Hachiya et al used the Peak Deflection Index (PDI) to identify a patient with outflow tract ventricular tachycardia who is unlikely to respond to radiofrequency catheter ablation (RFCA). These patients may have the origin of the tachycardia at a point not affected by the catheter ablation, either deep within the ventricular septum or at an epicardial site. The authors are from Tokyo Medical and Dental University.


Patient selection: with outflow tract ventricular tachycardia


ECG lead: inferior lead with with the tallest R wave (II, III, aVF)



(1) QRS duration in milliseconds

(2) time from QRS onset to peak of the R wave (earliest peak deflection)


peak deflection index =

= (time from QRS onset to R wave peak in milliseconds) / (QRS duration in ms)



• A PDI > 0.6 is associated with a high rate of RFCA failure.



• The sensitivity was 80% and specificity 90%.


To read more or access our algorithms and calculators, please log in or register.