Transthoracic Echocardiography for Diagnosing Pulmonary Embolism: A Systematic Review and Meta-Analysis


Pulmonary embolism (PE) is a common diagnosis with significant mortality if not appropriately treated. The use of transthoracic echocardiography in patients with PE is common; however, its diagnostic capabilities in this use are unclear. With the increased use of ultrasonography in medical settings, it is important to understand the strengths and limitations of echocardiography for the diagnosis of PE.


We conducted a systematic review of PubMed, CINAHL, and EMBASE through 2016 for articles assessing the diagnostic accuracy of transthoracic echocardiography for PE. Two authors independently abstracted relevant data from the studies. We assessed quality using the QUADAS-2 tool for diagnostic studies.


Undefined “right heart strain” was the most common sign used, and it had a sensitivity of 53% (95% CI, 45%–61%) and a specificity of 83% (95% CI, 74%–90%). Eleven other distinct signs were identified: ventricle size ratio, abnormal septal motion, tricuspid regurgitation, 60/60 sign, McConnell’s sign, right heart thrombus, right ventricle hypokinesis, pulmonary hypertension, right ventricular end-diastolic diameter, tricuspid annular plane systolic excursion, and right ventricular systolic pressure.


Studies show a consistently high specificity and low sensitivity for echocardiography in the diagnosis of PE, making it potentially adequate as a rule-in test at the bedside in critical care settings such as the emergency department and intensive care unit for patients with a suspicion of PE, especially those unable to get other confirmatory studies. Future research may continue to clarify the role of bedside echocardiography in conjunction with other tests and imaging in the overall management of PE.


  • The current article represents one of the most thorough meta-analyses of transthoracic echocardiography for pulmonary embolism to date and confirms a moderate sensitivity and high specificity across multiple echocardiographic parameters.

  • The test characteristics of echocardiography for pulmonary embolism are similar between cardiologists, cardiac sonographers, and physicians trained in point of care ultrasound.

  • Overall, echocardiography should not be used alone as test to rule out pulmonary embolism.

  • Findings of right heart strain on transthoracic echocardiography can guide management, especially in scenarios where confirmatory studies are either not available (resource-limited settings) or feasible (critically ill patients).

Venous thromboembolism (VTE), a clinical syndrome involving venous thrombosis followed by distant embolism, is the third most common cause of cardiovascular death and the leading cause of preventable hospital death. Estimates of the incidence of pulmonary embolism (PE) and VTE range from 1.05 to 1.48 per 1,000 patient-years. Of the nearly 300,000 patients who experience VTE each year, 15%–25% present with sudden death or die within 30 days of diagnosis. Approximately half of all PEs are diagnosed in the emergency setting, and prompt diagnosis and treatment have been shown to improve outcomes and survival.

Echocardiographic signs of right heart (RH) strain are often used as prognostic markers in patients with acute PE ; however, the ability of echocardiography to diagnose PE is not well understood. It is suspected to be relatively specific for PE in patients without known chronic cardiorespiratory disease. Recent guidelines by the European Society of Cardiology do not recommend echocardiography as part of the diagnostic workup in non-high-risk patients; however, signs of right ventricular (RV) overload in high-risk patients without another leading diagnosis justify emergent treatment if computed tomography (CT) or other confirmatory test is not immediately available.

Most systematic reviews on the diagnosis of PE have not focused on echocardiography. The last systematic review that reported test characteristics on echocardiography for diagnosing PE was done in 2005 and found only two studies on the topic. It is possible that the test characteristics have improved in light of the increased use of ultrasonography in the emergency department (ED) and the improvements in technology in recent years. Therefore, we sought to do a systematic review and meta-analysis to summarize the test characteristics of echocardiography using gold standards of CT and surgery in the diagnosis of PE in adult patients presenting to any health care provider with signs or symptoms of PE.


Search Techniques

We conducted a thorough and systematic literature search of English language articles published on transthoracic echocardiography used for the diagnosis of PE from January 1, 1980, to the end of year 2014 (exact search dates in Supplemental Appendix 1 , available at ) using PubMed (National Library of Medicine), CINAHL (EBSCO), and EMBASE (Elsevier). For the searches, we selected medical subject headings (MeSH) and keywords to capture the concepts of ultrasonography, echocardiography, RV, and PE. The search results were combined and exported to EndNote bibliographic management tool, and duplicate results were removed. The search was conducted in compliance with the Preferred Reporting in Systematic Reviews and Meta Analyses (PRISMA) guidelines. We updated the search using the same criteria in November 2016. Complete details of the search strategies including search terms are available ( Supplemental Appendix 1 , available at ).

All titles were independently reviewed for possible inclusion by two trained reviewers (J.D. and L.G.). Prior to beginning the review, both reviewers agreed to err on the side of inclusion. If either reviewer selected a reference, the full text was ordered for further review. Using this strategy, 464 articles were selected for further review. The reference sections of all included articles were checked for additional potentially relevant articles ( Figure 1 ).

Figure 1

Flow diagram for article selection in a systematic review and meta-analysis of the diagnostic accuracy of transthoracic echocardiography for diagnosis of PE.

Inclusion and Exclusion Criteria

Articles meeting the following criteria were eligible for review: English language, research of any design that reported quantitative data, focus on diagnosis of acute PE using echocardiography, and reporting of data that allowed for calculation of both sensitivity and specificity. Exclusion criteria included articles that were anecdotal or had no data; on >50% pregnant patients; prognostic studies; single case reports or had a sample size less than 10; studies that used healthy controls; or experimental studies using animals, animal tissue, or cadavers.

A priori, we defined the positive reference standard as either CT, pulmonary angiogram, high-probability ventilation/perfusion (V/Q) scan, intermediate-probability V/Q scan with any other confirmatory study (including leg ultrasound for venous thrombosis), surgery, or autopsy. We chose a wide range of gold standard studies to reflect the large amount of diagnostic studies that are used in practice and to ensure we did not bias our sample if different confirmatory tests were used on patients with different pretest probabilities of PE.

Data Collection and Processing

The team developed an abstraction tool designed to confirm final eligibility for full review, assess article characteristics, and extract data relevant to the study question, which was used by two reviewers (J.D. and L.G.) to independently abstract data from the articles. Data included test characteristics, reported results, location of study, gold standard test used, sonographer experience, and other ultrasonography studies done. If data important to the meta-analysis, specifically data related to the sensitivity and specificity, were needed, the corresponding author of the study was asked for the information by a single e-mail. The two abstractors and two senior team members (A.A. and J.M.F.) discussed the two independent abstractions and combined them into a final abstraction. All abstraction disagreements were minor and were quickly resolved via consensus discussion among the four team members.

In order to perform subgroup analyses, articles were categorized into those performed only in the ED, as focused cardiac ultrasound (FOCUS, previously referred to as “point of care”), and performed by a physician (instead of an cardiac sonographer, nurse, or other health care professional). These groups were not mutually exclusive, and studies could be in more than one group. For example, studies performed in ED patients could be comprehensive exams performed by cardiac sonographers or focused exams performed by physicians. Studies that did not report this information specifically were not included in these analyses.

Quality Assessment

Two reviewers (J.D. and L.G.) independently assessed the quality of the articles using the QUADAS-2 tool (University of Bristol, Bristol, UK) modified to conform to this meta-analysis of diagnostic accuracy. The resultant QUADAS-2 tool was used to assess studies for potential risk of bias involving methodology, reporting, and validity. Study heterogeneity was assessed using χ 2 analysis. All disagreements were minor and resolved via consensus of several members of the team (A.A., L.G., J.D., and J.M.F.).

We decided a priori the characteristics of each study that would meet the criteria for low risk of bias in each section of the QUADAS-2 tool. A more detailed description of the QUADAS-2 tool can be found in the Supplemental Appendix 2 (available at ).

Statistical Analysis

All statistical analyses were performed using R version 3.1. For interrater reliability, we determined both percent agreement and Cohen’s kappa. For the diagnostic accuracy meta-analysis, a hierarchical summary receiver operator curve (HSROC) was constructed that allows both fixed and random effects (for threshold and accuracy). The HSROC models were used to obtain sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratios. HSROC was chosen because it has been shown to be superior to other commonly used methods, it takes into account the correlation between sensitivity and 1-specificity and models the observations for each study, and it allows the meta-analyst to investigate heterogeneity between studies taking into account both within- and between-study variability. The use of a ROC to show the relationship between sensitivity and 1-specificity is especially important when different values for cutoffs are available, as in this study.

The distribution of the estimates of the random effects was taken into account, and a 95% confidence region and 95% prediction region around these values were calculated within which the operating characteristics may lie. All pooled meta-analytic statistics are reported with their respective 95% CIs. No attempt was made to assess for publication bias, as our explicit strategy was a controlling method. Subgroup analyses were carried out each of the tests separately and on those studies that reported being conducted in the ED, utilizing point-of-care ultrasonography, and those that were performed by physician.


Our systematic search strategy yielded 5,905 articles without duplicates (7,164 total). Of these, 464 were selected for full text review and 21 were deemed to meet all inclusion criteria and no exclusions for this review ( Figure 1 and Table 1 ). The percent agreement between the two reviewers for article selection was 94.3%, and Cohen’s kappa was κ = 0.908 (95% CI, 0.836–0.980; P < .001). We included one study that reported that one patient used a positron emission tomography as a reference standard, as all of the other patients met our inclusion criteria and it was impossible from the data provided to exclude this one patient. No new articles to include were found in the reference sections of the included articles. We updated our search using the same strategy in November 2016, and we identified three new articles to include out of the 1,079 references ( Figure 1 ). The interrater reliability of this new search was 98.1% and Cohen’s kappa was κ = 0.744.

Table 1

Characteristics of studies included in a meta-analysis of diagnostic accuracy of echocardiography for PE

First author Year Country Setting Patient selection Type of echocardiography Who performed echocardiography
Bova 2003 Italy ED and inpatient Consecutive patients referred to or hospitalized with signs or symptoms of PE Formal Three “trained cardiologists”
Ceccarelli 2003 Italy Inpatient Patients ages 75–95 admitted to geriatric ward with a suspected PE Unclear Unclear
Cetiner 2014 Turkey ED Retrospective selection of patients with suspicion of PE, select patients with PE compared with patients proven to not have a PE Unclear Unclear
Chen 2006 Taiwan ED to inpatient Retrospectively identified patients with PE compared with consecutive patients presenting with dyspnea Formal Two cardiologists “offline”
Daley 2016 USA ED Convenience sample of patients who were undergoing a CT angiogram for evaluation of a possible PE FOCUS Three point-of-care ultrasound fellowship-trained attendings, four emergency medicine ultrasound fellows, one emergency medicine resident, and one medical student with no prior ultrasound experience who received 2 weeks of training
Dresden 2014 USA ED Convenience sample of suspected or confirmed PE FOCUS Trained MD/investigator, quality checked by an expert sonographer
Firdous 2013 India Inpatient Retrospective review of hospitalized patients with a Wells score >2 Unclear/formal Blinded senior cardiologists
Grifoni 1998 Italy ED Patients with suspected PE Formal “standard” Unclear
Jackson 2000 USA ED Convenience sample of patients who were ordered a diagnostic test for suspected PE FOCUS Nurse and an cardiac sonographer
Kalkan 2016 Turkey ED Consecutive patients admitted to emergency service for acute chest pain and/or dyspnea and underwent pulmonary CT angiography due to suspicion of PE Formal “Two expert cardiologists”
Kasper 1997 Germany Unclear Patients with suspected PE Unclear (internal medicine/nuclear medicine) Physician
Kjaergaard 2006 Denmark Unclear Patients referred for V/Q scan Unclear/formal Unclear
Kurzyna 2002 Poland Unclear (tertiary referral center) Consecutive patients with suspicion of PE referred to the center Unclear/formal Unclear
Laursen 2013 Denmark ED Convenience sample of ED patients with a respiratory signs or symptoms FOCUS Physician
Lodato 2008 USA Various Retrospective review of patients who had CT to rule out PE Unclear Unclear (reviewed by a blinded reader)
Mansencal 2008 France ED Moderate to high PE suspicion with an elevated D-Dimer FOCUS Physician
McConnell 1996 USA Unclear (inpatient) Retrospective identification of all patients with an echo seeking RV function Unclear/formal Unclear, “two experienced echocardiographers”
Miniati 2001 Italy ED Clinically suspected PE Unclear/formal Physician
Nazerian 2014 Italy ED Clinically suspected PE FOCUS One of 13 physicians, including principal investigator, eight emergency medicine physicians, and four trained residents (two internal medicine and two emergency medicine)
Nazeyrollas 1996 France Cardiac intensive care unit Suspected PE or recent dyspnea or chest pain FOCUS Physician
Rudoni 1998 USA Unclear Retrospective review of patients with dyspnea and suspected PE who underwent echocardiography Formal Cardiac sonographer, read by a cardiologist
Sakuma 2006 Japan Unclear Prospective case registry of suspected PE Unclear Unclear
Tuzovic 2016 USA ED Retrospective review of ED patients with suspected PE who had a CT, biomarkers, and an echocardiogram within 2 days Formal Unclear
Viellard-Baron 1998 France Inpatient Patients admitted with suspected PE who had an echocardiogram completed Unclear “Experienced echocardiographer”

Data were collected from 24 unique studies on 12 unique signs suggestive of acute PE. The prevalence of disease in our study was 40.8%. Several studies included sensitivity and specificity data for multiple signs. As a result, 75 measures of sensitivity and specificity were collected. We treated these as 75 different studies. Three articles and two signs in two articles did not report the number of true positives, true negatives, false positives, and false negatives. Two of these authors returned raw data after an email request. The other signs without enough data were excluded, and the remaining 71 studies used in our analyses are displayed in Table 2 .

Table 2

Pooled estimates of sensitivity and specificity for transthoracic echocardiographic signs for diagnosis of PE

Sign Studies True negative False negative True positive False positive n Sensitivity (95% CI) Specificity (95% CI) Chi-square test for heterogeneity
Sensitivity Specificity
60/60 2 49 82 26 10 167 0.24 (0.16, 0.33) 0.84 (0.45, 0.97) 0.864 0.031
Hypokinesis 6 348 153 92 34 627 0.38 (0.31, 0.44) 0.91 (0.88, 0.94) <0.001 <0.001
McConnell 6 372 147 42 10 571 0.22 (0.16, 0.29) 0.97 (0.95, 0.99) <0.001 0.027
PAH 5 259 134 129 43 565 0.44 (0.19, 0.72) 0.84 (0.70, 0.92) <0.001 <0.001
RH strain 16 886 456 487 157 1986 0.53 (0.45, 0.61) 0.83 (0.74, 0.90) <0.001 <0.001
RHT 4 252 157 5 0 414 0.05 (0.02, 0.09) 0.99 (0.96, 1.00) 0.724 0.480
RV:LV 8 501 133 162 83 879 0.55 (0.49, 0.60) 0.86 (0.83, 0.89) <0.001 <0.001
RVEDD 4 228 40 156 49 473 0.80 (0.61, 0.92) 0.80 (0.67, 0.89) <0.001 0.006
Septal 8 530 269 97 29 925 0.26 (0.22, 0.31) 0.95 (0.93, 0.97) 0.862 0.003
TR 7 438 188 125 92 843 0.40 (0.35, 0.46) 0.83 (0.79, 0.86) <0.001 <0.001
TAPSE 2 190 35 95 62 382 0.64 (0.54, 0.73) 0.61 (0.56, 0.67) 0.428 <0.001
RVSP 3 110 28 48 29 215 0.47 (0.34, 0.61) 0.73 (0.65, .80) 0.022 <0.001
All signs 71 4,163 1,822 1,464 598 8,047

The most commonly cited use of echocardiography to detect PE was through a combination of findings suggestive of PE. These findings were termed and defined variably across 15 articles, but we combined them with the term RH strain. Terms for combined measures included RV dysfunction, RV strain, abnormal RH, and acute cor pulmonale. For the studies used in this combined term, these were the terms used in the original studies and no specific sign was mentioned in the original studies. The positive likelihood ratio for this combined term was 3.12, and the negative likelihood ratio was .57.

Other signs reported include the 60/60 sign ([1] tricuspid regurgitation (TR) jet gradient of less than 60 mmHg OR TR velocity less than 3.9 m/sec AND [2] pulmonary flow acceleration time of <60 msec), RV hypokinesis, McConnell’s sign (distinctive akinesia of the mid free wall with normal motion at the apex), pulmonary arterial hypertension (PAH), visualization of an RH thrombus (RHT), RV to left ventricle ratio (RV:LV), RV end-diastolic diameter (RVEDD), abnormal or paradoxical septal motion (septal), TR, tricuspid annular plane systolic excursion (TAPSE), and RV systolic pressure (RVSP). Other signs that only occurred in one study are not reported: inferior vena caval distension, RV isovolumetric acceleration, and LV end-diastolic diameter.

Pooled estimates and 95% CIs for the sensitivity and specificity for each of the 10 signs considered are displayed in Table 2 . Forest plots and summary ROC were created for the RH strain sign ( Figures 2 and 3 ), and ROCs are available for the other three signs with the greatest number of studies on them: RV:LV ratio, abnormal septal motion, and TR ( Figure 3 ). Forest plots for these three signs are available upon requests from the authors. Only four signs showed a low chance of heterogeneity: RHT (sensitivity and specificity), 60/60 sign (sensitivity), TAPSE (sensitivity), and abnormal septal motion (sensitivity).

Figure 2

Forest plot for RH strain for diagnosis of PE.

Figure 3

Summary ROC curves for (A) RH strain, (B) RV:LV ratio, (C) abnormal/paradoxical septal motion, and (D) RH strain curve for TR/insufficiency for diagnosis of PE.

We also conducted subgroup analyses on the studies that reported that they were performed by a physician, ( Table 3 ), performed as FOCUS ( Table 4 ), and performed only in the ED ( Table 5 ). For physician-performed studies, 60/60 sign and visualization of a RHT had only one study on it. For FOCUS studies, only RH strain, RV:LV ratio, and abnormal/paradoxical septal motion had more than one study on them. For ED studies, only 60/60 sign and McConnell’s sign had 0 or 1 studies on them.

Table 3

Pooled estimates of sensitivity and specificity for physician-performed ultrasonography studies

Sign Studies True negative False negative True positive False positive Subjects Sensitivity (95% CI) Specificity (95% CI) Chi-square test for heterogeneity
Sensitivity Specificity
60/60 0
Hypokinesis 3 272 67 62 3 404 0.47 (0.33, 0.61) 0.98 (0.95, 0.99) 0.068 0.276
McConnell 2 157 62 15 4 238 0.19 (0.11, 0.30) 0.98 (0.94, 0.99) 1 <0.123
PAH 2 90 39 75 24 228 0.65 (0.29, 0.91) 0.74 (0.50, 0.89) <0.001 0.095
RH strain 5 491 221 232 56 1000 0.61 (0.32, 0.84) 0.88 (0.83, 0.92) <0.001 0.002
RHT 1 92 54 2 0 148 0.04 (0.01, 0.14) 0.99 (0.92, 1.00) <0.001 <0.001
RV:LV 4 351 74 56 32 513 0.46 (0.32, 0.62) 0.91 (0.76, 0.97) 0.013 <0.001
RVEDD 3 209 22 133 42 406 0.86 (0.72, 0.93) 0.83 (0.69, 0.92) 0.041 0.003
Septal 2 204 62 24 4 294 0.28 (0.20, 0.39) 0.96 (0.91, 0.98) 1.000 0.104
TR 3 207 84 70 32 393 0.46 (0.28, 0.65) 0.87 (0.82, 0.90) 0.004 0.952
All signs 24 2,073 685 669 197 3,624

Table 4

Pooled estimates of sensitivity and specificity for ED studies

Sign Studies True negative False negative True positive False positive Subjects Sensitivity (95% CI) Specificity (95% CI) Chi-square test for heterogeneity
Sensitivity Specificity
60/60 0
Hypokinesis 3 272 67 62 3 404 0.47 (0.33, 0.61) 0.98 (0.95, 0.99) 0.068 0.276
McConnell 1 116 24 6 0 146 0.21 (0.10, 0.39) 1.00 (0.94, 1.00) 0.002 <0.001
PAH 3 217 91 55 26 389 0.30 (0.10, 0.62) 0.90 (0.79, 0.95) 0.001 0.023
RH strain 6 554 174 172 82 982 0.55 (0.32, 0.76) 0.87 (0.82, 0.90) <0.001 0.031
RHT 3 243 142 4 0 389 0.04 (0.02, 0.09) 0.99 (0.97, 1.00) 0.830 0.949
RV:LV 3 269 29 36 27 361 0.54 (0.41, 0.66) 0.91 (0.64, 0.98) 0.248 <0.001
RVEDD 3 209 22 133 42 406 0.86 (0.72, 0.93) 0.83 (0.69, 0.92) 0.041 0.003
Septal 4 351 132 44 8 535 0.26 (0.20, 0.33) 0.96 (0.93, 0.98) 0.807 0.208
TR 3 227 78 48 29 382 0.36 (0.17, 0.61) 0.88 (0.83, 0.92) <0.001 0.266
All signs 29 2,458 759 560 217 3,994

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Apr 15, 2018 | Posted by in CARDIOLOGY | Comments Off on Transthoracic Echocardiography for Diagnosing Pulmonary Embolism: A Systematic Review and Meta-Analysis

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