title: A Practical ECG Criterion to Unmask Left Accessory AV Connections in Patients With Subtle Preexcitation.
abstract: BACKGROUND
  Accessory AV-connections capable of antegrade conduction need to be recognized because of the potential for life-threatening arrhythmias. However, the preexcited ECG pattern may be subtle, especially among left-sided AV-connections. We explored whether additional ECG criteria might help identify left-sided AV-connections.
  
  
  METHODS
  We analyzed 156 patients who underwent an electrophysiology study (EPS) and ablation for paroxysmal supraventricular tachycardias (PSVT). Patients were divided into 2 groups: those with left-sided AV-connections (Group 1) and all other PSVT (Group 2). Various ECG parameters were compared before and after ablation in both groups.
  
  
  RESULTS
  The EPS identified left-sided AV-connections among 43 patients (Group 1) and excluded it among 113 (Group 2). Baseline ECG in Group 1 demonstrated obvious preexcitation among 24/43 patients (55.8%), the remaining 19/43 missing obvious preexcitation. R/S ratio > 0.5 in V1 was noted in 38/43 (88.4%) patients in Group 1 before ablation (median 1.00; IQR 0.58-2.20), including 16/19 (84.2%) patients lacking obvious left-sided AVconnections. Conversely, only 10/113 (8.8%) patients in Group 2 had R/S ratios in V1 ≥ 0.5 (0.20; 0.10-0.31), P < 0.0001. After ablation, the R/S ratio decreased significantly in Group 1 (0.29; 0.17-0.45), P < 0.0001. Thus, a combined criterion of classic preexcitation or R/S ratio ≥ 0.5 on ECG identified 40/43 left-sided AV-connections (sensitivity 93.0%). The negative predictive value of this combined criterion was 103/106 (97.2%).
  
  
  CONCLUSIONS
  In symptomatic patients, combining the R/S ratio (≥ 0.5) in lead V1 with the classic preexcitation pattern on ECG markedly improved the sensitivity to diagnose left-sided AV-connections. This ratio may be particularly useful among patients lacking obvious preexcitation.
authors.affiliation: Virginia Commonwealth University, Richmond, Virginia.
authors.forename: J Jenkins
authors.initials: JJ
authors.lastname: Thompson
authors.affiliation: University of Kentucky, Gill Heart Institute and VAMC, Cardiology, Lexington, Kentucky.
authors.forename: Jignesh
authors.initials: J
authors.lastname: Shah
authors.affiliation: University of Kentucky, Gill Heart Institute and VAMC, Cardiology, Lexington, Kentucky.
authors.forename: Richard
authors.initials: R
authors.lastname: Charnigo
authors.affiliation: University of Kentucky, Gill Heart Institute and VAMC, Cardiology, Lexington, Kentucky.
authors.forename: Andrea
authors.initials: A
authors.lastname: Tackett
authors.affiliation: University of Kentucky, Gill Heart Institute and VAMC, Cardiology, Lexington, Kentucky.
authors.forename: Yousef H
authors.initials: YH
authors.lastname: Darrat
authors.affiliation: University of Kentucky, Gill Heart Institute and VAMC, Cardiology, Lexington, Kentucky.
authors.forename: Alison
authors.initials: A
authors.lastname: Bailey
authors.affiliation: University of Kentucky, Gill Heart Institute and VAMC, Cardiology, Lexington, Kentucky.
authors.forename: Brian
authors.initials: B
authors.lastname: Delisle
authors.affiliation: University of Kentucky, Gill Heart Institute and VAMC, Cardiology, Lexington, Kentucky.
authors.forename: Bahram
authors.initials: B
authors.lastname: Kakavand
authors.affiliation: Texas Cardiac Arrhythmia Institute at St. David's Medical Center, Austin, Texas.
authors.forename: Luigi
authors.initials: L
authors.lastname: DI Biase
authors.affiliation: Texas Cardiac Arrhythmia Institute at St. David's Medical Center, Austin, Texas.
authors.forename: Andrea
authors.initials: A
authors.lastname: Natale
authors.affiliation: University of Kentucky, Gill Heart Institute and VAMC, Cardiology, Lexington, Kentucky.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Morales
authors.affiliation: University of Kentucky, Gill Heart Institute and VAMC, Cardiology, Lexington, Kentucky.
authors.forename: Claude S
authors.initials: CS
authors.lastname: Elayi
keywords: Wolff-Parkinson-White syndrome; ablation; accessory AV connections; accessory pathway; left accessory pathways; preexcitation; supraventricular tachycardia