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An automated ecg algorithm for detection of acute myocardial infarction in the presence of ECG confounders
Journal of Electrocardiology Vol. 36 Supplement 2003
Poster Session I
An Automated ECG Algorithm for Detection of Acute Myocardial Infarction in the Presence of ECG Confounders
Background: Percutaneous transluminal coronary angioplasty (PTCA) is an appropriate human model to study electrocardiographic changes due to transient regional ischemia. Aim: To evaluate the possibilities of dipolar electrocardiotopography (DECARTO) to visualize the subtle changes in the QRS complex during the transient ischemia at the peak balloon inflation during PTCA. Material and Methods: Frank orthogonal ECGs were extracted from body-surface potential mapping data recorded at Dalhousie University prior to and at peak inflation during PTCA in 93 patients. ECGs were transformed using a biomathematical model DECARTO, and presented as instantaneous maps of activated areas in 10 ms intervals from the onset of QRS (decartograms) in a form of a rectangle (matrix of 11 lines, 24 columns). For each point of this matrix the value of relative frequency (probability) of its occurrence in the activated state was calculated in three subgroups of patients according to the occlusion sites: LAD, RCA, and LCX coronary arteries. In these subgroups, the matrices before and during the balloon inflation were compared using the paired modification of KolmogorovSmirnov goodness-of-fit test. Results: In all subgroups the maximal differences between the baseline and peak values were observed in the 10th ms following the onset of QRS and these differences were statistically significant in each group (p ⬍ 0.001). In this instant of time, the maximal differences were found in the left superior anterior region during LAD occlusion, the left middle anterior region during LCX occlusion, and the middle anterior region during RCA occlusion. Conclusion: The dipolar electrocardiotopography (DECARTO) enabled visualization and analysis of subtle changes in QRS morphology caused by transient ischemia at peak inflation during PTCA.
Alan Andresen, Camilo Bruce, Sheng-le Cheng, Rick Myers, George Polizos, Robert A. Warner, Ronald H. Selvester‡. Inovise Medical, Inc., Newberg, OR, and ‡Memorial Medical Center, Long Beach, CA, USA Detection of acute myocardial infarction (AMI) in the presence of ECG confounders is challenging for both commercial electrocardiographic (ECG) algorithms and for clinicians. The combined prevalence of Left Bundle Branch Block (LBBB), Right Bundle Branch Block (RBBB), and Left Ventricular Hypertrophy w/STT Abnormality (LVH) in a population of patients with documented AMI at two large, metropolitan hospitals was found to be 25%. This prevalence highlights the need to aid clinicians in differentially diagnosing these confounding conditions from AMI. Audicor™ 3.5 detects AMI in the presence of these conditions with performance that is superior to that of existing ECG algorithms. The Audicor approach involves modeling STT changes due to the confounding conditions from which normalized ST deviations are then evaluated against thresholds established for detecting AMI. Comparative results were created by studying AMI positive and AMI negative populations. The positive group had AMI documented from elevated cardiac enzymes (⬎⫽3x normal limits). The control group included those evaluated for chest pain with normal levels of cardiac enzymes or those being treated for non-cardiac conditions. Two automated ECG methods are compared to Audicor for the detection of AMI. The comparative results below demonstrates a significant improvement in Audicor 3.5 for discriminating confounders from AMI. AMI Sensitivity Method
All
LBBB RBBB LVH
n 603 108 Alg #1 10% 5% Alg #2 12% 2% Audicor 21% 24%
AMI Specificity All
LBBB RBBB LVH
ECGScan: A Method for Digitizing Paper ECG Printouts
148 347 2502 499 787 1146 16% 10% 95% 98% 95% 92% 19% 12% 97% 100% 99% 95% 30% 16% 97% 97% 98% 96%
Fabio Badilini*, Tanju Erdem§, Wojtek Zareba†, Arthur J Moss†. * AMPS-LLC, New York, NY, USA, §Momentum, Inc., Istanbul, Turkey, †University of Rochester, New York, USA Analysis of electrocardiograms (ECG) in the context of pharmaceutical and clinical research is still largely performed on paper ECG records. Recent regulatory acts are enforcing the use of digital information and will likely trigger the need to convert existing paper records in digital format. This study presents ECGScan, a computer application designed for the conversion of scanned paper ECG records to digital ECG files. The method implemented is based on separate detection of grid and ECG waveforms using the concepts of active contours (a.k.a. snakes) and dynamic programming. The digital ECG waveform is represented as an active contour within an ECG image rectangle and that minimizes a set of “cost” functions. A “line” cost function is used to attach the active contour towards
The Use of Dipolar ElectroCARdioTOpography for Visualization of the Ischemic Changes of the QRS Complex During Coronary Occlusion of Balloon Angioplasty Bacharova L*, Mateasik A*, Katina S*, Horacek M†, Engblom H‡, Wagner G§. *International Laser Center, Bratislava, Slovak Republic, †Dalhousie University, Halifax, Nova Scotia, Canada, ‡ Lund University Hospital, Lund, Sweden, §Duke University Medical Center, Durham, NC, USA
© 2003 Elsevier Inc. All rights reserved.
39
Poster Session I
An Automated ECG Algorithm for Detection of Acute Myocardial Infarction in the Presence of ECG Confounders
Background: Percutaneous transluminal coronary angioplasty (PTCA) is an appropriate human model to study electrocardiographic changes due to transient regional ischemia. Aim: To evaluate the possibilities of dipolar electrocardiotopography (DECARTO) to visualize the subtle changes in the QRS complex during the transient ischemia at the peak balloon inflation during PTCA. Material and Methods: Frank orthogonal ECGs were extracted from body-surface potential mapping data recorded at Dalhousie University prior to and at peak inflation during PTCA in 93 patients. ECGs were transformed using a biomathematical model DECARTO, and presented as instantaneous maps of activated areas in 10 ms intervals from the onset of QRS (decartograms) in a form of a rectangle (matrix of 11 lines, 24 columns). For each point of this matrix the value of relative frequency (probability) of its occurrence in the activated state was calculated in three subgroups of patients according to the occlusion sites: LAD, RCA, and LCX coronary arteries. In these subgroups, the matrices before and during the balloon inflation were compared using the paired modification of KolmogorovSmirnov goodness-of-fit test. Results: In all subgroups the maximal differences between the baseline and peak values were observed in the 10th ms following the onset of QRS and these differences were statistically significant in each group (p ⬍ 0.001). In this instant of time, the maximal differences were found in the left superior anterior region during LAD occlusion, the left middle anterior region during LCX occlusion, and the middle anterior region during RCA occlusion. Conclusion: The dipolar electrocardiotopography (DECARTO) enabled visualization and analysis of subtle changes in QRS morphology caused by transient ischemia at peak inflation during PTCA.
Alan Andresen, Camilo Bruce, Sheng-le Cheng, Rick Myers, George Polizos, Robert A. Warner, Ronald H. Selvester‡. Inovise Medical, Inc., Newberg, OR, and ‡Memorial Medical Center, Long Beach, CA, USA Detection of acute myocardial infarction (AMI) in the presence of ECG confounders is challenging for both commercial electrocardiographic (ECG) algorithms and for clinicians. The combined prevalence of Left Bundle Branch Block (LBBB), Right Bundle Branch Block (RBBB), and Left Ventricular Hypertrophy w/STT Abnormality (LVH) in a population of patients with documented AMI at two large, metropolitan hospitals was found to be 25%. This prevalence highlights the need to aid clinicians in differentially diagnosing these confounding conditions from AMI. Audicor™ 3.5 detects AMI in the presence of these conditions with performance that is superior to that of existing ECG algorithms. The Audicor approach involves modeling STT changes due to the confounding conditions from which normalized ST deviations are then evaluated against thresholds established for detecting AMI. Comparative results were created by studying AMI positive and AMI negative populations. The positive group had AMI documented from elevated cardiac enzymes (⬎⫽3x normal limits). The control group included those evaluated for chest pain with normal levels of cardiac enzymes or those being treated for non-cardiac conditions. Two automated ECG methods are compared to Audicor for the detection of AMI. The comparative results below demonstrates a significant improvement in Audicor 3.5 for discriminating confounders from AMI. AMI Sensitivity Method
All
LBBB RBBB LVH
n 603 108 Alg #1 10% 5% Alg #2 12% 2% Audicor 21% 24%
AMI Specificity All
LBBB RBBB LVH
ECGScan: A Method for Digitizing Paper ECG Printouts
148 347 2502 499 787 1146 16% 10% 95% 98% 95% 92% 19% 12% 97% 100% 99% 95% 30% 16% 97% 97% 98% 96%
Fabio Badilini*, Tanju Erdem§, Wojtek Zareba†, Arthur J Moss†. * AMPS-LLC, New York, NY, USA, §Momentum, Inc., Istanbul, Turkey, †University of Rochester, New York, USA Analysis of electrocardiograms (ECG) in the context of pharmaceutical and clinical research is still largely performed on paper ECG records. Recent regulatory acts are enforcing the use of digital information and will likely trigger the need to convert existing paper records in digital format. This study presents ECGScan, a computer application designed for the conversion of scanned paper ECG records to digital ECG files. The method implemented is based on separate detection of grid and ECG waveforms using the concepts of active contours (a.k.a. snakes) and dynamic programming. The digital ECG waveform is represented as an active contour within an ECG image rectangle and that minimizes a set of “cost” functions. A “line” cost function is used to attach the active contour towards
The Use of Dipolar ElectroCARdioTOpography for Visualization of the Ischemic Changes of the QRS Complex During Coronary Occlusion of Balloon Angioplasty Bacharova L*, Mateasik A*, Katina S*, Horacek M†, Engblom H‡, Wagner G§. *International Laser Center, Bratislava, Slovak Republic, †Dalhousie University, Halifax, Nova Scotia, Canada, ‡ Lund University Hospital, Lund, Sweden, §Duke University Medical Center, Durham, NC, USA
© 2003 Elsevier Inc. All rights reserved.
39