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Use of a novel fragmentation map to identify the substrate for ventricular tachycardia in postinfarction
Bieito Campos1, Miguel E Jauregui1, Francis E Marchlinski2
1Electrophysiology Section, Department of Cardiology, Hospital Universitari Arnau de Vilanova, Lleida, Spain.
Insights
Automated analysis of electrogram fragmentation accurately identifies ventricular tachycardia (VT) isthmus sites in postinfarction cardiomyopathy. This objective tool can guide substrate-based VT ablation strategies.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Imaging
Background:
- Substrate ablation is crucial for postinfarction cardiomyopathy with ventricular tachycardia (VT).
- Identifying fragmented and late potentials during sinus rhythm is challenging and operator-dependent.
Purpose of the Study:
- To evaluate automated analysis for quantifying electrogram fragmentation.
- To determine the relationship between fragmented regions and the VT isthmus.
Main Methods:
- Left ventricular (LV) mapping in 14 patients with VT post-myocardial infarction and 14 controls.
- Entrainment mapping to identify VT isthmus sites.
- Time- and frequency-domain analysis of sinus rhythm LV electrograms to create fragmentation maps.
Main Results:
- Automated analysis defined cutoffs for abnormal electrogram fragmentation.
- Fractionated electrograms occupied a smaller LV surface area but contained all VT isthmus sites (time domain).
- Frequency domain analysis showed abnormal fractionation areas included 60% of VT isthmus sites.
Conclusions:
- Automated electrogram fragmentation analysis is an objective method for quantifying fragmentation and guiding VT ablation.
- Empiric ablation of identified regions may offer a novel substrate-guided VT ablation strategy.
Background:
Substrate ablation is commonly performed in patients with postinfarction cardiomyopathy and ventricular tachycardia (VT). Recognition of fragmented and late potentials during sinus rhythm is a tedious process subject to operator fatigue.
Objective:
The purpose of this study was to assess the value of automated analysis to quantify electrogram fragmentation and to determine the relationship of fragmented regions to the VT isthmus.
Methods:
Detailed left ventricular (LV) mapping was performed in 2 groups: (1) 14 patients with previous myocardial infarction and tolerated VT and (2) 14 controls with structurally normal hearts. In patients with VT, mid-isthmus sites were identified using entrainment mapping. Sinus rhythm endocardial LV electrograms underwent time- and frequency-domain analysis and were displayed as fragmentation or frequency maps. The region of fractionated electrograms and their relation to the VT isthmus sites were determined.
Results:
Cutoffs for abnormal electrogram fragmentation were ventricular fractionation index ≥ 7 and fast Fourier transform ratio ≥ 14%, respectively. In the time domain, LV surface area with fractionated electrograms was significantly smaller than the total scar surface area (27.3% ± 7.1% vs 42.1% ± 12.3%, P <.001), yet contained 100% of VT isthmus sites. In the frequency domain, areas of abnormal fractionation occupied 9.7% ± 6.9% of total LV surface area and included only 60% of the VT isthmus sites.
Conclusion:
Automated electrogram fractionation analysis represents an objective tool to rapidly quantify electrogram fragmentation and guide substrate-based ablation of VT. Empiric ablation of these regions may be a new strategy for substrate-guided VT ablation.
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