Frequency Analysis of the QRS Complex for Implantable Cardioverter Defibrillator Patients for Risk Stratification
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Authors
Hua, Thalia
Date
Type
thesis
Language
eng
Keyword
Sudden Cardiac Death , Risk Stratification , Signal Analysis
Alternative Title
Abstract
Background: Sudden cardiac death (SCD) is one of the leading causes of cardiovascular death in North America. A metric called Layered Symbolic Decomposition frequency (LSDf) has been found to independently predict risk of SCD by stratifying patients into high risk or low risk groups based on a threshold determined from a derivation patient cohort. Here, we aimed to 1) validate the LSDf threshold to associate with event outcomes, 2) determine the predictive potential of the threshold, and 3) investigate the underlying physiological relationship of LSDf with SCD.
Methods & Results: Signal Averaged ECG recordings were completed for all patients recruited into our studies. Event outcomes were defined as surrogates for SCD including sustained ventricular arrhythmias (>30sec), appropriate ICD shock or anti-tachycardia pacing, new onset of heart failure, or cardiac mortality. For aim 1, a cross-sectional cohort of 172 patients with previous cardiac defibrillator devices (ICD and CRT-D) were stratified by the pre-determined LSDf threshold of 13.25%. The rate of events was significantly higher for patients with an LSDf ≤13.25%, with a relative risk of 1.43 times higher for experiencing an event than LSDf >13.25% (RR: 1.43 [1.22 – 1.67], p<0.01). The odds of experiencing an event for LSDf ≤13.25% patients were 6.05 times greater than LSDf>13.25% patients. For aim 2, two prospective studies involving a CABG cohort and ICD cohort comprised of 172 and 61 patients respectively were stratified as high or low risk for events prior to the cardiac intervention. The overall accuracy of correctly identifying patients as high risk or low risk was 81.4% [74.8 – 86.9%] for CABG patients and 50.8 [37.7 – 63.9%] for ICD patients. For aim 3, LSDf was found to change significantly following VT ablation (1.76 ± 1.24%, p<0.01) in 13 patients, whereas there was no significant change in LSDf following procainamide infusion (0.705 ± 1.89%, p=0.295) in 12 patients.
Conclusions: LSDf is a promising metric to facilitate the identification for patients at risk of SCD and provide a novel method for patient screening that is both non-invasive and relatively inexpensive to implement into clinical settings.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.