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.