Abstract
Background
Cardiogenic shock, a life-threatening condition frequently encountered in emergency departments, requires rapid diagnosis and management. Point-of-care ultrasound (POCUS) is widely used as a bedside tool; however, its impact on prognosis in patients with suspected cardiogenic shock remains unclear. This systematic review aimed to evaluate whether POCUS improves the clinical outcomes in these patients.
Methods and Results
We searched PubMed, Web of Science, and Cochrane Library up to December 31, 2023, for studies evaluating the prognostic impact of POCUS in adults with undifferentiated shock, including cardiogenic shock. From 3,759 identified records, 2 studies (1 randomized controlled trial [RCT] and 1 observational study) involving 5,711 patients with shock were included. The RCT showed no significant differences in in-hospital mortality between the POCUS and non-POCUS groups (relative risk [RR] 0.99 [95% confidence interval (CI) 0.64–1.51]). The observational study reported higher mortality in patients receiving POCUS before intervention (RR 1.25 [95% CI 1.12–1.39]). Overall, POCUS did not significantly reduce mortality in patients with suspected cardiogenic shock. Given the limited number and quality of available studies, the certainty of evidence was low (RCT) and very low (observational study).
Conclusions
Although POCUS plays an essential role in diagnosis and clinical decision-making, our review suggests that it may not significantly improve prognosis in patients with suspected cardiogenic shock. Further studies are required to determine its prognostic value.
Key Words: Cardiogenic shock, Point-of-care ultrasound, Prognosis, Shock
Central Figure.
Cardiogenic shock is a critical condition frequently encountered in emergency departments that often leads to poor outcomes.1,2 Management of cardiogenic shock is highly challenging and requires rapid, precise diagnosis and treatment. Some patients present with subtle signs and unclear etiologies that complicate timely interventions. Early recognition and intervention for cardiogenic shock are crucial because delayed treatment is associated with increased mortality.3,4
Point-of-care ultrasound (POCUS) is a valuable bedside tool widely adopted across various pathophysiologies.5 This non-invasive, safe, and repeatable procedure is beneficial for the rapid assessment of shock conditions, allowing for timely diagnosis and clinical decision-making. POCUS plays a vital role in cardiology, particularly for evaluating cardiogenic shock, heart failure, and acute myocardial infarction (AMI).6–11 It is also useful in guiding the management of cardiogenic shock, including the initiation of mechanical circulatory support.3 Previous studies have demonstrated acceptable diagnostic accuracy of POCUS in patients with suspected cardiogenic shock,12 suggesting its potential to facilitate accurate diagnosis and timely intervention.
Despite its growing use in shock assessment, few studies have examined the prognostic impact of POCUS in patients with suspected cardiogenic shock. Therefore, we conducted this systematic review to evaluate the prognostic impact of POCUS in these patients.
Methods
The Japan Resuscitation Council (JRC) Emergency Cardiovascular Care Cardiovascular Shock Task Force was established by the Japanese Circulation Society, and the Japanese Society of Internal Medicine to develop the 2025 JRC guidelines. As a part of this study, the JRC Cardiovascular Shock Task Force formulated 12 key clinical questions. This article focused on addressing the following clinical question: Does POCUS improve clinical outcomes in patients with suspected cardiogenic shock?
P (patients): Adults (aged ≥18 years) admitted to the emergency department with suspected cardiogenic shock, including cardiac tamponade and pulmonary embolism.
I (intervention): Performing POCUS by emergency physicians.
C (comparison): Not performing POCUS by emergency physicians.
O (outcomes): All-cause mortality.
S (study design): All human studies, including randomized controlled trials (RCTs) and non-randomized controlled studies, which evaluated clinical outcomes of POCUS in patients with suspected cardiogenic shock.
T (time frame): All published research until December 31, 2023.
This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.13 Ethical approval was waived for this study due to collection and combination of data from previously published literature.
Search Strategy and Data Extraction
We included studies published in English that met all the PICOST criteria described above regardless of the study design. We conducted a comprehensive search for relevant literature on cardiogenic shock and POCUS using PubMed, Web of Science, and CENTRAL from inception to December 31, 2023. Our search strategy used the following keywords: shock, hypotension, ultrasound, echocardiography, point-of-care ultrasound, and POCUS (Supplementary Table). POCUS was defined as point-of-care echocardiography performed at the bedside to assess the etiology of shock during early clinical evaluation. Two investigators (T.O., N.N.) independently reviewed all the identified records (titles and abstracts) and assessed the selected full-text articles. Any discrepancies in the selection were resolved by discussion. Exclusion criteria were duplicates, studies without usable data, review articles, case reports/case series, letters, animal studies, and non-English studies.
Risk of Bias Assessment
Two authors independently assessed the methodological quality of the included studies. The risk of bias was evaluated using the revised Cochrane risk-of-bias tool (RoB 2) for RCTs and the risk of bias in non-randomized studies of intervention version 2 (ROBINS-I V2) for non-randomized studies based on their established guidelines.14,15 The risk of bias and applicability concerns were categorized as low, high, or unclear.
Rating the Certainty of Evidence
Using the GRADEpro system, we analyzed the quality of evidence for the studies and assessed factors such as the risk of bias, indirectness, inconsistency, imprecision, and publication bias, focusing on whether POCUS in the emergency department improved prognosis in patients with suspected cardiogenic shock. The certainty of evidence was judged as high, moderate, low, or very low.16
Statistical Analysis
Statistical analyses were performed using Stata 17.0 statistical software (Stata Corp., College Station, TX, USA). Relative risks (RRs) with 95% confidence intervals (CIs) were used to analyze dichotomous outcomes. We conducted separate systematic reviews for RCTs and observational studies due to anticipated heterogeneity in the study design and patient characteristics.
Results
Search Results and Characteristics of the Included Studies
A flow diagram of the data search and selection processes is shown in Figure 1. Overall, 3,759 articles were found in PubMed, Web of Science, and CENTRAL databases. After assessing titles and abstracts, 28 articles were included in the full-text review. Finally, 1 RCT and 1 observational study were included.17,18 Observational data complemented the limited evidence from the RCT and contributed to a broader understanding of the research question.
Figure 1.
Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart.
Table 1 presents the clinical characteristics of the included studies focusing on the prognostic impact of POCUS in patients with suspected cardiogenic shock. A total of 5,711 patients with undifferentiated shock were evaluated for the clinical effects of POCUS in those with suspected cardiogenic shock.
Table 1.
Baseline Clinical Characteristics of the Studies
| Study | Study type | Sample size |
Setting | Definition of shock |
POCUS performers | POCUS vs. non-POCUS |
|---|---|---|---|---|---|---|
| Prevalence of cardiogenic shock | ||||||
| Atkinson et al. (2018)17 |
RCT | 270 | Emergency department |
SBP <100 mmHg, or shock index >1.0 |
Emergency physicians certified in POCUS or residents under supervision |
11.6% vs. 9.6% |
| Mosier et al. (2019)18 |
Observational study |
5,441 | Emergency department |
Shock index >0.6 | POCUS-trained emergency medicine residents and faculties |
N/A |
N/A, not available; POCUS, point-of-care ultrasound; RCT, randomized controlled trial; SBP, systolic blood pressure.
RCT
In this trial,17 a total of 270 adult patients were analyzed after excluding those with predefined criteria. Eligible participants initially presented with sustained systolic blood pressure <100 mmHg or a shock index >1.0. Patients requiring cardiopulmonary resuscitation or mechanical circulatory support, those with electrocardiographic evidence of AMI, or those with an obvious cause of shock were excluded. In the analyzed cohort, cardiogenic shock was identified in 10.6% of patients. POCUS was performed in the emergency departments. A forest plot of all-cause mortality in this RCT is illustrated in Figure 2A. POCUS was not significantly associated with reduced mortality compared with non-POCUS. The all-cause mortality rates in this RCT are presented in Table 2. There were 4 fewer deaths per 1,000 patients (95% CI from 105 fewer to 98 more) in the POCUS group than in the non-POCUS group. The certainty of evidence in the RCT was downgraded due to imprecision, as the single RCT had a small sample size. In addition, because the study population included patients with conditions other than cardiogenic shock, the certainty of the evidence was downgraded due to indirectness. Consequently, the certainty of evidence in the RCT was low in the current clinical question.
Figure 2.
Forest plot of relative risk (RR) for all-cause mortality comparing the point-of-care ultrasound (POCUS) and non-POCUS groups in the randomized controlled trial (A), and the observational study (B). The central vertical line indicates an RR of 1.0.
Table 2.
Evidence Profile of this Study
| No. studies | Certainty assessment | No. patients | Effect | Certainty | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | POCUS | Non-POCUS | Relative (95% CI) | Absolute (95% CI) | ||
| All-cause mortality 1 | RCT | Not serious | Not serious | Serious | Serious | None | 32/136 (23.5%) | 32/134 (23.9%) | RR 0.99 (0.64–1.51) | 4 fewer per 1,000 (from 105 fewer to 98 more) |
⊕⊕○○ Low |
| All-cause mortality 1 | Observational study | Very serious | Not serious | Very serious | Not serious | None | 350/1,276 (27.4%) | 917/4,165 (22.0%) | RR 1.25 (1.12–1.39) | 54 more per 1,000 (from 27 more to 82 more) |
⊕○○○ Very low |
CI, confidence interval; RR, relative risk. Other abbreviations as in Table 1.
Observational Study
In this cohort, 5,441 adult patients were evaluated for hemodynamic instability, defined as a shock index >0.6 after excluding trauma. However, the prevalence of cardiogenic shock was not reported. POCUS examinations were performed in the emergency department setting. The forest plot of all-cause mortality in this observational study is shown in Figure 2B. POCUS was significantly associated with increased mortality compared with non-POCUS. There were 54 more deaths per 1,000 patients (95% CI from 27 more to 82 more), with the highest mortality observed in the group receiving POCUS before the intervention (Table 2). In this observational study, the risk of bias was judged to be critical and the certainty of evidence was downgraded by 2 levels (very serious). Regarding indirectness, we downgraded the certainty by 2 levels (very serious) because, in the POCUS group, examinations were conducted within 6 h of presentation, which may not fully reflect the real-world practice of POCUS by emergency physicians, and the included population was not limited to patients with cardiogenic shock. Consequently, the certainty of evidence in this observational study was very low.
Discussion
Although POCUS has been recognized as a valuable tool in the bedside assessment of patients with cardiogenic shock and has been integrated into practical diagnostic algorithms,19 our findings did not provide evidence supporting the idea that POCUS improves prognosis in patients with suspected cardiogenic shock.
Atkinson et al. recently reported the first RCT evaluating the prognostic impact of POCUS in patients with suspected cardiogenic shock.17 This international multicenter RCT was conducted across 3 emergency departments each in North America and South Africa. Patients with apparent AMI on a 12-lead electrocardiogram (ECG) were excluded. However, in real-world clinical practice, POCUS is particularly useful for patients with ECG findings mimicking AMI.7,20 For example, pericardial effusion may suggest myocarditis, whereas apical ballooning is characteristic of Takotsubo syndrome.21,22 These conditions differ from AMI in terms of pathophysiology and treatment strategies, and POCUS may contribute to appropriate treatment. Therefore, excluding these patients may reduce the applicability of our findings in real-world clinical settings.
Furthermore, echocardiography detection of regional wall motion abnormalities can enhance diagnostic accuracy beyond that of ECG alone. POCUS also enables the identification of mechanical complications associated with AMI that are often difficult to diagnose in a timely manner using ECG or computed tomography alone.23 Hence, echocardiography plays a critical role in determining the appropriate treatment strategies. Although patients with obvious underlying shock mechanisms were excluded from this RCT,17 incorporating POCUS could have further improved the diagnostic precision and supported optimal clinical decision-making. Despite being based on a single RCT, the certainty of evidence was low, indicating a low level of confidence in the findings.
The level of POCUS expertise may significantly influence diagnostic accuracy and patient outcomes. Physicians without sufficient training in POCUS may overlook critical findings, delay necessary diagnoses, or misinterpret results, potentially leading to inappropriate clinical decision-making.24 In the RCT, the examinations were conducted by trained physicians, which likely contributed to the low rate of misdiagnosis.17 Interestingly, this did not consistently lead to an accurate categorization. The limited improvement in diagnostic accuracy could be due to insufficient training in POCUS or its inherent limitations. Additionally, the findings suggest that relying too heavily on the imaging results of POCUS while overlooking clinical assessments may adversely affect clinical decision-making.
Mosier et al. conducted an observational study to evaluate the effect of POCUS in patients with undifferentiated shock.18 The study was conducted at 2 medical centers in the United States and categorized patients into 3 groups: non-POCUS, POCUS performed before the intervention, and POCUS performed after the intervention. Trained emergency medicine residents and faculty members performed POCUS examinations.
Interestingly, the highest mortality rate was observed in the group that underwent POCUS before the intervention compared with the non-POCUS group. The patients in this group also received fewer emergency department interventions, including lower volumes of intravenous fluid and reduced intubation rates. These findings suggest that treatment delays associated with POCUS timing may negatively influence clinical outcomes. However, an important limitation was that in the POCUS group, ultrasonography was performed within 6 h before the intervention. In contrast, in real-world emergency settings, POCUS may be performed later in the clinical course. This discrepancy could reduce the applicability of the study findings in routine practice. Moreover, the certainty of evidence derived from this observational study was rated as very low, indicating that the findings are highly uncertain. Therefore, these results should not be interpreted as definitive evidence for the utility of POCUS in clinical practice.
The clinical utility of POCUS likely varies depending on whether the cause of shock is immediately apparent. When the etiology is already clear, POCUS may function primarily as a confirmatory tool with minimal impact on management. In contrast, for patients with undifferentiated shock, POCUS offers real-time assessment of cardiac filling, volume status, and ventricular function, enabling more precise and potentially life-saving treatment decisions.
Although POCUS is widely used in the routine assessment of patients with shock in the real world, high-quality evidence supporting its prognostic impact remains limited, highlighting a critical knowledge gap. Although the present study did not demonstrate a clear benefit in improving outcomes, these results should not be considered as conclusive evidence against the clinical use of POCUS because of the limitations of the included studies.17,18
Study Limitations
This study has several limitations. First, this systematic review was limited by the small number of studies, consisting of only 1 RCT and 1 observational study. Given the differences in patient backgrounds between RCT and observational studies, the reliability of these conclusions remains uncertain. Second, this study did not perform subgroup analyses based on shock etiology, such as cardiogenic shock. In the observational study, the proportion of patients with cardiogenic shock was not clearly reported. The diagnostic accuracy of POCUS varies according to the shock type, potentially leading to different prognostic implications.12 Third, this study was conducted overseas, limiting its applicability to Japanese clinical settings. Due to discrepancies in emergency department systems between Japan and other countries, the results of this study must be interpreted with caution. Addressing these limitations requires large-scale studies.
Conclusions
Our systematic review suggests that POCUS may not significantly improve the prognosis in patients with suspected cardiogenic shock. Further large-scale studies are needed to clarify the potential prognostic benefits of POCUS.
Disclosures
T. Matoba is a member of Circulation Reports’ Editorial Team. The other authors have no conflicts of interest to declare with regard to this article. T. Matoba reported research grants from Amgen. T.K. received lecture fees from Abbott Japan LLC, AstraZeneca K.K., Boehringer Ingelheim, Ono Pharmaceutical Co., Ltd, Kowa Company, Ltd, and Kyowa Kirin Co., Ltd., and Novartis Pharma K.K. T. Mano received research grants from Abbott Medical Japan. The other authors have no conflicts of interest to disclose.
IRB Information
Not applicable.
Supplementary Files
Supplementary Table.
Acknowledgments
This work was supported by the Japan Resuscitation Council, Japan Circulation Society, and JSPS KAKENHI (grant no. JP23K08454). The authors thank Mr. Shunya Suzuki and Ms. Tomoko Nagaoka, librarians at the Dokkyo Medical University, Tochigi, Japan, for their support in the literature search.
Funding Statement
Sources of Funding: The authors have no relevant financial relationships to disclose.
Data Availability
All data analyzed in this study were extracted from published articles and are available in the article.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Supplementary Table.
Data Availability Statement
All data analyzed in this study were extracted from published articles and are available in the article.