Aetna considers body surface potential mapping (also known as body surface mapping) experimental and investigational for the evaluation of acute coronary syndromes (e.g., acute cardiac ischemia and myocardial infarction) and other indications because the clinical effectiveness of this procedure has not been established.

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

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.