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Embolism

Cardiovascular Medicine · NLM MeSH · updated 2026-10-29 · version 1

Citations verified against PubMedNot yet clinician-reviewed9 referencesApproximately 4 min read

Blocking of a blood vessel by an embolus which can be a blood clot or other undissolved material in the blood stream.

Table of Contents

1. Definition2. Research landscape3. Reading the evidence4. Open-access studies5. Key reviews6. References7. About this article

Definition and research guide

This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.

Content available: 3 complete abstracts (840 words), 9 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.

Definition

Blocking of a blood vessel by an embolus which can be a blood clot or other undissolved material in the blood stream.

Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.

Also known as: Embolisms; Embolus.

Where it fits in the MeSH classification

Broader topics
Embolism and Thrombosis
Narrower topics
Embolism, Air; Embolism, Amniotic Fluid; Embolism, Fat; Pulmonary Embolism
See also
Embolectomy

Research landscape

PubMed indexes 70,179 records tagged with the MeSH heading “Embolism” (counts retrieved 2026-10-29). 10,248 of them (14.6%) were published from 2020 onward, and the busiest period so far is through 1999 with 31,729 records.

Reviews account for 8,928 records (12.7%) and meta-analyses for 840. Randomized controlled trials number 1,200 (1.7%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.

PubMed records by publication periodthrough 1999: 31,729 records; 2000-2009: 12,394 records; 2010-2019: 15,808 records; 2020 onward: 10,248 records31,729through 199912,3942000-200915,8082010-201910,2482020 onward
Records in PubMed indexed with this heading, by publication period. Real counts from NCBI E-utilities; the final period covers only part of the current year. Volume reflects how much has been published, not how strong the evidence is.
Show the data
PeriodRecords
through 199931,729
2000-200912,394
2010-201915,808
2020 onward10,248
Share of records by publication typeReviews: 12.7 percent; Meta-analyses: 1.2 percent; Randomized controlled trials: 1.7 percentReviews12.7% (8,928)Meta-analyses1.2% (840)Randomized controlled trials1.7% (1,200)
Share of all PubMed records on this heading that carry each publication type. Types overlap with other records, so the shares do not sum to 100%.
Publication-type chart data
Publication types among 70,179 PubMed records
TypeRecordsShare
Reviews8,92812.7%
Meta-analyses8401.2%
Randomized controlled trials1,2001.7%

Method: PubMed query "Embolism"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-29.

Reading the evidence in cardiovascular medicine

Cardiovascular medicine has an unusually large body of randomized trials, so the type of outcome matters: hard clinical events such as death, heart attack and stroke carry more weight than changes in blood pressure, cholesterol or imaging markers that only predict risk. Observational studies can show associations but are confounded by age, lifestyle and other illness. Check whether a result is about prevention or treatment, the baseline risk of participants, and the absolute rather than only the relative size of any benefit.

Evidence from open-access studies

These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.

Study comparison — selected abstracts, not a systematic review
Study / authorsYearSource label / designEurope PMC citationsLicence / source
Inflammation-Based Hematologic Indices as Prognostic Markers in Pulmonary Arterial and Chronic Thromboembolic Pulmonary Hypertension: A Hypothesis-Generating Registry Study
Iancu DG, Mares RG, Cristescu L, Suteu RA, Varga A, Tilea I
2025Research article
Design not recorded in structured metadata
4cc by
PMID 41303423 · DOI · PMC12652508
Haemodynamic and clinical impacts of switching phosphodiesterase-5 inhibitors to riociguat in patients with chronic thromboembolic pulmonary hypertension (CTEPH) after balloon pulmonary angioplasty (BPA) - a prospective cohort study
Kam THH, Kam KKH, Wong MKL, Yan BPY, Tan G
2026Research article
Design not recorded in structured metadata
2cc by
PMID 41484960 · DOI · PMC12866028
Association of Shock Index and Variants with Mortality in Acute Pulmonary Embolism
Upchurch CP, Sanfilippo K, Lew D, Samant M, McDonald R
2025Research article
Design not recorded in structured metadata
2cc by
PMID 41554168 · DOI · PMC12815569

Inflammation-Based Hematologic Indices as Prognostic Markers in Pulmonary Arterial and Chronic Thromboembolic Pulmonary Hypertension: A Hypothesis-Generating Registry Study [1]

Research article Iancu DG, Mares RG, Cristescu L, Suteu RA, Varga A, Tilea I · · 2025 · cited 4 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are characterized by high morbidity and mortality.
Closing excerpt
Inflammation-based hematologic indices, particularly NPAR, SII, and NLR, may provide valuable prognostic information and may serve as practical, non-invasive tools for predicting hospitalization duration and mortality in PAH and CTEPH.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (229 words)

Pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) are characterized by high morbidity and mortality. We retrospectively analyzed 468 hospital admissions from 80 patients to evaluate the prognostic value of inflammation-based hematologic indices, including the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), neutrophil-percentage-to-albumin ratio (NPAR), lymphocyte-to-monocyte ratio (LMR), and systemic immune-inflammation index (SII). All biomarker-outcome associations were specified a priori as exploratory in this hypothesis-generating design. In PAH, both NPAR and SII were associated with in-hospital mortality (odds ratio [OR] 1.129, 95% confidence interval [CI] 1.011-1.261, p = 0.031; OR 1.001, 95% CI 1.000-1.002, p = 0.002), post-discharge mortality (NPAR OR 1.181, 95% CI 1.062-1.313, p = 0.002), and poorer overall survival (log-rank p = 0.002 and p = 0.012, respectively). Higher LMR was associated with reduced in-hospital mortality (OR 0.291, 95% CI 0.108-0.790, p = 0.015), while NLR predicted increased in-hospital mortality. In CTEPH, NLR and LMR were the strongest predictors, correlating with worse survival (log-rank p = 0.007 and p = 0.044) and higher post-discharge mortality (NLR OR 1.289, 95% CI 1.029-1.615, p = 0.027). Receiver operating characteristic (ROC) analysis suggests the potential value of SII in PAH and the promising performance of NPAR in CTEPH. Inflammation-based hematologic indices, particularly NPAR, SII, and NLR, may provide valuable prognostic information and may serve as practical, non-invasive tools for predicting hospitalization duration and mortality in PAH and CTEPH.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41303423 · DOI · PMC12652508

Haemodynamic and clinical impacts of switching phosphodiesterase-5 inhibitors to riociguat in patients with chronic thromboembolic pulmonary hypertension (CTEPH) after balloon pulmonary angioplasty (BPA) - a prospective cohort study [2]

Research article Kam THH, Kam KKH, Wong MKL, Yan BPY, Tan G · · 2026 · cited 2 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
BackgroundFor patients with chronic thromboembolic pulmonary hypertension (CTEPH), balloon pulmonary angioplasty (BPA) has been associated with superior reductions in mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) when compared to riociguat.
Closing excerpt
gov Identifier NCT06715280 retrospectively registered on 26/11/2024.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (302 words)

BackgroundFor patients with chronic thromboembolic pulmonary hypertension (CTEPH), balloon pulmonary angioplasty (BPA) has been associated with superior reductions in mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) when compared to riociguat. In patients with pulmonary arterial hypertension (PAH), greater clinical improvements were observed after switching from phosphodiesterase-5 inhibitors (PDE5i) to riociguat. However, the impact of transitioning from PDE5i to riociguat on pulmonary haemodynamics and functional outcomes after BPA remains unclear.MethodsThis prospective, open-label, single-arm, study enrolled CTEPH patients who remained symptomatic following BPA. After a 24-hour PDE5i washout period, patients were switched to riociguat. At week 26, primary outcomes assessed changes in haemodynamics including PVR and mPAP. Secondary endpoints evaluated cardiac index; functional status including WHO functional class, 6-minute walking distance (6MWD), REVEAL Lite 2 score; biochemical markers such as N-terminal prohormone of brain natriuretic peptide (NT-proBNP); and echocardiographic measurements of right-heart function. Treatment-related adverse events and clinical worsening were monitored throughout the study.ResultsFrom July 2024 to January 2025, 16 patients (mean age 62.3 ± 14.6 years; 75% female) were recruited, with 14 completing the 26-week follow-up. At week 26, significant reductions occurred in PVR (-2.16 Wood units; CI -3.64 to -0.69; p = 0.007) and mPAP (-4.79 mmHg; Confidence Interval [CI] -8.05 to -1.52; p = 0.007). Significant improvements were also noted in cardiac index, WHO functional class, 6MWD, REVEAL Lite 2 score and NT-proBNP levels. Echocardiographic measurements of right-heart function did not demonstrate significant improvement. Treatment-related adverse events were observed in 11 patients (68.75%). Clinical worsening occurred in four patients, including two deaths unrelated to treatment and two unplanned hospitalisations due to pulmonary hypertension.ConclusionIn CTEPH patients after completion of BPA, replacing PDE5i with riociguat significantly enhanced pulmonary haemodynamics and functional capacity but was accompanied by a considerable risk of treatment-related adverse events.Trial registrationClinicalTrials.gov Identifier NCT06715280 retrospectively registered on 26/11/2024.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41484960 · DOI · PMC12866028

Association of Shock Index and Variants with Mortality in Acute Pulmonary Embolism [3]

Research article Upchurch CP, Sanfilippo K, Lew D, Samant M, McDonald R · · 2025 · cited 2 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
IntroductionPulmonary embolism (PE) is common with potential for morbidity and mortality.
Closing excerpt
Further investigation regarding use of the age-adjusted SI for prognostication of acute PE and implications on PE management is warranted.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (309 words)

IntroductionPulmonary embolism (PE) is common with potential for morbidity and mortality. Several PE risk-stratification tools exist; however, more granular and patient-specific indicators of potential decompensation or short-term mortality that can be easily obtained are needed for the bedside clinician to further sub-stratify risk and inform management decisions. We sought to determine the association of early emergency department (ED) measurement of the shock index (SI) and SI variants (modified SI, SI to peripheral oxygen saturation ratio, age-adjusted SI, respiratory-adjusted SI, and double product) and mortality among patients with acute PE.MethodsThis was an observational case-control study of adult patients who presented to the ED at a single health system (January 2021-April 2023) and had PE response team (PERT) activation for newly diagnosed acute PE. We evaluated the association of 30-day in-hospital mortality with the SI (heart rate/systolic blood pressure) and variants of the SI-modified SI = heart rate/mean arterial pressure; SI to peripheral oxygen saturation ratio = SI/peripheral oxygen saturation; age-adjusted SI = age x SI; respiratory-adjusted SI = SI x (respiratory rate/10); double product = systolic blood pressure x heart rate-in addition to the Simplified Pulmonary Embolism Severity Index (sPESI) and European Society of Cardiology (ESC) risk schema. We used the area under the receiver operating characteristic curve (AUC) to assess discriminatory efficiency of the SI and each variant with the primary outcome. Multivariable logistic regression measured the association between SI and variants with 30-day mortality.ResultsOf 121 patients included in the study, 12 (9.9%) died. The SI and variants were all significantly different between survivors and non-survivors (P ConclusionAmong patients presenting to the ED who had a PERT activation for acute PE, the age-adjusted SI had the highest discriminatory efficiency for mortality, followed by the SI and its other variants. Further investigation regarding use of the age-adjusted SI for prognostication of acute PE and implications on PE management is warranted.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41554168 · DOI · PMC12815569

Key reviews and meta-analyses

The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.

  • Research article Thrombolysis for pulmonary embolism and risk of all-cause mortality, major bleeding, and intracranial hemorrhage: a meta-analysis [4]
    Chatterjee S, Chakraborty A, Weinberg I, Kadakia M, Wilensky RL, Sardar P, et al. · JAMA · 2014 · cited 593 times (Europe PMC)
  • Research article Systemic thrombolytic therapy for acute pulmonary embolism: a systematic review and meta-analysis [5]
    Marti C, John G, Konstantinides S, Combescure C, Sanchez O, Lankeit M, et al. · Eur Heart J · 2015 · cited 409 times (Europe PMC)
  • Research article Pulmonary Embolism and Deep Vein Thrombosis in COVID-19: A Systematic Review and Meta-Analysis [6]
    Suh YJ, Hong H, Ohana M, Bompard F, Revel MP, Valle C, et al. · Radiology · 2021 · cited 319 times (Europe PMC)
  • Research article Predictive Value of Computed Tomography in Acute Pulmonary Embolism: Systematic Review and Meta-analysis [7]
    Meinel FG, Nance JW, Schoepf UJ, Hoffmann VS, Thierfelder KM, Costello P, et al. · Am J Med · 2015 · cited 248 times (Europe PMC)
  • Research article Identification of intermediate-risk patients with acute symptomatic pulmonary embolism [8]
    Bova C, Sanchez O, Prandoni P, Lankeit M, Konstantinides S, Vanni S, et al. · Eur Respir J · 2014 · cited 198 times (Europe PMC)
  • Research article COVID-19 and Venous Thromboembolism: A Meta-analysis of Literature Studies [9]
    Di Minno A, Ambrosino P, Calcaterra I, Di Minno MND · Semin Thromb Hemost · 2020 · cited 196 times (Europe PMC)

References

  1. Iancu DG, Mares RG, Cristescu L, Suteu RA, Varga A, Tilea I. Inflammation-Based Hematologic Indices as Prognostic Markers in Pulmonary Arterial and Chronic Thromboembolic Pulmonary Hypertension: A Hypothesis-Generating Registry Study. . 2025. PMID 41303423 · DOI · PMC12652508
  2. Kam THH, Kam KKH, Wong MKL, Yan BPY, Tan G. Haemodynamic and clinical impacts of switching phosphodiesterase-5 inhibitors to riociguat in patients with chronic thromboembolic pulmonary hypertension (CTEPH) after balloon pulmonary angioplasty (BPA) - a prospective cohort study. . 2026. PMID 41484960 · DOI · PMC12866028
  3. Upchurch CP, Sanfilippo K, Lew D, Samant M, McDonald R. Association of Shock Index and Variants with Mortality in Acute Pulmonary Embolism. . 2025. PMID 41554168 · DOI · PMC12815569
  4. Chatterjee S, Chakraborty A, Weinberg I, Kadakia M, Wilensky RL, Sardar P, et al.. Thrombolysis for pulmonary embolism and risk of all-cause mortality, major bleeding, and intracranial hemorrhage: a meta-analysis. JAMA. 2014. PMID 24938564 · DOI
  5. Marti C, John G, Konstantinides S, Combescure C, Sanchez O, Lankeit M, et al.. Systemic thrombolytic therapy for acute pulmonary embolism: a systematic review and meta-analysis. Eur Heart J. 2015. PMID 24917641 · DOI · PMC4352209
  6. Suh YJ, Hong H, Ohana M, Bompard F, Revel MP, Valle C, et al.. Pulmonary Embolism and Deep Vein Thrombosis in COVID-19: A Systematic Review and Meta-Analysis. Radiology. 2021. PMID 33320063 · DOI · PMC7745997
  7. Meinel FG, Nance JW, Schoepf UJ, Hoffmann VS, Thierfelder KM, Costello P, et al.. Predictive Value of Computed Tomography in Acute Pulmonary Embolism: Systematic Review and Meta-analysis. Am J Med. 2015. PMID 25680885 · DOI
  8. Bova C, Sanchez O, Prandoni P, Lankeit M, Konstantinides S, Vanni S, et al.. Identification of intermediate-risk patients with acute symptomatic pulmonary embolism. Eur Respir J. 2014. PMID 24696111 · DOI
  9. Di Minno A, Ambrosino P, Calcaterra I, Di Minno MND. COVID-19 and Venous Thromboembolism: A Meta-analysis of Literature Studies. Semin Thromb Hemost. 2020. PMID 32882719 · DOI · PMC7645842

About this article

Sources
NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
Verification
Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
Review state
automated source verified; no human expert review has been recorded yet.
Version
1, last updated 2026-10-29.

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At a glance

70,179
PubMed records on this heading
15%
published since 2020
8,928
review articles
1,200
randomized trials
9
verified references below

Counts come from PubMed on 2026-10-29; they show how much has been written, not how strong the evidence is.

Related topics See all →

  • Budd-Chiari SyndromeCardiovascular Medicine
  • Coronary ThrombosisCardiovascular Medicine
  • Retinal Vein OcclusionCardiovascular Medicine
  • ThromboembolismCardiovascular Medicine
  • Venous ThromboembolismCardiovascular Medicine

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