A major responsibility of cardiac care unit (CCU) nurses is to monitor patients following coronary angioplasty for signs and symptoms of cardiac ischemia which may signal the complication of sudden coronary artery reocclusion with subsequent acute myocardial infarction. The rationale for interventions to re-establish blood flow following reocclusion is that patients who develop extensive infarction often have numerous repeated hospitalizations for congestive heart failure and chronic, debilitating symptoms such as shortness of breath, inability to perform daily activities, and fatigue. A noninvasive technique more sensitive than the patient's symptoms for detecting recurrent cardiac ischemia is the patient's 12-lead electrocardiogram (ECG). However, because the ECG abnormalities are transient, cardiac ischemia is often missed by the patient's daily 12-lead ECG. The proposed study seeks to determine the sensitivity and accuracy of continuous bedside cardiac ischemia ST segment monitoring using a """"""""derived"""""""" 12-lead """"""""ECGD"""""""" compared to the routinely- monitored dual-lead method for detecting recurrent cardiac ischemia following coronary angioplasty. A secondary aim is to determine whether there are gender differences in the sensitivity and accuracy of differences between the 2 lead methods in these patients. 416 subjects will have 12-lead ECGDs recorded with balloon inflation, during coronary angioplasty to record the patient's ischemic pattern during """"""""controlled"""""""" ischemia. Information will be elicited from the patient at the same time as to their symptoms of cardiac ischemia. Patients will serve as their own controls and be monitored with both lead methods in the CCU following angioplasty. The sensitivity will be analyzed using a 2-factor repeated measures analysis of variance, where the dependent variable is defined as the proportion of true ischemic events detected by each method. To compare the accuracy of the 2 lead methods, 2 nurse experts will independently determine whether both methods contain the same pattern of ST elevation, depression, or isoelectric ST segments compared to corresponding leads of the patient's 12-lead ECGD recorded during coronary angioplasty. Nurse expert ratings will be placed into a 3 X 3 contingency table, where the table rows will contain """"""""same,"""""""" """"""""related"""""""" and """"""""different"""""""" ratings for Method I (routinely-monitored dual leads) and table columns will contain ratings for Method II(12-lead ECGD). The contingency table will be analyzed under a non-parametric """"""""correlated proportions"""""""" statistical model. The Stuart extension of the McNemar test will be used to test for the equality of the correlated marginal probabilities.
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