of 99m Tc-CNP ventilation imaging is the diagnostic evaluation for suspicion of pulmonary embolism using ventilation-perfusion quotient (V/Q) imaging. Because of 99m Tc-CNP's long pulmonary residence, tomographic imaging emerged as the preferred V/Q methodology. The FDA-approved ventilation imaging agents are primarily suitable for planar imaging, which is less sensitive. After the FDA approval of Technegas, the US practice will likely shift to tomographic V/Q. The 99m Tc-CNP use is of particular interest in the COVID-19 pandemic because it offers an option of a dry radioaerosol that takes approximately only 3 to 5 tidal breaths, allowing the shortest exposure to and contact with possibly infected patients. Indeed, countries where 99m Tc-CNP was approved for clinical use continued using it throughout the COVID-19 pandemic without known negative viral transmission consequences. Conversely, the ventilation imaging was halted in most US facilities from the beginning of the pandemic. This review is intended to familiarize the US clinical nuclear medicine community with the basic science of 99m Tc-CNP ventilation imaging and its clinical applications, including common artifacts and interpretation criteria for tomographic V/Q imaging for pulmonary embolism.

Pulmonary Embolism and Respiratory Deterioration in Chronic Cardiopulmonary Disease: A Narrative Review

Patients with chronic cardiopulmonary pathologies have an increased risk of developing venous thromboembolic events. The worsening of dyspnoea is a frequent occurrence and often leads patients to consult the emergency department. Pulmonary embolism can then be an exacerbation factor, a differential diagnosis or even a secondary diagnosis. The prevalence of pulmonary embolism in these patients is unknown, especially in cases of chronic heart failure. The challenge lies in needing to carry out a systematic or targeted diagnostic strategy for pulmonary embolism. The occurrence of a pulmonary embolism in patients with chronic cardiopulmonary disease clearly worsens their prognosis. In this narrative review, we study pulmonary embolism and chronic obstructive pulmonary disease, after which we turn to pulmonary embolism and chronic heart failure.

Diagnostic Strategy for Suspected Pulmonary Embolism in Emergency Departments Based on the 4-Level Pulmonary Embolism Clinical Probability Score: Study Protocol of SPEED&PEPS Trial

Introduction: Several strategies have been devised to safely limit the use of thoracic imaging in patients suspected of pulmonary embolism (PE). However, they are based on different rules for clinical probability (CP) assessment, rendering their combination difficult. The four-level pulmonary embolism probability score (4PEPS) allows the combination of all other strategies using a single CP assessment. Methods and analysis: Pragmatic cluster-randomized trial in 20 EDs. Patients with suspected PE will be included and followed for 90 days (number of patients to be included: 2560, 1280 in each arm). Ten centers will be allocated to the control group where physicians will be free to do as they see fit but they will be given the recommendation to apply a validated strategy. Ten centers will be allocated to the interventional group where the physicians will be given the recommendation to apply the 4PEPS strategy. The primary objective will be to demonstrate that the application of the 4PEPS strategy by the emergency physicians, in comparison to current practices, (i) does not increase the risk of serious events related to diagnostic strategies and (ii) significantly reduces the use of thoracic imaging. Ethics and dissemination: The study will be submitted for approval to an institutional ethics review board for all participating centers. If successful, the SPEED&PEPS trial will have an important impact for patients suspected of PE limiting their irradiation and for public health in substantial savings in terms of the direct cost of diagnostic investigations and the indirect cost of hospitalizations due to waiting times or delayed harmful effects. Funding: This work is funded by a French Public Health grant (PREPS-N 2019). The funding source plays no role in the study design, data collection, analysis, interpretation or the writing of the manuscript. Trial registration: ongoing. Trial status: not started.

A 60-Year-Old Woman with a 6-Week History of Shortness of Breath and Intermittent Chest Pain Due to Chronic Thromboembolic Pulmonary Disease Undetected by Computed Tomography Pulmonary Angiography (CTPA) and Diagnosed by Ventilation-Perfusion Imaging

BACKGROUND Chronic thromboembolic pulmonary disease (CTEPD) is the persistent occlusion of pulmonary arteries resulting from 1 or more thrombo-emboli. Its presentation is often non-specific, with exertional dyspnea and fatigue, yet if left undiagnosed risks of chronic thromboembolic pulmonary hypertension and right-sided cardiac failure can ensue. Computed tomography pulmonary angiography (CTPA) and ventilation/perfusion (V/Q) imaging are most commonly utilized for investigating CTEPD. This report is of a 60-year-old woman with a 6-week history of breathlessness and intermittent chest pain due to CTEPD, undetected by CTPA and diagnosed by V/Q imaging. CASE REPORT A 60-year-old woman presented with a 6-week history of breathlessness, intermittent chest pain, and reduced mobility. Her past medical history included chronic obstructive pulmonary disease, pulmonary sarcoidosis, and obesity. Screening tests for infective and ischemic cardiac etiologies were unremarkable. A calculated Wells score was 6, making CTEPD the main differential diagnosis, and she was commenced on therapeutic dose anticoagulation. A CTPA performed on day 2 of admission showed no evidence of acute thromboembolic pulmonary disease or CTEPD. Instead, V/Q scintigraphy on day 6 revealed a perfusion mismatch in the right lung apex, consistent with CTEPD. The patient improved clinically and was discharged on long-term apixaban. CONCLUSIONS A negative CTPA does not necessarily exclude CTEPD. The sensitivity of CTPA for CTEPD is lower than that of V/Q imaging, and can hence lead to false-negative results, as this case highlights. When there is a high clinical suspicion for CTEPD but a negative CTPA study, V/Q imaging should always be undertaken.

Acute Pulmonary Embolism: A Review

IMPORTANCE

Pulmonary embolism (PE) is characterized by occlusion of blood flow in a pulmonary artery, typically due to a thrombus that travels from a vein in a lower limb. The incidence of PE is approximately 60 to 120 per 100 000 people per year. Approximately 60 000 to 100 000 patients die from PE each year in the US.

OBSERVATIONS

PE should be considered in patients presenting with acute chest pain, shortness of breath, or syncope. The diagnosis is determined by chest imaging. In patients with a systolic blood pressure of at least 90 mm Hg, the following 3 steps can be used to evaluate a patient with possible PE: assessment of the clinical probability of PE, D-dimer testing if indicated, and chest imaging if indicated. The clinical probability of PE can be assessed using a structured score or using clinical gestalt. In patients with a probability of PE that is less than 15%, the presence of 8 clinical characteristics (age <50 years, heart rate <100/min, an oxygen saturation level of > 94%, no recent surgery or trauma, no prior venous thromboembolism event, no hemoptysis, no unilateral leg swelling, and no estrogen use) identifies patients at very low risk of PE in whom no further testing is needed. In patients with low or intermediate clinical probability, a D-dimer level of less than 500 ng/mL is associated with a posttest probability of PE less than 1.85%. In these patients, PE can be excluded without chest imaging. A further refinement of D-dimer threshold is possible in patients aged 50 years and older, and in patients with a low likelihood of PE. Patients with a high probability of PE (ie, >40% probability) should undergo chest imaging, and D-dimer testing is not necessary. In patients with PE and a systolic blood pressure of 90 mm Hg or higher, compared with heparin combined with a vitamin K antagonist such as warfarin followed by warfarin alone, direct oral anticoagulants such as apixaban, edoxaban, rivaroxaban, or dabigatran, are noninferior for treating PE and have a 0.6% lower rate of bleeding. In patients with PE and systolic blood pressure lower than 90 mm Hg, systemic thrombolysis is recommended and is associated with an 1.6% absolute reduction of mortality (from 3.9% to 2.3%).

CONCLUSIONS AND RELEVANCE

In the US, PE affects approximately 370 000 patients per year and may cause approximately 60 000 to 100 000 deaths per year. First-line therapy consists of direct oral anticoagulants such as apixaban, edoxaban, rivaroxaban, or dabigatran, with thrombolysis reserved for patients with systolic blood pressure lower than 90 mm Hg.

Role of Dual-energy Computed Tomography in Diagnosis of Acute Pulmonary Emboli, a Review

Prompt diagnosis of pulmonary embolism is essential to avert morbidity and mortality. There are a number of diagnostic options for identification of a pulmonary embolism, including laboratory and imaging investigations. While computed tomography pulmonary angiography (CTPA) has largely supplanted nuclear medicine ventilation/perfusion studies, there remain significant limitations in the optimal performance of CTPA. Dual-energy computed tomography has the ability to overcome many of the limitations of standard of care CTPA, including rescue of poor contrast boluses and the ability to evaluate pulmonary perfusion defects.

Use of Computed Tomography Pulmonary Angiography in Emergency Departments: A Literature Review

Computed tomography pulmonary angiography (CTPA) has become the most widely used technique for diagnosis or exclusion of a pulmonary embolism (PE). It has been suggested that overuse of this imaging type may be prevalent, especially in emergency departments (EDs). The purpose of this literature review was to explore the use of CTPAs in EDs worldwide. A review following PRISMA guidelines was completed, with research published between September 2010 and August 2020 included. Five key topics emerged: use of CTPAs; explanations for overuse; use of D-dimer; variability in ordering practices between clinicians; and strategies to reduce overuse. This review found that CTPAs continue to be overused in EDs, leading to superfluous risks to patients. Published studies identify that while clinical practice guidelines (CPGs) have a strong effect on reducing unnecessary CTPAs with no significantly increased risk of missed diagnosis, the adoption of these tools by ED clinicians has remained low. This literature review highlights the need for further research into why CTPAs continue to be overused within EDs and why clinicians are hesitant to use CPGs in the clinical setting. Moreover, investigations into other potential strategies that may combat the overuse of this diagnostic tool are essential to reduce potential harm.

Influence of using recommended radiological criteria on MDCT-angiography diagnosis of single isolated subsegmental pulmonary embolism

OBJECTIVES

We assessed the rate of false-positive diagnoses of MDCT-pulmonary angiography (MDCT-A) in patients with single isolated subsegmental pulmonary embolism (SISSPE).

METHODS

All patients who underwent MDCT-A between 2006 and 2017 for ruling out acute pulmonary embolism (PE) and received an initial diagnosis of SISSPE were included. The MDCT-A of these patients were reviewed retrospectively by four experienced thoracic radiologists, who applied radiological criteria recommended by the American College of Chest Physicians Antithrombotic Guidelines (ACCP 2016) for the diagnosis of SISSPE. Data extracted from medical records were history of venous thromboembolism (VTE), alternative diagnoses, other diagnostic studies for VTE, anticoagulation, bleeding complications, and VTE over the following 3 months.

RESULTS

Of 3839 patients undergoing MDCT-A, PE was found in 1021 (26.6%) and SISSPE in 59 (1.5% overall and 5.8% of all patients with PE). An alternative diagnosis to PE was made on the basis of CT in 33 (55.9%) patients. Forty-one (69.5%) patients received anticoagulants, and major life-threatening bleeding complications occurred in 2, with one death. Recurrent PE was not documented in any patient with SISSPE. In the retrospective assessment of the 59 cases of SISSPE, 21 were negative for PE, with a false-positive rate of 35.6% (21/59); so the percentage of SISSPE cases after the revision was 3.7% of all patients with PE; 11 of these 21 patients received anticoagulation.

CONCLUSIONS

Radiologists should be aware of the high rate of false-positives when making the diagnosis of SISSPE on MDCT-A without using strict diagnostic criteria. Misdiagnosis exposes patients to unnecessary anticoagulation.

KEY POINTS

• Radiologist should be aware of the high rate of false-positive diagnoses of single isolated subsegmental pulmonary embolism (SISSPE) in MDCT-pulmonary angiography (MDCT-A) performed for ruling out pulmonary embolism. • Misdiagnosis of SISSPE in MDCT-A can be reduced by using strict diagnostic radiological criteria recommended by the American College of Chest Physicians Antithrombotic Guidelines. • Unnecessary anticoagulation therapy with potential severe bleeding complications may result from misdiagnosis of SISSPE.

The Effect of Limiting the Scan Range of Computed Tomography Pulmonary Angiography (to Reduce Radiation Exposure) on the Detection of Pulmonary Embolism: A Systematic Review

(1) Background: Computed tomography pulmonary angiography (CTPA) is the standard imaging test for the evaluation of acute pulmonary embolism (PE), but it is associated with patients' exposure to radiation. Studies have suggested that radiation exposure can be reduced without compromising PE detection by limiting the scan range (the z-axis, going from up to down); (2) Methods: A literature search was conducted in MEDLINE and EMBASE on 17 July 2021. Studies were included if they enrolled patients who had undergone a CTPA and described the yield of PE diagnoses, number of missed filling defects and/or other diagnoses using a reduced z-axis in comparison to a full-length scan. To assess risk of bias, we modified an existing risk of bias tools for observational studies, the Newcastle-Ottawa Scale. Results were synthesized in a narrative review. Primary outcomes were the number of missed PE diagnoses (based on at least one filling defect) and filling defects; the secondary outcome was the number of other missed findings; (3) Results: Eleven cohort studies and one case-control study were included reporting on a total of 3955 scans including 1025 scans with a diagnosis of PE. Six different reduced scan ranges were assessed; the most studied was from the top of the aortic arch to below the heart, in which no PEs were missed (seven studies). One sub-segmental PE was missed when the scan coverage was 10 cm starting from the bottom of the aortic arch and 14.7 cm starting from the top of the arch. Five studies that reported on other findings all found that other diagnoses were missed with a reduced z-axis. Most of the included studies had a high risk of bias; (4) Conclusions: CTPA scan coverage reduction from the top of aortic arch to below the heart reduced radiation exposure without affecting PE diagnoses, but studies were generally at high risk of bias.

Contemporary management of acute pulmonary embolism

This review examines the recent progress in the initial management of pulmonary embolism (PE). Diagnostic strategies allowing the safe decrease of imaging testing have been proposed. New modalities of catheter-based interventions have emerged for hemodynamically unstable PE patients. For normotensive PE patients, direct oral anticoagulant treatment has become the new norm and a large proportion of patients are eligible for home treatment.

Derivation and Validation of a 4-Level Clinical Pretest Probability Score for Suspected Pulmonary Embolism to Safely Decrease Imaging Testing

Importance

In patients with suspected pulmonary embolism (PE), overuse of diagnostic imaging is an important point of concern.

Objective

To derive and validate a 4-level pretest probability rule (4-Level Pulmonary Embolism Clinical Probability Score [4PEPS]) that makes it possible to rule out PE solely on clinical criteria and optimized D-dimer measurement to safely decrease imaging testing for suspected PE.

Design, Setting, and Participants

This study included consecutive outpatients suspected of having PE from US and European emergency departments. Individual data from 3 merged management studies (n = 11 114; overall prevalence of PE, 11%) were used for the derivation cohort and internal validation cohort. The external validation cohorts were taken from 2 independent studies, the first with a high PE prevalence (n = 1548; prevalence, 21.5%) and the second with a moderate PE prevalence (n = 1669; prevalence, 11.7%). A prior definition of pretest probability target values to achieve a posttest probability less than 2% was used on the basis of the negative likelihood ratios of D-dimer. Data were collected from January 2003 to April 2016, and data were analyzed from June 2018 to August 2019.

Main Outcomes and Measures

The rate of PE diagnosed during the initial workup or during follow-up and the rate of imaging testing.

Results

Of the 5588 patients in the derivation cohort, 3441 (61.8%) were female, and the mean (SD) age was 52 (18.5) years. The 4PEPS comprises 13 clinical variables scored from -2 to 5. It results in the following strategy: (1) very low probability of PE if 4PEPS is less than 0: PE ruled out without testing; (2) low probability of PE if 4PEPS is 0 to 5: PE ruled out if D-dimer level is less than 1.0 μg/mL; (3) moderate probability of PE if 4PEPS is 6 to 12: PE ruled out if D-dimer level is less than the age-adjusted cutoff value; (4) high probability of PE if 4PEPS is greater than 12: PE ruled out by imaging without preceding D-dimer test. In the first and the second external validation cohorts, the area under the receiver operator characteristic curves were 0.79 (95% CI, 0.76 to 0.82) and 0.78 (95% CI, 0.74 to 0.81), respectively. The false-negative testing rates if the 4PEPS strategy had been applied were 0.71% (95% CI, 0.37 to 1.23) and 0.89% (95% CI, 0.53 to 1.49), respectively. The absolute reductions in imaging testing were -22% (95% CI, -26 to -19) and -19% (95% CI, -22 to -16) in the first and second external validation cohorts, respectively. The 4PEPS strategy compared favorably with all recent strategies in terms of imaging testing.

Conclusions and Relevance

The 4PEPS strategy may lead to a substantial and safe reduction in imaging testing for patients with suspected PE. It should now be tested in a formal outcome study.

Suspected Acute Pulmonary Embolism: Gestalt, Scoring Systems, and Artificial Intelligence

Pulmonary embolism (PE) remains a diagnostic challenge in 2021. As the pathology is potentially fatal and signs and symptoms are nonspecific, further investigations are classically required. Based on the Bayesian approach, clinical probability became the keystone of the diagnostic strategy to rule out PE in the case of a negative testing. Several clinical probability assessment methods are validated: gestalt, the Wells score, or the revised Geneva score. While the debate persists as to the best way to assess clinical probability, its assessment allows for the good interpretation of the investigation results and therefore directs the correct diagnostic strategy. The wide availability of computed tomography pulmonary angiography (CTPA) resulted in a major increase in investigations with a moderate increase in diagnosis, without any notable improvement in patient outcomes. This leads to a new challenge for PE diagnosis which is the limitation of the number of testing for suspected PE. We review different strategies recently developed to achieve this goal. The last challenge concerns the implementation in clinical practice. Two approaches are developed: simplification of the strategies versus the use of digital support tools allowing more sophisticated strategies. Artificial intelligence with machine-learning algorithms will probably be a future tool to guide the physician in this complex approach concerning acute PE suspicion.

Crucial considerations: Sex differences in the epidemiology, diagnosis, treatment, and outcomes of acute pulmonary embolism in non-pregnant adult patients

Acute pulmonary embolism (PE) affects over 600,000 Americans per year and is a common diagnostic consideration among emergency department patients. Although there are well-documented differences in the diagnosis, treatment, and outcomes of cardiovascular conditions, such as ischemic heart disease and stroke, the influence of sex and gender on PE remains poorly understood. The overall age-adjusted incidence of PE is similar in women and men, but women have higher relative rates of PE during early and mid-adulthood (ages 20-40 years); whereas, men have higher rates of PE after age 60 years. Women are tested for PE at far higher rates than men, yet women who undergo computed tomography pulmonary angiography are ultimately diagnosed with PE 35%-55% less often than men. Among those diagnosed with PE, women are more likely to have severe clinical features, such as hypotension and signs of right ventricular dysfunction. When controlled for PE severity, women are less likely to receive reperfusion therapies, such as thrombolysis. Finally, women have more bleeding complications for all types of anticoagulation. Further investigation of possible sex-specific diagnostic and treatment algorithms is necessary in order to more accurately detect and treat acute PE in non-pregnant adults.

Incidence and risk factors of venous thromboembolism in ANCA-associated vasculitis: a metaanalysis and metaregression

The incidence of venous thromboembolism (VTE) in ANCA-associated vasculitis patients varies in different populations. Moreover, the risk factors for VTE in these patients are poorly described due to the small number of events. Ovid MEDLINE, EMBASE, and the Cochrane Library were searched for eligible articles. The inclusion criteria included observational studies that enrolled patients age ≥ 18 years diagnosed with ANCA-associated vasculitis. The incidence of VTE is the outcome of interest. Of 1362 citations, a total of 21 studies (n = 4422) dated from 2006 to 2019 were included in the systematic review. The mean age was 54.2 ± 4.0 years. Most were male (52.0%) and Caucasian (80.9%). With a mean follow-up duration of 5.2 ± 2.8 years, the pooled incidence of VTE in ANCA-associated vasculitis patients was 12.4% (95% CI, 8.8-17.2). Of these, 63.4% (95% CI, 57.3-69.1) had deep vein thrombosis and 26.3% (95% CI, 17.6-37.4) had pulmonary embolism. Recurrent VTE occurred in 10.0% (95% CI, 5.2-18.6). From the metaregression adjusted for age, sex, and ethnicity; positive MPO-ANCA, increasing Birmingham Vasculitis Activity Score at time of vasculitis diagnosis, and presence of renal involvement were positively associated with increased VTE events. Positive PR3-ANCA profile was inversely associated with increased VTE events. Increasing follow-up duration was not associated with increased VTE events. VTE in ANCA-associated vasculitis is common. Positive MPO-ANCA, increasing vasculitis activity, and presence of renal involvement were significant risk factors for VTE while positive PR3-ANCA was inversely associated with increased VTE. Key Points • Venous thromboembolism (VTE) is common in ANCA-associated vasculitis with a pooled incidence of 12.4% • Deep vein thrombosis accounts for two-third of total VTE cases • Positive MPO-ANCA profile, higher disease activity at ANCA-associated vasculitis diagnosis, and renal involvement are risk factors for VTE • Positive PR3-ANCA profile is protective factor for VTE.

Venous thromboembolism and major bleeding in patients with COVID-19: A nationwide population-based cohort study

Background

Venous thromboembolism (VTE) is a potentially fatal complication of SARS-CoV-2 infection and thromboprophylaxis should be balanced against risk of bleeding. This study aimed to examine risks of VTE and major bleeding in hospitalized and community-managed SARS-CoV-2 patients compared with control populations.

Methods

Using nationwide population-based registries, 30-day risks of VTE and major bleeding in SARS-CoV-2 positive patients were compared with those of SARS-CoV-2 test-negative patients and with an external cohort of influenza patients. Medical records of all COVID-19 patients at six departments of infectious diseases in Denmark were reviewed in detail.

Results

The overall 30-day risk of VTE was 0.4% (40/9,460) among SARS-CoV-2 patients (16% hospitalized), 0.3% (649/226,510) among SARS-CoV-2 negative subjects (12% hospitalized), and 1.0% (158/16,281) among influenza patients (59% hospitalized). VTE risks were higher and comparable in hospitalized SARS-CoV-2 positive (1.5%), SARS-CoV-2 negative (1.8%), and influenza patients (1.5%). Diagnosis of major bleeding was registered in 0.5% (47/9,460) of all SARS-CoV-2 positive individuals and in 2.3% of those hospitalized. Medical record review of 582 hospitalized SARS-CoV-2 patients observed VTE in 4% (19/450) and major bleeding in 0.4% (2/450) of ward patients, of whom 31% received thromboprophylaxis. Among intensive care patients (100% received thromboprophylaxis), risks were 7% (9/132) for VTE and 11% (15/132) for major bleeding.

Conclusions

Among people with SARS-CoV-2 infection in a population-based setting, VTE risks were low to moderate and were not substantially increased compared with SARS-CoV-2 test-negative and influenza patients. Risk of severe bleeding was low for ward patients, but mirrored VTE risk in the intensive care setting.

CTA utilization for evaluation of suspected pulmonary embolism in a tertiary pediatric emergency department

OBJECTIVE

To evaluate changes in the utilization of computed tomography angiography (CTA) for evaluating suspected pulmonary embolism (PE) and the positive rate of ancillary for those studies negative for PE in the last 13 years.

MATERIALS AND METHODS

A retrospective review of patient ≤ 20 years of age who underwent a chest CT angiography to rule out PE was performed in a 13-year-period. CT angiographies were grouped into three categories: Positive for PE, negative for PE and positive for ancillary findings, and negative for any pathology. From the exams with ancillary findings, we examined how many of these had a chest radiograph perform within 24 h prior to the CTA and how many of them had an impression stating the same conclusion as the CTA.

RESULTS

307 chest CT angiographies for suspected PE were included. 50 (16%) were reported as positive for PE and 91 (30%) were negative for PE but positive for ancillary findings. The most frequent ancillary findings were pneumonia (n = 26) and pleural effusion (n = 11). Out of 91, 73 patients had a previous chest radiograph and 28 of them reported a similar diagnosis than the CTA. The number of CT angiographies indicated for PE increased by 3.2 studies per year. The rate of CT angiographies positive for ancillary findings (slope = 1.5) and positive for PE (slope = 0.3) remained similar throughout the same period.

CONCLUSIONS

CTA orders for PE have been increasing without any increased detection of PE or ancillary findings in children.

Coccidioidomycosis and Pulmonary Emboli: A Report of 5 Cases

Case series

Patient: Male, 35-year-old

Final Diagnosis: Coccidioidomycosis infection

Symptoms: Dyspena

Medication: —

Clinical Procedure: —

Specialty: Infectious Diseases

Anticoagulant treatment for subsegmental pulmonary embolism

BACKGROUND

Acute pulmonary embolism (PE) is a common cause of death, accounting for 50,000 to 200,000 deaths annually. It is the third most common cause of mortality among the cardiovascular diseases, after coronary artery disease and stroke. The advent of multi-detector computed tomographic pulmonary angiography (CTPA) has allowed better assessment of PE regarding visualisation of the peripheral pulmonary arteries, increasing its rate of diagnosis. More cases of peripheral PEs, such as isolated subsegmental PE (SSPE) and incidental PE, have thereby been identified. These two conditions are usually found in patients with few or none of the classic PE symptoms such as haemoptysis or pleuritic pain, acute dyspnoea or circulatory collapse. However, in patients with reduced cardiopulmonary reserve, classic PE symptoms can be found with isolated SSPEs. Incidental SSPE is found casually in asymptomatic patients, usually by diagnostic imaging performed for other reasons (for example routine CT for cancer staging in oncology patients). Traditionally, all PEs are anticoagulated in a similar manner independent of their location, or number and size of the thrombi. It has been suggested that many patients with SSPE may be treated without benefit, increasing adverse events by a possible unnecessary use of anticoagulants. Patients with isolated SSPE, or incidental PE, may have a more benign clinical presentation compared to those with proximal PEs. However, the clinical significance in patients, and their prognosis, needs to be studied to evaluate whether anticoagulation therapy is required. This is the second update of the Cochrane systematic review published in 2014.

OBJECTIVES

To assess the effectiveness and safety of anticoagulation therapy versus control in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL and AMED databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 26 November 2019. We also undertook reference checking to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials of anticoagulation therapy versus control in patients with SSPE or incidental SSPE.

DATA COLLECTION AND ANALYSIS

Two review authors inspected all citations identified to ensure reliable assessment. If relevant studies were identified, we planned for two review authors to independently extract data and to assess the methodological quality of identified trials using the criteria recommended in the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We did not identify any studies that met the inclusion criteria.

AUTHORS' CONCLUSIONS

There is no evidence from randomised controlled trials to assess the effectiveness and safety of anticoagulation therapy versus control in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE. Well-conducted research is required before informed practice decisions can be made.

Too much or too little medicine? Overdiagnosis, underdiagnosis, overtreatment and undertreatment in respiratory diseases

At a time when technical possibilities for medical investigations are plentiful and ever expanding, there is growing awareness that more is not always better and that “too much medicine” may be harmful. In recent years, the global Choosing Wisely educational campaign has aimed to bring attention to unnecessary healthcare. Unnecessary healthcare includes overtesting, overdiagnosis and overtreatment [1]. The March issue of Breathe aims to challenge us to rethink our clinical practice, to reflect on the evidence, and to identify potential cognitive biases that might influence us to provide “too much” or “too little” medicine [2].

The March issue of Breathe focuses on overdiagnosis, underdiagnosis, overtreatment and undertreatment in respiratory diseaseshttp://ow.ly/63OW30ntCeu