Spontaneous variation of ventriculoatrial interval after tachycardia induction: determinants and usefulness in the diagnosis of supraventricular tachycardias with long ventriculoatrial interval

Abstract Funding Acknowledgements Type of funding sources: None. Background Determining the mechanism supraventricular tachycardias with prolonged ventriculoatrial (VA) intervals is sometimes a challenge, because usual diagnostic manoeuvers based on pacing during ongoing tachycardia cannot be performed or do not offer accuracy. Purpose To analyse determinants, time course and accuracy (atypical atrioventricular nodal reentrant [AVNRT] versus orthodromic through an accessory pathway [ORT]) spontaneous VA variation in patients narrow QRS VA. Methods A total 156 induced were studied (44 atypical AVNRT 112 ORT). Two sets 10 measurements for each patient: after induction one minute later. VV determined. Results Among AVNRT, there was marked variability (Mn-VA: mean beat-to-beat VA; MX-VA: maximum variation). Figure 1. No significant differences found interval between slow-slow fast-slow AVNRTs (p>0.5 all comparisons). And, even though at continued to considerable, it tended decrease induction. However, as shown 1, subjects ORT, no relevant changes duration seen, neither nor The values ORT septal free-wall pathways similar. Additionally, 9 (20%) 11 (10%) Dif-VA increased from minute, increment being 29 ms 6 ms, respectively. difference longest shortest (Dif-VA) correlates significantly diagnosis (C coefficient=0.95 0.85 respectively; p<0.001). ≥15 presents sensitivity specificity 50% 99%, respectively induction, 27% 100% 2. We robust correlation fluctuations (Coefficient Rho: 0.56 0.76, p<0.001 both) but ORTs. Conclusions analysis later correctly discriminates almost cases. Such related AVRNTs