Journal of Arrhythmia (2017-06-01)

A proposal of clinical ECG index “vagal score” for determining the mechanism of paroxysmal atrioventricular block

  • Sayaka Komatsu, MD,
  • Masataka Sumiyoshi, MD,
  • Seiji Miura, MD,
  • Yuki Kimura, MD,
  • Tomoyuki Shiozawa, MD,
  • Keiko Hirano, MD,
  • Fuminori Odagiri, MD,
  • Haruna Tabuchi, MD,
  • Hidemori Hayashi, MD,
  • Gaku Sekita, MD,
  • Takashi Tokano, MD,
  • Yuji Nakazato, MD,
  • Hiroyuki Daida, MD

DOI
https://doi.org/10.1016/j.joa.2016.10.004
Journal volume & issue
Vol. 33, no. 3
pp. 208 – 213

Abstract

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Background: Paroxysmal atrioventricular block (P-AVB) is a well-known cause of syncope; however, its underlying mechanism is difficult to determine. This study aimed to evaluate a new ECG index, the “vagal score (VS),” to determine the mechanism of P-AVB. Methods: We evaluated the VS in 20 patients with P-AVB (13 men, 7 women; aged 25–78 years [mean, 59.3 years]). The VS was developed by assigning 1 point each for the following: (1) no AVB or intraventricular conduction disturbance on the baseline ECG, (2) PR prolongation immediately before P-AVB, (3) sinus slowing immediately before P-AVB, (4) initiation of P-AVB by PP prolongation, (5) sinus slowing during ventricular asystole, and (6) resumption of AV conduction with PP shortening, and by assigning –1 point each for (7) the initiation of P-AVB by a premature beat, and (8) resumption of AV conduction by an escape beat. Based on the clinical situations and electrophysiologic findings, we considered the mechanism of P-AVB as vagally mediated or intrinsic conduction disease (ICD). Results: The VS ranged from 5 to –2 points for each patient. Five patients with a definite vagally mediated P-AVB had high VSs (3–5 points). We observed characteristic ECG findings of ICD consisting of changes in AV conduction by an extrasystole and/or escape beat in only 5 of the 6 patients (83%) with a low VS (1 to –2). Conclusions: The VS is simple and potentially useful for determining the mechanism of P-AVB. P-AVB with a VS ≥3 strongly suggested a vagally mediated mechanism.

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