Pretest Probability Of Pulmonary Embolism Research Articles

Impact of COVID-19 on Ventilation-Perfusion (V/Q) Scans: A Comparative Analysis of Pre-COVID-19 Era V/Q Scans and Post-COVID-19 Era Perfusion Scans.

Introduction The COVID-19 pandemic has profoundly impacted medical practices, including nuclear medicine. To minimize aerosol transmission risks, lung perfusion scintigraphy was preferred over traditional ventilation-perfusion (V/Q) scintigraphy during the pandemic. This study compares lung perfusion scans performed during COVID-19 with V/Q scans from the pre-COVID era. After reviewing this study, the reader will learn about V/Q scintigraphy and lung perfusion. Methods This retrospective observational study, conducted from December 2018 to July 2021, involved 868 patients - 511 in the pre-COVID era and 357 in the post-COVID era - at a single tertiary care center. The pretest probability of pulmonary embolism (PE) was determined using Wells' criteria, and data including demographics, clinical findings, and diagnostic test results (V/Q or lung perfusionscintigraphy) were collected. Results A 30% decline in lung scans was observed during the pandemic. In the pre-COVID era, 68.3% of scans had low, 27.8% had intermediate, and 3.9% had high probability for PE. During the pandemic, perfusion-only scans showed 57.3% low, 32.9% indeterminate, and 9.8% high probability for PE. Among COVID-19-positive patients, 48.9% had intermediate, and 11.1% had high probability scans. The rise in indeterminate and high-probability scans during the pandemic is attributed to COVID-19-related lung changes and hypercoagulability. Conclusion The perfusion component of lung scans is typically sufficient for evaluating acute PE. Omitting the ventilation part of the V/Q scan had minimal impact, with only a 5.1% increase in indeterminate/non-diagnostic scans using perfusion-only modified Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) criteria during the post-COVID-19 era, likely due to underlying lung parenchymal involvement in COVID-19 patients. Additionally, there was a 5.9% rise in high-probability scans, attributed to the hypercoagulability and vascular complications associated with COVID-19.

Results from Multisite Implementation of Electronic Health Record Tools for Clinical Pre-Test Probability of Pulmonary Embolism in the Emergency Department

Introduction: Use of validated risk stratification tools for work up of suspected pulmonary embolism (PE) is an endorsed recommendation of the American Society of Hematology and the American College of Emergency Physicians. Due to variations in clinical practice, electronic health record (EHR) systems, and medical provider trainings, the use, documentation, and implementation of these tools vary widely. Current processes do not allow for electronic capture and quality reporting at most institutions. Methods: We sought to design and implement clinical pre-test probability (PTP) tools at three large healthcare institutions for use in emergency departments (ED). At each site, a hematologist partnered with ED physician leadership and local information technology experts to design and implement PTP tools in clinical workflows. Overall, 38 EDs (high volume tertiary EDs and smaller regional EDs) located in the United States along the East Coast and Midwest regions were involved. A major goal of implementation was integration into clinical workflow and automatic documentation. After design and implementation, awareness and education of the new EHR tool was distributed electronically to ED providers. After implementation, use of PTP tools was analyzed between September 12, 2022 and January 11, 2023. PTP use was examined as percent of visits for which patients underwent CT pulmonary angiography (CTPA). Results: Each institution chose the 3 tier Wells' Score for implementation while one site designed an integrated Wells'/PERC or YEARS score calculator. Two sites implemented the tool as an optional flowsheet and one site implemented the tool as mandatory parameters within the orders for PE imaging studies. The mandatory tool could be bypassed with prespecified selections or if a D-dimer existed within 48 hours . Complete details of the site-specific implementation are shown in Table 1. Over the 4-month evaluation timeframe, there was a total of 270,214 ED encounters. Uptake and utilization of the PTP tools are shown in Table 2. Use of PTP was highest at the site with forced PTP documentation which ranged from 49-53% of ordered CTPAs, compared to Site 2 where use was 2-3%, and Site 1 where use ranged from 1-3%. At Site 1, use of PTP increased slightly over the study period with signs that PE yield on imaging was increasing as well (3.4% to 5.9%). At Site 2, PE yield on imaging was overall high (9-10%), and remained similar with similar use of PTP tools over the study period. Use of PTP and PE yield (6-8%) on imaging also remained similar throughout the study at Site 3. Conclusion: Forced use of PTP within the orders for CTPA led to the highest use of PTP (Site 3) but this did not result in meaningfully higher PE yield on CTPA compared to the other sites. PE yield at each site was at or above the 5% yield for PE on CTPA which has been previously reported. Given that PTP uptake was relatively stable over the measurement period at Site 2 and 3, this indicates the process had mostly stabilized and that other strategies are needed to improve uptake of PTP, reduce utilization of CTPA, and further increase yield on CTPA. Increasing PTP use and rising PE yield at Site 1 demonstrated ongoing potential for improvements past this study timeframe.

Bedside exclusion of pulmonary embolism in children without radiation (BEEPER): a national study of the Pediatric Emergency Care Applied Research Network—Study protocol

BackgroundThe Pulmonary Embolism Rule Out Criteria (PERC) Peds rule, derived from the PERC rule, was derived to estimate a low pretest probability for pulmonary embolism (PE) in children but has not been prospectively validated. ObjectiveThe objective of this study was to present a protocol for an ongoing multicenter prospective observational study that evaluates the diagnostic accuracy of the PERC-Peds rule. MethodsThis protocol is identified by the acronym, BEdside Exclusion of Pulmonary Embolism without Radiation in children. The study aims were designed to prospectively validate, or if necessary, refine, the accuracy of PERC-Peds and D-dimer in excluding PE among children with clinical suspicion or testing for PE. Multiple ancillary studies will examine clinical characteristics and epidemiology of the participants. Children aged 4 through 17 years were being enrolled at 21 sites through the Pediatric Emergency Care Applied Research Network (PECARN). Patients taking anticoagulant therapy are excluded. PERC-Peds criteria data, clinical gestalt, and demographic information are collected in real time. The criterion standard outcome is image-confirmed venous thromboembolism within 45 days, determined from independent expert adjudication. We assessed interrater reliability of the PERC-Peds, frequency of PERC-Peds use in routine clinical care, and descriptive characteristics of missed eligible and missed patients with PE. ResultsEnrollment is currently 60% complete with an anticipated data lock in 2025. ConclusionsThis prospective multicenter observational study will not only test whether a set of simple criteria can safely exclude PE without need for imaging but also provide a resource to fill a critical knowledge gap about clinical characteristics of children with suspected and diagnosed PE.

Palla's sign and the challenge of optimizing the imaging strategy in patients with high pretest probability of pulmonary embolism.

Palla's sign and the challenge of optimizing the imaging strategy in patients with high pretest probability of pulmonary embolism.

Response to: Palla's sign and the challenge of optimizing the imaging strategy in patients with high pretest probability of pulmonary embolism.

Response to: Palla's sign and the challenge of optimizing the imaging strategy in patients with high pretest probability of pulmonary embolism.

Barriers to the Use of Clinical Decision Support for the Evaluation of Pulmonary Embolism: Qualitative Interview Study.

BackgroundClinicians often disregard potentially beneficial clinical decision support (CDS).ObjectiveIn this study, we sought to explore the psychological and behavioral barriers to the use of a CDS tool.MethodsWe conducted a qualitative study involving emergency medicine physicians and physician assistants. A semistructured interview guide was created based on the Capability, Opportunity, and Motivation-Behavior model. Interviews focused on the barriers to the use of a CDS tool built based on Wells’ criteria for pulmonary embolism to assist clinicians in establishing pretest probability of pulmonary embolism before imaging.ResultsInterviews were conducted with 12 clinicians. Six barriers were identified, including (1) Bayesian reasoning, (2) fear of missing a pulmonary embolism, (3) time pressure or cognitive load, (4) gestalt includes Wells’ criteria, (5) missed risk factors, and (6) social pressure.ConclusionsClinicians highlighted several important psychological and behavioral barriers to CDS use. Addressing these barriers will be paramount in developing CDS that can meet its potential to transform clinical care.

Pulmonary Embolism in Sickle Cell Disease: Retrospective Analysis of the Use and Yield of Radiographic Studies

▪Venous thromboembolism is a well-known complication of sickle cell disease1-3 and is associated with significant morbidity and mortality, particularly in the case of pulmonary embolisms. On the other hand, concerns have been raised regarding the overuse of imaging when evaluating for PE.4,5 Multiple algorithms have been developed, including the Geneva score,6 Wells' criteria,7 and Pulmonary Embolism Rule-Out Criteria (PERC),8 to better determine the pre-test probability of pulmonary embolism and help curtail the utilization of imaging. Patients with sickle cell disease, particularly when in vaso-occlusive crisis, may have a presentation that confounds the data incorporated into the algorithms, such as abnormal vital signs or d-dimer measurements, making the evaluation challenging. Furthermore, acute chest syndrome (ACS) is another notable acute clinical manifestation of sickle cell disease and can have symptoms and objective measures that are similar to PE with PE itself being a potential trigger for ACS. There is limited data on the extent to which SCD patients undergo scans to evaluate for PE and on the yield of these scans. While complications of SCD including ACS have been found to be more common in patients with hemoglobin SS than SC or sickle beta thalassemia,9 venous thromboembolism has been found to be more prevalent in SC and sickle beta thalassemia.2The sickle cell center at Grady Memorial Hospital, Atlanta, GA currently has more than 1,100 adult patients enrolled, accounting for the largest adult sickle cell population in North America. Through a retrospective chart review of these patients, we determined the prevalence of use of imaging to evaluate for pulmonary embolism and the yield from these radiographic studies, comparing this data across the hemoglobin genotypes. We also assessed for how often these these patients were ultimately diagnosed with ACS instead of or in addition to PE.In total, the charts of 1,143 patients were reviewed. 1,127 of these patients had clearly documented hemoglobin (Hgb) phenotypes; the 16 charts without known Hgb phenotype were excluded from further analysis. Of the 1,127 patients, 709 patients were Hgb SS, 311 SC, 87 sickle beta plus thalassemia (Sb+), 18 sickle beta zero thalassemia (Sb°), 1 SD, and 1 O-Arab. 231 (32.6%) of the Hgb SS patients had imaging while 69 (22.2%) of the SC patients (Table 1), 20 (23.0%) of the Sb+ patients, and 3 (16.7%) of the Sb° patients had imaging. SS patients had 21 (6.2%) studies positive for PE while SC patients had 17 (17.3%) (Table 1), Sb+ patients had 4 (13.3%), and Sb° patients had 2 (9.1%) such studies. Of the PEs diagnosed via CT scans, 13 out of the 17 positive studies for SS patients involved segmental vessels, which was the case with 11 out of 15 for SC patients. When imaged, either inpatient or outpatient, 81 (24.0%) of the cases involving SS patients resulted in a diagnosis of acute chest syndrome; this occurred in 15 (15.3%) of SC patient cases, 4 (13.3%) of Sb+ cases, and 1 (4.5%) of Sb° cases.In this study, we demonstrate that a significantly higher proportion of the Hgb SS patients underwent radiographic studies to evaluate for a pulmonary embolism compared to their SC counterparts despite having a significantly lower yield on these studies. However, the SS patients were more likely to be diagnosed with ACS, suggesting that this diagnosis may need to be more seriously considered before PE in this cohort. This data also suggests that though literature may have previously suggested that thromboembolic disease is more prevalent in SC than SS patients, there may be less awareness of such data among providers, who may be assuming that all sickle cell complications are most common in SS patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Clinician Gestalt in Managing Pediatric Pneumonia: Can We Predict the Future?

* Abbreviation: CAP — : community acquired pneumonia > It’s tough to make predictions, especially about the future. > > Yogi Berra In this issue of Pediatrics , Gao et al1 examine the value of clinical gestalt in predicting the progression to severe disease in children presenting to an urban pediatric emergency department with suspected community acquired pneumonia (CAP). CAP is one of the most common serious infections of childhood, accounting for ∼2 million annual ambulatory visits and 124 000 annual hospitalizations in the United States alone.2–5 Globally, childhood pneumonia accounts for significant morbidity and mortality, particularly in low- and middle-income countries.6 Complications of CAP include pleural effusions, empyema, sepsis, and others that may require additional procedures, ICU stays, and prolonged antibiotic courses. The management of CAP relies on appropriate diagnosis as well as thoughtful risk stratification to inform decisions, such as antimicrobial choice, patient disposition, and follow-up timing. Clinicians are often required to make these types of diagnoses and initial management decisions on the basis of brief encounters with patients. The impressions made on these visits often rely on a heuristic (ie, shortcut) approach to diagnosis and management. Much of medical decision-making relies on pattern recognition, which can include gestalt, gut feeling, or intuition.7 In this prospective cohort study, pediatric emergency medicine physicians were asked to estimate the probability that patients with suspected pneumonia (based on initial patient encounter and chest radiograph findings) will develop a complicated and/or severe pneumonia.1 The authors found that clinician gestalt was most sensitive (>90%) when the estimate for a complicated pneumonia was low and most specific (>90%) when the probability for complications to develop was judged to be … Address correspondence to Louis M. Bell, MD, Children’s Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104. E-mail: belll{at}chop.edu

Abstract 13313: Venous Thromboembolism as a Presenting Finding and Complication of Covid-19: A Case Series

Background: Although not yet fully understood, the pathogenesis of the novel RNA betacoronavirus2 currently named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is thought to involve thrombotic microangiopathy, as evidenced by autopsy. To date, the number of pulmonary embolism (PE) reports in the setting of COVID-19 is increasing, with many presenting in acute cor pulmonale. In this case series, we aim to describe our center’s experience with COVID-19 and PE. Methods: A total of 10 patients with a diagnosis of PE in the setting of positive qualitative SARS-CoV-2 through RT-PCR were identified and managed by our service. Results: The mean age was 58 years old with 60% being males. The majority of the population was Hispanic (70%) with 30% self-identifying as black. All of our patients were middle-aged except for one elder and one young adult, and they had other risk factors for thromboembolism, (e.g. obesity, heart failure, COPD, and HIV). The mean time from presentation to diagnosis of PE was 100 hours. Hemodynamic instability was present in 30% of the cases. There was a whole spectrum of PE involvement, the vast majority of which were segmental and subsegmental (60%) compared to distal main arteries (20%) and saddle PE (20%). Mortality rate was 10% and the rest of the patients were successfully discharged on oral anticoagulation. Although our cohort comprised low-to-intermediate pretest probability for PE per Wells criteria (1.5-3), high clinical suspicion prompted further imaging studies with computed tomography angiography and 2D-echocardiogram. Currently, many hospital systems are avoiding advanced imaging for concerns of infection control, which likely contributes to the underdiagnosis of VTE in patients with COVID-19. Conclusion: As we continue to understand the pathophysiology of this emerging disease, clinicians should maintain a high degree of suspicion to differentiate causes of hypoxemic respiratory failure and hemodynamic instability in the setting of COVID-19. Overt PE may increase inpatient mortality and post-discharge mobility due to the burden of pulmonary hypertension in this population. Further research is required to elucidate the relationship between these entities and the best management approach.

Comparison of the Wells score and the revised Geneva score as a tool to predict pulmonary embolism in outpatients over age 65

TitleComparison of the Wells score and the revised Geneva score as a tool to predict pulmonary embolism in outpatients over 65 years of age. IntroductionThe incidence and mortality of pulmonary embolism (PE) is high in the elderly. The Wells score (SW) and the revised Geneva score (RGS) have been validated in patient populations with a large age range. The aim of this study was to compare the predictive accuracy of these two scores in diagnosis of PE in patients over 65 years of age. MethodA prospective multicentre study (nine French and three Belgian centres) was conducted at the same time as the PERCEPIC study. A total of 1757 patients admitted with suspected PE were included and divided into two groups according to age (≥65 years or <65 years). The pre-test probability of PE was assessed prospectively for the RGS. The SW was calculated retrospectively. The predictive accuracy of the two scores was compared by the area under the curve (AUC) of the ROC curves. ResultsThe overall prevalence of PE was 11.3%. The prevalence among patients aged ≥65 in the low, moderate and high pre-test probability groups, evaluated using the WS and was respectively 13.5% (CI 95%: CI 9.9–17.3), 28.2% (CI 22.1–34.3), 50% (CI 26–74) and 8.1% (CI 3.2–12.9), 22.3% (CI 18.2–26.3), 43.7% (CI 25.6–61.9) using the RGS. The AUC for the WS and RGS for patients aged ≥65 was 0.632 (CI 0.574–0.691) and 0.610 (CI 0.555–0.666). The difference between the AUCs was not statistically significant (p = .441). ConclusionIn the population for this study, the WS and RGS have the same PE diagnostic accuracy in patients over age 65. This result should be validated in a prospective study that directly compares these scores.

P1267 Negative baseline diagnostic imaging does not exclude pulmonary embolism in patients with reccurrent syncope

Abstract INTRODUCTION In patients who are admitted to a hospital due to episode of syncope, acute pulmonary embolism (PE) is rarely considered as a possible cause. This report presents two cases illustrating PE as a cause of syncope with elevated cardiac troponin (cTn) and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels despite normal echocardiographic examination and negative Doppler ultrasound imaging. Case 1: An 83-year-old woman admitted to the ER due to episodes of recurrent syncopes. According to her anamnesis, she had four episodes of syncopes during last three weeks without chest pain, dyspnea, palpitation or hemoptysis. ECG revealed a normal sinus rhythm with a heart rate of 70 bpm without ischemic changes. Laboratory tests revealed raised levels of cTn and NT-proBNP. Transthoracic echocardiography (TTE) demonstrated preserved left and right ventricular systolic functions without any cardiac chamber enlargement and mild tricuspid regurgitation with a PAP of 35 mmHg. Patient’s pre-test probability for pulmonary embolism was low (Wells’ score &amp;lt; 2) but D-dimer level was elevated. Doppler imaging for detection of deep vein thrombosis was negative. Computed tomography pulmonary angiography (CTPA) showed filling defects in the pulmonary arteries consistent with pulmonary embolism (Panel A). The patient was discharged with rivaroxaban therapy without any complication. Case 2: A 69- year-old woman presented to ER with symptoms of chest pain and recurrent episodes of syncope for the last 2 days. Her medical history revealed hypertension and hyperlipidemia. On admission ECG showed a normal sinus rhythm with a heart rate of 105 bpm and T-wave inversions in inferior leads. Laboratory tests showed elevated levels of cTn and NT-proBNP. TTE demonstrated normal left ventricular systolic function with an ejection fraction of 55% and normal right ventricular function and chamber size with a tricuspid annular plane systolic excursion of 22 mm. Diagnostic coronary angiography was performed to exclude acute ischemia revealed non-significant coronary artery stenosis. Doppler ultrasound imaging for detection of deep vein thrombosis was negative. CTPA showed filling defects in the bilateral main pulmonary arteries consistent with acute bilateral pulmonary embolism (Panel B-C). The patient was discharged with rivaroxaban therapy after four days of hospitalization period without any complication. CONCLUSION Elevated cTn and NT-proBNP leves on admission strongly suggest transient hemodynamic impairment causing cardiac injury and syncope. Normal admission ECG and TTE can exclude most possible acute cardiac causes of syncope. Although acute right ventricular dsyfunction is the most frequent finding of acute massive PE causing hemodymanic impairment resulting with syncope, diagnosis of acute PE should only be excluded with CTPA in patients with similar clinical characteristics despite normal TTE and negative venous Doppler ultrasound imaging. Abstract P1267 Figure

Overdiagnosis of pulmonary embolism: definition, causes and implications.

Overuse of computed tomography pulmonary angiography to diagnose pulmonary embolism in people who have only a low pre-test probability of pulmonary embolism has received significant attention in the past. The issue of overdiagnosis of pulmonary embolism, a potential consequence of overtesting, has been less explored. The term “overdiagnosis”, used in a narrow sense, describes a correct (true positive) diagnosis in a person but without any associated harm. The aim of this review is to summarise literature on the topic of overdiagnosis of pulmonary embolism and translate this epidemiological concept into the clinical practice of respiratory professionals. The review concludes that the location of pulmonary embolism at a subsegmental level, rather than whether a diagnosis was made incidentally or following an investigation for suspected pulmonary embolism, is the best predictor for situations in which anticoagulation may not be necessary. In the absence of strong evidence of the optimal management of subsegmental pulmonary embolism, treatment decisions should be made case by case, taking into account the patient's situation and preference.Key pointsSince the introduction of computed tomography pulmonary angiography in 1998, there has been a steep increase in the diagnosis of pulmonary embolism (PE).An increased incidence of PE diagnoses, but an almost stable mortality from PE in the population, together with a decreased case fatality, point towards overdiagnosis (in the absence of more effective treatment).Whether PE is diagnosed as an incidental finding or following an investigation for suspected PE does not appear to influence the need for anticoagulation therapy.An isolated subsegmental PE may not require anticoagulation therapy, and treatment decisions should be made case by case, taking into account the patient's situation and preference.A suggested definition of overdiagnosis of PE: a diagnosis of PE that, if left untreated, would not lead to more harm than if it were treated with anticoagulation therapy, independent of symptoms.Educational aimsTo understand the term “overdiagnosis” based on its narrow definition and be able to apply it to PE.To outline the diagnostic approach to PE.To summarise what is known about the treatment of incidentally detected PE.To summarise what is known about the treatment of subsegmental PE.To understand in which situations anticoagulation therapy for PE may not be beneficial.

Pulmonary Embolism

Pulmonary embolism is caused by a blood clot that travels from the deep veins through the heart and then lodges in the pulmonary vasculature. Common symptoms include pleuritic chest pain, dyspnea, or palpitations. Clinical scores such as the Wells score and Revised Geneva score can be used to assess the pretest probability of pulmonary embolism (PE) and guide work-up such as deciding to order D-dimer testing or imaging. However, clinical gestalt can also accurately assess the pretest probability of PE. The Pulmonary Embolism Rule-out Criteria is a decision rule that can be used to rule out PE without further testing. Imaging modalities include computed tomography pulmonary angiogram or ventilation/perfusion scanning. Novel or new oral anticoagulants are becoming the mainstay of treatment for the hemodynamically stable patient with pulmonary embolism. For the patient who is hemodynamically unstable, treatment modalities include intravenous alteplase, catheter-directed thrombolysis, surgical embolectomy, and catheter-directed embolectomy. A subset of patients with PE can be treated as outpatients. This review contains 1 figure, 4 tables, and 55 references. Key Words: anticoagulants, antithrombins, D-dimer, low-molecular-weight heparin, mechanical thrombolysis, multidetector computed tomography, radionuclide imaging, unfractionated heparin, pulmonary embolism, tissue plasminogen activator, warfarin

Complex calculation or quick glance? Mean platelet volume - new predictive marker for pulmonary embolism.

BackgroundWells and Geneva scores are widely used in the assessment of pretest probability of pulmonary embolism (PE).ObjectiveThe objective of this study was to examine the hypothesis that mean platelet volume (MPV) may better predict PE than the clinical prediction rules.MethodsA study was performed among patients with PE. Baseline characteristics and complete blood counts including MPV were prospectively recorded upon admission. To assess clinical probability in patients with PE risk, we used Wells and Geneva scores.ResultsData records of 136 patients (males: 44%) with median age of 66 years (interquartile range [IQR] 57.5–78.0) diagnosed with PE at the Intensive Cardiac Therapy Clinic in Lodz (Poland) were analyzed. Baseline characteristics indicate that patients suffered from arterial hypertension (65%), obesity (32%), and diabetes mellitus (24%). Furthermore, they reported active smoking (21%), prolonged immobilization (20%), major surgery (21%), pregnancy (4%), and oral contraceptives (9%). Patients presented with various symptoms. The MPV, plateletcrit, and D-dimer values on admission were respectively as follows: 10.71 (IQR 3.29–13.67), 0.2 (IQR 0.15–0.24), and 9.23 (IQR 8.5–9.85). The study revealed that Wells score correlated significantly with an elevated MPV value (P<0.05) per contra to Geneva score (P>0.05). According to our results, there is a lack of coherence between Wells and Geneva scores (P>0.05). Finally, we determined that the optimum MPV level cutoff point for PE on admission with reference to the original Wells score is 9.6 fL.ConclusionMPV may be considered useful as an adjunctive or independent predictive marker for PE used in lieu of clinical prediction rules.

Preemptive Anticoagulation in Patients With a High Pretest Probability of Pulmonary Embolism: Are Guidelines Followed?

Guidelines suggest anticoagulation of patients with high pretest probability of pulmonary embolism (PE) while awaiting diagnostic test results (preemptive anticoagulation). Data relevant to the practice of preemptive anticoagulation are not available. We reviewed 3,500 consecutive patients who underwent CT pulmonary angiography (CTPA) at two EDs. We classified the pretest probability for PE using the revised Geneva Score (RGS) as low (RGS 0-3), intermediate (RGS 4-10), or high (RGS 11-18). We classified patients with a high pretest probability of PE as receiving preemptive anticoagulation if therapeutic anticoagulation was given before CTPA completion. Patients with a high bleeding risk and those receiving treatment for DVT before CTPA were excluded from the preemptive anticoagulation analysis. We compared the time elapsed between ED registration and CTPA completion for patients with a low, intermediate, and high pretest probability for PE. We excluded three of 3,500 patients because CTPA preceded ED registration. Of the remaining 3,497 patients, 167 (4.8%) had a high pretest probability for PE. After excluding 29 patients for high bleeding risk and 21 patients who were treated for DVT prior to CTPA, only two of 117 patients (1.7%) with a high pretest probability for PE received preemptive anticoagulation. Furthermore, 37 of the remaining 115 patients (32%) with a high pretest probability for PE had a preexisting indication for anticoagulation but did not receive preemptive anticoagulation. The time from ED registration to CTPA completion did not differ based on the pretest probability of PE. Physicians rarely use preemptive anticoagulation in patients with a high pretest probability for PE. Clinicians do not expedite CTPA examinations for patients with a high pretest probability for PE.

Comparing Prevalence of Pulmonary Embolism in an Urban Tertiary Care Center After Implementation of CHEST/ATS Practice Guidelines on Choosing Wisely Regarding Imaging Tests

SESSION TITLE: Venous Thromboembolism SESSION TYPE: Original Investigation Poster PRESENTED ON: Wednesday, November 1, 2017 at 01:30 PM - 02:30 PM PURPOSE: The Choosing Wisely initiative aims to minimize the number of chest computed tomography (CT) scans performed when the pretest probability for pulmonary embolism (PE) is low. As a consequence of this initiative, a screening protocol for PE was initiated in our Emergency Room. This protocol mandated the calculation of PERC, Geneva, or Well’s prior to ordering a diagnostic test to evaluate for PE. We compared the prevalence of PE before and after protocol initiation. We hypothesized that unnecessary testing decreased after protocol implementation. METHODS: We conducted a retrospective cohort study of patients suspected of having a PE between January-June 2010 and October-December 2016. We included all consecutive subjects who had a CT chest with PE protocol or ventilation-perfusion scan. Baseline demographics, pretest probability scoring, and imaging results were collected. A positive CT chest with PE protocol or a high probability V/Q scan was diagnostic for PE. Our primary outcome was the prevalence of PE before and after the protocol was started. Secondary outcomes included the diagnostic yield of PERC, revised Geneva, and Wells criteria as the most appropriate screening tool. Fisher’s exact test was used for categorical variables while student’s t-test was used to compare means. Mann-Whitney U was used to compare nonparametric linear variables. The area under the receiver operator curve (AUROC) was used to determine which test was most accurate. All analyses were two tailed and a p-value <0.05 was considered statistically significant. RESULTS: The post-protocol cohort included 104 subjects (mean age: 64.1+/-15.5; male: 51%). The pre-protocol cohort consisted of 1677 patients [mean age: 50.6+/-16.5 (P=0.13); male: 29.5% (P<0.0001)]. Before implementation of the protocol, 6.4% of subjects were diagnosed with PE compared to 10.6% post-intervention (P=0.105). After protocol initiation, PERC was low probability in only 4.8%, while Geneva was 22.1% and Wells was 51.0%. The AUROC for each screening tool was as follows: PERC: 0.62 (95% CI: 0.48-0.77), Geneva: 0.54 (95% CI: 0.35-0.73), Well’s: 0.83 (95% CI: 0.70-0.97). CONCLUSIONS: The prevalence of PE did not change significantly after implementation of a protocol designed to decrease the use of needless diagnostic imaging for PE. However, PERC was low probability in very few patients which may indicate a shift in practice patterns and that fewer low probably PERC patients were diagnostically imaged. There was a trend towards improved diagnostic yield using Wells criteria. However, limitations include the sample size and the retrospective nature of this study. CLINICAL IMPLICATIONS: Decreasing the use of diagnostic imaging for PE was unsuccessful at our institution. This may suggest that Choosing Wisely may not be applicable on an individual institutional basis or our institution’s inability to strictly implement the protocol. Perhaps shifting to the Wells criteria instead of PERC or Geneva will improve our outcomes. DISCLOSURE: The following authors have nothing to disclose: Bilal ElChaarani, Kimberley Doucette, Tanuj Sharma, Genese Lamare, Chee Chan No Product/Research Disclosure Information

Safety of multidetector computed tomography pulmonary angiography to exclude pulmonary embolism in patients with a likely pretest clinical probability

Background In patients with suspected pulmonary embolism (PE) classified as having a likely or high pretest clinical probability, the need to perform additional testing after a negative multidetector computed tomography pulmonary angiography (CTPA) finding remains a matter of debate. Objectives To assess the safety of excluding PE by CTPA without additional imaging in patients with a likely pretest probability of PE. Patients/Methods We retrospectively analyzed patients included in two multicenter management outcome studies that assessed diagnostic algorithms for PE diagnosis. Results Two thousand five hundred and twenty-two outpatients with suspected PE were available for analysis. Of these 2522 patients, 845 had a likely clinical probability as assessed by use of the simplified revised Geneva score. Of all of these patients, 314 had the diagnosis of PE excluded by a negative CTPA finding alone without additional testing, and were left without anticoagulant treatment and followed up for 3 months. Two patients presented with a venous thromboembolism (VTE) during follow-up. Therefore, the 3-month VTE risk in likely-probability patients after a negative CTPA finding alone was 2/314 (0.6%; 95% confidence interval [CI] 0.2-2.3%). Conclusions In outpatients with suspected PE and a likely clinical probability as assessed by use of the simplified revised Geneva score, CTPA alone seems to be able to safely exclude PE, with a low 3-month VTE rate, which is similar to the VTE rate following the gold standard, i.e. pulmonary angiography.

Correlation of Ventilation-Perfusion (V/Q) Scan Results as Compared with Clinical Probability of Pulmonary Embolism in African American Population.

IntroductionCurrent guidelines suggest the use of the more specific Wells' score could safely reduce the number of unnecessary scans. There is a lack of research to support whether these guidelines apply to the African American population. This study aims to evaluate the correlation of clinical pretest probability of pulmonary embolism (PE) with ventilation-perfusion (V/Q) scan results in a predominantly African American population and to test whether current guidelines based on studies conducted in other populations hold true in this group.Material and MethodsA retrospective descriptive study to determine the diagnostic utility of the V/Q scan was conducted among patients who were seen during January 2012 to January 2016. The study population included patients who underwent a V/Q scan for evaluation of PE. One hundred and seventy-five charts were reviewed and 49 were excluded due to poor quality data. A review of the initial history, as well as discharge summaries, was performed. Wells' probability of PE was compared with the results of the scan. Laboratory tests and imaging studies were reviewed and analyzed.ResultThe median age of the study population was 63.02 ± 16.12 years. The majority of the study population, 121 patients (92.4%), was African American. Sixty-four (48.9%) VQ scans were done for a low clinical probability for pulmonary embolism as defined by the Wells' clinical score. The most common clinical presentations were shortness of breath (SOB) - 74 (58%), leg pain or swelling - 39 (29.8%), chest pain - 36 (27.4%), and syncope - 4 (3.1%). Sixty-two (96.9 %) patients with low clinical probability had low probability VQ scans (P = 0.03). Among the patients who underwent CT angiography and V/Q scanning, a low probability scan was noted in 25 patients with no pulmonary embolism on CT (96.2 %) (P = 0.006).ConclusionsThis study showed a strong correlation between low clinical probability and low probability V/Q scans and its utility to safely rule out PE in a predominantly black population. Studies conducted in other populations have detected similar findings.

Multidetector computed tomographic pulmonary angiography in patients with a high clinical probability of pulmonary embolism

ESSENTIALS: When high probability of pulmonary embolism (PE), sensitivity of computed tomography (CT) is unclear. We investigated the sensitivity of multidetector CT among 134 patients with a high probability of PE. A normal CT alone may not safely exclude PE in patients with a high clinical pretest probability. In patients with no clear alternative diagnosis after CTPA, further testing should be strongly considered. Whether patients with a negative multidetector computed tomographic pulmonary angiography (CTPA) result and a high clinical pretest probability of pulmonary embolism (PE) should be further investigated is controversial. This was a prospective investigation of the sensitivity of multidetector CTPA among patients with a priori clinical assessment of a high probability of PE according to the Wells criteria. Among patients with a negative CTPA result, the diagnosis of PE required at least one of the following conditions: ventilation/perfusion lung scan showing a high probability of PE in a patient with no history of PE, abnormal findings on venous ultrasonography in a patient without previous deep vein thrombosis at that site, or the occurrence of venous thromboembolism (VTE) in a 3-month follow-up period after anticoagulation was withheld because of a negative multidetector CTPA result. We identified 498 patients with a priori clinical assessment of a high probability of PE and a completed CTPA study. CTPA excluded PE in 134 patients; in these patients, the pooled incidence of VTE was 5.2% (seven of 134 patients; 95% confidence interval [CI] 1.5-9.0). Five patients had VTEs that were confirmed by an additional imaging test despite a negative CTPA result (five of 48 patients; 10.4%; 95% CI 1.8-19.1), and two patients had objectively confirmed VTEs that occurred during clinical follow-up of at least 3 months (two of 86 patients; 2.3%; 95% CI 0-5.5). None of the patients had a fatal PE during follow-up. A normal multidetector CTPA result alone may not safely exclude PE in patients with a high clinical pretest probability.

C0197: Optimization of the Diagnostic Management of Clinically Suspected Pulmonary Embolism in Hospitalized Patients

Background: Identical diagnostic algorithms for suspected pulmonary embolism (PE) [clinical decision rule (CDR) followed by D-dimer testing and/or computed tomography pulmonary angiography (CTPA)] are used for in-and outpatients, while D-dimer levels, risk factors and pre-test probability for PE differ. We firstly evaluated the efficacy of the standard algorithm in a validation cohort of inpatients and secondly aimed to optimize the algorithm in this cohort combined with a previous cohort of inpatients. Methods: Efficiency (number of CTPAs) and safety (3-month venous thromboembolism (VTE) incidence rates) of the standard algorithm were studied in a validation cohort.We further studied the potential of increasing the D-dimer threshold and/or the CDR threshold in this and a previous cohort and derived a new CDR based on a multivariate regression analysis. Results: In the validation cohort (n = 140), only 2% (3/140; 95% CI 0.4-6.1) were managed without CTPA. Combining two cohorts (n = 624), overall PE prevalence was 25%, standard management resulted in a 3-month VTE incidence rate of 0.0% (95% CI 0.0-7.3) and 92% of patients underwent CTPA. Applying an age-adjusted D-dimer threshold resulted in a-4.5 percentage points (95% CI 1.2-7.8) reduction of CTPAs with a VTE incidence rate of 1.9% (95% CI 0.9-3.6%). None of the other adjustments, nor the newly derived CDR, resulted in a higher efficiency with an acceptable failure rate. Conclusions: The standard CDR combined with the age-adjusted D-dimer threshold resulted in a limited increase of efficiency with an acceptable failure rate. Our additional attempts to safely reduce the high need for CTPA were unsuccessful.