- Email: [email protected]
P5-61
S280 Background: Previously, we demonstrated that H558R-SCN5A is a functionally significant, common polymorphism whereby individuals homozygous for the minor allele have an estimated 30% diminution in peak sodium current. Recently, clinical studies suggest that the R allele is over-represented in Brugada syndrome and protective in heart failure. In this study, we sought to evaluate the effect of H558R-SCN5A on the electrocardiographic (ECG) phenotype in a large cross-sectional, population-based study of predominantly Caucasians in Olmsted County, Minnesota. Methods: H558R genotype status was determined using restriction fragment length polymorphism analysis on genomic DNA derived from 2042 individuals (1058 females, average age 62 ⫾ 11yrs, 1024 with cardiovascular disease). Spearman’s correlations (r) coefficient was used to measure the association between genotype and ECG phenotype. Continuous variables are summarized as mean ⫾ one standard deviation. Results: Overall, 60.4% were HH genotype, 34.5% HR genotype, and 5.1% RR genotype, yielding a major allelic frequency of 0.78 that was in Hardy-Weinberg equilibrium and was independent of sex and health status. There was no significant association between H558R genotype and QTc. Twenty (0.98%) subjects had a Brugada ECG pattern, but the R allele was not over-represented. Only 1 subject displayed a type 1, cove-shaped Brugada pattern and was HH genotype. Among the 30 subjects (1.5%) with atrial fibrillation, there was a trend towards over-representation of the R allele (p ⫽ 0.08). H558R genotype was significantly associated with PR interval in those with cardiovascular disease (r⫽ -0.079, p⬍0.02) and females [161 ⫾ 24 ms (HH), 158 ⫾ 28 (HR) and 154 ⫾ 17(RR), r⫽ -0.076, p⬍0.02] but not males. Conclusions: This study represents the largest population-based study to examine the association of H558R-SCN5A to various ECG phenotypes. Herein, the H558R common polymorphism i) was associated with shorter PR intervals in a sex-specific fashion, ii) was not associated with QTc or manifest Brugada pattern, and iii) trended towards increased likelihood for atrial fibrillation. P5-60 A RANDOMIZED STUDY OF METOPROLOL CR/XL AFTER DC CARDIOVERSION AND RE-CARDIOVERSION OF ATRIAL FIBRILLATION - A NEW STRATEGY TO MAINTAIN SINUS RHYTHM Anna K. Nergardh, MD, Mårten Rosenqvist, MD, PhD, Rolf Nordlander, MD, PhD and Mats Frick, MD, PhD. Karolinska Institute at Stockholm South Hospital, Stockholm, Sweden. Background: In patients (pts) with symptomatic persistent atrial fibrillation (AF) relapse after DC cardioversion is common. The pro-arrhythmic risk with class I and III anti-arrhythmic agents as well as the importance of shortening the actual time in AF emphasize the need of alternative strategies. Methods: Consecutive outpatients with first time persistent AF were randomized to treatment with oral metoprolol CR/XL or placebo in a double-blind fashion, initiated at least one week before scheduled DC cardioversion. A 12-lead ECG was obtained once a week during the first six weeks following cardioversion. In the case of relapse during this period a second DC cardioversion was performed within five days, without any change in study treatment. Total treatment and follow-up time was six months. Results: A total of 168 pts were included. Mean age were 67.3 (⫾11.2) and mean duration in AF were 5.1 (⫾2.9) months. The pts were randomized in a double-blind fashion to treatment with metoprolol (n⫽83) or placebo (n⫽85), no other antiarrhythmic treatment was allowed. Baseline characteristics, echocardiographic data or pharmacological treatment did not differ significant between the treatment groups. The dose of study treatment at DC cardioversion was 168.7 ⫾ 47.1 mg in the metoprolol group and 179.6 ⫾ 40.1 mg in the placebo group (p⬎0.05). A second DC cardioversion was performed in 41 pts in the metoprolol group and 40 pts in the placebo group (p⬎0.05). In an intention to treat analyses 46 pts (55%) in the metoprolol group and 34 pts (40%) in the placebo group (p⫽ 0.045) had sinus rhythm (SR) one week after cardioversion, 42 pts (51%) compared to 28 pts (33%) after six weeks (p⫽0.02), and 38 pts (46%) in
Heart Rhythm, Vol 3, No 5, May Supplement 2006 metoprolol group compared to 22 pts (26%) in placebo group had SR after six months (p⫽0.007). Conclusion: A treatment strategy of metoprolol CR/XL in combination with immediate second cardioversion in case of early relapse (1-6 weeks) significantly increases the number of patients in SR during six months of follow-up after DC cardioversion. P5-61 REMOTE CATHETER MAPPING AND ABLATION OF KENT BUNDLE IN PATIENTS WITH PREVIOUS FAILED PROCEDURE Carlo Pappone, MD, PhD, Andrea Radinovic, MD, Nicoleta Sora, MD, Simone Sala, MD, Giuseppe Augello, MD, Giuseppe Augello, MD, Gabriele Vicedomini, MD and Vincenzo Santinelli, MD. San Raffaele University Hospital, Milan, Italy. Background: Transcatheter ablation of accessory pathways (APs) with radiofrequency energy (RF) requires extremely precise localization of APs but at times also requires a lengthy procedure or a second ablation session, or both. We report our experience on efficacy of magnetic catheter (MC) guidance for mapping and ablation of APs among patients with previous failed procedure. Methods: The subjects of this study were 9 patients (6 males; median age, 16 years) with previously failed RF ablation of APs despite several RF applications attempts at right posteroseptal region after right and left mapping with standard catheters (SC). In the first procedure no AP potential was recorded. Patients were scheduled for remote magnetic navigation and ablation with NIOBE (Stereotaxis, Inc.). Results: MC was able to navigate in the right and left atrium (transeptal route). In all cases a stable Kent (K) potential was recorded at left septal side remaining stable even during RF applications. Failure to recognize target sites as being left-sided instead of right-sided was the primary cause of previous unsuccessful ablation. Disappearance of K just after the onset (2-5 sec) of RF applications by MC (55°C, max 50 W, 60 sec) was obtained by the same operator in the same laboratory in all patients. Ablation of K resulted in simultaneous disappearance of d wave on ECG in all cases. Fragmentation of the bypass tract deflection before block occurred in 4 patients and in one of them fragmentation of K coincided with normalization of the QRS complex. During AVRT K deflection disappeared. The overall median mapping and ablation time was 18 min (range, 10 to 30 min). Two RF applications were delivered in each case. During a mean follow-up of 5.3 months no ventricular preexcitation was seen on ECG and no tachyarrhythmias occurred. Conclusions: Among patients with ventricular preexcitation and failed procedure, mapping and ablation by MC can be useful in definitively eliminating accessory pathways conduction. The Kent potential recording by MC is common and represents the best target for successful ablation particularly in challenging sites minimizing the number of unnecessary applications of RF. P5-62 EARLY AND DELAYED PACEMAKER IMPLANTATION AFTER RADIOFREQUENCY CATHETER ABLATION OF SLOW PATHWAY Anahita Kowsar, MD, Isabelle Labioche, MD, Thomas Arentz, MD, Marc Zimmerman, MD, Frederic Georger, MD, Pascal Defaye, MD, Philippe Lagrange, MD, Luc De Roy, MD, Patick Blanc, MD, Serge Boveda, MD and Patrice Virot, MD. CHU Limoges, Limoges, France, Herz Zentrum, Badkrozingen, Germany, FMH Cardiologie, Meyrin, Switzerland, UCL, Mt. Gondine, Belgium, CHU, Grenoble, France and Toulouse, France. Radiofrequency catheter ablation of the slow pathway as a cure for Atrioventricular nodal reentrant tachycardia (AVNRT) has been reported to be highly effective and safe. In most of the published studies the incidence of complete atrioventricular block (AVB) requiring pacemaker (PM) therapy could be underestimated as result of the short duration of FU (a few years)
Heart Rhythm, Vol 3, No 5, May Supplement 2006 metoprolol group compared to 22 pts (26%) in placebo group had SR after six months (p⫽0.007). Conclusion: A treatment strategy of metoprolol CR/XL in combination with immediate second cardioversion in case of early relapse (1-6 weeks) significantly increases the number of patients in SR during six months of follow-up after DC cardioversion. P5-61 REMOTE CATHETER MAPPING AND ABLATION OF KENT BUNDLE IN PATIENTS WITH PREVIOUS FAILED PROCEDURE Carlo Pappone, MD, PhD, Andrea Radinovic, MD, Nicoleta Sora, MD, Simone Sala, MD, Giuseppe Augello, MD, Giuseppe Augello, MD, Gabriele Vicedomini, MD and Vincenzo Santinelli, MD. San Raffaele University Hospital, Milan, Italy. Background: Transcatheter ablation of accessory pathways (APs) with radiofrequency energy (RF) requires extremely precise localization of APs but at times also requires a lengthy procedure or a second ablation session, or both. We report our experience on efficacy of magnetic catheter (MC) guidance for mapping and ablation of APs among patients with previous failed procedure. Methods: The subjects of this study were 9 patients (6 males; median age, 16 years) with previously failed RF ablation of APs despite several RF applications attempts at right posteroseptal region after right and left mapping with standard catheters (SC). In the first procedure no AP potential was recorded. Patients were scheduled for remote magnetic navigation and ablation with NIOBE (Stereotaxis, Inc.). Results: MC was able to navigate in the right and left atrium (transeptal route). In all cases a stable Kent (K) potential was recorded at left septal side remaining stable even during RF applications. Failure to recognize target sites as being left-sided instead of right-sided was the primary cause of previous unsuccessful ablation. Disappearance of K just after the onset (2-5 sec) of RF applications by MC (55°C, max 50 W, 60 sec) was obtained by the same operator in the same laboratory in all patients. Ablation of K resulted in simultaneous disappearance of d wave on ECG in all cases. Fragmentation of the bypass tract deflection before block occurred in 4 patients and in one of them fragmentation of K coincided with normalization of the QRS complex. During AVRT K deflection disappeared. The overall median mapping and ablation time was 18 min (range, 10 to 30 min). Two RF applications were delivered in each case. During a mean follow-up of 5.3 months no ventricular preexcitation was seen on ECG and no tachyarrhythmias occurred. Conclusions: Among patients with ventricular preexcitation and failed procedure, mapping and ablation by MC can be useful in definitively eliminating accessory pathways conduction. The Kent potential recording by MC is common and represents the best target for successful ablation particularly in challenging sites minimizing the number of unnecessary applications of RF. P5-62 EARLY AND DELAYED PACEMAKER IMPLANTATION AFTER RADIOFREQUENCY CATHETER ABLATION OF SLOW PATHWAY Anahita Kowsar, MD, Isabelle Labioche, MD, Thomas Arentz, MD, Marc Zimmerman, MD, Frederic Georger, MD, Pascal Defaye, MD, Philippe Lagrange, MD, Luc De Roy, MD, Patick Blanc, MD, Serge Boveda, MD and Patrice Virot, MD. CHU Limoges, Limoges, France, Herz Zentrum, Badkrozingen, Germany, FMH Cardiologie, Meyrin, Switzerland, UCL, Mt. Gondine, Belgium, CHU, Grenoble, France and Toulouse, France. Radiofrequency catheter ablation of the slow pathway as a cure for Atrioventricular nodal reentrant tachycardia (AVNRT) has been reported to be highly effective and safe. In most of the published studies the incidence of complete atrioventricular block (AVB) requiring pacemaker (PM) therapy could be underestimated as result of the short duration of FU (a few years)