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. 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 and includes a conducting gel that is applied to the patient’s chest and back. The vest can be affixed to the patient in less than 5 minutes. This system displays clinical data in 3 forms; a colorimetric 3-D torso image, an 80-lead single beat view, and the 12-lead electrocardiograph (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 through 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 approximately 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 is 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).