Introduction: It is unknown if the functional characteristics of endocardial scar change over time from initial VT diagnosis.
Hypothesis: Patients with longer duration from index VT have more complex scar at the time of elective VT ablation.
Methods: 80 subjects with structural heart disease who underwent catheter-based VT ablation with endocardial mapping between 2014 and 2016 were included. Mapping was performed both in sinus rhythm or RV apical pacing and VT when feasible with the procedural endpoints of targeting critical isthmi, eliminating areas of local abnormal ventricular activation (LAVA) and VT non-inducibility. Pearson correlation and one way ANOVA were used for statistical analysis.
Results: Patients with longer duration of VT diagnosis required larger areas of scar ablation (p = 0.01), which was mainly driven by more prevalent LAVA. There was no correlation between the duration of VT diagnosis and the total scar area (bipolar < 1.5 mV). Subgroup analysis for thirty-three subjects revealed that patients with longer duration of VT had larger areas of slow activation measured using isochronal late activation mapping (ILAM). This was noticed as soon as two years after VT diagnosis and was more profound after nine years (p < 0.001).
Conclusion: Our analysis reveals progressive endocardial scar and need for more extensive ablation with increased duration since index VT diagnosis.
Figure 1. Patients with longer VT diagnosis require more extensive ablation (A, error bars = SEM), and exhibit larger areas of slow activation on ILAM (B, error bars = 95% CI).