Comparison of Standard and Derived 12-Lead Electrocardiograms for Diagnosis of Coronary Angioplasty-Induced Myocardial Ischemia

To determine whether a derived 12-lead electrocardiogram (ECG) would demonstrate typical ST-segment changes of ischemia during percutaneous transluminal coronary angioplasty (PTCA), 207 patients were monitored with continuous 12-lead ST-segment monitoring during angioplasty. Additionally, to compare the derived and standard ECGs during known periods of ischemia with PTCA balloon inflation, 151 patients were recorded with both electrocardiographic methods during the procedure. Of the 207 patients recorded with the derived ECG, 171 (83%) had typical ischemic ST-segment changes during PTCA balloon inflation. The amplitudes of these ST deviations were similar to those observed during transient myocardial ischemia observed in clinical settings (median peak ST deviation, 225 μV). There was agreement regarding presence or absence of ischemia in 150 of the 151 patients recorded with both derived and standard electrocardiographic methods (>99% agreement). With use of the standard ECG as the “gold standard” for ischemia diagnosis, there were no false-positive results and only 1 false-negative result with the derived ECG. Furthermore, there was nearly perfect agreement between the two 12-lead methods in terms of anterior versus inferior wall patterns of ischemia. Future studies are required to determine whether continuous monitoring with a derived ECG would improve diagnosis and lead to better patient outcomes. tudy examines the value of a 12-lead electrocardiogram derived from a simple lead configuration for diagnosing myocardial ischemia in 207 patients. Excellent agreement was found between derived and standard 12-lead electrocardiograms recorded during coronary angioplasty balloon inflation in terms of presence or absence of ischemic ST changes, lead with peak ST deviation, and anterior versus inferior wall ischemic patterns.