Systematic identification of low voltage-high frequency electrogram zones at sites of left atrial reentrant tachycardia termination

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: Private company. Main funding source(s): Abbott Laboratories BACKGROUND: Localization of the critical isthmus of conduction of LAMRT circuits within scar tissue is challenging (Panel A). Low voltage (LV) has been used as a marker for the arrhythmic substrate. However, voltage amplitudes due to near field (NF) vs. far-field (FF) electrogram (EGM) components are not clearly differentiated. The peak frequency (PF) associated with bipolar EGM’s is a novel parameter which may distinguish them (Panel B). PURPOSE: To compare the ability of LV vs. LVHF to discriminate the LAMRT termination region METHODS: Bipolar voltage and activation maps were generated with a 16-pole grid catheter (Advisor HD Grid) during LAMRT (Panels A,C). Peak frequency maps were retrospectively computed (Panels B,D). LAMRT’s were included if acute termination could be achieved by focal RF lesion set restricted to a boundary <1.5cm diameter. The left atrial (LA) mapped surface was sub-regioned into the termination (T-ZONE) and non-termination (NT-ZONE) zones. The T-ZONE surface was centered about the site of termination and was allowed to extend to a rectangular kernel >0.5cm and <1.5cm across perpendicular axes, with the NT-ZONE encompassing the remainder of the mapped surface area (SA). Sensitivity (SE) and specificity (SP) of discrimination of the T-ZONE vs. NT-ZONE was measured according to the %T-ZONE vs. %NT-ZONE SA occupied at LV thresholds ranging from 0.1-1.0mV in increments of 0.1mV (Panel E). In addition to LV, LVHF at peak frequency cutoffs of 150Hz (LVHF150), 200Hz (LVHF200), 250Hz (LVHF250) and 300Hz (LVHF300) were also assessed for T-ZONE discrimination (Panels F,G). RESULTS: Of 16 consecutive patients with 24 ATs prospectively enrolled, 13 LAMRT’s from 13 patients met the termination criteria for inclusion. LAMRT termination consisted of a mean of 2.85±2.82 focal RF lesions. The T-ZONE occupied a mean SA of 0.82±0.30cm2 (41±19 EGM points) vs. 158.6±42.2cm2 (2967±1227 points) for the NT-ZONE. While the mean voltage from the T-ZONE was significantly lower vs. the NT-Zone (0.12±0.05mV vs. 0.60±0.28mV respectively), mean T-ZONE peak frequency of the was significantly higher vs. the NT-ZONE (345±76Hz vs. 255±34Hz). The maximum EGM duration in the T-ZONE was 172±63ms. ROC discrimination of the T-ZONE resulted in AUC’s of 0.69- LV, 0.76- LVHF150, 0.80- LVHF200, 0.81- LVHF250 and 0.76- LVHF300. LVHF200 and LVHF250 yielded the best improvements in AUC vs. LV unconstrained by high PF (11.3% and 12.2% respectively)(Panel G). LVHF200 with a cutoff of 0.2mV yielded a balanced SE/SP of 0.86/0.83 respectively, while LVHF250 with a cutoff of 0.3mV yielded a balanced SE/SP of 0.85/0.84. CONCLUSION: During AT, systematic identification of EGM regions of high frequency within low voltage can significantly improve discrimination of the site of AT. termination, beyond. [Figure: see text]