Vectorcardiographic predictors of ventricular arrhythmia inducibility in patients with tetralogy of Fallot.

INTRODUCTION Vectorcardiography (VCG) may have predictive value in Tetralogy of Fallot (TOF) patients undergoing ventricular arrhythmia inducibility (VAI) electrophysiology studies (EPs). MATERIALS AND METHODS Blinded, retrospective analyses of 37 adult TOF patients undergoing EPs prior to pulmonary valve replacements were performed (21 female, median age 37years). VAI was evaluated from EPs and resting 12-lead electrocardiograms, respectively using QRS and heart rate adjusted Q-T intervals, spatial QRS-T angles (peaks), T-wave and QRS-wave (QRSwave vc) component vector root mean squares. Differences were assessed (Student t-tests, Mann Whitney U-tests, Analysis of Variance). Relative risks were calculated. RESULTS 16 patients had VAI (6 monomorphic, 10 polymorphic). Only the QRSwave vc showed significant differences between those with and without VAI, 10.5±2.4 dmV vs. 13.9±4.5dmV, respectively (p=0.002), area under the ROC curve of 0.78 and relative risk of 2.52. CONCLUSION VCG evidence of depolarization differences was significant between TOF patients with and without inducible VA.