Best Clinical Practice: Current Controversies in Pulmonary Embolism Imaging and Treatment of Subsegmental Thromboembolic Disease

Role of Physical Therapists in the Management of Individuals at Risk for or Diagnosed With Venous Thromboembolism: Evidence-Based Clinical Practice Guideline 2022

No matter the practice setting, physical therapists work with patients who are at risk for or who have a history of venous thromboembolism (VTE). In 2016, the first clinical practice guideline (CPG) addressing the physical therapist management of VTE was published with support by the American Physical Therapy Association's Academy of Cardiovascular and Pulmonary Physical Therapy and Academy of Acute Care, with a primary focus on lower extremity deep vein thrombosis (DVT). This CPG is an update of the 2016 CPG and contains the most current evidence available for the management of patients with lower extremity DVT and new key action statements (KAS), including guidance on upper extremity DVT, pulmonary embolism, and special populations. This document will guide physical therapist practice in the prevention of and screening for VTE and in the management of patients who are at risk for or who have been diagnosed with VTE. Through a systematic review of published studies and a structured appraisal process, KAS were written to guide the physical therapist. The evidence supporting each action was rated, and the strength of statement was determined. Clinical practice algorithms based on the KAS were developed that can assist with clinical decision-making. Physical therapists, along with other members of the health care team, should implement these KAS to decrease the incidence of VTE, improve the diagnosis and acute management of VTE, and reduce the long-term complications of VTE.

Single versus multiple and incidental versus symptomatic subsegmental pulmonary embolism: clinical characteristics and outcome

It remains unexplored if the clinical picture and outcome of subsegmental pulmonary embolism (SSPE) differ between single versus multiple, and incidental versus symptomatic embolism. Consecutive patients anticoagulated for SSPE at the Mayo Thrombophilia Clinic (03/01/2013-12/31/2020) were followed forward to assess venous thromboembolism (VTE) recurrence, mortality, major bleeding, and clinically relevant non-major bleeding (CRNMB); expressed as a rate per 100 person-years. Among 3878 VTE patients, 1541 had pulmonary embolism including 224 (14.6%) with SSPE either single (n = 139) or multiple (n = 85; 46 bilateral and 39 unilateral emboli); 134 had incidental and 90 symptomatic SSPE. Patients with single were less often symptomatic and less often had coexisting DVT than multiple SSPE. Patients with incidental had a two-fold higher frequency of cancer compared to symptomatic SSPE. During the study period, 1 patient with single and 2 with multiple SSPE had VTE recurrence (rate of 1.14 vs 3.63, p = 0.280). Single SSPE patients experienced 2 episodes of major bleeding (rate of 2.36) while the multiple SSPE group had no major bleeding. Seven patients in each group had CRNMB events (rate of 8.20 vs 13.58 for single and multiple SSPE, respectively, p = 0.282). Patients with single SSPE had a higher death rate compared to multiple SSPE (43.07 vs 22.22, p = 0.031) but no difference was noted after adjusting for cancer (p = 0.388). Also, incidental had similar clinical outcomes to symptomatic SSPE.Interpretation Anticoagulated SSPE patients with single and multiple as well as incidental and symptomatic have a different clinical profile but similar clinical outcomes.

Anticoagulation Therapy in Cancer Patients with Thrombosis in the Outpatient Sector of Germany (The CERTIFICAT Initiative)-German Practice of Anticoagulation Therapy of Cancer Patients with Thrombosis

OBJECTIVE

 This article aims to investigate the reality of anticoagulation treatment for cancer patients with thrombosis in the outpatient sector of Germany.

METHODS

 For the analysis period 2012 to 2015, anonymized data from 4.1 million statutory insured patients were analyzed. Cancer patients with incident thrombosis and an outpatient prescription of anticoagulant drugs were identified and evaluated for three subsequent quarters with regard to anticoagulant use.

RESULTS

 A total of 7,313 cancer patients with incident thrombosis (ICD-10: I80*) were evaluated. About, 90% of patients with thromboses were diagnosed and treated in the ambulatory sector. More than 80% of the prescriptions were issued by general practitioners. And 57% of patients were anticoagulated predominantly (>50% of the time) with different low-molecular-weight heparins (LMWHs), 24% predominantly with vitamin K antagonists (VKAs), and 17% with direct oral anticoagulants (DOACs). Anticoagulants were prescribed for an average of 4.5 months. LMWH had a substantially longer prescription period (90-135 days) than VKA (53 days) or DOAC (47 days). Gastrointestinal bleeding in conjunction with hospitalization was documented in 1.76% of patients with a range of 1.3 to 3% for the different LMWHs.

CONCLUSION

 The prescription practice documented by this representative and comprehensive evaluation demonstrates an anticoagulation duration in accordance with the guidelines, although the choice of the respective anticoagulant was often not in compliance with the contemporary label or guidelines.

Adherence to Best Practice Advice for Diagnosis of Pulmonary Embolism

PURPOSE

This study evaluated clinician adherence to the American College of Physicians Best Practice Advice for diagnosis of pulmonary embolism.

DESIGN

A prospective, single-center, descriptive design was utilized.

METHODS

A heterogeneous sample of 111 hemodynamically stable adult inpatients with a computed tomography pulmonary angiogram ordered was consented. Electronic medical records were reviewed for demographic and clinical variables to determine adherence. The 6 individual best practice statements and the overall adherence were evaluated by taking the sum of "yes" answers divided by the sample size.

RESULTS

Overall adherence was 0%. Partial adherence was observed with clinician-recorded clinical decisions rules and obtaining d-dimer (3.6% [4/111] and 10.2% [9/88], respectively) of low/intermediate probability scorers. Age adjustment of d-dimer was not recorded. Computed tomography pulmonary angiogram was the first diagnostic test in 89.7% (79/88) in low/intermediate probability patients.

CONCLUSION

In hemodynamically stable, hospitalized adults, adherence to best practice guidelines for diagnosis of pulmonary embolism was minimal. Clinical utility of the guidelines in hospitalized adults needs further evaluation. Systems problems (eg, lack of standardized orders, age-adjusted d-dimer values, information technology support) likely contributed to poor guideline adherence.

Development of a machine learning model using electrocardiogram signals to improve acute pulmonary embolism screening

Aims

Clinical scoring systems for pulmonary embolism (PE) screening have low specificity and contribute to computed tomography pulmonary angiogram (CTPA) overuse. We assessed whether deep learning models using an existing and routinely collected data modality, electrocardiogram (ECG) waveforms, can increase specificity for PE detection.

Methods and results

We create a retrospective cohort of 21 183 patients at moderate- to high suspicion of PE and associate 23 793 CTPAs (10.0% PE-positive) with 320 746 ECGs and encounter-level clinical data (demographics, comorbidities, vital signs, and labs). We develop three machine learning models to predict PE likelihood: an ECG model using only ECG waveform data, an EHR model using tabular clinical data, and a Fusion model integrating clinical data and an embedded representation of the ECG waveform. We find that a Fusion model [area under the receiver-operating characteristic curve (AUROC) 0.81 ± 0.01] outperforms both the ECG model (AUROC 0.59 ± 0.01) and EHR model (AUROC 0.65 ± 0.01). On a sample of 100 patients from the test set, the Fusion model also achieves greater specificity (0.18) and performance (AUROC 0.84 ± 0.01) than four commonly evaluated clinical scores: Wells' Criteria, Revised Geneva Score, Pulmonary Embolism Rule-Out Criteria, and 4-Level Pulmonary Embolism Clinical Probability Score (AUROC 0.50-0.58, specificity 0.00-0.05). The model is superior to these scores on feature sensitivity analyses (AUROC 0.66-0.84) and achieves comparable performance across sex (AUROC 0.81) and racial/ethnic (AUROC 0.77-0.84) subgroups.

Conclusion

Synergistic deep learning of ECG waveforms with traditional clinical variables can increase the specificity of PE detection in patients at least at moderate suspicion for PE.

The Function of microRNAs in Pulmonary Embolism: Review and Research Outlook

Pulmonary embolism (PE) is a common pathologic condition that frequently occurs in patients with deep venous thrombosis. Severe PE may critically suppress cardiopulmonary function, thereby threatening the life of patients. Chronic pulmonary hypertension caused by PE may lead to deterioration of respiratory dysfunction, resulting in complete disability. MicroRNAs (miRNAs) are a group of abundantly expressed non-coding RNAs that exert multiple functions in regulating the transcriptome via post-transcriptional targeting of mRNAs. Specifically, miRNAs bind to target mRNAs in a matching mechanism between the miRNA seed sequence and mRNA 3ʹ UTR, thus modulating the transcript stability or subsequent translation activity by RNA-induced silencing complex. Current studies have reported the function of miRNAs as biomarkers of PE, revealing their mechanism, function, and targetome in venous thrombophilia. This review summarizes the literature on miRNA functions and downstream mechanisms in PE. We conclude that various related miRNAs play important roles in PE and have great potential as treatment targets. For clinical application, we propose that miRNA biomarkers combined with traditional biomarkers or miRNA signatures generated from microchips may serve as a great predictive tool for PE occurrence and prognosis. Further, therapies targeting miRNAs or their upstream/downstream molecules need to be developed more quickly to keep up with the progress of routine treatments, such as anticoagulation, thrombolysis, or surgery.

Ultrasound-Facilitated Catheter-Directed Thrombolysis via Dual Right Upper Extremity Venous Access Into the Basilic Vein in a Case of Submassive Pulmonary Embolism

Traditionally, massive, life-threatening pulmonary embolism (PE) has been treated with systemic thrombolytic therapy while submassive and smaller acute PEs have been treated with systemic anticoagulation therapy. Given that thrombolytic therapy is associated with the risk of life-threatening complications including intracranial hemorrhage, it has not been routinely used or recommended for submassive PEs. In 2017, the Food and Drug administration (FDA) approved ultrasound-facilitated catheter-directed thrombolysis (USCDT) for acute massive and sub-massive pulmonary embolism. USCDT has primarily been performed using jugular or femoral venous access. There have been isolated reports of USCDT performed through upper extremity venous access. We present a case of USCDT in a submassive PE patient with dual right upper extremity venous access where both sheaths were advanced into the basilic vein (due to anatomic variation). Based on recent clinical trial data suggesting that shorted duration USCDT is as effective as longer duration, tissue plasminogen activator (tPA) was infused in this case for 6 hours. This strategy for intervention can enhance patient comfort with USCDT therapy and can be particularly helpful in patients at high risk for access site complications and those unable to lie supine for the long duration of infusion therapy.

Symptomatic subsegmental versus more central pulmonary embolism: Clinical outcomes during anticoagulation

BACKGROUND

The optimal therapy of patients with acute subsegmental pulmonary embolism (PE) is controversial.

METHODS

We used the RIETE (Registro Informatizado Enfermedad TromboEmbólica) database to compare the rate of symptomatic PE recurrences during anticoagulation in patients with subsegmental, segmental, or more central PEs.

RESULTS

Among 15 963 patients with a first episode of symptomatic PE, 834 (5.2%) had subsegmental PE, 3797 (24%) segmental, and 11 332 (71%) more central PE. Most patients in all subgroups received initial therapy with low-molecular-weight heparin, and then most switched to vitamin K antagonists. Median duration of therapy was 179, 185, and 204 days, respectively. During anticoagulation, 183 patients developed PE recurrences, 131 developed deep vein thrombosis (DVT), 543 bled, and 1718 died (fatal PE, 135). The rate of PE recurrences was twofold higher in patients with subsegmental PE than in those with segmental (hazard ratio [HR], 2.13; 95% confidence interval [CI], 1.16-3.85) or more central PE (HR, 1.89; 95% CI, 1.12-3.13). On multivariable analysis, patients with subsegmental PE had a higher risk for PE recurrences than those with central PE (adjusted HR, 1.75; 95% CI, 1.02-3.03). After stratifying patients with subsegmental PE according to ultrasound imaging in the lower limbs, the rate of PE recurrences was similar in patients with DVT, in patients without DVT, and in those with no ultrasound imaging.

CONCLUSIONS

Our study reveals that the risk for PE recurrences in patients with segmental PE is not lower than in those with more central PE, thus suggesting that the risk of PE recurrences is not influenced by the anatomic location of PE.

Venous thromboembolism in the critically ill: A prospective observational study of occurrence, risk factors and outcome

BACKGROUND

The aim of the study was to explore occurrence, risk factors and outcome of venous thromboembolism (VTE) in intensive care unit (ICU) patients.

METHODS

Prospective observational study of ICU patients receiving thromboprophylaxis at Oslo University Hospital in Norway. Adult medical and surgical patients with ICU length of stay (LOS) longer than 48 hours were included. For detection of VTE, Doppler ultrasound screening of neck, upper and lower extremity veins was used, and computed tomography angiography when clinically indicated for any medical reason.

RESULTS

Among 70 included patients, 79% were males and mean age was 62 (±12.1) years. All received thromboprophylaxis with dalteparin, and 44 (63%) used graduated compression stockings. VTE was found in 19 (27%) patients; deep vein thrombosis in 15 (21%) and pulmonary embolism in 4 (6%). Among the VTEs, 11 (58%) presented within the first 48 hours after admission, two (11%) were located in the lower limbs and five (26%) were symptomatic. Risk factors for VTE in multivariable analyses were malignancy, abdominal surgery and SAPS II score <41 with an AuROC (95% CI) of 0.72 (0.58-0.85, P = 0.01). Patients with and without VTE had comparable ICU LOS (13 vs 11 days, P = 0.27) and mortality (16% vs 20%, P = 0.72).

CONCLUSION

Venous thromboembolism was observed in 27% of ICU patients receiving thromboprophylaxis. Factors associated with increased risk of VTE were malignancy, abdominal surgery and SAPS II score <41. Presence of VTE did not impact on patient outcome.

Safety of the Combination of PERC and YEARS Rules in Patients With Low Clinical Probability of Pulmonary Embolism: A Retrospective Analysis of Two Large European Cohorts

BACKGROUND

This study aimed to determine the failure rate of a combination of the PERC and the YEARS rules for the diagnosis of pulmonary embolism (PE) in the emergency department (ED).

METHODS

We performed a retrospective analysis of two European cohorts of emergency patients with low gestalt clinical probability of PE (PROPER and PERCEPIC). All patients we included were managed using a conventional strategy (D-dimer test, followed, if positive, by computed tomographic pulmonary angiogram (CTPA). We tested a diagnostic strategy that combined PERC and YEARS to rule out PE. The primary endpoint was a thromboembolic event diagnosed in the ED or at 3-months follow-up. Secondary endpoints included a thromboembolic event at baseline in the ED and a CTPA in the ED. Ninety-five percent confidence intervals (CIs) of proportions were calculated with the use of Wilson's continuity correction.

RESULTS

We analyzed 1,951 patients (mean ± SD age = 47 ± 18 years, 56% women) with an overall proportion of patients with PE of 3.5%. Both PERC and YEARS strategies were associated with 11 missed PE in the ED: failure rate 0.57 (95% CI = 0.32-1.02). At 3-month follow-up, the overall failure rate was 0.83% (95% CI = 0.51-1.35). Among the 503 patients who underwent a CTPA (26%), the use of the PERC-YEARS combination would have ruled out PE without CTPA in 249 patients (50% [95%CI = 45%-54%], absolute reduction 13% (95% CI = 11%-14%]).

CONCLUSION

The combination of PERC then YEARS was associated with a low risk of PE diagnostic failure and would have resulted in a relative reduction of almost half of CTPA.

Wells and Geneva Scores Are Not Reliable Predictors of Pulmonary Embolism in Critically Ill Patients: A Retrospective Study

BACKGROUND

Critically ill patients are at high risk for pulmonary embolism (PE). Specific PE prediction rules have not been validated in this population. The present study assessed the Wells and revised Geneva scoring systems as predictors of PE in critically ill patients.

METHODS

Pulmonary computed tomographic angiograms (CTAs) performed for suspected PE in critically ill adult patients were retrospectively identified. Wells and revised Geneva scores were calculated based on information from medical records. The reliability of both scores as predictors of PE was determined using receiver operating characteristic (ROC) curve analysis.

RESULTS

Of 138 patients, 42 (30.4%) were positive for PE based on pulmonary CTA. Mean Wells score was 4.3 (3.5) in patients with PE versus 2.7 (1.9) in patients without PE (P < .001). Revised Geneva score was 5.8 (3.3) versus 5.1 (2.5) in patients with versus without PE (P = .194). According to the Wells and revised Geneva scores, 56 (40.6%) patients and 49 (35.5%) patients, respectively, were considered as low probability for PE. Of those considered as low risk by the Wells score, 15 (26.8%) had filling defects on CTA, including 2 patients with main pulmonary artery embolism. The area under the ROC curve was 0.634 for the Wells score and 0.546 for the revised Geneva score. Wells score >4 had a sensitivity of 40%, specificity of 87%, positive predictive value of 59%, and negative predictive value of 77% to predict risk of PE.

CONCLUSIONS

In this population of critically ill patients, Wells and revised Geneva scores were not reliable predictors of PE.

Multicenter Evaluation of the YEARS Criteria in Emergency Department Patients Evaluated for Pulmonary Embolism

BACKGROUND

It may be possible to safely rule out pulmonary embolism (PE) in patients with low pretest probability (PTP) using a higher than standard D-dimer threshold. The YEARS criteria, which include three questions from the Wells PE score to identify low-PTP patients and a variable D-dimer threshold, was recently shown to decrease the need for imaging to rule out PE by 14% in a multicenter study in the Netherlands. However, the YEARS approach has not been studied in the United States.

METHODS

This study was a prospective, observational study of consecutive adult patients evaluated for PE in 17 U.S. emergency departments. Prior to diagnostic testing, we collected the YEARS criteria: "Does the patient have clinical signs or symptoms of DVT?" "Does the patient have hemoptysis?" "Are alternative diagnoses less likely than PE?" with YEARS (+) being any "yes" response. A negative D-dimer was <1000 mg/dL for YEARS (-) patients and <500 mg/dL for YEARS (+) patients. We calculated test characteristics and used Fisher's exact test to compare proportions of patients who would have been referred for imaging and patients who would have had PE "missed."

RESULTS

Of 1,789 patients, 84 (4%) had PE, 1,134 (63%) were female, 1,038 (58%) were white, and mean (±SD) age was 48 (±16) years. Using the standard D-dimer threshold, 940 (53%) would not have had imaging, with two (0.2%, 95% confidence interval [CI] = 0.02%-0.60%) missed PE. Using YEARS adjustment, 1,204 (67%, 95% CI = 65%-69%) would not have been referred for imaging, with six (0.5%, 95% CI = 0.18%-1.1%) missed PE, and using "alternative diagnoses less likely than PE" adjustment, 1,237 (69%, 95% CI = 67%-71%) would not have had imaging with six (0.49%, 95% CI = 0.18%-1.05%) missed PE. Sensitivity was 97.6% (95% CI = 91.7%-99.7%) for the standard threshold and 92.9% (95% CI = 85%-97%) for both adjusted thresholds. Negative predictive value (NPV) was nearly 100% for all approaches.

CONCLUSIONS

D-dimer adjustment based on PTP may result in a reduced need for imaging to evaluate possible PE, with some additional missed PE but no decrease in NPV.

Systematic Review and Meta-analysis of Outcomes of Patients With Subsegmental Pulmonary Embolism With and Without Anticoagulation Treatment

BACKGROUND

This systematic review addresses the controversy over the decision to anticoagulate patients with subsegmental pulmonary embolism (SSPE).

METHODS

We searched Ovid MEDLINE, PubMed, Embase, the Cochrane Library, Scopus, Web of Science, ClinicalTrials.gov, Google Scholar, and bibliographies in March 2017. Two authors reviewed and retained papers with symptomatic patients who underwent computerized tomographic pulmonary angiography and had sufficient information to determine SSPE; decision to treat (or not) with systemic anticoagulation; and outcomes of bleeding, venous thromboembolism (VTE) recurrence, and death. Papers were assessed for selection and publication bias and heterogeneity, with Eggers and the inconsistency indexes (I² ).

RESULTS

From 1,512 papers screened, we included 14 studies comprising 15,563 patients for full-length review and analysis. Pooled data demonstrated I²  = 99% with an Eggers p < 0.001, suggesting significant publication bias. The pooled prevalence of SSPE was 4.6% (95% confidence interval [CI] = 1.8%-8.5%). The frequency of bleeding in SSPE patients treated with anticoagulation (n = 589) was 8.1% (95% CI = 2.8%-15.8%), with no available bleeding data in untreated patients (n = 126). The frequency of VTE recurrence within 90 days was 5.3% (95% CI = 1.6%-10.9%) for treated versus 3.9% (95% CI = 4.8%-13.4%) for untreated, while the frequency of death was 2.1% (95% CI = 3.4%-5.2%) for treated versus 3.0% (95% CI = 2.8%-8.6%) for untreated.

CONCLUSION

This systematic review highlights the lack of any clinical trial to make a clear inference about harm or benefit of anticoagulation for SSPE. Comparison of pooled data from uncontrolled outcome studies shows no increase in VTE recurrence or death rates for patients who were not anticoagulated. These data suggest clinical equipoise for decision to anticoagulate or not anticoagulate patients with SSPE. However, this inference is limited by small numbers, imprecision, and the lack of a controlled clinical trial.

Radiology report annotation using intelligent word embeddings: Applied to multi-institutional chest CT cohort

We proposed an unsupervised hybrid method - Intelligent Word Embedding (IWE) that combines neural embedding method with a semantic dictionary mapping technique for creating a dense vector representation of unstructured radiology reports. We applied IWE to generate embedding of chest CT radiology reports from two healthcare organizations and utilized the vector representations to semi-automate report categorization based on clinically relevant categorization related to the diagnosis of pulmonary embolism (PE). We benchmark the performance against a state-of-the-art rule-based tool, PeFinder and out-of-the-box word2vec. On the Stanford test set, the IWE model achieved average F1 score 0.97, whereas the PeFinder scored 0.9 and the original word2vec scored 0.94. On UPMC dataset, the IWE model's average F1 score was 0.94, when the PeFinder scored 0.92 and word2vec scored 0.85. The IWE model had lowest generalization error with highest F1 scores. Of particular interest, the IWE model (trained on the Stanford dataset) outperformed PeFinder on the UPMC dataset which was used originally to tailor the PeFinder model.