Use of correlation waveform analysis in discrimination between anterogradeand retrograde atrial electrograms during ventricular tachycardia

Correlation Waveform Analysis. Introduction: Discriminating between ventric ular tachycardia (VT) with 1:1 ventriculoatrial association and sinus tachy cardia can be difficult, even when assisted by intracardiac tracings. In th is 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% +/- 1 6% were analyzed. A template of an intracardiac high right atrial electrogr am was obtained during sinus rhythm (SR). Atrial electrograms during SR and VT were compared with the template using the new algorithm, and correlatio n coefficients (rho) were generated. The correlation coefficient of SR beat s 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 retrogra de conduction, rho was 70.6% +/- 11.3% (P < 0.0001). At a cutoff of 85%, <r ho> had positive and negative predictive values of 99% and 96%, respectivel y. Conclusion: Our findings, indicate that the new algorithm can reliably sepa rate between anterograde and retrograde atrial activation during VT. It can , therefore, discriminate between sinus tachycardia and VT with 1:1 ventric uloatrial conduction and may be useful in preventing inappropriate shocks f rom dual chamber defibrillators.