Prediction of the Exit Site of Ventricular Tachycardia Based on Different ECG Lead Systems

The effectiveness of a computer-based method forlocalization of arrhythmia exit sites was studied.The proposed algorithm works on any set of 3 or moreECG leads. The QRS complex integral of an ectopic beatis reduced to principal components treated as coordinatesof the exit site in ECG space and then projected to realspace by a linear transformation. The accuracy of themethod was tested on 5 patient-tailored models of humanheart and torso. For each model ~500 simulations wererun, each for different stimulus location. All locationswere then estimated from simulated surface ECGs andmethod accuracy was investigated.The algorithm performed better for the left ventriclethan for the right ventricle. The group mean absolute andrelative (to a neighboring stimulation site) localizationerrors in millimeters were: 11.5 (SD=2.5), 2.6 (SD=0.5)for the 252-lead ECG; 12.2 (SD=2.7), 2.7 (SD=0.5) forthe 12-lead ECG; and 11.7 (SD=2.4), 2.7 (SD=0.5) forthe Frank VCG.This study suggest that the proposed method canpredict exit sites with a precision in the order of acentimeter. Low values of error for neighbouringactivation sites suggest opportunity for algorithmimprovement. The use of vectorcardiographic leads isenough to obtain a precision comparable to a 252-leadECG