Each year, an estimated 785,000 Americans will have a new coronary attack, or acute coronary syndrome (ACS). The pathophysiology of ACS involves rupture of an atherosclerotic plaque; hence, treatment is aimed at plaque stabilization in order to prevent cellular death. However, there is considerable debate among clinicians, about which treatment pathway is best: early invasive using percutaneous coronary intervention (PCI/ stent) when indicated or a conservative approach (i.e., medication only with PCI/stent if recurrent symptoms occur).There are three types of ACS: ST elevation myocardial infarction (STEMI), non-ST elevation MI (NSTEMI), and unstable angina (UA). Among the three types, NSTEMI/UA is nearly four times as common as STEMI. Treatment decisions for NSTEMI/UA are based largely on symptoms and resting or exercise electrocardiograms (ECG). However, because of the dynamic and unpredictable nature of the atherosclerotic plaque, these methods often under detect myocardial ischemia because symptoms are unreliable, and/or continuous ECG monitoring was not utilized.Continuous 12-lead ECG monitoring, which is both inexpensive and non-invasive, can identify transient episodes of myocardial ischemia, a precursor to MI, even when asymptomatic. However, continuous 12-lead ECG monitoring is not usual hospital practice; rather, only two leads are typically monitored. Information obtained with 12-lead ECG monitoring might provide useful information for deciding the best ACS treatment.Purpose. Therefore, using 12-lead ECG monitoring, the COMPARE Study (electroCardiographic evaluatiOn of ischeMia comParing invAsive to phaRmacological trEatment) was designed to assess the frequency and clinical consequences of transient myocardial ischemia, in patients with NSTEMI/UA treated with either early invasive PCI/stent or those managed conservatively (medications or PCI/stent following recurrent symptoms). The purpose of this manuscript is to describe the methodology used in the COMPARE Study.Method. Permission to proceed with this study was obtained from the Institutional Review Board of the hospital and the university. Research nurses identify hospitalized patients from the emergency department and telemetry unit with suspected ACS. Once consented, a 12-lead ECG Holter monitor is applied, and remains in place during the patient's entire hospital stay. Patients are also maintained on the routine bedside ECG monitoring system per hospital protocol. Off-line ECG analysis is done using sophisticated software and careful human oversight.

Background Treatment for unstable angina (UA) or non-STEMI (NSTEMI) is aimed at plaque stabilization to prevent infarction. Two treatment strategies are: (1) invasive (i.e., cardiac catheterization laboratory < 24 hours after admission), or (2) selectively invasive (i.e., medications with cardiac catheterization laboratory > 24 hours for recurrent symptoms). However, it is not known if the frequency of transient myocardial ischemia (TMI), or complications during hospitalization varies by treatment. Purpose We examine; (1) occurrence of TMI in UA/NSTEMI, (2) compare frequency of TMI by treatment pathway and (3) determine predictors of in-hospital complications (i.e., death, MI, pulmonary edema, shock, arrhythmia w/intervention). Method Hospitalized patients with CAD (i.e., history of MI, PCI/stent, CABG, > 50% lesion via angiogram, or positive troponin) were recruited and 12-lead ECG Holter initiated. Clinicians, blinded to Holter data, decided treatment strategy; off-line analysis was done post discharge. TMI was defined as > 1 mm ST-segment ↑ or ↓, in > 1 ECG lead, > 1 minute. Results Of 291 patients, 91% were white, 66% male, 44% prior MI, and 59% prior PCI/stent or CABG. Treatment pathway was early in 123 (42%), and selective in 168 (58%). Forty-nine (17%) had TMI; 19 (15%) early invasive, 30 (18%) selective (p = 0.637). Acute MI after admission was higher in patients with TMI regardless of treatment strategy (early no TMI 4% vs yes TMI 21%; p = 0.020; selective no TMI 1% vs yes TMI 13%; p = .0004). Predictors of major in-hospital complication were TMI (OR 9.9; 95% CI, 3.84 to 25.78), and early invasive (OR 3.5; 95% CI, 1.23 to 10.20). Conclusions In UA/NSTEMI patients treated with contemporary therapies, TMI in not uncommon. The presence of TMI and early invasive treatment are predictors of major in-hospital complications.