Abstract
Background
Handheld echocardiography (HHE) is concordant with standard transthoracic echocardiography (TTE) in a variety of settings but has not been thoroughly compared to traditional TTE in patients with acute myocardial infarction (AMI).
Hypothesis
Completed by experienced operators, HHE provides accurate diagnostic capabilities compared with standard TTE in AMI patients.
Methods
This study prospectively enrolled patients admitted to the coronary care unit with AMI. Experienced sonographers performed HHE with a V‐scan. All patients underwent clinical TTE. Each HHE was interpreted by 2 experts blinded to standard TTE. Agreement was assessed with κ statistics and concordance correlation coefficients.
Results
Analysis included 82 patients (mean age, 66 years; 74% male). On standard TTE, mean left ventricular (LV) ejection fraction was 46%. Correlation coefficients between HHE and TTE were 0.75 (95% confidence interval: 0.66 to 0.82) for LV ejection fraction and 0.69 (95% confidence interval: 0.58 to 0.77) for wall motion score index. The κ statistics ranged from 0.47 to 0.56 for LV enlargement, 0.55 to 0.79 for mitral regurgitation, and 0.44 to 0.57 for inferior vena cava dilatation. The κ statistics were highest for the anterior (0.81) and septal (0.71) apex and lowest for the mid inferolateral (0.36) and basal inferoseptal (0.36) walls.
Conclusions
In patients with AMI, HHE and standard TTE demonstrate good correlation for LV function and wall motion. Agreement was less robust for structural abnormalities and specific wall segments. In experienced hands, HHE can provide a focused assessment of LV function in patients hospitalized with AMI; however, HHE should not substitute for comprehensive TTE.
Keywords: Acute Coronary Care, Acute Coronary Syndrome, Echocardiography, Myocardial Infarction
1. INTRODUCTION
Transthoracic echocardiography (TTE) plays an important role in the management of patients with acute myocardial infarction (AMI).1, 2 However, the standard TTE unit remains a bulky apparatus, which may hinder its utility in rapid bedside assessment of critically ill intensive care unit patients. Therefore, the development of portable handheld ultrasound devices with adequate cardiac diagnostic capabilities, also known as handheld echocardiography (HHE), has the potential to facilitate beside clinical assessment, expedite triage, and, ultimately, improve outcomes in patients with AMI.
Prior studies have found that HHE can accurately evaluate left ventricular (LV) ejection fraction (LVEF), ventricular size, regional wall motion, and the presence of a pericardial effusion when compared with standard TTE.3, 4, 5, 6, 7, 8, 9, 10, 11 HHE can augment the physical exam and alter clinical decision‐making in general cardiology settings.12, 13
However, HHE devices also carry limitations. Evaluation of valvular heart disease with HHE does not correlate as well with standard TTE as do other parameters.8, 10 Also, accuracy of HHE remains highly dependent on the experience of the user.6, 14, 15 Even in experienced hands, HHE can fail to detect important diagnostic findings.11 Finally, studies evaluating HHE have typically enrolled unselected patients, performed limited examinations, or had only single or a few individuals obtain images with the handheld devices.3, 4, 5, 6, 7, 9, 10
Despite this prior work, studies of the current HHE devices have not validated their diagnostic capabilities in patients with AMI. It is important to understand the accuracy of HHE devices in this setting as the use of HHE, by users with highly variable training backgrounds, grows. Therefore, this study sought to assess the diagnostic accuracy of HHE in the hands of experienced operators vs standard TTE in hospitalized patients with AMI. We hypothesized that HHE, when performed by experienced sonographers and interpreted by expert clinicians, provides accurate diagnostic capabilities compared with standard TTE in patients with AMI.
2. METHODS
2.1. Patient selection
We conducted a prospective study of patients admitted to a 16‐bed coronary care unit (CCU) at Mayo Clinic Hospital with AMI. We included patients with either a non–ST‐segment elevation myocardial infarction (NSTEMI) or an ST‐segment elevation myocardial infarction (STEMI). We defined NSTEMI and STEMI based on standard criteria.16 Patients were enrolled from February 18, 2013, through September 13, 2013. To determine eligibility, study authors (MWC, JBG) reviewed the daily CCU morning census and identified newly admitted patients with an AMI. A research sonographer approached eligible patients for informed consent. The Mayo Clinic Institutional Review Board approved this study.
2.2. Equipment
This study used a Vivid E9 (GE Healthcare, Waukesha, WI) or iE33 (Philips Healthcare, Andover, MA) for the standard TTE examinations. HHE was performed with a V‐scan (GE Healthcare, Waukesha, WI) in all patients (see Supporting Information, Figure, in the online version of this article). The V‐scan weighs 13.8 ounces (391 g) and measures 5.3 × 2.9 × 1.1 inches (13.5 × 7.4 × 2.8 cm) in size. It obtains 2‐dimensional grayscale and color Doppler images with a 3.8‐MHz phased‐array transducer. The V‐scan does not possess zoom, spectral Doppler, or the ability to perform velocity or time measurements. No electrocardiogram interface is present. The V‐scan analyzes the ultrasound image to detect and store images 1 cardiac cycle in length. If the V‐scan cannot identify a cardiac cycle, it stores a 2‐second clip. The US Food and Drug Administration approved the V‐scan in 2009.17
2.3. Echocardiographic examination
If patients consented to the study, the sonographer performed an echocardiogram in as comprehensive a manner as technically possible with the V‐scan. The HHE examination included 2‐dimensional and color Doppler images from the standard parasternal, apical, and subcostal windows. All HHE exams were uploaded to the V‐scan's viewing software. Experienced, level 3–trained echocardiography experts (authors NSA, JWA, and JKO) interpreted the following criteria on the HHE examination: LV size (normal, mildly enlarged, ≥moderately enlarged), visually estimated LVEF, LV regional wall‐motion abnormality (present vs absent) based on the 16‐segment model,18 right ventricular (RV) function (normal vs decreased), stenotic valvular heart disease (present vs absent), regurgitant valvular heart disease (≤mild vs ≥ moderate), pericardial effusion (present vs absent), and inferior vena cava size (normal vs dilated). Reviewers did not perform regular quantitative analysis of the HHE images due to the lack of practically applicable measuring and calculation tools on the HHE. We felt this approach was reasonable because qualitative analysis of HHE images most accurately reflects their use in daily practice. However, rudimentary calipers were available for the reviewers to use at their discretion. All interpretations of stenotic and regurgitant lesion severity were based on qualitative visual assessment given the V‐scan's lack of quantitative Doppler capabilities. The pulmonary valve was not assessed. The review included a qualitative global assessment of HHE image quality on a 4‐level ordinal scale (in descending order of quality: excellent, good, adequate, and inadequate for interpretation). The interpreters remained blinded to the results of the standard TTE. Two experts reviewed each HHE exam.
Patients also underwent standard TTE as part of routine clinical care. Sonographers attempted to perform the HHE as close in time as possible to the standard TTE. Data from the clinical report of the standard TTE were collected through our institutional echocardiography database. Different sonographers performed the clinical TTE and HHE exams, thus limiting the possibility for bias. Given that they were clinical studies, we did not perform global quality assessment of the standard TTEs as we did for the HHE exams.
Data regarding the diagnosis (NSTEMI or STEMI), coronary territory impacted, and treatment were obtained through medical‐record review. Infarct territory was determined from the overall clinical impressions of the treating physicians and not solely based on echocardiogram results.
2.4. Statistical analysis
Continuous variables are reported as mean ± SD or median (interquartile range). Categorical variables are reported as number (%) of the total group. Agreement between the HHE and standard TTE was assessed with the Cohen κ statistic or weighted κ for categorical variables and correlation coefficients for continuous variables. For continuous variables, Lin's concordance correlation coefficients were estimated by variance components. The κ statistic for HHE vs standard TTE was calculated for each of the 3 reviewers due to repeated measures within each subject; κ statistics of 0.41 to 0.60 were considered moderate agreement; 0.61 to 0.80, good agreement; and ≥0.81 excellent agreement.19 Agreement was also assessed using the methods of Bland and Altman.20 Results from the standard TTE were considered the gold standard for this study.
3. RESULTS
3.1. Patient characteristics
This study enrolled 100 patients, of which 18 were excluded: 7 because the sonographer was unable to complete the HHE exam, frequently due to clinical instability; 9 because the patient did not undergo a standard TTE during their hospitalization; and 2 because the patients were ultimately diagnosed with a stress‐induced cardiomyopathy rather than AMI. Therefore, the study group under analysis included 82 patients. Mean age was 66 ± 14 years, and 74% were male. Infarct treatment included percutaneous coronary intervention with or without thrombolytics in 65 patients (79%), surgical revascularization in 5 patients (6%), and medical treatment alone in 12 patients (15%). Table 1 outlines the characteristics of the study patients.
Table 1.
Clinical and echocardiographic characteristics of the study population
| Mean age, y | 66 ± 14 |
| Male sex | 61 (74) |
| Diagnosis | |
| STEMI | 61 (74) |
| NSTEMI | 21 (26) |
| MI territory | |
| Anterior | 29 (35) |
| Inferior | 30 (37) |
| Lateral | 4 (5) |
| Indeterminate | 19 (23) |
| Treatment | |
| Medical | 12 (15) |
| Surgical revascularization | 5 (6) |
| PCI | 58 (71) |
| Thrombolysis + PCI | 7 (9) |
| Median LVEF on standard TTE, % | 47 (35–58) |
| LVEF ≤40% on standard TTE | 29 (35) |
| Median WMSI on standard TTE | 1.6 (1.3–2.0) |
Abbreviations: IQR, interquartile range; LVEF, left ventricular ejection fraction; MI, myocardial infarction; NSTEMI, non–ST‐segment elevation myocardial infarction; PCI, percutaneous coronary intervention; SD, standard deviation; STEMI, ST‐segment elevation myocardial infarction; TTE, transthoracic echocardiography; WMSI, wall motion score index.
Data are presented as n (%), mean ± SD, or median (IQR).
3.2. Echocardiography examinations
HHE was performed a median of 4.5 hours before the standard TTE (interquartile range, 11.7 hours before to 1.1 hours after the standard TTE). Coronary revascularization occurred between the time of HHE and TTE in only 2 patients. The mean duration of the HHE studies was 10 ± 2 minutes, with a mean of 41 ± 9 stored images. The standard TTE studies included a mean of 96 ± 28 stored images.
The most frequent quality score from a single reviewer was “good” (39% of observations) and the second most frequent was “adequate” (31% of observations). Five studies received an “inadequate for interpretation” score from both reviewers, and 4 studies received an “excellent” score from both reviewers.
Table 2 displays the distribution of echocardiographic findings on the standard TTE. LV enlargement was present in 26 subjects (32%). RV dysfunction was present in 25 patients (31%), and the inferior vena cava was dilated in 23 patients (31%) when visualized. Significant valvular regurgitation or stenosis was a relatively infrequent finding on standard TTE, with the most common abnormality, mitral regurgitation, occurring in only 9 patients (11%). Significant LV dysfunction (ie, LVEF ≤40%) was present in 29 patients (35%).
Table 2.
Agreement between HHE and standard TTE for each reviewer of the HHE studies
| Finding | Prevalence of Finding on Standard TTE, n (%)a | Reviewer 1, n = 56, κ | Reviewer 2, n = 52, κ | Reviewer 3, n = 56, κ |
|---|---|---|---|---|
| LV enlargement | 0.49 (0.21 to 0.77) | 0.47 (0.78 to 0.15) | 0.56 (0.31 to 0.81) | |
| None | 56 (68) | |||
| Borderline to mild | 15 (18) | |||
| ≥Moderate | 11 (13) | |||
| RV dysfunction | 25 (31) | 0.10 (–0.18 to 0.39) | 0.24 (–0.03 to 0.50) | 0.10 (–0.13 to 0.33) |
| Aortic stenosis, ≥mild | 4 (5) | 0.00 (–5.4E‐7 to 5.4E‐7) | 0.54 (0.08 to 1.00) | 0.54 (0.09 to 1.00) |
| Aortic regurgitation, ≥moderateb | 1 (1) | 0.66 (0.03 to 1.3) | NAg | –0.03 (–0.06 to 0.01) |
| Mitral regurgitation, ≥moderatec | 9 (11) | 0.79 (0.39 to 1.2) | 0.55 (0.17 to 0.94) | 0.67 (0.37 to 0.97) |
| Tricuspid regurgitation, ≥moderated | 6 (7) | 0.78 (0.48 to 1.1) | 0.48 (–0.14 to 1.0)h | 0.55 (0.10 to 0.99) |
| Pericardial effusion, presente | 9 (11) | 0.62 (0.28 to 0.96) | 0.16 (–0.22 to 0.53) | 0.56 (0.18 to 0.94) |
| IVC dilatationf | 23 (31) | 0.44 (0.17 to 0.71) | 0.48 (0.13 to 0.84) | 0.57 (0.32 to 0.81) |
| LVEF ≤40% | 29 (35) | 0.44 (0.17 to 0.71) | 0.48 (0.13 to 0.84) | 0.57 (0.32 to 0.81) |
Abbreviations: CI, confidence interval; HHE, handheld echocardiography; IVC, inferior vena cava; LV, left ventricular; LVEF, left ventricular ejection fraction; NA, not available; RV, right ventricular; TTE, transthoracic echocardiography.
Percentages are based on the 82 analyzed patients in the study, unless otherwise indicated.
Aortic regurgitation severity was not reported on the standard TTE in 6 patients and therefore available in 76 patients.
Mitral regurgitation severity was not reported on the standard TTE in 3 patients and therefore available in 79 patients.
Tricuspid regurgitation was not reported on the standard TTE in 1 patient and therefore available for analysis in 81 patients.
All pericardial effusions present in this study were tiny or small based on standard TTE.
IVC dilatation was not reported on the standard TTE in 7 patients and therefore available for analysis in 75 patients.
No aortic regurgitation ≥moderate was present on the studies from Reviewer 2.
The upper bound of the CI was 1.1, which exceeds the upper bound of Cohen's κ. Therefore, this value was set to 1.0.
3.3. Agreement and correlation
3.3.1. LVEF
Figure 1A demonstrates the correlation for LVEF between the standard TTE and HHE. Concordance correlation coefficient was 0.75 (95% confidence interval [CI]: 0.66 to 0.82). Figure 1C demonstrates the Bland–Altman plot for agreement between HHE and TEE for assessing LVEF. The largest difference in LVEF between the HHE and standard TTE occurred in the middle of the reported range, between 40% and 55%. Table 3 displays the correlation of LVEF between the standard TTE and HHE according to the territory of MI. No significant difference existed in LVEF across MI territory.
Figure 1.
(A and B) Linear correlation between standard TTE and HHE for (A) LVEF and (B) WMSI. Overall correlation was good, with a concordance correlation coefficient of 0.75 for LVEF and 0.69 for WMSI. (C and D) Bland–Altman correlation between standard TTE and HHE for (C) LVEF and (D) WMSI. The light‐dashed line represents the mean of the difference between TTE and HHE. The darker dashed lines represent 1 and 2 SDs away from the mean difference. (C) For LVEF, Bland–Altman correlation demonstrates a larger difference between the TTE and HHE within the mid‐range of LVEF. (D) For WMSI, Bland–Altman correlation demonstrates a similar difference between the standard and handheld echocardiograms across levels of wall‐motion scores. The LVEF and WMSI on HHE were calculated by averaging the reported LVEF and WMSI from the 2 reviewers of each HHE study. Abbreviations: HHE, handheld echocardiography; LVEF, left ventricular ejection fraction; SD, standard deviation; TTE, transthoracic echocardiography; WMSI, wall motion score index.
Table 3.
Concordance correlation between HHE and standard TTE according to infarct territorya
| Infarct Territoryb | n (%) | LVEF | WMSI |
|---|---|---|---|
| All patients | 82 (100) | 0.75 (0.66 to 0.82) | 0.69 (0.58 to 0.77) |
| Anterior | 29 (35) | 0.77 (0.62 to 0.87) | 0.66 (0.45 to 0.80) |
| Inferior | 30 (37) | 0.59 (0.38 to 0.75) | 0.47 (0.23 to 0.66) |
| Indeterminate | 19 (23) | 0.69 (0.44 to 0.84) | 0.76 (0.55 to 0.88) |
Abbreviations: CI, confidence interval; HHE, handheld echocardiography; LVEF, Left ventricular ejection fraction; TTE, transthoracic echocardiography; WMSI, wall motion score index.
Concordance correlation coefficients are reported with 95% CIs.
Four patients suffered lateral infarctions and were not included as a separate row in this table due to the small group size.
Due to poor image quality, LVEF could not be estimated on the HHE by ≥1 reviewer in 5 patients and by both reviewers in 1 patient. In this patient, the standard TTE utilized echocardiographic contrast to enhance endocardial border definition, and the reviewer of the clinical study commented that image quality was poor despite the use of echocardiographic contrast.
3.3.2. Wall‐motion analysis
Figure 1B demonstrates the correlation for wall motion score index (WMSI) between the standard TTE and HHE. Concordance correlation coefficient was 0.69 (95% CI: 0.58 to 0.77). Figure 1D demonstrates the Bland–Altman plot for agreement between HHE and TEE for assessing WMSI. Similar differences in WMSI were present across the distribution of wall‐motion scores. Table 3 also demonstrates the correlation of WMSI between the standard TTE and HHE according to the territory of MI. As with LVEF, no significant difference existed in WMSI correlation across MI territory.
Table 4 demonstrates agreement for the presence of segmental regional wall‐motion abnormalities between the HHE and standard TTE. The reported κ statistics represent the average of the κ values for HHE reviewer 1 vs standard TTE and HHE reviewer 2 vs standard TTE. Agreement was highest for the anterior‐septal and apical regions and lower in the inferior and inferior lateral segments at the basal and mid‐ventricular levels.
Table 4.
LV regional wall motion abnormality agreement between HHE and standard TTE and wall‐segment visualization on HHE
| Segment | Agreement Between Standard TTE and HHEa | Frequency With Which Segment Not Visualized by ≥1 HHE Reviewer, n (%)b |
|---|---|---|
| Basal anterior | 0.39 | 9 (11) |
| Basal anterior lateral | 0.41 | 6 (7) |
| Basal inferior lateral | 0.51 | 6 (7) |
| Basal inferior | 0.67 | 6 (7) |
| Basal inferior septal | 0.36 | 5 (6) |
| Basal anterior septal | 0.61 | 6 (7) |
| Mid anterior | 0.64 | 9 (11) |
| Mid anterior lateral | 0.43 | 6 (7) |
| Mid inferior lateral | 0.36 | 7 (9) |
| Mid inferior | 0.40 | 5 (6) |
| Mid inferior septal | 0.46 | 5 (6) |
| Mid anterior septal | 0.66 | 5 (6) |
| Apical anterior | 0.81 | 8 (10) |
| Apical lateral | 0.59 | 8 (10) |
| Apical inferior | 0.48 | 7 (9) |
| Apical septal | 0.71 | 8 (10) |
Abbreviations: HHE, handheld echocardiography; LV, left ventricular; TTE, transthoracic echocardiography.
Agreement is presented as κ statistics for the presence of regional wall motion abnormalities, calculated from the average of κ for HHE Reviewer 1 vs standard TTE and HHE Reviewer 2 vs standard TTE.
Percentages are based on the 82 analyzed patients in the study.
Table 4 also displays the frequency with which the HHE could not appropriately visualize a wall segment to make a definitive determination regarding the presence or absence of a wall‐motion abnormality. The anterior basal wall and the anterior mid‐ventricular wall were the most common segments that were not visualized. In 2 HHE studies, multiple LV wall segments were not visualized by both HHE reviewers. Both of these patients required use of echocardiographic contrast during their standard TTE to improve endocardial border definition. One of these studies was the same in which neither HHE reviewer could estimate LVEF.
3.3.3. Other echocardiographic parameters
Table 2 outlines agreement between HHE and standard TTE across each HHE reviewer for the additional echocardiographic parameters in this study. Agreement was moderate for LV enlargement (κ = 0.47–0.56) and poor for RV dysfunction (κ = 0.10–0.24). Agreement was moderate to good for detection of significant mitral and tricuspid regurgitation (κ = 0.55–0.79 and 0.48–0.78, respectively). Agreement was moderate for inferior vena cava dilatation (κ = 0.44–0.57) and moderate for LVEF ≤40% (κ = 0.44–0.57).
4. DISCUSSION
This study sought to compare the diagnostic capabilities of HHE with standard TTE in CCU patients hospitalized with AMI. In contrast to prior studies where clinicians with varying degrees of training performed HHE exams, we asked experienced sonographers to perform a comprehensive examination as close in time as possible to the standard TTE. We found that HHE and standard TTE demonstrated good correlation for LV function (concordance correlation coefficient: 0.75) and overall wall‐motion assessment (concordance correlation coefficient: 0.69). Correlation for LVEF and WMSI did not vary according to the territory of the MI. Agreement between HHE and standard TTE for LV size, RV dysfunction, pericardial effusions, and inferior vena cava dilatation was less robust. Furthermore, agreement was highly variable for interpretation of wall‐motion abnormalities in specific LV segments; and the correlation for LVEF, although typically considered “good,” may not be high enough for clinicians to consider HHE and TTE interchangeable. These findings suggest that, in experienced hands, HHE may provide a focused assessment of global LV systolic function and wall motion in patients with AMI. However, HHE should not be used for a comprehensive assessment of cardiac structure and function.
The prevalence of valvular disease or other significant structural abnormalities in our patients was low (Table 2). Although agreement for ≥moderate mitral and tricuspid regurgitation was adequate, this study cannot adequately comment on the ability of HHE to detect mechanical complications of AMI. HHE devices are significantly limited, however, in their Doppler capabilities. The V‐scan device our study used has basic color Doppler capabilities but no ability to perform continuous‐wave or pulsed‐wave Doppler assessment. Measurements are limited to simple linear dimensions. Thus, the ability of HHE devices to quantify regurgitant lesions, evaluate the severity of stenotic valvular disease, and assess diastolic function and filling pressures is rudimentary at best. Therefore, though experienced operators may use HHE to augment their bedside assessment of AMI patient, HHE should not replace standard TTE.
The major findings of this study align well with existing literature. As in the current investigation, prior work has demonstrated good correlation between HHE and standard TTE for LVEF when experienced users perform the HHE exams.6, 9 Assessment of regional wall motion has proven more difficult with HHE. Other studies have found that assessment of regional wall‐motion abnormalities with HHE produces more variability than with standard TTE.9 Furthermore, results from our institution show that discrepancies in wall‐motion assessment can occur between TTE and HHE, even in experienced hands.11 Our study reports good correlation in overall WMSI between standard TTE and HHE (Figure), with more variable agreement on a segmental basis (Table 4). The good correlation between standard TTE and HHE for WMSI likely reflects overall agreement for LV systolic function. The reduced agreement on a segmental basis may be related to the decreased image quality and limited ability to optimize images with HHE devices. The finding that reviewers were not able to visualize specific segments in many HHE studies (Table 4) also suggests that HHE devices do not offer sufficient image quality for precise segmental wall‐motion analysis.
Our work extends the findings of previous HHE studies to patients with AMI. This carries clinical importance because prior studies have not specifically addressed this patient cohort. The need to rapidly diagnose and triage AMI patients makes the use of HHE particularly appealing. Our findings demonstrate that, in the hands of experienced users, HHE may provide a gross evaluation of cardiac function. However, it should not be used to perform precise structural and functional assessments, particularly if standard TTE is readily available. The findings of this study did not vary based on territory of the AMI (Table 3), suggesting that performance of HHE is not more or less reliable in different regions of MIs.
Our study excluded 2 patients who, after a comprehensive evaluation including comprehensive TTE and invasive coronary angiography, were diagnosed with a stress‐induced cardiomyopathy rather than an AMI. Although it is not unreasonable to perform HHE in patients when attempting to differentiate a stress‐induced cardiomyopathy from an AMI, given the established diagnostic limitations of echocardiography in the evaluation of stress‐induced cardiomyopathy, all patients in whom the diagnosis of stress‐induced cardiomyopathy is entertained still require an anatomic assessment of the coronary arterial system by current standards.21
4.1. Study limitations
This is a single‐institution study with a relatively small sample size. However, we collected the data prospectively and focused on a specific patient population (ie, critically ill patients with AMIs). The HHE and standard TTE exams were performed a mean of 4.5 hours apart. Given the physiological variability in patients with AMI, it is possible that evolution of patients' cardiac function and hemodynamics could account for some of the variation between the HHE and TTE findings. This may be particularly relevant to assessment of inferior vena cava size, as a reflection of changing central venous pressures and could explain some of the disagreement for that variable between HHE and TTE. Notably, 7 patients were excluded because the research sonographer could not complete the HHE exam, often because of clinical instability. Therefore, this analysis did not include perhaps the most labile patients, where one might expect the largest change in physiology and hemodynamics over time.
It is possible that some of the disagreement between standard TTE and HHE reflects interobserver variability between the reviewers of the HHE studies. As previously documented, visual estimation of LVEF can be subject to substantial variation both within and between interpreters.22 However, it is unlikely that interobserver variability accounts for all of the disagreement. Prior data from our laboratory demonstrated agreement in resting wall‐motion assessment in 96% of segments examined in patients undergoing dobutamine echocardiography.23 Therefore, some of the disagreement between TTE and HEE likely reflects the inability of the HHE to detect subtle findings that standard TTE can identify.
5. CONCLUSION
In summary, we found that HHE, when performed and interpreted by experienced operators, offers good correlation against standard TTE with regard to global LV function assessment and wall motion in patients with AMIs. HHE, in the hands of experienced users, can facilitate the rapid bedside assessment of AMI patients. However, HHE does not offer sufficient image quality to reliably assess segmental regional wall motion. Agreement is also less robust for LV size and RV function. Therefore, HHE should not serve as a substitute for comprehensive echocardiography in patients with AMI, particularly when standard TTE is readily available.
Conflicts of interest
The authors declare no potential conflicts of interest.
Supporting information
Figure S1. The V‐scan from GE Healthcare (Waukesha, Wisconsin) was the HHE device we used in this study (image from http://www3.gehealthcare.com/en/products/categories/ultrasound/vscan_family/vscan, accessed May 29, 2017).
Cullen MW, Geske JB, Anavekar NS, Askew JW, Lewis BR, and Oh JK. Handheld echocardiography during hospitalization for acute myocardial infarction. Clin Cardiol. 2017;40:993–999. 10.1002/clc.22754
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Associated Data
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Supplementary Materials
Figure S1. The V‐scan from GE Healthcare (Waukesha, Wisconsin) was the HHE device we used in this study (image from http://www3.gehealthcare.com/en/products/categories/ultrasound/vscan_family/vscan, accessed May 29, 2017).