A novel pacing manoeuvre to diagnose atrial tachycardia

Aims: Currently used diagnostic manoeuvres at the electrophysiologystudy do not always allow for consistent identification of atrialtachycardia (AT), either because of inapplicability of the techniqueor because of low predictive value and specificity. The aimof this study was to determine whether overdrive atrial pacingduring paroxysmal supraventricular tachycardia (SVT) with thesame cycle length from both the high right atrium and the coronarysinus can accurately identify or exclude AT by examining thedifference between the V–A intervals of the first returningbeat of tachycardia between the two pacing sites. Methods and results: Fifty-two patients were included; 24 patients with atrioventricularnodal re-entry tachycardia (AVNRT), 13 patients with atrioventricularre-entry tachycardia (AVRT), and 15 patients with AT. Comparingthe 37 non-AT patients with the 15 AT patients, there was ahighly significant difference between the mean V–A intervaldifference, (delta V–A) 2.1 ± 1.8 ms (range 0–9ms) vs. 79.1 ± 42 (range 22–267 ms) (P < 0.001),respectively. None of the patients in the non-AT group had adelta V–A > 10 ms. In contrast, all 15 patients withAT had a delta V–A interval >10 ms. Thus, the diagnosticaccuracy of the delta V–A interval cut-off of >10 mswas 100%, with a 95% confidence interval of 93.1–100%for AT. In 11 (73%) of the 15 AT patients, the standard ventricularoverdrive pacing manoeuvre was not possible. In 14 of the 15patients (93%) in the AT group, standard atrial overdrive pacingshowed variable V–A intervals, correctly diagnosing AT.In all 52 patients, this measurement was repeated during pacingfrom the other location. In five patients from the AT group,the result of the second attempt was different from the resultof the first attempt. Conclusion: We found that atrial differential pacing during paroxysmal SVTwithout termination of tachycardia and the finding of variablereturning V–A interval was highly sensitive and specificfor the diagnosis of AT. The manoeuvre can be easily performedin all patients with SVT and is highly reproducible. It is auseful adjunct to the currently available ventricular and atrialpacing manoeuvres.