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Schäfer M, Mitchell MB, Brateng C, Ivy DD, Hunter KS, Nash DB, von Alvensleben JC. Extraction and Digitization of ECG Signals from Standard Clinical Portable Document Format Files for the Principal Component Analysis of T-wave Morphology. Cardiovasc Eng Technol 2023; 14:631-639. [PMID: 37491551 DOI: 10.1007/s13239-023-00673-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 07/17/2023] [Indexed: 07/27/2023]
Abstract
INTRODUCTION T-wave analysis from standard electrocardiogram (ECG) remains one of the most available clinical and research methods for evaluating myocardial repolarization. T-wave morphology was recently evaluated to aid with diagnosis and characterization of diastolic dysfunction. Unfortunately, PDF stored ECG datasets limit additional numerical post-processing of ECG waveforms. In this study, we apply a simple custom process pipeline to extract and re-digitize T-wave signals and subject them to principal component analysis (PCA) to define primary T-wave shape variations. METHODS We propose simple pre-processing and digitization algorithms programmable as a MATLAB tool using standard thresholding functions without the need for advanced signal analysis. To validate digitized datasets, we compared clinically standard measurements in 20 different ECGs with the original ECG machine interpreted values as a gold standard. Afterwards, we analyzed 212 individual ECGs for T-wave shape analysis using PCA. RESULTS The re-digitized signal was shown to preserve the original information as evidenced by excellent agreement between original - machine interpreted and re-digitized clinical variables including heart rate: bias ~ 1 bpm (95% CI: -1.0 to 3.5), QT interval: bias ~ 0.000 ms (95% CI: -0.012 to 0.012), PR interval: bias = -0.015 ms (95% CI: -0.015 to 0.003), and QRS duration: bias = -0.001 ms (95% CI: -0.007 to 0.006). PCA revealed that the first principal component universally modulates the T-wave height or amount of repolarization voltage regardless of the investigated ECG lead. The second and third principal components described variation in the T-wave peak onset and the T-wave peak morphology, respectively. CONCLUSION This study presents a straightforward method for re-digitizing ECGs stored in the PDF format utilized in many academic electronic medical record systems. This process can yield re-digitized lead specific signals which can be retrospectively analyzed using advanced custom post-processing numerical analysis independent of commercially available platforms.
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Affiliation(s)
- Michal Schäfer
- Division of Cardiology, Heart Institute, Children's Hospital Colorado, University of Colorado Denver, 13123 E 16th Ave, Anschutz Medical Campus, Aurora, CO, 80045-2560, USA.
| | - Max B Mitchell
- Section of Pediatric Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Caitlin Brateng
- Division of Cardiology, Heart Institute, Children's Hospital Colorado, University of Colorado Denver, 13123 E 16th Ave, Anschutz Medical Campus, Aurora, CO, 80045-2560, USA
- Division of Cardiology, Section of Electrophysiology, Heart Institute, Children's Hospital Colorado, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - D Dunbar Ivy
- Division of Cardiology, Heart Institute, Children's Hospital Colorado, University of Colorado Denver, 13123 E 16th Ave, Anschutz Medical Campus, Aurora, CO, 80045-2560, USA
| | - Kendall S Hunter
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Dustin B Nash
- Division of Cardiology, Heart Institute, Children's Hospital Colorado, University of Colorado Denver, 13123 E 16th Ave, Anschutz Medical Campus, Aurora, CO, 80045-2560, USA
- Division of Cardiology, Section of Electrophysiology, Heart Institute, Children's Hospital Colorado, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Johannes C von Alvensleben
- Division of Cardiology, Heart Institute, Children's Hospital Colorado, University of Colorado Denver, 13123 E 16th Ave, Anschutz Medical Campus, Aurora, CO, 80045-2560, USA
- Division of Cardiology, Section of Electrophysiology, Heart Institute, Children's Hospital Colorado, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
- Division of Cardiology, Section of Adult Congenital Heart Disease, Heart Institute, Children's Hospital Colorado, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
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False Negative ECG Device Results May Increase the Risk of Adverse Events in Clinical Oncology Trials. Ther Innov Regul Sci 2022; 56:667-676. [PMID: 35471562 PMCID: PMC9135776 DOI: 10.1007/s43441-022-00405-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 04/07/2022] [Indexed: 12/03/2022]
Abstract
Background Sites participating in clinical trials may not have the expertise and infrastructure to accurately measure cardiac intervals on 12-lead ECGs and rely heavily on the automated ECG device generated results for clinical decision-making. Methods Using a dataset of over 260,000 ECGs collected in clinical oncology studies, we investigated the mean difference and the rate of false negative results between the digital ECG machine QTc and QRS measurements compared to those obtained by a centralized ECG core lab. Results The mean differences between the core lab and the automated algorithm QTcF and QRS measurements were + 1.8 ± 16.0 ms and − 1.0 ± 8.8 ms, respectively. Among the ECGs with a centralized QTcF value > 450 or > 470 ms, 39.5% and 47.8% respectively had a device reported QTcF value ≤ 450 ms or ≤ 470 ms. Among the ECGs with a centrally measured QTcF > 500 ms, 55.8% had a device reported value ≤ 500 ms. Automated QTcF measurements failed to detect a QTcF increase > 60 ms for 53.9% of the ECGs identified by the core lab. Automated measurements also failed to detect QRS prolongation, though to a lesser extent than failures to detect QTc prolongation. Among the ECGs with a centrally measured QRS > 110 or 120 ms, 7.9% and 7.3% respectively had a device reported QRS value ≤ 110 ms or ≤ 120 ms. Conclusion Relying on automated measurements from ECG devices for patient inclusion and treatment (dis)continuation decisions poses a potential risk to patients participating in oncology studies.
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