|MP 2.02.23||Electrocardiographic Body Surface Mapping|
|Original Policy Date
|Last Review Status/Date
Reviewed with literature review/8:2012
|Return to Medical Policy Index|
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Electrocardiographic body surface mapping (BSM) is an electrocardiographic (ECG) technique that uses multiple (generally 80 or more) electrocardiography leads to detect cardiac electrical activity. It is suggested that the use of multiple leads may result in improved diagnostic accuracy compared to the standard 12-lead ECG. One potential use of this device is in the early evaluation of occult ischemia in patients who do not meet the current definition of ST-elevation myocardial infarction (STEMI). Another potential use is a more rapid stratification of low-risk chest pain patients who present to the emergency department.
Electrocardiographic body surface mapping (BSM) consists of an 80-lead disposable electrode array in the form of a vest that includes a conducting gel that is applied to the patient’s chest and back. The vest can be applied in less than 5 minutes. This system displays clinical data in three forms; a colorimetric 3-D torso image, an 80-lead single beat view, and the 12-lead ECG. The colorimetric torso images are said to allow the practitioner to rapidly scan the heart for significant abnormalities.
Currently, in patients presenting to the emergency department with symptoms suggestive of myocardial ischemia, a standard 12-lead ECG is obtained. In the presence of ST segment elevation on the ECG, personnel are activated to respond in a timely manner to open a presumed coronary artery occlusion, either by mechanical means though balloon angioplasty, or medically through intravenous thrombolytic drugs. The 12-lead ECG has a specificity of 94%, leading to relatively few erroneous interventions. However, the sensitivity is about 50%. These patients may be further stratified by scoring systems and time-sensitive cardiac enzymes, which may require up to 24 hours of monitored observation.
BSM is being considered as a method to assist in the rapid identification of patients who would benefit from earlier coronary artery intervention than currently achieved utilizing current standard of care. The negative predictive value of the test, which has the potential to identify patients who do not require further evaluation with serial cardiac enzymes and clinical observation, is not currently receiving attention as a research topic.
In March 2002, the device “PRIME ECG®” (Verathon, Bothell, WA) was cleared for marketing by the U.S. Food and Drug Administration (FDA) through the 510(k) process. The FDA determined that the device was substantially equivalent to existing devices for use in recording of ECG signals on the body surface.
Note: This policy only addresses use of this technique in the diagnosis or management of acute myocardial infarction or acute coronary syndrome and not the diagnosis or management of coronary artery disease (CAD).
Electrocardiographic body surface mapping is considered investigational for the diagnosis or management of cardiac disorders including acute coronary syndrome.
Beginning July 1, 2007, there are 3 CPT category III codes specific to this procedure:
0178T: Electrocardiogram, 64 leads or greater, with graphic presentation and analysis; with interpretation and report
0179T: tracing and graphics only, without interpretation and report
0180T: interpretation and report only
BlueCard/National Account Issues
Some state or federal mandates (e.g., FEP) prohibit Plans from denying FDA-approved technologies as investigational. In these instances, Plans may have to consider the coverage eligibility of FDA-approved technologies on the basis of medical necessity alone.
This policy was originally created in 2007 and was regularly updated with searches of the MEDLINE database. The most recent literature search was performed for the period of June 2011 to June 2012. Following is a summary of the key literature to date:
Assessment of a diagnostic technology focuses on the following three parameters: 1) its technical performance; 2) diagnostic parameters (sensitivity, specificity, positive and negative predictive value) in different populations of patients; and 3) demonstration that the diagnostic information can be used to improve patient outcomes (clinical utility).
The investigation of additional leads in electrocardiography and body surface mapping is not new. Patterns of electric potentials in normal subjects have been established, and the significance of abnormal signals has been explored over past decades. (1-2)
A 2006 publication describes the use of the 80-lead technique in the evaluation of patients with chest pain in the emergency department. (3) The authors comment that use of this approach has been hampered by slow acquisition time and the complexity of interpretation but that technological advances are overcoming these limitations. However, they also add that the future of BSM in emergency medicine is unclear and that more research is needed to define its benefits and limitations.
In 2007, Lefebvre and colleagues described the improvements in technical performance and ease of use in recent modifications to body surface mapping technologies. A standardized vest improves lead placement, and changes to software direct clinicians’ attention to locations on the body mapping that may be significant, possibly reducing the amount of training needed. (4)
For patients with suspected ischemia, does electrocardiographic body surface mapping (BSM) improve the accuracy of diagnosis for acute myocardial infarction (AMI) and/or acute coronary syndrome (ACS), compared to standead 12-lead ECG?
A systematic review of BSM was published by the National Heart Attack Alert Program Working Group in 2001. (5) Four studies with a total subject population of 897 were identified related to the use of BSM in the diagnosis of acute myocardial infarction (AMI) and one study with 52 patients was identified related to the diagnosis of acute coronary syndrome (AMI plus unstable angina). No studies related to clinical outcomes were identified. For the identification of AMI, sensitivity ranged from 59 to 83%; specificity ranged from 76 to 93%. For the identification of AMI plus unstable angina (one study), sensitivity was 96% while specificity was 41%.
In 2010, the Agency for Healthcare Research and Quality (AHRQ) published a technology assessment on the diagnostic utility of electrocardiographic (ECG)-based signal analysis technologies for patients at low to intermediate risk of coronary artery disease (CAD). (6) The AHRQ assessment combined data from 6 studies on the PRIME ECG totaling 1,869 patients. Using a bivariate, random-effects model, the summary estimate for sensitivity was 68% (95% confidence interval [CI]: 63-74), and for specificity was 86% (95% CI: 83-90). The likelihood ratio positive was 5.0 (95% CI: 3.5-6.5), and the likelihood ratio negative was 0.37 (95% CI: 0.30-0.43). These combined summary estimates were compared to summary estimates compiled from 5 studies reporting 12-lead ECG performance on a total of 1,555 patients. The summary estimates from these 5 studies were sensitivity of 61% (95% CI: 46-76), specificity of 94% (95% CI: 92-96), likelihood ratio positive of 8.8 (95% CI: 5.8-11.7), and likelihood ratio negative of 0.52 (95% CI: 0.46-0.59). The AHRQ assessment found ECG body surface mapping demonstrated “slightly more favorable performance characteristics compared to the standard ECG among patients with ischemic-type chest pain.” However, the authors concluded “the differences were not large and are unlikely to affect current diagnostic strategies.”
While most studies have shown higher sensitivity for BSM, some have shown lower specificity. Menown reported that use of BSM improved the early diagnosis of right ventricular or posterior infarcts in those with acute inferior wall infarction. (6) Among 62 patients with inferior myocardial infarction, posterior ST changes of at least 1 mV were seen on ECG in 1 patient compared to posterior wall BSM changes in 17 patients.
In a retrospective study conducted at four centers, Ornato and colleagues reviewed the cardiac enzyme-confirmed cases of acute MI against results of 12-lead ECG and BSM. (7) Due to a change in standard practice during the study, AMI was defined by either elevated troponin, or heart-specific creatinine kinase (CK-MB). Of 647 patients, 58 (8.9%) were not analyzed due to lack of enzyme data. Sensitivity comparison between BSM and 12-lead ECG in the CK-MB group favored BSM (100% vs. 72.7%, p =.031; n =364), and also in the troponin group (92.9% vs. 60.7%, p =.022; n =225). Specificity for BSM was not significantly different from 12-lead ECG in either group (96.5% vs. 97.1 and 94.9 vs. 96.4 both respectively).
In a retrospective study of 755 patients presenting to emergency, mobile cardiac care or in hospital with symptoms of ischemic chest pain, Owens and colleagues reported on BSM sensitivity and specificity to detecting troponin-positive ischemia. Each patient’s clinical course was guided by standard American College of Cardiology 12-lead ST-segment criteria and subsequent cardiac enzymes, if electrocardiographically negative. A cardiologist blinded to the clinical details measured BSM retrospectively. AMI was defined by elevated cardiac troponin levels. The standard 12-lead electrocardiograph demonstrated a sensitivity of 45% and specificity 92%. When non-ST electrographic changes were permitted as part of the criteria for AMI, sensitivity increased (51% to 68%) but specificity decreased (71% to 89%). In this study, BSM performed with a sensitivity of 76% and specificity of 92%.
Fermann and colleagues found very different performance characteristics of BSM in comparison to 12-lead ECG from previous studies. (10) A convenience sample of 150 patients with chest pain presenting to the emergency department had BSM measured within 30 minutes of the standard ECG. Emergency physicians, who had been trained in BSM, interpreted both the BSM and ECGs at the time of presentation. Both were stored electronically for review by a BSM expert over read; after the study had ended, a convenience sample of 135 BSMs were over read. Ten out of 43 (23.3%) patients judged to have normal BSM by the emergency physician were judged to have abnormal findings or frank infarction by the expert interpreter. Overall correlation between the emergency physicians and expert reviewer was only fair (correlation coefficient κ =0.627; 95% confidence interval [CI]: 0.530-0.724). Sensitivity of both standard ECG and BSM were low at 10.5 (95% CI: 1.8-34.5) and 15.8 (95% CI: 4.2-40.5) respectively. This low sensitivity likely reflects the spectrum of patients in the study. Specificities were also comparable between the two groups at 90.1(95% CI: 83.3-94.4) and 86.3(95% CI: 78.9-91.4) respectively.
In 2010, O’Neil and colleagues published results from a secondary analysis of the Optimal Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction (OCCULT-MI) trial. (11) A multicenter (10-site), prospective, observational study, the OCCULT-MI trial enrolled 1,830 subjects presenting to the emergency department with moderate- to high-risk chest pain. Patients were simultaneously tested with 12-lead and 80-lead ECGs, with clinicians able to access the 12-lead results only. The patients were treated by standard care based on 12-lead result or clinical suspicion. Off-site clinicians, who were not involved in the patients’ care, reviewed the 80-lead ECG and made a diagnostic determination, validated through multiple reviewers.
In this publication, 12-lead ECG was compared to 80-lead ECG mapping for detecting high-risk ECG abnormalities. Patients diagnosed with ST elevation myocardial infarction (STEMI) by 12-lead ECG (n =91), and patients with missing data (n =255) were excluded from the analysis on specificity and sensitivity. When detecting myocardial infarction (MI) and acute coronary syndrome (ACS), the 80-lead ECG mapping sensitivity was significantly higher than the 12-lead ECG for MI (19.4% vs. 10.7%, p =0.0014) and for ACS (12.3% vs. 7.1%, p =0.0025). The authors attributed these low sensitivity rates to the exclusion of STEMI patients in this analysis. Specificity for the 80-lead ECG mapping was significantly lower than the 12-lead ECG for MI (93.9% vs. 96.4%, p =0.0005) and for ACS (93.7% vs. 96.4%, p =0.0005). Positive and negative predictive values and negative and positive likelihood ratios were not statistically different between the 12-lead and 80-lead groups. The 80-lead ECG mapping resulted in the identification of 18 additional MI patients and 21 additional ACS patients who could potentially have benefited from more aggressive treatment. However, the 80-lead ECG mapping results were not incorporated into treatment decision making, and thus no conclusions can be made from this study on the impact of this technology on patient outcomes. Also, the authors did not explore the impact of decreased specificity, and increased false positive rates, on patient outcomes. Other limitations of this study include lack of enrollment of low-risk emergency department patients and the lack of power to detect differences in ACS diagnosis.
In 2012, Daly et al. also compared 12-lead ECG to 80-lead ECG mapping in a retrospective review of 2,810 consecutive patients admitted with ischemic-type chest pain. (12) All patients included in the study had coronary angiography and cardiac troponin levels during admission. The analysis was confined to patients with significant left main stem (LMS) coronary stenosis (greater than 70%), which was found in 116 (4.1%) patients. Of these 116 patients with LMS coronary stenosis, 92 (79%) had AMI, diagnosed when cardiac troponin levels were 0.03 µg/L or higher. BSM was found to be more sensitive for diagnosing AMI in patients with LMS coronary stenosis compared to 12-lead ECG. BSM detected STEMI in 85/92 patients for an 88% sensitivity, 83% specificity, 95% positive predictive value, and 65% negative predictive value. 12-lead ECG (using Minnesota 9-2 criteria) detected STEMI in 13 patients (11%), for a 12% sensitivity and 92% specificity. The c-statistic for the diagnosis of AMI in patients with LMS stenosis by 12-lead ECG was 0.580 (95% CI: 0.460–0.701, p=0.088) compared to 0.800 [95% CI: 0.720–0.881; p<0.001] using physician interpretation of BSM or 0.792 (95% CI: 0.690–0.894, p<0.001) using the “PRIME ECG®” algorithm.
Conclusions. Numerous published studies compare the accuracy of BSM with standard 12-lead electrocardiography for the diagnosis of ACS. These studies are mostly retrospective and do not enroll the ideal clinical populations, i.e., consecutive patients presenting with clinical signs/symptoms of ischemia. They also compare the accuracy of BSM alone with 12-lead EKG alone. This is less clinically relevant because 12-lead EKG is not used alone to diagnose ACS, but rather is combined with the clinical presentation and results of cardiac enzymes.
The results of the available studies report that BSM has a higher sensitivity for diagnosing ACS compared to 12-lead EKG. The difference in sensitivity is variable among the available studies, and the clinical significance of the difference in sensitivity is uncertain. The specificity of BSM may be lower than 12-lead EKG, as some studies report lower specificity but others do not. Because of the uncertainty in the sensitivity and specificity in the available studies, it is not possible to estimate the tradeoff between additional cases of ACS detected and false-positive results leading to further unnecessary testing. Further prospective studies are needed that include relevant clinical populations and that compare the incremental value of BMS when used as part of the overall diagnostic workup for ACS.
Does electrocardiographic body surface mapping (BSM) lead to changes in management that improve health outcomes?
The AHRQ assessment, noted above, found: 'There is currently little available evidence that pertains to the utility of ECG-based signal analysis technologies as a diagnostic test among patients at low to intermediate risk of CAD who present in the outpatient setting with the chief complaint of chest pain.” (6) The assessment concluded, “Further research is needed to better characterize the performance characteristics of these devices to determine in what circumstances, if any, these devices might precede, replace, or add to the standard ECG for the diagnosis of CAD among patients who present with chest pain in the outpatient setting. The randomized controlled trial (RCT) study design is best suited for evaluating the impact that ECG-based signal analysis technologies may have on clinical decision making and patient outcomes, but there are indirect approaches that might be applied to answer these questions.'
In another publication on the OCCULT-MI trial described above, in 2009, Hoekstra and colleagues published primary study results. (11,12) This trial was mentioned in the 2010 AHRQ assessment but was not included in the summary analysis since it was published after the assessment’s search date. Primary outcome in the OCCULT-MI trial was door-to-sheath time in 12-lead STEMI patients versus door-to-sheath time in patients with ST elevations noted on 80-lead testing. Secondary outcomes were clinical outcomes at 30 days and angiographic data. Of the 1,830 subjects, 91 had a discharge diagnosis of STEMI, 84 of whom underwent cardiac catheterization with a mean door-to-sheath time of 54 minutes. Twenty-five subjects (1.4% of the study population) met criteria for ST elevation in the 80-lead alone, 14 of whom underwent cardiac catheterization with a mean door-to-sheath time of 1,002 minutes (estimated treatment difference: 881; 95% CI: 181 to 1,079 minutes, respectively). Neither 30-day clinical outcomes, nor adverse events, differed significantly in the identified at-risk groups. These 25 patients were in addition to the 91 STEMI patients identified on 12-lead, leading the authors to conclude that the additional leads identified 27.5% more acute MI patients than 12-lead alone (25/91).
An accompanying editorial by Hollander acknowledges the limitation of 12-lead ECG in identifying patients with acute MI. However, a distinction is made between those patients for whom it is well established that early intervention is beneficial (i.e., STEMI on standard 12-lead ECG) and those for whom BSM is positive but 12-lead is not. It is not known whether these patients benefit from early intervention. The editor suggests that the patients identified thusly are more similar to the non-ST elevation myocardial infarction (NSTEMI) patients based on peak troponin levels found in the Hoekstra et al. study (12) and that identification of these patients should not lead to a change in treatment. (14)
Conclusions. There are no studies that demonstrate how BSM can be used to change clinical management in ways that improve health outcomes. Indirect evidence suggests that BSM might be used in a subset of patients presenting with suspected ACS to reduce the time to diagnosis and thereby provide revascularization more expediently. Whether this strategy improves outcomes has yet to be demonstrated. In order to demonstrate clinical utility, the ideal study design is a randomized controlled trial in which patients are randomized to BSM or standard 12-lead EKG, and patients are followed for changes in management and clinical outcomes.
Ongoing Clinical Trials
A search of the online site ClinicalTrials.gov, in July 2012, did not identify any ongoing studies on BSM. One large study (NCT00560248), the Best Expert Agreement for Care of Occult Myocardial Infarction Nationally (BEACON) has been terminated due to loss of funding.
Electrocardiographic body surface mapping (BSM) is an electrocardiographic (ECG) technique that uses multiple (generally 80 or more) electrocardiography leads to detect cardiac electrical activity. The use of multiple leads may result in improved diagnostic accuracy, compared to that of the standard 12-lead ECG.
A number of studies have examined the association between electrocardiographic body surface mapping and acute myocardial infarction, but no prospective trials using body surface mapping to guide treatment have been conducted. Results of published studies have been variable, but under ideal conditions, it is possible that body surface mapping has a higher sensitivity than 12-lead ECG alone for acute coronary events. However, the data also suggest that the specificity may be lower, highlighting concerns regarding false-positive results. In clinical practice, patients with symptoms suspicious for ischemia are not diagnosed with 12-lead ECG alone but in combination with clinical presentation and serial cardiac enzymes. There is no evidence demonstrating that electrocardiographic body surface mapping leads to changes in management that improve health outcomes. Therefore, clinical utility of the body surface mapping technique, both in terms of benefits and risks and burdens, has not been demonstrated. As a result, this technique is considered investigational.
Practice Guidelines and Position Statements
The American College of Cardiology Foundation guidelines for electrocardiography standardization and interpretation recognize that while the studies of body surface maps from large electrode arrays have provided useful information about localization of ECG information on the thorax, at this time their complexity precludes their use as a substitute for the standard 12-lead ECG for routine recording purposes. (15)
Medicare National Coverage
There is no national coverage decision.
|CPT||0178T||Electrocardiogram, 64 leads or greater, with graphic presentation and analysis; with interpretation and report (effective 7/1/07)|
|0179T||tracing and graphics only, without interpretation and report (effective 7/1/07)|
|0180T||interpretation and report only (effective 7/1/07)|
|ICD-9 Diagnosis||Investigational for all diagnoses|
|ICD-10-CM (effective 10/1/13)||Investigational for all diagnoses|
|ICD-10-PCS (effective 10/1/13)||ICD-10-PCS codes are only used for inpatient services.|
|4A02X4Z||Measurement, physiological systems, cardiac, external, electrical activity|
Electrocardiography, 64 leads or greater
|06/14/07||Add to Medicine section, Cardiology subsection||New policy|
|07/10/08||Replace policy||Policy updated with literature search, reference number 5 added. No change in policy statement.|
|07/09/09||Replace policy||Policy updated with literature search, reference number 6 added. No change in policy statement|
|08/12/10||Replace policy||Policy updated with literature search, reference 1, 2, 5, 7-12 added. No change in policy statement.|
|8/11/11||Replace policy||Policy updated with literature search, references 6 and 11 added. No change in policy statement.|
|08/09/12||Replace policy||Policy updated with literature search, reference 12 added. No change in policy statement.|