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Computerized ECG-based time-insensitive predictive instruments for the diagnosis of an acute myocardial infarction
Selected Abstracts From the Eighteenth International
continuous infusion on contrast medium and were traced manually. RAV and the left atria1 volume (LAV) were calculated from the sum of these traced data. Atria1 volume was measured in 53 patients with sinus rhythm (group A) and 17 patients with atria1 fibrillation (group B) who had no organic heart disease. RAV and LAV were 70.0 -+ 24.6 and 78.9 + 22.5 ml in group A; 124.3 4 59.8 and 147.1 2 57.1 ml in group B, respectively. There were significant differences in both RAV and LAV between group A and B (p < 0.01). Thus, patients with atria1 fibrillation have a significantly larger RAV and LAV than patients with sinus rhythm.
Body Surface Potential Map Patterns in Acute Non-Q Wave Myocardial Infarction Fred Kornreich, Terrence J. Montague, Pentti M. Rautaharju, Free University of Brussels, Belgium, and the University of Alberta, Edmonton, Canada Discriminant analysis was performed on 120-lead data recorded simultaneously in 159 normal subjects and 304 patients with various types of myocardial infarction (MI) using as features instantaneous voltages on time-normalized P, PR, QRS, and ST-T waveforms as well as the duration of these waveforms. Leads and features for optimal separation of 159 normal subjects from 183 patients with recent or old Q Ml were selected. A total of six features from six torso sites accounted for a specificity of 96% and a sensitivity of 94%. All lead positions were outside the conventional electrode sites and selected features were voltages at mid-P, in early and mid-QRS, and before and after the peak of the T wave. The disciminant function was then tested on 53 patients with acute non-Q MI and 68 patients with acute Q MI. Rates of correct classification were 9 1% and 93%, respectively. Group mean body surface potential maps were plotted for the three MI groups at successive instants throughout the PQRST waveform. Typical patterns for each MI group were identified during PQRST by removing from sequential MI maps the corresponding normal variability at each electrode site. Striking similarities were observed between the three MI groups, particularly at mid-QRS and throughout ST-T. The closest resemblance was between acute non-Q MI and old Q MI. Discriminant analysis was also performed on the 12-lead ECG and achieved a specificity of 92% and a sensitivity of 72%.
Congress on Electrocardiology
245
Computerized ECG-Based Timeinsensitive Predictive instruments for the Diagnosis of an Acute Myocardial Infarction Michael M. Laks, Charles B. Cairns, James T. Niemann, Harry P. Selker, Harbor-UCLA Medical Center, Torrance, California, and New England Medical Center, Boston, Massachusetts With the availability of thrombolytic therapy, the early diagnosis of an acute myocardial infarction (AMI) is paramount. A time-insensitive predictive instrument (TIPI) was developed by HPS to detect acute cardiac ischemia using ECG waveforms, demographics, and clinical history. Our group developed a computerized ECG-based program linking history codes into the Hewlett-Packard ECG language. A 3-month prospective, single-blind study was performed on emergency department (ED) patients over 35 years of age who presented with chest pain and-showed no abnormalities on the chest radiograph or history of thoracic trauma. A 12-lead real-time computer-generated TIP1 probability score of acute cardiac ischemia was generated in the ED. The ED physician was unaware of the TIP1 score and completed a form indicating the probability of diagnosis of AM1 and patient disposition. AMI was diagnosed by CPK elevation and MB fractions 2 5%. In the 101 patients studied, a TIP1 score of 2 38% had a sensitivity of 93% and specificity of 74% with a positive predictive accuracy of 59% and a negative predictive accuracy of 96% for the prediction of AM1 and/or complications. A receiver operational characteristic curve for the prediction of an AM1 and/or complications was 0.85 for the TIP1 and 0.64 for the ED physicians’ probability. A computerized TIP1 score using clinical and ECG criteria has been developed for clinical use in the ED. The score can be used to predict which chest pain patients will have an AM1 or complications. The computer-based ECG interpretive program appears to be as good as and may be even better than ED physicians in making AM1 triage decisions.
Body Surface Potential Mapping in Children Jerome Liebman, C. W. Thomas, Y. Rudy, Department of Pediatrics and Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio Over the past decade since the development of our color-coded 180-electrode body surface potential mapping (BSPM) system, we have concentrated our
continuous infusion on contrast medium and were traced manually. RAV and the left atria1 volume (LAV) were calculated from the sum of these traced data. Atria1 volume was measured in 53 patients with sinus rhythm (group A) and 17 patients with atria1 fibrillation (group B) who had no organic heart disease. RAV and LAV were 70.0 -+ 24.6 and 78.9 + 22.5 ml in group A; 124.3 4 59.8 and 147.1 2 57.1 ml in group B, respectively. There were significant differences in both RAV and LAV between group A and B (p < 0.01). Thus, patients with atria1 fibrillation have a significantly larger RAV and LAV than patients with sinus rhythm.
Body Surface Potential Map Patterns in Acute Non-Q Wave Myocardial Infarction Fred Kornreich, Terrence J. Montague, Pentti M. Rautaharju, Free University of Brussels, Belgium, and the University of Alberta, Edmonton, Canada Discriminant analysis was performed on 120-lead data recorded simultaneously in 159 normal subjects and 304 patients with various types of myocardial infarction (MI) using as features instantaneous voltages on time-normalized P, PR, QRS, and ST-T waveforms as well as the duration of these waveforms. Leads and features for optimal separation of 159 normal subjects from 183 patients with recent or old Q Ml were selected. A total of six features from six torso sites accounted for a specificity of 96% and a sensitivity of 94%. All lead positions were outside the conventional electrode sites and selected features were voltages at mid-P, in early and mid-QRS, and before and after the peak of the T wave. The disciminant function was then tested on 53 patients with acute non-Q MI and 68 patients with acute Q MI. Rates of correct classification were 9 1% and 93%, respectively. Group mean body surface potential maps were plotted for the three MI groups at successive instants throughout the PQRST waveform. Typical patterns for each MI group were identified during PQRST by removing from sequential MI maps the corresponding normal variability at each electrode site. Striking similarities were observed between the three MI groups, particularly at mid-QRS and throughout ST-T. The closest resemblance was between acute non-Q MI and old Q MI. Discriminant analysis was also performed on the 12-lead ECG and achieved a specificity of 92% and a sensitivity of 72%.
Congress on Electrocardiology
245
Computerized ECG-Based Timeinsensitive Predictive instruments for the Diagnosis of an Acute Myocardial Infarction Michael M. Laks, Charles B. Cairns, James T. Niemann, Harry P. Selker, Harbor-UCLA Medical Center, Torrance, California, and New England Medical Center, Boston, Massachusetts With the availability of thrombolytic therapy, the early diagnosis of an acute myocardial infarction (AMI) is paramount. A time-insensitive predictive instrument (TIPI) was developed by HPS to detect acute cardiac ischemia using ECG waveforms, demographics, and clinical history. Our group developed a computerized ECG-based program linking history codes into the Hewlett-Packard ECG language. A 3-month prospective, single-blind study was performed on emergency department (ED) patients over 35 years of age who presented with chest pain and-showed no abnormalities on the chest radiograph or history of thoracic trauma. A 12-lead real-time computer-generated TIP1 probability score of acute cardiac ischemia was generated in the ED. The ED physician was unaware of the TIP1 score and completed a form indicating the probability of diagnosis of AM1 and patient disposition. AMI was diagnosed by CPK elevation and MB fractions 2 5%. In the 101 patients studied, a TIP1 score of 2 38% had a sensitivity of 93% and specificity of 74% with a positive predictive accuracy of 59% and a negative predictive accuracy of 96% for the prediction of AM1 and/or complications. A receiver operational characteristic curve for the prediction of an AM1 and/or complications was 0.85 for the TIP1 and 0.64 for the ED physicians’ probability. A computerized TIP1 score using clinical and ECG criteria has been developed for clinical use in the ED. The score can be used to predict which chest pain patients will have an AM1 or complications. The computer-based ECG interpretive program appears to be as good as and may be even better than ED physicians in making AM1 triage decisions.
Body Surface Potential Mapping in Children Jerome Liebman, C. W. Thomas, Y. Rudy, Department of Pediatrics and Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio Over the past decade since the development of our color-coded 180-electrode body surface potential mapping (BSPM) system, we have concentrated our