title: Effects of inadvertent atrioventricular block on clinical outcomes during cryoablation of the slow pathway in the treatment of atrioventricular nodal re-entrant tachycardia.
abstract: OBJECTIVE
  The study aimed at evaluating the long-term effects of transient atrioventricular (AV) block on clinical outcomes during atrioventricular nodal re-entrant tachycardia (AVNRT) cryoablation.
  
  
  RESULTS
  In 150 consecutive patients (39 +/- 14 years, ineffective anti-arrhythmic drugs 1.9 +/- 1.3), slow-pathway cryoablation for AVNRT was performed. A 7 Fr 6 mm-tip cryocatheter was used. After successful cryomapping (-30 degrees C), defined as jump abolition or AV nodal refractory period prolongation, cryoablation (-80 degrees C for 4 min) was applied if no AV block occurred. Atrioventricular nodal re-entrant tachycardia inducibility was checked after 30 min. Acute success (AVNRT non-inducibility) was achieved in 142 patients (95%). Overall, after a follow-up of 18 +/- 10 months, 118 of 150 patients (79%) were recurrence-free (including 2 patients for whom the procedure was unsuccessful). Among successful procedures, 116 of 142 (82%) patients were recurrence-free. During cryoablation, inadvertent transient AV block of varying degrees occurred in 34 patients (22.7%), namely, increased PR in 17 patients and a 2nd-3rd AV block in the remaining 17. In 24 patients, AV block occurred at the last effective site (increased PR in 13 patients and a 2nd-3rd AV block in 11). In the study population as a whole, univariate predictors of recurrence in the follow-up were AVNRT inducibility (P < 0.001), increased PR at the last effective site (P < 0.001), residual jump (P < 0.02), and small Koch's triangle (X-ray distance < 11 mm between the His and coronary sinus ostium catheters; P < 0.02). Atrioventricular nodal re-entrant tachycardia inducibility (P < 0.03), increased PR (P < 0.01), and small Koch's triangle (P< 0.04) were independently significant. For attempts at the last effective site, 3 groups of patients were compared: 13 patients with increased PR duration (Group A), 11 with a 2nd-3rd AV block (Group B), and 126 without AV block (Group C). Cryo-application time was 277 +/- 203 s in Group A, 75 +/- 87 s in Group B, and 253 +/- 135 s in Group C (A vs. B, P < 0.01; B vs. C, P < 0.001; and C vs. A, P= NS). There was no statistical difference among groups in the atriogram/ventriculogram amplitude ratio at the site of the last attempt, unsuccessful acute procedure, small Koch's triangle, and residual jump. Actuarial incidence of recurrence-free status at 12 months was 38% in A, 82% in B, and 82% in C (A vs. B, P < 0.05; B vs. C, P = NS; and C vs. A, P < 0.001).
  
  
  CONCLUSIONS
  All AV blocks occurring during cryoablation were transient, confirming the safety of this method. An increased PR duration at the last effective site is associated with a higher recurrence rate, whereas a 2nd-3rd degree AV block has a recurrence rate similar to that of patients without AV block despite a shorter cryo-application time at the last site.
authors.affiliation: Rhythmology Department, Cardiology Institute, Pitié-Salpetrière Hospital, Paris, France.
authors.forename: Antonio
authors.initials: A
authors.lastname: De Sisti
authors.forename: Joelci
authors.initials: J
authors.lastname: Tonet
authors.forename: Fatima
authors.initials: F
authors.lastname: Gueffaf
authors.forename: Faouzi
authors.initials: F
authors.lastname: Touil
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Leclercq
authors.forename: Philip
authors.initials: P
authors.lastname: Aouate
authors.forename: Jerome
authors.initials: J
authors.lastname: Lacotte
authors.forename: Francoise
authors.initials: F
authors.lastname: Hidden-Lucet
authors.forename: Robert
authors.initials: R
authors.lastname: Frank
mesh_terms: D000328:Adult; D054537:Atrioventricular Block / Q000175:diagnosis / Q000453:epidemiology*; D015897:Comorbidity; D003452:Cryosurgery / Q000706:statistics & numerical data*; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D011183:Postoperative Complications / Q000453:epidemiology*; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000453:epidemiology* / Q000601:surgery*