Use of correlation waveform analysis in discrimination between anterograde and retrograde atrial electrograms during ventricular tachycardia.

INTRODUCTION: Discriminating between ventricular tachycardia (VT) with 1:1 ventriculoatrial association and sinus tachycardia can be difficult, even when assisted by intracardiac tracings. In this study, we used a new computer algorithm to perform correlation waveform analyses on intracardiac atrial electrograms to help distinguish between VT and sinus tachycardia. METHODS AND
RESULTS: Electrophysiologic studies of 28 patients (22 men; age 66 +/- 14 years) with inducible VT and mean ejection fraction of 37% +/- 16% were analyzed. A template of an intracardiac high right atrial electrogram was obtained during sinus rhythm (SR). Atrial electrograms during SR and VT were compared with the template using the new algorithm, and correlation coefficients (rho) were generated. The correlation coefficient of SR beats with the template was 96.4% +/- 3.4%. During VT with AV dissociation and persistent SR, rho was 94.5% +/- 3.7% (P = NS). During VT with 1:1 retrograde conduction, rho was 70.6% +/- 11.3% (P < 0.0001). At a cutoff of 85%, rho had positive and negative predictive values of 99% and 96%, respectively.
CONCLUSION: Our findings indicate that the new algorithm can reliably separate between anterograde and retrograde atrial activation during VT. It can, therefore, discriminate between sinus tachycardia and VT with 1:1 ventriculoatrial conduction and may be useful in preventing inappropriate shocks from dual chamber defibrillators.