title: Adenosine testing in atrial flutter ablation: unmasking of dormant conduction across the cavotricuspid isthmus and risk of recurrence.
abstract: BACKGROUND
  Adenosine-induced hyperpolarization may identify pulmonary veins at risk of reconnection following electrical isolation for atrial fibrillation. The potential role of adenosine testing in other arrhythmic substrates, such as cavotricuspid isthmus (CTI)-dependent atrial flutter, remains unclear. We assessed whether dormant conduction across the CTI may be revealed by adenosine after ablation-induced bidirectional block, and its association with recurrent flutter.
  
  
  RESULTS
  Patients undergoing catheter ablation for CTI-dependent flutter were prospectively studied. After confirming bidirectional block across the CTI by standard pacing maneuvers, adenosine (≥ 12 mg IV) was administered to assess resumption of conduction, followed by isoproterenol (ISP) bolus. Further CTI ablation was performed for persistent (but not transient) resumption of conduction. Bidirectional block across the CTI was achieved in all 81 patients (63 males), age 61.2 ± 11.0 years. The trans-CTI time increased from 71.9 ± 18.1 milliseconds preablation to 166.2 ± 26.4 milliseconds postablation. Adenosine elicited resumption of conduction across the CTI in 7 patients (8.6%), 2 of whom had transient recovery. No additional patient with dormant conduction was identified by ISP. Over a follow-up of 11.8 ± 8.0 months, atrial flutter recurred in 4 (4.9%) patients, 3/7(42.9%) with a positive adenosine challenge versus 1/74 (1.3%) with a negative response, P = 0.0016 (relative risk 31.7).
  
  
  CONCLUSIONS
  Adenosine challenge following atrial flutter ablation provoked transient or persistent resumption of conduction across the CTI in almost 9% of patients and identified a subgroup at higher risk of flutter recurrence. It remains to be determined whether additional ablation guided by adenosine testing during the index procedure may further improve procedural outcomes.
authors.affiliation: University of Kentucky, Lexington, Kentucky; Lexington VA Medical Center, Lexington, Kentucky.
authors.forename: Gustavo X
authors.initials: GX
authors.lastname: Morales
authors.forename: Laurent
authors.initials: L
authors.lastname: Macle
authors.forename: Paul
authors.initials: P
authors.lastname: Khairy
authors.forename: Richard
authors.initials: R
authors.lastname: Charnigo
authors.forename: Evan
authors.initials: E
authors.lastname: Davidson
authors.forename: Sergio
authors.initials: S
authors.lastname: Thal
authors.forename: C K
authors.initials: CK
authors.lastname: Ching
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lellouche
authors.forename: Matthew
authors.initials: M
authors.lastname: Whitbeck
authors.forename: Brian
authors.initials: B
authors.lastname: Delisle
authors.forename: Jenks
authors.initials: J
authors.lastname: Thompson
authors.forename: Luigi
authors.initials: L
authors.lastname: Di Biase
authors.forename: Andrea
authors.initials: A
authors.lastname: Natale
authors.forename: Stanley
authors.initials: S
authors.lastname: Nattel
authors.forename: Claude S
authors.initials: CS
authors.lastname: Elayi
mesh_terms: D000241:Adenosine; D000368:Aged; D001282:Atrial Flutter / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D017115:Catheter Ablation / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors; D014261:Tricuspid Valve / Q000502:physiology*
chemical_list: D000241:Adenosine
keywords: adenosine; atrial flutter; catheter ablation; supraventricular tachycardia; transient conduction