Correlation of Extent of Left Ventricular Endocardial Unipolar Low Voltage Zones with Ventricular Tachycardia in Non-ischemic Cardiomyopathy

BACKGROUND Endocardial electrogram (EGM) characteristics in non-ischemic cardiomyopathy (NICM) have not been explored adequately for prognostication. OBJECTIVES We aim to study correlation of bipolar and unipolar EGM characteristics with left ventricular ejection fraction (LVEF) and ventricular tachycardia (VT) in NICM. METHODS Electroanatomical mapping of LV was performed. Correlation of EGM characteristics with LVEF was performed. Differences between groups with and without VT and predictors of VT were studied. RESULTS In 43 patients, unipolar EGM variables had better correlation with baseline LVEF than bipolar EGM variables: unipolar voltage (r=+0.36), peak negative unipolar voltage (r=-0.42), peak positive unipolar voltage (r=+0.38), and percentage area of unipolar LVZ (r=-0.41). Global mean unipolar voltage (HR- 0.4; 95% C.I 0.2-0.8), extent of unipolar LVZ (HR- 1.6; 95% CI 1.1-2.3) and % area of unipolar LVZ (HR- 1.6; 95% CI 1.1-2.3) were significant predictors of VT. For classification of patients with VT, extent of unipolar LVZ had AUC of 0.82 (95% CI 0.69-0.95; p<0.001), and % area of unipolar LVZ had AUC of 0.83 (95% CI 0.71-0.96; p=0.01). Cut-off of >3 segments for extent of unipolar LVZ had the best diagnostic accuracies (sensitivity- 90%; specificity- 67%) and cut-off of 33% for percentage area of unipolar LVZ had the best diagnostic accuracy (sensitivity- 95%; specificity- 60%) for VT. CONCLUSION In NICM, extent and percentage area of unipolar low voltage zones are significant predictors of VT. Cut-offs of >3 segments of unipolar LVZ and >33% area of unipolar LVZ, have good diagnostic accuracies for association with VT.