Body Surface Potential Mapping

Number: 0705

Policy

Aetna considers body surface potential mapping (also known as body surface mapping) experimental and investigational for the following indications (not an all-inclusive list):

• Evaluation of acute coronary syndromes (e.g., acute cardiac ischemia and myocardial infarction)
• Evaluation of atrial fibrillation
• Evaluation of Brugada syndrome
• Guidance of atrial fibrillation ablation
• Prediction of response in cardiac resynchronization therapy

See also CPB 0664 - Signal-Averaged Electrocardiography (SAECG).

Background

The conventional 12-lead electrocardiogram (ECG) is the principal risk stratification device for patients presenting with chest pain to the emergency department.  However, it has been suggested that the 12-lead ECG may not be optimal in the diagnostic assessment of acute coronary syndromes such as acute cardiac ischemia and myocardial infarction (MI) since the coverage of the standard pre-cordial leads over the thorax is limited.  Some researchers have attempted to address this problem via the use of additional leads or body surface potential mapping (BSPM), also known as body surface mapping.  Body surface potential mapping is a relatively new technology that has been developed for use in the emergency department, cardiac care unit, or the cardiac catheterization laboratory to assist in the early diagnosis of an acute cardiac ischemia and MI.

Body surface potential mapping uses 64 or more electrodes (as many as 120) to record and measure electrocardiac activity over a much larger portion of the torso than the traditional 12 lead-ECG to provide a comprehensive 3-dimensional picture of the effects of electrical currents from the heart on the body surface.  It has been used for patients with conditions such as pulmonary embolism, aortic dissection and acute coronary syndromes.  It has also been used for diagnosing old inferior MI, localizing the bypass pathway in Wolff-Parkinson-White syndrome, recognizing ventricular hypertrophy, and ascertaining the location, size, and severity of the infarcted area in acute MI and the effects of different interventions designed to reduce the size of the infarct.  Currently, the main limiting factor for the advent of this new technology is the complexity of the recording and analysis, which requires multiple leads, sophisticated instrumentation, and dedicated personnel. PRIME-ECG (Meridian Medical Technologies Inc., Columbia, MD) is a BSPM system cleared by the Food and Drug Administraion (FDA) through the 510(k) process.

Although ongoing research continues to address the role of BSPM, the clinical effectiveness of this procedure has not been established.  In this regard, this procedure is not discussed in the American College of Cardiology/American Heart Association Guideline Updates for the management of patients with MI or heart disease (Braunwald et al, 2002).  In addition, it is not listed by the American Heart Association (2005) as a test for detecting heart damage or one of the non-invasive tests for diagnosing heart disease.  Additionally, a study by Hänninen et al (2003) stated that BSPM presently serves as a research tool for studying the electrophysiological manifestations of acute coronary syndrome to the body surface.  The improved characterization of these phenomena may help in non-invasive localization and estimation of the size of the infarcted myocardial region.  However, more research is needed to ascertain the value of BSPM in the diagnostic assessment of acute coronary syndromes.

Carley and colleagues (2005) determined if body surface mapping (BSM) is better than the standard 12-lead ECG in the diagnosis of acute MI amongst emergency department patients.  Subjects were individuals presenting to an emergency department with symptoms compatible with myocardial ischemia/MI.  Main outcome measures were MI as defined by either standard 12-lead ECG changes with associated cardiac marker rise: troponin T greater than 0.1 ug/ml at over 12 hours, or autopsy/surgical findings of fresh macroscopic infarction.  BSM had an overall sensitivity of 47.1 % versus 40 % for the 12 lead ECG (p < 0.001).  Specificity for the BSM was 85.6 % versus 93.7 % for the 12-lead ECG (p < 0.001).  These findings were consistent for low-/moderate- and high- risk subgroups.  Bayesian analysis demonstrates that indiscriminate use of BSM would result in a clinically important over-diagnosis of MI among emergency department patients.  The authors concluded that BSM has a higher sensitivity, but a lower specificity for the diagnosis of MI.

Tragardh et al (2006) stated that the number of leads needed in clinical ECG depends on the clinical problem to be solved.  The standard 12-lead ECG is so well-established that alternative lead systems must prove their advantage through well-conducted clinical studies to achieve clinical acceptance.  Certain additional leads seem to add valuable information in specific patient groups.  The use of a large number of leads (e.g., in BSPM) may add clinically relevant information, but it is cumbersome and its clinical advantage is yet to be proven.

Lefebvre and Hoekstra (2007) stated that the future of BSM in the emergency department is not yet known; but will be aided by the ongoing large-scale Optimal Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction (OCCULT-MI) trial.

Hoekstra et al (2009) examined the prevalence, clinical care patterns, and clinical outcomes of patients with ST-elevation myocardial infarction (STEMI) identified on 80-lead but not on 12-lead (80-lead-only STEMI).  The OCCULT-MI trial was a multi-center prospective observational study of moderate- to high-risk chest pain patients presenting to the emergency department (ED).  Patients received simultaneous 12-lead and 80-lead ECGs as part of their initial evaluation and were treated according to the standard of care, with clinicians blinded to the 80-lead results.  The primary outcome of the trial was door-to-sheath time in patients with 80-lead-only STEMI versus patients with STEMI identified by 12-lead alone (12-lead STEMI).  Secondary outcomes included angiographical and clinical outcomes at 30 days.  A total of 1,830 patients were evaluated, 91 had a discharge diagnosis of 12-lead STEMI, and 25 patients met criteria for 80-lead-only STEMI; 84 of the 91 12-lead STEMI patients underwent cardiac catheterization, with a median door-to-sheath time of 54 mins, versus 14 of the 25 80-lead-only STEMI patients, with a door-to-sheath time of 1,002 mins (estimated treatment difference in median = 881; 95 % confidence interval [CI]: 181 to 1,079 mins).  Clinical outcomes and re-vascularization rates, however, were similar between 80-lead-only STEMI and 12-lead STEMI patients.  The authors concluded that the 80-lead ECG provides an incremental 27.5 % increase in STEMI detection versus the 12-lead.  Patients with 80-lead-only STEMI have adverse outcomes similar to those of 12-lead STEMI patients but are treated with delayed or conservative invasive strategies.

O'Neil and colleagues (2010) noted that the initial 12-lead ECG has low sensitivity to detect MI and acute coronary syndromes (ACS) in the ED.  Yet, early therapies in these patients have been shown to improve outcomes.  This secondary analysis analyzed the incremental value of the 80-lead over the 12-lead in the detection of high-risk ECG abnormalities (ST-segment elevation or ST depression) in patients with MI and ACS, after eliminating all patients diagnosed with STEMI by 12-lead ECG.  Chest pain patients presenting to 1 of 12 academic EDs were diagnosed and treated according to the standard care of that site and its clinicians; the clinicians were blinded to 80-lead results.  Myocardial infarction was defined by discharge diagnosis of non-ST-elevation MI (NSTEMI) or unstable angina (UA) with an elevated troponin.  Acute coronary syndrome was defined as discharge diagnosis of NSTEMI or UA with at least 1 positive test result (angiogram, stress test, troponin) or re-vascularization procedure.  Of the 1,830 patients enrolled in the trial, 91 patients with physician-diagnosed STEMI and 225 patients with missing 80-lead or 12-lead data were eliminated from the analysis; no discharge diagnosis was available for 1 additional patient.  Of the remaining 1,513 patients, 408 had ACS, 206 had MI, and 1 had missing status.  The sensitivity of the 80-lead was significantly higher than that of the 12-lead for detecting MI (19.4 % versus 10.4 %, p = 0.0014) and ACS (12.3 % versus 7.1 %, p = 0.0025).  Specificities remained high for both tests, but were somewhat lower for 80-lead than for 12-lead for detecting both MI and ACS.  Negative and positive likelihood ratios (LR) were not statistically different between groups.  In patients with severe disease (defined by stenosis greater than 70 % at catheterization, percutaneous coronary intervention, coronary artery bypass graft, or death from any cause), the 80-lead had significantly higher sensitivity for detecting MI (with equivalent specificity), but not ACS.  The authors concluded that among patients without ST elevation on the 12-lead ECG, the 80-lead BSM technology detects more patients with MI or ACS than the 12-lead, while maintaining a high degree of specificity.

A technology assessment prepared for the Agency for Healthcare Research and Quality's on ECG-based signal analysis technologies (Coeytaux et al, 2010) stated that the reliability and test performance of BSM in coronary artery disease (CAD) is promising.  The horizon scan identified 7 potentially relevant devices, including 3 that use BSM and 1 that uses mathematical signal analysis.  Of the 7 devices, only the PRIME ECG by Heartscape Technologies (BSM) and the 3DMP/MCG/ mfEMT by Premier Heart (mathematical signal analysis; referred to as the 3DMP) are cleared for marketing by the FDA and commercially available.  One BSM device (Visual ECG/Cardio3KG by NewCardio) is commercially available but not cleared; the other devices are not commercially available.  The assessment concluded: "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.  The limited evidence that is available demonstrates proof of concept, particularly for the PRIME ECG and 3DMP devices.  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 decisionmaking and patient outcomes, but there are indirect approaches that might be applied to answer these questions".

Cochet et al (2014) demonstrated the feasibility of comprehensive assessment of cardiac arrhythmias by combining BSM and imaging.  A total of 27 patients referred for electrophysiologic procedures in the context of ventricular tachycardia (VT) (n = 9), Wolff-Parkinson-White (WPW) syndrome (n = 2), atrial fibrillation (AF) (n = 13), or scar-related ventricular fibrillation (VF) (n = 3) were examined.  Patients underwent BSM and imaging with multi-detector computed tomography (CT) (n = 12) and/or delayed enhanced magnetic resonance (MR) imaging (n = 23).  Body surface mapping was performed by using a 252-electrode vest that enabled the computation of epicardial electrograms from body surface potentials.  The epicardial geometry used for BSM was registered to the epicardial geometry segmented from imaging data by using an automatic algorithm.  The output was a 3-D cardiac model that integrated cardiac anatomy, myocardial substrate, and epicardial activation.  Acquisition, segmentation, and registration were feasible in all patients.  In VT, this enabled a non-invasive assessment of the arrhythmia mechanism and its location with respect to the myocardial substrate, coronary vessels, and phrenic nerve.  In WPW syndrome, this enabled understanding of complex accessory pathways resistant to previous ablation.  In AF and VF, this enabled the non-invasive assessment of arrhythmia mechanisms and the analysis of rotor trajectories with respect to the myocardial substrate.  In all patients, models were successfully integrated in navigation systems and used to guide mapping and ablation.  The authors concluded that by combining information on anatomy, substrate, and electrical activation, the fusion of BSM and imaging enables comprehensive non-invasive assessment of cardiac arrhythmias, with potential applications for diagnosis, prognosis, and ablation targeting.  The effectiveness of BSM for these potential clinical applications need to be ascertained in well-designed studies.

In a pilot study, Kania and colleagues (2014) evaluated myocardial ischemia by analysis of ST-segment changes in high-resolution BSPM (HR-BSPM) measured at rest and during an exercise stress test.  The study was carried out on a group of 28 patients with stable CAD and 15 healthy volunteers.  The HR-BSPMs were measured at rest and during the exercise stress test on a supine ergometer.  The work-load was increased in stages by 25 W every 2 mins, beginning at 50 W.  The maps of ST-segment depression (ST60) were calculated from time averaged recordings at rest and at maximal work-load.  The efficiency in detection of myocardial ischemia was higher for HR-BSPM than for standard 12-lead ECG when both methods were evaluated by outcomes of coronarography.  The sensitivity of HR-BSPM was 82.4 % while for the standard 12-lead ECG exercise stress test it was 58.8 %.  For some patients significant changes in the ST segment were observed at stress HR-BSPM but were not visible in standard 12-lead ECG recorded under the same conditions.  The authors concluded that obtained high values of sensitivity and specificity in myocardial ischemia detection suggested that maps of ST60 calculated from HR-BSPM can improve detection of patients with ischemic heart disease in comparison to the standard electrocardiographic exercise stress test examinations.  The findings of this pilot study need to be validated by well-designed studies.

Evaluation/Guidance of Atrial Fibrillation

Konrad et al (2014) stated that techniques facilitating individual mapping and ablation of arrhythmogenic substrates are desired to enhance the understanding of persistent AF (persAF) mechanisms as a pre-requisite to increasing the success rates of single procedure persAF catheter ablation.  The technique of BSPM involves the use of multiple electrodes to collect the potentials over a large body surface area and, with the use of a computed tomography scan, it facilitates their correlation to a 3-D model of the atrial structures.  During AF, the visualization and localization of AF driver activity, both re-entrant and focal wave-fronts, is possible with this technique.  The ECVUE system from CardioInsight was examined for this indication in clinical studies and showed a termination rate of persAF of 63 % in a large multi-center trial (AFACART) with a promising low recurrence rate during follow-up.  The authors concluded that from their initial experience, the system appeared to be effective in persAF patients who have continuous AF for less than 1 year.  However, they stated that the utility of the system for highly challenging cases like long-standing persistent AF and patients with very short AF cycle length remains to be explored.  They stated that further studies are needed to confirm these data and answer the multitude of open questions in this field.

Furthermore, UpToDate reviews on “The electrocardiogram in atrial fibrillation” (Olshansky, 2015), “Overview of atrial fibrillation” (Cheng and Kumar, 2015), and “Management of new onset atrial fibrillation” (Phang and Olshansky, 2015) do not mention body surface potential mapping as a management tool.

UpToDate reviews on “Catheter ablation to prevent recurrent atrial fibrillation: Clinical applications” (Passman, 2016a), “Catheter ablation to prevent recurrent atrial fibrillation: Technical considerations” (Passman, 2016b), “Maintenance of sinus rhythm in atrial fibrillation: Catheter ablation versus antiarrhythmic drug therapy” (Passman, 2016c), and “Surgical ablation to prevent recurrent atrial fibrillation” (Lee, 2016) do not mention the use of body surface potential mapping for guiding AF ablation.

Evaluation of Brugada Syndrome

Ueoka and colleagues (2016) stated that clinical and experimental studies have shown the existence of an arrhythmogenic substrate in the right ventricular outflow tract (RVOT) in patients with Brugada syndrome (BrS). These researches evaluated the activation pattern of induced ventricular tachyarrhythmias using BSM in patients with BrS.  They examined 14 patients with BrS in whom ventricular tachyarrhythmias were induced by programmed electrical stimulation.  The 87-lead BSM was recorded during induced ventricular tachyarrhythmias, and an activation map and an isopotential map of QRS complexes every 5 ms were constructed to evaluate the activation pattern of ventricular tachyarrhythmias.  Body surface mapping during 20 episodes of ventricular tachyarrhythmias induced at the RVOT showed that repetitive excitation was generated at the RVOT and propagated to the inferior RV and left ventricle, and then returned to the RVOT.  Polymorphic QRS change during ventricular tachyarrhythmias was associated with migration of the earliest activation site and rotor.  Body surface mapping during 4 episodes of ventricular fibrillation (VF) showed that the excitation front moved randomly with formation of multiple wave-fronts.  The authors concluded that programmed stimulation initiated repetitive firing from the RVOT.  Migration and competition of the earliest activation site and rotor and local conduction delay changed the QRS morphology.  Degeneration of the re-entrant circuit into multiple wave-fronts resulted in VF.

Furthermore, an UpToDate review on “Brugada syndrome: Clinical presentation, diagnosis, and evaluation” (Wylie and Garlitski, 2016) does not mention body surface mapping as a management tool.

Prediction of Response in Cardiac Resynchronization Therapy

Gage and colleagues (2017) noted that electrical activation is important in cardiac resynchronization therapy (CRT) response.  Standard electrocardiographic analysis may not accurately reflect the heterogeneity of electrical activation.  These researchers compared changes in left ventricular size and function after CRT to native electrical dyssynchrony and its change during pacing.  Body surface isochronal maps using 53 anterior and posterior electrodes as well as 12-lead electrocardiograms were acquired after CRT in 66 consecutive patients.  Electrical dyssynchrony was quantified using standard deviation of activation times (SDAT).  Ejection fraction (EF) and left ventricular end-systolic volume (LVESV) were measured before CRT and at 6 months.  Multiple regression evaluated predictors of response.  Changes in LVESV correlated with changes in SDAT (p = 0.007), but not with changes in QRS duration (p = 0.092).  Patients with SDAT greater than or equal to 35 ms had greater increase in EF (13 ± 8 units versus 4 ± 9 units; p < 0.001) and LVESV (-34 % ± 28 % versus -13 % ± 29 %; p = 0.005).  Patients with greater than or equal to 10 % improvement in SDAT had greater changes in EF (11 ± 9 units versus 4 ± 9 units; p = 0.010) and changes in LVESV (-33 % ± 26 % versus -6 % ± 34 %; p = 0.001).  SDAT greater than or equal to 35 ms predicted changes in EF, while changes in SDAT, sex, and left bundle branch block predicted changes in LVESV.  In 34 patients without class I indication for CRT, SDAT greater than or equal to 35 ms (p = 0.015) and changes in SDAT greater than or equal to 10 % (p = 0.032) were the only predictors of ∆EF.  The authors concluded that BSM of SDAT and its changes predicted CRT response better than did QRS duration.  They stated that BSM may potentially improve selection or optimization of CRT patients.  These preliminary findings need to be validated by well-designed studies.

Assessment of Ischemic Heart Disease

Kania and associates (2019) noted that standard 12-lead ECG exercise testing is commonly used for screening of ischemic heart disease (IHD).  These researchers examined if HR-BSPM during exercise offers advantages over current standards in non-invasive evaluation of IHD.  This study was performed in 90 IHD patients and 33 healthy controls.  The 67-lead HR-BSPM was recorded at rest and during exercise; 21 ECG parameters including classical ST criteria were compared.  The effectiveness of methods was verified based on the findings of SPECT and coronary angiography.  The most effective parameters in the diagnosis of IHD were: amplitude parameter ΔST60 and δT parameter showing T-wave morphology changes during exercise.  The sensitivities/specificities of ΔST60 and δT parameters for the HR-BSPM were 70/69 and 59/62 %, while for the standard 12-lead ECG system they were: 63/62 and 59/56 %.  These results demonstrated the usefulness of HR-BSPM measurements during exercise; HR-BSPM resulted in higher sensitivities and specificities compared to the standard 12-lead exercise test.  The advantage was partially associated with observed ischemic changes outside standard precordial leads position that were not visible when using the standard 12-lead exercise test.  The authors concluded that these findings justified further research into optimization of the number and position of ECG leads in exercise studies of myocardial ischemia.  These researchers stated that the HR-BSPM recording during exercise could have much more to offer (e.g., the diagnostic value of a multi-parameter analysis or the use of spatial patterns in the maps to non-invasively locate ischemic areas in the heart may be the subject of future studies).

Prediction of Atrial Fibrillation

Bai and colleagues (2019) noted that AF is the most common type of persistent arrhythmia.  Early diagnosis and intervention of AF is essential to avert the further fatality.  The technique of non-invasive electrical mapping, especially BSPM, has a more practical application in the study of predicting AF, when compared with the invasive electrical mapping methods such as the epicardial mapping and interventional catheter mapping.  However, the prediction of AF with non-invasive signals has been inadequately studied.  These investigators analyzed the properties of atrial dynamic system based on the non-invasive BSPM signals (BSPMs), using the recurrence complex network, and consequently to evaluate its role in predicting the recurrence of AF in clinical aspect.  A total of 12 patients with persistent AF were included in this study.  Their pre-operative and post-operative BSPMs were recorded.  Initially, the preoperative BSPMs were transformed into the recurrence complex network to characterize the complexity property of the atria.  Subsequently, the parameters of recurrence ratio (REC), determinism (DET), entropy of the diagonal structure distribution (ENTR), and laminarity (LAM) were calculated.  Furthermore, the difference in the parameters in the 4r regions of the body and the difference obtained from the dominant frequency (DF) method were compared.  Finally, the results obtained for the atrial dynamic system complexity from a 12-lead ECG from the BSPMs were discussed.  This study showed that patients whose REC was greater than an average threshold, and with a lower LAM presented a much higher possibility of AF recurrence, after the AF surgery.  The authors concluded that the recurrence complex network analysis method was applied into BSPMs for the prediction of AF recurrence.  In patients with AF, whose pre-operative BSPMs had higher REC and lower LAM, could have greater possibility of AF recurrence after surgery.  Compared with the DF method, this method was insensitive to the lead position and it paid more attention to the relationship of the different leads, which could reveal the inner law of the atrial system.  These researchers stated that recurrence complex network has a potential role in the understanding of predicting the recurrence of, nevertheless, more attention needs to be paid to obtain more data from the clinical scenario to confirm these findings. 

The above policy is based on the following references: