Abstract
BackgroundMyocardial slow conduction is a cornerstone of ventricular tachycardia (VT). Prolonged electrogram (EGM) duration is a useful surrogate parameter and manual annotation of EGM characteristics are widely used during catheter-based ablation of the arrhythmogenic substrate. However, this remains time-consuming and prone to inter-operator variability. We aimed to develop an algorithm for 3-D visualization of EGM duration relative to the 17-segment American Heart Association model.MethodsTo calculate and visualize EGM duration, in sinus rhythm acquired high-density maps of patients with ischemic cardiomyopathy undergoing substrate-based VT ablation using a 64-mini polar basket-catheter with low noise of 0.01 mV were analyzed. Using a custom developed algorithm based on standard deviation and threshold, the relationship between EGM duration, endocardial voltage and ablation areas was studied by creating 17-segment 3-D models and 2-D polar plots.Results140,508 EGMs from 272 segments (n = 16 patients, 94% male, age: 66±2.4, ejection fraction: 31±2%) were studied and 3-D visualization of EGM duration was performed. Analysis of signal processing parameters revealed that a 40 ms sliding SD-window, 15% SD-threshold and >70 ms EGM duration cutoff was chosen based on diagnostic odds ratio of 12.77 to visualize rapidly prolonged EGM durations. EGMs > 70 ms matched to 99% of areas within dense scar (<0.2 mV), in 95% of zones within scar border zone (0.2–1.0 mV) and detected ablated areas having resulted in non-inducibility at the end of the procedure. Ablation targets were identified with a sensitivity of 65.6% and a specificity of 94.6% avoiding false positive labeling of prolonged EGMs in segments with healthy myocardium.ConclusionThe novel algorithm allows rapid visualization of prolonged EGM durations. This may facilitate more objective characterization of arrhythmogenic substrate in patients with ischemic cardiomyopathy.
Highlights
Ventricular tachycardia (VT) in patients with ischemic cardiomyopathy (ICM) is a major cause of sudden cardiac death [1]
The arrhythmogenic substrate that is targeted during ventricular tachycardia (VT) ablation is located predominantly at the border between normal and scarred myocardium [3]
Local electrograms (EGM) with abnormal characteristics serve as a surrogate parameter for slow conducting zones during substrate-based VT ablation and might improve the characterization of possible arrhythmogenic ablation targets [4,5]
Summary
Ventricular tachycardia (VT) in patients with ischemic cardiomyopathy (ICM) is a major cause of sudden cardiac death [1]. As manual identification of EGM duration during sinus rhythm is time-consuming and prone to inter-operator variability, an automated algorithm may reduce procedure time. In this study, we developed a novel algorithm for 3-dimensional (3-D) visualization of EGM duration relative to the 17-segment American Heart Association model [11] to objectively identify potential arrhythmogenic areas of slow conduction in patients with ICM and VT in an automated and time-saving way. Prolonged electrogram (EGM) duration is a useful surrogate parameter and manual annotation of EGM characteristics are widely used during catheter-based ablation of the arrhythmogenic substrate. This remains time-consuming and prone to inter-operator variability. We aimed to develop an algorithm for 3-D visualization of EGM duration relative to the 17-segment American Heart Association model
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