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.