Catheter Ablation -> Ventricular Arrhythmias -> Mapping & Imaging D-PO06 - Poster Session VI (ID 26) Poster

D-PO06-111 - Analysis Of Endocardial Electrogram Characteristics To Predict Left Ventricular Free Wall Intramural Scar (ID 671)


Background: Limited information exists on the value of endocardial (ENDO) electrograms (EGMs) for identifying free wall intramural scar (FW IS) in LV nonischemic cardiomyopathy (NICM).
Objective: To define ENDO EGM voltage and signal type that can predict MRI-defined FW IS.
Methods: 15 consecutive patients (12 men, 47±21 yrs) with LV NICM and FW IS on preprocedural cardiac MRI had LV maps (194 ± 75 points/map, range: 129 - 409) with evidence of preserved ENDO bipolar (BI) voltage (>1.5mV). The LV electroanatomic map and MRI images were divided according to 17-segment AHA model. FW segments were assessed for: 1) BI and unipolar (UNI) voltage that best detect FW IS using a graded voltage analysis (BI: 2.5-4 mV, UNI: 5-8.3 mV, using increments of 0.5 mV); 2) Presence of split BI EGMs with a higher amplitude “near field” deflection (>1.5 mV), followed by distinct 2nd smaller (<1.0 mV) “far field” component which represents activation on outer side of scar.
Results: 133/165 LV segments were analyzable on MRI (82 had no evidence of scar, 20 had IS, 22 epicardial scar, 3 ENDO scar, and 6 transmural scar). The best BI cutoff associated with IS was 3 mV (sensitivity 63%, specificity 78%, positive predictive value, PPV, 56%, and negative predictive value, NPV, 82%, p=0.001) and optimal UNI cutoff was 6 mV (sensitivity 50%, specificity 79%, PPV 50%, NPV 79%, p=0.01). BI split EGMs predicted FW IS with sensitivity 63%, specificity 80%, PPV 58%, NPV 83%, p<0.0001. Combining the BI cutoff, UNI cutoff, and presence of BI split EGMs, increased the specificity to 96% (PPV 78%, NPV 76%, p=0.001).
Conclusion: A BI cutoff of 3 mV, a UNI cutoff of 6 mV, and presence of split BI EGMs provide accurate detection of MRI-defined FW IS in LV NICM.