New diagnostic criteria for accurately localizing the focus of ventricular tachycardia of outflow tract from surface electrocardiogram analysis

The ventricular outflow tract is considered the commonest site of Idiopathic ventricular tachycardia (VT) and premature ventricular contractions (PVCs) in the absence of clinically apparent structural heart disease.

To assess the diagnostic accuracy of precordial QRS complex voltage in surface ECG for localizing the origin of outflow tract premature ventricular contraction (PVC) and ventricular tachycardia (VT) in patients without structural heart disease.

Among 81 consecutive (20 left-sided origin foci) patients, who underwent acutely successful outflow tract ablation, surface ECG was analysed and voltage of QRS and R wave of precordial leads of the PVCs or VT measured.

Of the different various criteria for determining a left from right-sided origin focus;

The ratio of Σ (R-voltage) /Σ (QRS-voltage) of all precordial leads was the best discriminator cut-off values of 0.7 with area under the curve (AUC) values based on receiver operator characteristics (ROCs) of 0.892, P<0.001, sensitivity= 0.80(CI:0.743– 1.0) and specificity= 0.966 (CI:0.82- 0.99).

Surface ECG analysis allows accurate and reproducible determination left from right-sided ventricular outflow tract foci facilitating mapping and ablation.

ROC curve of equation