Optimal cut-off value for endocardial bipolar voltage mapping using a multipoint mapping catheter to characterize the scar regions described in cardio-CT with myocardial thinning.

INTRODUCTION: To investigate whether the current standard voltage cut-off of <0.5 for dense scar definition on endocardial bipolar voltage mapping (EBVM), using a high-resolution multipoint mapping catheter with microelectrodes (HRMMC), correctly identifies the actual scar area described on CT with myocardial thinning (CT MT). METHODS: Forty patients (39 men; 67.0 ± 9.0 y/o) with a history of transmural myocardial infarction (mean time interval since MI 15.0 ± 7.9 years) and sustained ventricular tachycardia (VT) were consecutively enrolled. A CT MT was performed in each patient before VT ablation. The CT MT 3D anatomical model, including MT layers, was merged with the 3D electroanatomical and EBVM. Different predefined cut-off settings for scar definition on EBVM were used to identify the optimal ones, which showed the best overlap in terms of scar area with the different MT layers. RESULTS: A cut-off value of <0.2 mV demonstrated the best correlation in terms of scar area with the 2 mm thinning on CT MT (p = .04) and a cut-off of <1 mV best overlapped with the 5 mm thinning (p = .003). The currently used <0.5 mV cut-off for scar definition on EBVM proved to be the best area correlation with 3 mm thinning (p = .0002). CONCLUSION: In order to better identify the real extent of scar areas after transmural MI as described on preprocedural CT MT, higher cut-off values for scar definition should be applied if the EBVM is performed using a HRMMC.