Clinical Electrophysiology -> SVT/AVNRT/WPW/AT: -> Physiology-Pharmacology D-PO05 - Poster Session V (ID 39) Poster

D-PO05-212 - VA Linking Following Sensed Premature Atrial Complexes - A Unique Method Of Distinguishing Mechanisms Of Supraventricular Tachycardia (ID 595)


Background: Ventricular pacing manoeuvres are commonly used for distinguishing supraventricular tachycardia (SVT) mechanisms but are often limited by poor VA conduction or SVT termination. We propose a method to distinguish SVT mechanism by assessing VA linking following sensed PACs.
Objective: To assess for return beat VA linking following PACs amongst different SVT mechanisms.
Methods: Forty-five patients underwent EP study for SVT, resulting in diagnoses of orthodromic AVRT using a robust accessory pathway (AP) (n=11), AVRT using a decremental AP (n = 4), typical AVNRT (n = 11), atypical AVNRT (slow/slow or fast/slow, n = 12) and focal AT (n = 7). PACs from the proximal coronary sinus were successfully introduced during SVT at varying coupling intervals in all patients. The VA interval on the return beat (VAreturn) was compared to the VA interval during SVT (VAsvt). VA linking was defined as VAreturn - VAsvt ≤ 5 ms.
Results: All patients with typical AVNRT and AVRT utilizing a traditional (non-decremental) AP demonstrated VA linking across all PAC coupling intervals (e.g. Panel A/B). Patients with atypical AVNRT or AVRT utilizing decremental AP demonstrated VA linking with late coupled PACs, whilst VAreturn progressively prolonged with shorter coupled PACs (e.g. Panel C/D). Patients with focal AT did not demonstrate reliable VA linking (e.g. Panel E). Late coupled resetting PACs demonstrated VA linking in most cases of AVNRT and AVRT (Panel F).
Conclusion: VA linking across all PAC coupling intervals is seen only with typical AVNRT and AVRT utilising non-decremental APs. VA linking with late coupled resetting PACs may distinguish atypical AVNRT or AVRT utilising decremental APs from focal AT.