Evaluation of Regional Wall Motion Abnormalities with Echocardiography in the Emergency Department

Abstract

Introduction Acute coronary syndrome (ACS) is a major cardiovascular disease, particularly in cases where standard electrocardiogram findings are equivocal. Focused cardiac ultrasound (FOCUS) has become increasingly accepted as a tool in emergency medicine. The primary objective of this study was to evaluate the accuracy, sensitivity, and specificity of FOCUS in detecting regional wall motion abnormalities (RWMA) compared with standard echocardiography (ECHO).

Materials and Methods This prospective observational study included 91 patients who presented to the emergency department between June 1, 2023, and November 30, 2023. Senior emergency physicians performed FOCUS examinations, which were performed by an emergency assistant or specialist who works in the emergency department, has at least 2 years of experience in ultrasonography (USG), and has basic USG and advanced USG certificates. The examinations assessed the presence of RWMA in each patient's left ventricle.

Results All 91 patients were included in the study for comparison with formal ECHO. The mean age was 58, and 32% of patients were female. Compared with the criterion standard of formal ECHO, the sensitivity of FOCUS performed by emergency physicians for detecting RWMA was 85% (95% confidence interval [CI], 73–92), the specificity was 53% (95% CI, 36–69), and the overall accuracy was 74% (95% CI, 64–82).

Conclusion Our study demonstrates the potential utility of FOCUS performed by emergency physicians in detecting RWMA in patients with high suspicion of ACS.

Keywords

acute coronary syndrome - echocardiography - electrocardiogram - focused cardiac ultrasound - regional wall motion abnormalities

Introduction

Acute coronary syndrome (ACS) is a major cardiovascular disease with high morbidity and mortality worldwide.[1] [2] Early diagnosis of ACS is critical in implementing effective treatment strategies and improving patient outcomes. In this context, additional diagnostic tools are needed to assist emergency physicians in diagnosing ACS, particularly in cases where standard electrocardiogram (ECG) findings are equivocal.[3]

Focused cardiac ultrasound (FOCUS) has become increasingly accepted as a tool in emergency medicine.[3] [4] [5] FOCUS is a noninvasive imaging modality that can be used quickly and effectively in the emergency department. Specifically, it may be useful in the detection of left ventricular (LV) regional wall motion abnormalities (RWMA), particularly in acute myocardial infarction.[6] [7] However, the sensitivity and specificity of FOCUS in detecting RWMA can vary between emergency physicians with different levels of training and experience. This variation may be a significant factor in the effectiveness and reliability of FOCUS use in the emergency department.

The primary objective of this study was to evaluate the accuracy, sensitivity, and specificity of FOCUS in detecting RWMA compared with standard echocardiography (ECHO). The assessment by the emergency physician performing FOCUS was considered positive if abnormal motion was detected in at least one wall of the LV and if these findings were consistent with the results of standard ECHO performed by a cardiologist or with specific anatomical site occlusions identified during cardiac catheterization. Standard ECHO is defined as ECHO performed directly by a cardiologist or a cardiology fellow under the supervision of a cardiologist. Secondary endpoints include determining the sensitivity of FOCUS in detecting RWMA in patients with obstructive myocardial infarction (OMI) confirmed by cardiac catheterization and assessing the sensitivity of cardiac FOCUS in detecting RWMA in patients without OMI.

Materials and Methods

Design and Settings

This prospective observational study included 91 patients who presented to the emergency department with suspected ACS within a specified time frame. The study was conducted at the Emergency Department of Antalya Training and Research Hospital between June 1, 2023, and November 30, 2023. The Ethics Committee of Antalya Training and Research Hospital approved the study, and all patients gave written informed consent before participating.

Inclusion criteria were patients aged 18 years and older with suspected ACS who underwent FOCUS in the emergency department. Exclusion criteria were patients with ST-segment elevation on the ECG, patients who did not underwent percutaneous coronary intervention within 72 hours, patients without records, patients for whom FOCUS cannot be performed, and conditions unsuitable for FOCUS (e.g., severe respiratory failure).

FOCUS Application

Senior emergency physicians performed FOCUS examinations. It was performed by an emergency assistant or specialist who works in the emergency department, has at least 2 years of experience in ultrasonography (USG), and has basic USG and advanced USG certificates. These doctors had different levels of expertise in performing FOCUS scans. They assessed the presence of RWMA in each patient's LV.

Study Protocol and Data Collection

This study evaluated patients with suspected ACS based on ECG findings and clinical features in our emergency department. Patients who met the criteria for ST-segment elevation myocardial infarction (STEMI) on ECG were consulted with a cardiology specialist and referred for coronary angiography (CA) without undergoing FOCUS.

Patients presenting with symptoms of ACS and suspected of having an OMI based on ECG changes but not meeting STEMI criteria were assessed with FOCUS by the emergency physician and with standard ECHO by a cardiologist. The emergency physicians recorded the FOCUS data without reviewing the standard ECHO findings.

Data extracted from the hospital information system included the presence or absence of RWMA on FOCUS or subsequent formal ECHO, cardiac catheterization results (if performed), patient status, and survival. Data collectors remained blinded to outcome data.

Senior emergency physicians performed FOCUS examinations. It was performed by an emergency assistant or specialist who works in the emergency department, has at least 2 years of experience in USG, and has basic USG and advanced USG certificates. Physicians participating in the study were experienced in defining RWMA and had previously received training in certification programs. The LV walls were simplified as anterior, inferior, lateral, and posterior. Formal ECHO used 17-segment guidelines, while FOCUS was performed with parasternal long, parasternal short, apical four-chamber, and apical two-chamber views. RWMA was considered positive if abnormalities were detected in one or more regions. We did not assess the specific regions of wall motion abnormalities or the exact location of the abnormalities.

Patient demographics, presenting symptoms, ECG results, and FOCUS findings were recorded on admission. Each RWMA identified during FOCUS was documented for each patient. ECHO and CA results performed by cardiologists were recorded by reviewing hospital system reports.

Statistical Analysis

Descriptive statistics were used to summarize the data. Categorical variables were presented as numbers and percentages, while continuous variables were summarized using means and standard deviations and medians and interquartile ranges. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and their 95% confidence intervals (95% CIs) were calculated using binary categorical tables. Statistical analysis was performed with SPSS version 29.

Result

Between June 1, 2023 and November 30, 2023, 91 patients considered at high risk of ACS were enrolled in the study. All 91 patients underwent FOCUS procedures in the emergency department. The presence or absence of RWMA was recorded for all 91 patients. All 91 patients were included in the study for comparison with formal ECHO. The mean age was 58, and 32% of patients were female. Additional patient characteristics are shown in [Table 1].

Table 1 Demographic and clinical characteristics of the patients

Characteristics		Data[a]
Gender	Female	29 (32%)
	Male	62 (65%)
Age (y)	Mean (SD)	58.5 (8.5)
	Median (IQR)	58 (52–65)
History	Diabetes	23 (25%)
	Hypertension	39 (43%)
	Hyperlipidemia	24 (26%)
	Congestive heart failure	18 (20%)
	Coronary artery disease	44 (48%)
Door-FOCUS time (min)	Mean (SD)	20.6 (8.5)
	Median (IQR)	20 (15–25)
Door-ECHO time (min)	Mean (SD)	127.5 (23)
	Median (IQR)	120 (120–140)
PCI	OMI +	59 (65%)
	OMI –	32 (35%)

Abbreviations: ECHO, echocardiography; FOCUS, focused cardiac ultrasound; IQR, interquartile range; OMI, obstructive myocardial infarction; PCI, percutaneous coronary intervention; SD, standard deviation.

^a Data are frequency (%) unless otherwise specified.

Compared with the criterion standard of formal ECHO, the sensitivity of FOCUS performed by emergency physicians for detecting RWMA was 85% sensitivity (95% CI, 73–92), the specificity was 53% (95% CI, 36–69), PPV was 77 (95% CI, 65–85), NPV was 65 (95% CI, 46–81), and the overall accuracy was 74% (95% CI, 64–82).

All 91 patients underwent either emergency or nonemergency CA, and 65% were diagnosed with OMI on CA. FOCUS, performed by emergency physicians, detected RWMA in 85% of patients with OMI, confirmed by CA ([Table 2]).

Table 2 Comparison of FOCUS and PCI results

		PCI
		Acute OMI absent	Acute OMI positive
FOCUS	RWMA +	17 (53%)	9 (15%)
	RWMA –	15 (47%)	50(85%)

Abbreviations: FOCUS, focused cardiac ultrasound; OMI, obstructive myocardial infarction; PCI, percutaneous coronary intervention; RWMA, regional wall motion abnormalities.

Discussions

Our study, a high-risk cohort of patients with high suspicion of ACS, demonstrated that FOCUS used by emergency physicians accurately identified RWMA in a cohort undergoing high-risk emergency cardiac catheterization. Notably, these findings were more definitive in patients with OMI identified by cardiac catheterization. These data suggest that the presence of RWMA in a patient with a high suspicion of ACS based on history, physical examination, and ECG further increases the suspicion of OMI. However, the absence of RWMA does not decrease the likelihood of OMI. These findings, together with other studies, suggest that using FOCUS in cases of OMI without meeting STEMI criteria in the emergency setting may benefit patients.[6] [7] [8] In such scenarios, activating the emergency catheterization laboratory requires diagnostic tests beyond the ECG (e.g., serum troponin levels, ongoing ischemic symptoms, etc.).[9] Therefore, the presence of RWMA in a cardiac region consistent with the ECG, even if not meeting STEMI criteria, may be sufficient to activate the emergency catheterization laboratory. However, further studies are needed.

Our study was conducted in patients undergoing emergency cardiological assessment and urgent reperfusion. This reflects clinical practice (e.g., limited time for FOCUS, difficult patient positioning due to noncooperation, etc.). Although this may have affected the quality of the FOCUS results to a lesser or suboptimal extent, it made the results more generalizable and reflective of the current clinical environment.

Given the different conditions that can cause RWMA in the absence of ACS, our study practically investigated RWMA in cases of OMI confirmed by cardiac catheterization, which is ultimately the cohort that emergency physicians aim to identify. Another strength of our study was the inclusion of patients at high risk of ACS despite not meeting STEMI criteria.[10-13] Using ultrasound in this population is important for emergency physicians and cardiology teams in equivocal ECG situations and may aid in diagnosing OMI. This cohort of patients represents a target group where delays to cardiac catheterization in current algorithms for the management of ACSs may lead to increased mortality. Future studies should investigate the performance characteristics of FOCUS performed by emergency physicians in cases of non-STEMI but suspected OMI.[14] In such studies, those with STEMI on their ECG may be excluded due to door-to-balloon time metrics and, in some cases, direct admission to the catheterization laboratory, bypassing the emergency department entirely or rapidly.

Our study has several limitations. The limited use of FOCUS in many cases may further limit its validity. A larger prospective study is needed to explore this issue further.

In addition, the emergency physicians performing FOCUS needed to be briefed on the clinical information, particularly the ECG. This could lead to observer bias, particularly in reporting regional wall involvement. However, this reflects current clinical practice, where presentation and ancillary investigations are performed concurrently. Our important limitation is that ECHOs performed by cardiology are performed by only one physician, even if an expert or experienced person performs them. Another limitation is that we should have specifically assessed the volume of FOCUS examinations performed by our emergency physicians before they participated in this study. Clinicians with more experience and comfort with FOCUS are more likely to perform and document ultrasound more frequently, potentially reducing the generalizability of the study. In addition, certain patient groups, such as obese individuals, those with chest wall abnormalities, or those with positioning difficulties, may have been underrepresented or not included in the study, potentially biased the data.

Similarly, image acquisition and interpretation are two different skills. If the clinician performing FOCUS cannot obtain high-quality images, interpretation may be compromised. In addition, this patient population may not be generalizable to patients with underlying cardiac disease. Such patients (e.g., structural heart disease, conduction abnormalities, etc.) may have abnormal wall motion defects, further limiting the usefulness of FOCUS in diagnosing OMI. Finally, this study includes a population at high risk for acute coronary occlusion. All patients in this study underwent cardiac catheterization, and high rates of OMI were observed during cardiac catheterization. Therefore, these results may not be generalizable to patients with low to moderate ACS risk.

Conclusion

Our study demonstrates the potential utility of FOCUS performed by emergency physicians in detecting RWMA in patients with high suspicion of ACS. This may be particularly beneficial in cases where the ECG is inconclusive, but the clinician maintains a high suspicion for OMI and in patients without STEMI on ECG. The presence of RWMA in such cases may lead to earlier activation of the emergency catheterization laboratory, but this requires further investigation. While the presence of RWMA may help to identify OMI, its absence should not rule it out. Further research is required to validate these findings.

Conflict of Interest

None declared.

Authors' Contributions

Y.K. and C.B.: Conceptualization, data curation, investigation, methodology, supervision, validation, visualization, writing – original draft, writing – review and editing. F.S. and O.Z.: Supervision, validation, visualization, writing – original draft, writing – review and editing.

Compliance with Ethical Principles

The study was approved by the Health Science University Antalya Training and Research Hospital Ethical Committee. Informed consent was obtained from the participants before data collection.

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Publikationsverlauf

Artikel online veröffentlicht:
11. Juli 2024