Roger Abächerli | Lucerne University of Applied Sciences and Arts (original) (raw)
Papers by Roger Abächerli
Circulation, 2017
Background: The Cardiac Electrical Biomarker (CEB) is a novel electrocardiographic (ECG) marker q... more Background: The Cardiac Electrical Biomarker (CEB) is a novel electrocardiographic (ECG) marker quantifying the dipolar activity of the heart with higher levels indicating myocardial injury. Method...
Swiss medical weekly, 2016
The 12-lead electrocardiogram (ECG) is the most frequently used technology in clinical cardiology... more The 12-lead electrocardiogram (ECG) is the most frequently used technology in clinical cardiology. It is critical for evidence-based management of patients with most cardiovascular conditions, including patients with acute myocardial infarction, suspected chronic cardiac ischaemia, cardiac arrhythmias, heart failure and implantable cardiac devices. In contrast to many other techniques in cardiology, the ECG is simple, small, mobile, universally available and cheap, and therefore particularly attractive. Standard ECG interpretation mainly relies on direct visual assessment. The progress in biomedical computing and signal processing, and the available computational power offer fascinating new options for ECG analysis relevant to all fields of cardiology. Several digital ECG markers and advanced ECG technologies have shown promise in preliminary studies. This article reviews promising novel surface ECG technologies in three different fields. (1) For the detection of myocardial ischaemi...
PloS one, 2015
This study presents a 2-stage heartbeat classifier of supraventricular (SVB) and ventricular (VB)... more This study presents a 2-stage heartbeat classifier of supraventricular (SVB) and ventricular (VB) beats. Stage 1 makes computationally-efficient classification of SVB-beats, using simple correlation threshold criterion for finding close match with a predominant normal (reference) beat template. The non-matched beats are next subjected to measurement of 20 basic features, tracking the beat and reference template morphology and RR-variability for subsequent refined classification in SVB or VB-class by Stage 2. Four linear classifiers are compared: cluster, fuzzy, linear discriminant analysis (LDA) and classification tree (CT), all subjected to iterative training for selection of the optimal feature space among extended 210-sized set, embodying interactive second-order effects between 20 independent features. The optimization process minimizes at equal weight the false positives in SVB-class and false negatives in VB-class. The training with European ST-T, AHA, MIT-BIH Supraventricular...
2014 8th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO), 2014
ABSTRACT Nowadays, standalone dry electrode-sensors allow for acquiring ECGs with a signal qualit... more ABSTRACT Nowadays, standalone dry electrode-sensors allow for acquiring ECGs with a signal quality similar to those of standard ECG recorders. Moreover, standalone electrode-sensors are much easier to connect than the usual electrodes and do not require a specific electronic box for the recorder (the measured biopotentials are recorded directly in the electrode-sensors). This results in very high overall integration, and increased comfort and reliability. The main innovation presented in this paper is the circuit and mechanism (patent pending) allowing perfect synchronization of all the attached standalone electrode-sensors.
Sensors, 2015
For the long-time monitoring of electrocardiograms, electrodes must be skin-friendly and non-irri... more For the long-time monitoring of electrocardiograms, electrodes must be skin-friendly and non-irritating, but in addition they must deliver leads without artifacts even if the skin is dry and the body is moving. Today's adhesive conducting gel electrodes are not suitable for such applications. We have developed an embroidered textile electrode from polyethylene terephthalate yarn which is plasma-coated with silver for electrical conductivity and with an ultra-thin titanium layer on top for passivation. Two of these electrodes are embedded into a breast belt. They are moisturized with a very low amount of water vapor from an integrated reservoir. The combination of silver, titanium and water vapor results in an excellent electrode chemistry. With this belt the long-time monitoring of electrocardiography (ECG) is possible at rest as well as when the patient is moving.
Physiological Measurement, 2009
Electrocardiogram (ECG) is required during magnetic resonance (MR) examination for monitoring pat... more Electrocardiogram (ECG) is required during magnetic resonance (MR) examination for monitoring patients under anaesthesia or with heart diseases and for synchronizing image acquisition with heart activity (triggering). Accurate and fast QRS detection is therefore desirable, but this task is complicated by artefacts related to the complex MR environment (high magnetic field, radio-frequency pulses and fast switching magnetic gradients). Specific signal processing has been proposed, whether using specific MR QRS detectors or ECG denoising methods. Most state-of-the-art techniques use a connection to the MR system for achieving their task, which is a major drawback since access to the MR system is often restricted. This paper introduces a new method for on-line ECG signal enhancement, called ICARE, which takes advantage of using multi-lead ECG and does not require any connection to the MR system. It is based on independent component analysis (ICA) and applied in real time. This algorithm yields accurate QRS detection for efficient triggering.
Physiological Measurement, 2012
This paper presents a system for detection of the most common noise types seen on the electrocard... more This paper presents a system for detection of the most common noise types seen on the electrocardiogram (ECG) in order to evaluate whether an episode from 12-lead ECG is reliable for diagnosis. It implements criteria for estimation of the noise corruption level in specific frequency bands, aiming to identify the main sources of ECG quality disruption, such as missing signal or limited dynamics of the QRS components above 4 Hz; presence of high amplitude and steep artifacts seen above 1 Hz; baseline drift estimated at frequencies below 1 Hz; power-line interference in a band ±2 Hz around its central frequency; high-frequency and electromyographic noises above 20 Hz. All noise tests are designed to process the ECG series in the time domain, including 13 adjustable thresholds for amplitude and slope criteria which are evaluated in adjustable time intervals, as well as number of leads. The system allows flexible extension toward application-specific requirements for the noise levels in acceptable quality ECGs. Training of different thresholds' settings to determine different positive noise detection rates is performed with the annotated set of 1000 ECGs from the PhysioNet database created for the Computing in Cardiology Challenge 2011. Two implementations are highlighted on the receiver operating characteristic (area 0.968) to fit to different applications. The implementation with high sensitivity (Se = 98.7%, Sp = 80.9%) appears as a reliable alarm when there are any incidental problems with the ECG acquisition, while the implementation with high specificity (Sp = 97.8%, Se = 81.8%) is less susceptible to transient problems but rather validates noisy ECGs with acceptable quality during a small portion of the recording.
Heart Rhythm, 2009
BACKGROUND Abnormally long and short QT intervals are recognized to be associated with an increas... more BACKGROUND Abnormally long and short QT intervals are recognized to be associated with an increased risk for life-threatening ventricular arrhythmias. It is therefore important to define the upper and lower border of the normal QT. OBJECTIVE The aim of this study was to describe the normal distribution of the QT interval in a contemporary population of young conscripts and to define long and short limits of the QT interval. METHODS In Switzerland, all young male citizens must undergo compulsory conscription for the Swiss Army at the age of 18 to 19 years. In every conscript, an electrocardiogram (ECG) is performed. Retrospectively, 41,767 consecutive ECGs of Swiss citizens who underwent conscription for the army between March 1, 2004, and July 31, 2006, were analyzed. RESULTS The mean QTc Bazett interval was 394 Ϯ 22 ms. One percent of the conscripts had a Bazett QTc shorter than 347 ms, and one percent had a Bazett QTc longer than 445 ms, respectively. None of the subjects presented a QTc Bazett Ͻ 300 ms; the prevalence of a QTc Bazett Ͻ 320 ms was 0.02%. CONCLUSION The present study shows the distribution of QT intervals in an unselected young population. Because none of the subjects presented a QTc Ͻ 300 ms, it may be concluded that the short QT syndrome is a very rare entity in the population of young male adults.
Heart Rhythm, 2012
BACKGROUND/ OBJECTIVE The purpose of the present study was to analyze the prevalence of physiolog... more BACKGROUND/ OBJECTIVE The purpose of the present study was to analyze the prevalence of physiologic and pathologic ECG abnormalities in a cohort of young conscripts that represents the whole young generation of today. METHODS ECGs of all Swiss citizens who underwent conscription for the army during a 29-month period were analyzed manually. RESULTS ECGs of 43,401 conscripts (mean age 19.2 Ϯ 1.1 years) were analyzed; 158 conscripts were female. Incomplete right bundle branch block was found in 5870 (13.5%) and left anterior fascicular block in 360 (0.83%). First-degree AV block was present in 329 (0.8%) and Mobitz type I (Wenckebach) second-degree AV block in 3 (0.01%). Early repolarization was observed in 1035 (2.4%), T-wave inversion in 39 (0.09%), and minor T-wave changes in 182 (0.42%). Brugada-like abnormalities were observed in 6 (0.01%). None of the conscripts had atrial fibrillation or flutter. CONCLUSION ECG abnormalities can be found in a relatively large proportion of young individuals. Incomplete right bundle branch block, left fascicular block, and first-degree AV block are the most frequent findings. No conscript presented with atrial fibrillation or flutter.
2009 IEEE International Conference on Acoustics, Speech and Signal Processing, 2009
Automatic Electrocardiogram (ECG) analysis, especially QRS detection, is still a challenging task... more Automatic Electrocardiogram (ECG) analysis, especially QRS detection, is still a challenging task. This is even more the case when ECG is acquired during Magnetic Resonance (MR) examination. The MR environment highly distorts ECG, with Hall Effect, due to the important static magnetic field, and artifacts, caused by fast switching magnetic field gradients. Detection of QRS complexes is then affected. In this paper, a new specific MR QRS detector is presented. This method is based on the modulus maximum lines and on the Lipschitz exponent estimation they offer. The use of this regularity characterization enables to distinguish between QRS complexes and MR artifacts. This detector outperforms existing algorithms with almost 99% sensitivity and positive prediction value.
International Journal of Cardiology
Cardiology journal, Apr 3, 2018
While prolongation of QRS duration and QTc interval during acute myocardial infarction (AMI) has ... more While prolongation of QRS duration and QTc interval during acute myocardial infarction (AMI) has been reported in animals, limited data is available for these readily available electrocardiography (ECG) markers in humans. Diagnostic and prognostic value of QRS duration and QTc interval in patients with suspected AMI in a prospective diagnostic multicentre study were prospectively assessed. Digital 12-lead ECGs were recorded at presentation. QRS duration and QTc interval were automatically calculated in a blinded fashion. Final diagnosis was adjudicated by two independent cardiologists. The prognostic endpoint was all-cause mortality during 24 months of follow-up. Among 4042 patients, AMI was the final diagnosis in 19% of patients. Median QRS duration and median QTc interval were significantly greater in patients with AMI compared to those with other final diagnoses (98 ms [IQR 88-108] vs. 94 ms [IQR 86-102] and 436 ms [IQR 414-462] vs. 425 ms [IQR 407-445], p < 0.001 for both com...
Biomedical Signal Processing and Control, 2017
British Journal of Sports Medicine, 2016
Introduction ECG in pre-participation screening in athletes is still debated. It is of relevant i... more Introduction ECG in pre-participation screening in athletes is still debated. It is of relevant interest to have an automatic detection for this screening. 44’000 person a year are undergoing the screening at the age of 19 in Switzerland during Swiss Army conscription. Objectives We hypothesise that is possible to perform automatic detection using the Seattle Criteria published for athlete screening based on a 10s 12-lead resting ECG. Methods We performed a retrospective analysis of 274’468 digital standard 12-lead resting ECGs from military conscription acquired between 2008 and 2013. The Seattle Criteria were directly integrated into an automatic resting ECG measurement and interpretation software (ETM, SCHILLER AG) without any modification. Verification of proper implementation of the algorithm was done on the same dataset by visually and manually checking a randomly selected subset of abnormal (true positives) and normal ECGs (true negatives). The percentage of detection of any subtype as well as of the general finding ‘normal/abnormal ECG’ was calculated. Results We found that the categories ’Q-wave pathologies’, ‘ST-segment depressions’ and ‘Left axis deviations’ have a detection rate higher than 1%. All other Seattle Criteria detection rates were lower. ‘Brugada-like pattern’ and ‘Profound sinus bradycardia’ were not detected. The overall detection rate of 6.5% of abnormal ECGs is comparable to the found value of 4.5% (2) among elite athletes (false positive rate of 4.2%). Conclusion It is possible to perform automatic detection abnormal ECG using the published Seattle Criteria. The 6.47% abnormal ECGs correspond to 2’850 male individuals per year which would warrant a more profound clinical, and/or electrophysiological and genetic investigation to confirm or exclude the presence of an acquired or familial cardiac disease. Abstract O-6 Figure 1 Percentage of automatically detected Seattle criteria Reference Drezner JA, Ackerman MJ, Anderson J et al. Electrocardiographic interpretation in athletes: the ‘Seattle criteria’. Br J Sport Med 2013 Feb;47(3):122–124.
Computer methods and programs in biomedicine, 2017
The first-order high-pass filter (AC coupling) has previously been shown to affect the ECG for hi... more The first-order high-pass filter (AC coupling) has previously been shown to affect the ECG for higher cut-off frequencies. We seek to find a systematic deviation in computer measurements of the electrocardiogram when the AC coupling with a 0.05 Hz first-order high-pass filter is used. The standard 12-lead electrocardiogram from 1248 patients and the automated measurements of their DC and AC coupled version were used. We expect a large unipolar QRS-complex to produce a deviation in the opposite direction in the ST-segment. We found a strong correlation between the QRS integral and the offset throughout the ST-segment. The coefficient for J amplitude deviation was found to be -0.277 µV/(µV⋅s). Potential dangerous alterations to the diagnostically important ST-segment were found. Medical professionals and software developers for electrocardiogram interpretation programs should be aware of such high-pass filter effects since they could be misinterpreted as pathophysiology or some pathop...
European Heart Journal: Acute Cardiovascular Care
Aim: Exercise stress testing is used to detect myocardial ischaemia, but is limited by low sensit... more Aim: Exercise stress testing is used to detect myocardial ischaemia, but is limited by low sensitivity and specificity. The authors investigated the value of the analysis of high-frequency QRS components as a marker of abnormal depolarization in addition to standard ST-deviations as a marker of abnormal repolarization to improve the diagnostic accuracy. Methods and results: Consecutive patients undergoing bicycle exercise stress nuclear myocardial perfusion imaging were prospectively enrolled. Presence of myocardial ischaemia, the primary diagnostic endpoint, was adjudicated using MPI and coronary angiography. Automated high-frequency QRS analysis was performed in a blinded fashion. The prognostic endpoint was major adverse cardiac events (MACEs) during two years of follow-up. Exercise-induced ischaemia was detected in 147/662 patients (22%). The sensitivity of high-frequency QRS was similar to ST-deviations (46% vs. 43%, p=0.59), while the specificity was lower (75% vs. 87%, p<0...
European Heart Journal: Acute Cardiovascular Care
Background: Recent advances in digital electrocardiography technology allow evaluating ST-segment... more Background: Recent advances in digital electrocardiography technology allow evaluating ST-segment deviations in all 12 leads as quantitative variables and calculating summed ST-segment deviation scores. The diagnostic and prognostic utility of summed ST-segment deviation scores is largely unknown. Methods: We aimed to explore the diagnostic and prognostic utility of the conventional and the modified ST-segment deviation score (Better Analysis of ST-segment Elevations and Depressions in a 12- Lead-ECG-Score (BASEL-Score): sum of elevations in the augmented voltage right - lead (aVR) plus absolute, unsigned ST-segment depressions in the remaining leads) in patients presenting with suspected non-ST-segment elevation myocardial infarction. The diagnostic endpoint was non-ST-segment elevation myocardial infarction, adjudicated by two independent cardiologists. Prognostic endpoint was mortality during two-year follow up. Results: Among 1330 patients, non-ST-segment elevation myocardial in...
Journal of Electrocardiology
Journal of Electrocardiology
Circulation, 2017
Background: The Cardiac Electrical Biomarker (CEB) is a novel electrocardiographic (ECG) marker q... more Background: The Cardiac Electrical Biomarker (CEB) is a novel electrocardiographic (ECG) marker quantifying the dipolar activity of the heart with higher levels indicating myocardial injury. Method...
Swiss medical weekly, 2016
The 12-lead electrocardiogram (ECG) is the most frequently used technology in clinical cardiology... more The 12-lead electrocardiogram (ECG) is the most frequently used technology in clinical cardiology. It is critical for evidence-based management of patients with most cardiovascular conditions, including patients with acute myocardial infarction, suspected chronic cardiac ischaemia, cardiac arrhythmias, heart failure and implantable cardiac devices. In contrast to many other techniques in cardiology, the ECG is simple, small, mobile, universally available and cheap, and therefore particularly attractive. Standard ECG interpretation mainly relies on direct visual assessment. The progress in biomedical computing and signal processing, and the available computational power offer fascinating new options for ECG analysis relevant to all fields of cardiology. Several digital ECG markers and advanced ECG technologies have shown promise in preliminary studies. This article reviews promising novel surface ECG technologies in three different fields. (1) For the detection of myocardial ischaemi...
PloS one, 2015
This study presents a 2-stage heartbeat classifier of supraventricular (SVB) and ventricular (VB)... more This study presents a 2-stage heartbeat classifier of supraventricular (SVB) and ventricular (VB) beats. Stage 1 makes computationally-efficient classification of SVB-beats, using simple correlation threshold criterion for finding close match with a predominant normal (reference) beat template. The non-matched beats are next subjected to measurement of 20 basic features, tracking the beat and reference template morphology and RR-variability for subsequent refined classification in SVB or VB-class by Stage 2. Four linear classifiers are compared: cluster, fuzzy, linear discriminant analysis (LDA) and classification tree (CT), all subjected to iterative training for selection of the optimal feature space among extended 210-sized set, embodying interactive second-order effects between 20 independent features. The optimization process minimizes at equal weight the false positives in SVB-class and false negatives in VB-class. The training with European ST-T, AHA, MIT-BIH Supraventricular...
2014 8th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO), 2014
ABSTRACT Nowadays, standalone dry electrode-sensors allow for acquiring ECGs with a signal qualit... more ABSTRACT Nowadays, standalone dry electrode-sensors allow for acquiring ECGs with a signal quality similar to those of standard ECG recorders. Moreover, standalone electrode-sensors are much easier to connect than the usual electrodes and do not require a specific electronic box for the recorder (the measured biopotentials are recorded directly in the electrode-sensors). This results in very high overall integration, and increased comfort and reliability. The main innovation presented in this paper is the circuit and mechanism (patent pending) allowing perfect synchronization of all the attached standalone electrode-sensors.
Sensors, 2015
For the long-time monitoring of electrocardiograms, electrodes must be skin-friendly and non-irri... more For the long-time monitoring of electrocardiograms, electrodes must be skin-friendly and non-irritating, but in addition they must deliver leads without artifacts even if the skin is dry and the body is moving. Today's adhesive conducting gel electrodes are not suitable for such applications. We have developed an embroidered textile electrode from polyethylene terephthalate yarn which is plasma-coated with silver for electrical conductivity and with an ultra-thin titanium layer on top for passivation. Two of these electrodes are embedded into a breast belt. They are moisturized with a very low amount of water vapor from an integrated reservoir. The combination of silver, titanium and water vapor results in an excellent electrode chemistry. With this belt the long-time monitoring of electrocardiography (ECG) is possible at rest as well as when the patient is moving.
Physiological Measurement, 2009
Electrocardiogram (ECG) is required during magnetic resonance (MR) examination for monitoring pat... more Electrocardiogram (ECG) is required during magnetic resonance (MR) examination for monitoring patients under anaesthesia or with heart diseases and for synchronizing image acquisition with heart activity (triggering). Accurate and fast QRS detection is therefore desirable, but this task is complicated by artefacts related to the complex MR environment (high magnetic field, radio-frequency pulses and fast switching magnetic gradients). Specific signal processing has been proposed, whether using specific MR QRS detectors or ECG denoising methods. Most state-of-the-art techniques use a connection to the MR system for achieving their task, which is a major drawback since access to the MR system is often restricted. This paper introduces a new method for on-line ECG signal enhancement, called ICARE, which takes advantage of using multi-lead ECG and does not require any connection to the MR system. It is based on independent component analysis (ICA) and applied in real time. This algorithm yields accurate QRS detection for efficient triggering.
Physiological Measurement, 2012
This paper presents a system for detection of the most common noise types seen on the electrocard... more This paper presents a system for detection of the most common noise types seen on the electrocardiogram (ECG) in order to evaluate whether an episode from 12-lead ECG is reliable for diagnosis. It implements criteria for estimation of the noise corruption level in specific frequency bands, aiming to identify the main sources of ECG quality disruption, such as missing signal or limited dynamics of the QRS components above 4 Hz; presence of high amplitude and steep artifacts seen above 1 Hz; baseline drift estimated at frequencies below 1 Hz; power-line interference in a band ±2 Hz around its central frequency; high-frequency and electromyographic noises above 20 Hz. All noise tests are designed to process the ECG series in the time domain, including 13 adjustable thresholds for amplitude and slope criteria which are evaluated in adjustable time intervals, as well as number of leads. The system allows flexible extension toward application-specific requirements for the noise levels in acceptable quality ECGs. Training of different thresholds&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; settings to determine different positive noise detection rates is performed with the annotated set of 1000 ECGs from the PhysioNet database created for the Computing in Cardiology Challenge 2011. Two implementations are highlighted on the receiver operating characteristic (area 0.968) to fit to different applications. The implementation with high sensitivity (Se = 98.7%, Sp = 80.9%) appears as a reliable alarm when there are any incidental problems with the ECG acquisition, while the implementation with high specificity (Sp = 97.8%, Se = 81.8%) is less susceptible to transient problems but rather validates noisy ECGs with acceptable quality during a small portion of the recording.
Heart Rhythm, 2009
BACKGROUND Abnormally long and short QT intervals are recognized to be associated with an increas... more BACKGROUND Abnormally long and short QT intervals are recognized to be associated with an increased risk for life-threatening ventricular arrhythmias. It is therefore important to define the upper and lower border of the normal QT. OBJECTIVE The aim of this study was to describe the normal distribution of the QT interval in a contemporary population of young conscripts and to define long and short limits of the QT interval. METHODS In Switzerland, all young male citizens must undergo compulsory conscription for the Swiss Army at the age of 18 to 19 years. In every conscript, an electrocardiogram (ECG) is performed. Retrospectively, 41,767 consecutive ECGs of Swiss citizens who underwent conscription for the army between March 1, 2004, and July 31, 2006, were analyzed. RESULTS The mean QTc Bazett interval was 394 Ϯ 22 ms. One percent of the conscripts had a Bazett QTc shorter than 347 ms, and one percent had a Bazett QTc longer than 445 ms, respectively. None of the subjects presented a QTc Bazett Ͻ 300 ms; the prevalence of a QTc Bazett Ͻ 320 ms was 0.02%. CONCLUSION The present study shows the distribution of QT intervals in an unselected young population. Because none of the subjects presented a QTc Ͻ 300 ms, it may be concluded that the short QT syndrome is a very rare entity in the population of young male adults.
Heart Rhythm, 2012
BACKGROUND/ OBJECTIVE The purpose of the present study was to analyze the prevalence of physiolog... more BACKGROUND/ OBJECTIVE The purpose of the present study was to analyze the prevalence of physiologic and pathologic ECG abnormalities in a cohort of young conscripts that represents the whole young generation of today. METHODS ECGs of all Swiss citizens who underwent conscription for the army during a 29-month period were analyzed manually. RESULTS ECGs of 43,401 conscripts (mean age 19.2 Ϯ 1.1 years) were analyzed; 158 conscripts were female. Incomplete right bundle branch block was found in 5870 (13.5%) and left anterior fascicular block in 360 (0.83%). First-degree AV block was present in 329 (0.8%) and Mobitz type I (Wenckebach) second-degree AV block in 3 (0.01%). Early repolarization was observed in 1035 (2.4%), T-wave inversion in 39 (0.09%), and minor T-wave changes in 182 (0.42%). Brugada-like abnormalities were observed in 6 (0.01%). None of the conscripts had atrial fibrillation or flutter. CONCLUSION ECG abnormalities can be found in a relatively large proportion of young individuals. Incomplete right bundle branch block, left fascicular block, and first-degree AV block are the most frequent findings. No conscript presented with atrial fibrillation or flutter.
2009 IEEE International Conference on Acoustics, Speech and Signal Processing, 2009
Automatic Electrocardiogram (ECG) analysis, especially QRS detection, is still a challenging task... more Automatic Electrocardiogram (ECG) analysis, especially QRS detection, is still a challenging task. This is even more the case when ECG is acquired during Magnetic Resonance (MR) examination. The MR environment highly distorts ECG, with Hall Effect, due to the important static magnetic field, and artifacts, caused by fast switching magnetic field gradients. Detection of QRS complexes is then affected. In this paper, a new specific MR QRS detector is presented. This method is based on the modulus maximum lines and on the Lipschitz exponent estimation they offer. The use of this regularity characterization enables to distinguish between QRS complexes and MR artifacts. This detector outperforms existing algorithms with almost 99% sensitivity and positive prediction value.
International Journal of Cardiology
Cardiology journal, Apr 3, 2018
While prolongation of QRS duration and QTc interval during acute myocardial infarction (AMI) has ... more While prolongation of QRS duration and QTc interval during acute myocardial infarction (AMI) has been reported in animals, limited data is available for these readily available electrocardiography (ECG) markers in humans. Diagnostic and prognostic value of QRS duration and QTc interval in patients with suspected AMI in a prospective diagnostic multicentre study were prospectively assessed. Digital 12-lead ECGs were recorded at presentation. QRS duration and QTc interval were automatically calculated in a blinded fashion. Final diagnosis was adjudicated by two independent cardiologists. The prognostic endpoint was all-cause mortality during 24 months of follow-up. Among 4042 patients, AMI was the final diagnosis in 19% of patients. Median QRS duration and median QTc interval were significantly greater in patients with AMI compared to those with other final diagnoses (98 ms [IQR 88-108] vs. 94 ms [IQR 86-102] and 436 ms [IQR 414-462] vs. 425 ms [IQR 407-445], p < 0.001 for both com...
Biomedical Signal Processing and Control, 2017
British Journal of Sports Medicine, 2016
Introduction ECG in pre-participation screening in athletes is still debated. It is of relevant i... more Introduction ECG in pre-participation screening in athletes is still debated. It is of relevant interest to have an automatic detection for this screening. 44’000 person a year are undergoing the screening at the age of 19 in Switzerland during Swiss Army conscription. Objectives We hypothesise that is possible to perform automatic detection using the Seattle Criteria published for athlete screening based on a 10s 12-lead resting ECG. Methods We performed a retrospective analysis of 274’468 digital standard 12-lead resting ECGs from military conscription acquired between 2008 and 2013. The Seattle Criteria were directly integrated into an automatic resting ECG measurement and interpretation software (ETM, SCHILLER AG) without any modification. Verification of proper implementation of the algorithm was done on the same dataset by visually and manually checking a randomly selected subset of abnormal (true positives) and normal ECGs (true negatives). The percentage of detection of any subtype as well as of the general finding ‘normal/abnormal ECG’ was calculated. Results We found that the categories ’Q-wave pathologies’, ‘ST-segment depressions’ and ‘Left axis deviations’ have a detection rate higher than 1%. All other Seattle Criteria detection rates were lower. ‘Brugada-like pattern’ and ‘Profound sinus bradycardia’ were not detected. The overall detection rate of 6.5% of abnormal ECGs is comparable to the found value of 4.5% (2) among elite athletes (false positive rate of 4.2%). Conclusion It is possible to perform automatic detection abnormal ECG using the published Seattle Criteria. The 6.47% abnormal ECGs correspond to 2’850 male individuals per year which would warrant a more profound clinical, and/or electrophysiological and genetic investigation to confirm or exclude the presence of an acquired or familial cardiac disease. Abstract O-6 Figure 1 Percentage of automatically detected Seattle criteria Reference Drezner JA, Ackerman MJ, Anderson J et al. Electrocardiographic interpretation in athletes: the ‘Seattle criteria’. Br J Sport Med 2013 Feb;47(3):122–124.
Computer methods and programs in biomedicine, 2017
The first-order high-pass filter (AC coupling) has previously been shown to affect the ECG for hi... more The first-order high-pass filter (AC coupling) has previously been shown to affect the ECG for higher cut-off frequencies. We seek to find a systematic deviation in computer measurements of the electrocardiogram when the AC coupling with a 0.05 Hz first-order high-pass filter is used. The standard 12-lead electrocardiogram from 1248 patients and the automated measurements of their DC and AC coupled version were used. We expect a large unipolar QRS-complex to produce a deviation in the opposite direction in the ST-segment. We found a strong correlation between the QRS integral and the offset throughout the ST-segment. The coefficient for J amplitude deviation was found to be -0.277 µV/(µV⋅s). Potential dangerous alterations to the diagnostically important ST-segment were found. Medical professionals and software developers for electrocardiogram interpretation programs should be aware of such high-pass filter effects since they could be misinterpreted as pathophysiology or some pathop...
European Heart Journal: Acute Cardiovascular Care
Aim: Exercise stress testing is used to detect myocardial ischaemia, but is limited by low sensit... more Aim: Exercise stress testing is used to detect myocardial ischaemia, but is limited by low sensitivity and specificity. The authors investigated the value of the analysis of high-frequency QRS components as a marker of abnormal depolarization in addition to standard ST-deviations as a marker of abnormal repolarization to improve the diagnostic accuracy. Methods and results: Consecutive patients undergoing bicycle exercise stress nuclear myocardial perfusion imaging were prospectively enrolled. Presence of myocardial ischaemia, the primary diagnostic endpoint, was adjudicated using MPI and coronary angiography. Automated high-frequency QRS analysis was performed in a blinded fashion. The prognostic endpoint was major adverse cardiac events (MACEs) during two years of follow-up. Exercise-induced ischaemia was detected in 147/662 patients (22%). The sensitivity of high-frequency QRS was similar to ST-deviations (46% vs. 43%, p=0.59), while the specificity was lower (75% vs. 87%, p<0...
European Heart Journal: Acute Cardiovascular Care
Background: Recent advances in digital electrocardiography technology allow evaluating ST-segment... more Background: Recent advances in digital electrocardiography technology allow evaluating ST-segment deviations in all 12 leads as quantitative variables and calculating summed ST-segment deviation scores. The diagnostic and prognostic utility of summed ST-segment deviation scores is largely unknown. Methods: We aimed to explore the diagnostic and prognostic utility of the conventional and the modified ST-segment deviation score (Better Analysis of ST-segment Elevations and Depressions in a 12- Lead-ECG-Score (BASEL-Score): sum of elevations in the augmented voltage right - lead (aVR) plus absolute, unsigned ST-segment depressions in the remaining leads) in patients presenting with suspected non-ST-segment elevation myocardial infarction. The diagnostic endpoint was non-ST-segment elevation myocardial infarction, adjudicated by two independent cardiologists. Prognostic endpoint was mortality during two-year follow up. Results: Among 1330 patients, non-ST-segment elevation myocardial in...
Journal of Electrocardiology
Journal of Electrocardiology