Diagnosis of Acute Myocardial Infarction with Body Surface Potential Mapping

ABSTRACT

PURPOSE: A 12-lead ECG is only 50% sensitive for the detection of an acute myocardial infarction (AMI). The majority of leads for optimal classification of an AMI probably lie outside the area covered by the 6 precordial leads. Thus, body surface potential mapping (BSPM) may be more helpful in diagnosing AMI, because a large thoracic area is sampled. METHODS: Two hundred sixty-eight consecutive patients with ischemic-type chest pain, who visited our emergency medical center from August 2002 to January 2003, were recruited prospectively. A 12-lead ECG and an 80-lead BSPM were recorded at presentation. Cardiac markers were measured. Acute myocardial infarction was defined as 1) chest pain with a duration greater than 20 minutes and, 2) elevated cardiac enzyme. The diagnoses of the 12-lead ECGs and the BSPM algorithms were categorized into two subgroups, AMI and non-AMI, and were compared. RESULTS: Of the 268 patients, 81 patients (30.2%) were confirmed as having an acute myocardial infarction. The 12-lead ECGs identified 32 patients with AMI (sensitivity 39.5%, specificity 93.0%), and the BSPM algorithm identified 56 patients with AMI (sensitivity 69.1%, specificity 85.6%). Patients with a positive BSPM diagnosis were much more likely to have AMI (odds ratio 13.3, 95% Confidence interval 7.1~24.8) than patients with a positive 12-lead ECG diagnosis. Thirty AMI patients that had not been detected with 12-lead ECGs were detected with 80-lead BSPMs (sensitivity 61.2%, specificity 87.9%). CONCLUSION: When compared with the 12-lead ECG, the BSPM algorithm has a higher sensitivity for detection of AMI, particularly in patients presenting with chest pain and nondiagnostic ECG changes. The use of the BSPM algorithm in such patients may lead to earlier detection of an AMI.