PRIME ECG improves emergency department diagnosis and management in moderate- to high-risk unstable angina/non–ST elevation myocardial infarction patients

Abstract

Study objectives: The 12-lead ECG is the current criterion standard for the diagnosis and early evaluation of patients with chest pain. A significant proportion of patients with unstable angina (UA) or non–ST elevation myocardial infarction (NSTEMI) do not manifest ischemic changes on the 12-lead ECG. The recently developed PRIME 80-lead ECG Body Surface Mapping System (Meridian) may be clinically useful in the diagnosis and management of UA/NSTEMI. Recent studies have looked at this 80-lead ECG to see if sensitivity and specificity for acute coronary syndromes could improve with this instrument. Some researchers have shown in 53 patients with enzymatically confirmed acute myocardial infarction (AMI) that the 80-lead ECG doubled the diagnostic sensitivity of AMI compared with 12-lead ECG. Other researchers compared 18 patients with left bundle-branch block and enzymatically confirmed AMI and showed that the sensitivity of 80-lead ECG for early detection of AMI was double that of the 12-lead ECG. The objective of this study is to determine whether 80-lead ECG can improve early detection of ischemic changes in emergency department (ED) patients with UA/NSTEMI over 12-lead ECG. Our hypothesis is that the PRIME ECG body map compared with the 12-lead ECG improves the diagnosis and management of ED patients with acute coronary syndromes. Methods: This is a prospective study performed on a convenience sample of suspected moderate- to high-risk UA/NSTEMI ED patients, defined as a Thrombolysis in Myocardial Infarction (TIMI) risk score of 3 or greater, positive biomarkers, or new (or not known to be old) ischemic ECG changes, who present within 12 hours of the most recent ischemic symptom. Enrolled patients had a 12-lead ECG and also a PRIME 80-lead ECG performed oof 4), blinded to patient data other than medical history and physical examination, interpreted the ECG and PRIME for their effect on patient disposition and therapy including the probability of AMI and cardiac care unit or cardiac step-down admission. The physicians recorded whether the PRIME ECG after evaluation of the 12-lead ECG changed either the patient therapy or disposition. Outcomes were 1-month major adverse coronary events (MACEs), defined as death, AMI, percutaneous transluminal coronary angioplasty or stent, coronary artery bypass graft surgery (CABG), or coronary stenosis greater than 50%. Data were analyzed using descriptive statistics. Results: Thirty-four patients have been enrolled to date. Sixty-eight percent of those enrolled had 1 of the prespecific MACEs, (32% NSTEMI, 41% PCI, 18% CABG, 17% >50% stenosis). The PRIME ECG added additional information to the 12-lead ECG in 59% (20/34) of patients. The PRIME ECG changed ED disposition or therapy in 21% (7/34) of patients. Of the 13 patients for whom the PRIME ECG added additional data without changing management, 62% (8/13) had a MACE. Of the 7 patients for whom the PRIME ECG changed management, 86% (6/7) had a MACE. The 1 patient of the 7 without a MACE was post-CABG, had significant stenosis (80% to 100%) thought to be old, and was treated with aggressive therapy. Conclusion: The use of the PRIME ECG in moderate- to high-risk UA/NSTEMI patients improved the ED diagnosis and management.