Europace Advance Access originally published online on December 23, 2008
Europace 2009 11(2):133-134; doi:10.1093/europace/eun354
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EDITORIALS
Catheter ablation procedures: role of nation-wide registries
Division of Cardiology, University Jean Monnet of Saint-Etienne (ADC), 42000 Saint-Etienne, France
Manuscript submitted 19 November 2008. Accepted after revision 19 November 2008.
* Corresponding author: Cardiology Department, North Hospital, University of Saint-Etienne, 42 055 Saint-Etienne Cedex 2, France. Tel: +33 4 77 82 82 42, Fax: +33 4 77 82 81 64, Email: dakosta{at}aol.com
Since its introduction in the early 1990s, a number of studies have demonstrated the efficacy of radiofrequency catheter ablation (RFA) mainly in supra-ventricular arrhythmias.1
–4 Accordingly, RFA has modified significantly the treatment of symptomatic patients with AV node re-entry tachycardia (AVNRT), tachycardia mediated by accessory pathway (AP) or cavo-tricuspid isthmus atrial flutter (AFL),1–5 representing a cost-effective approach with low rates of complication for symptomatic patients and constituting an alternative management to life-long drug treatment.1,2
If catheter ablation of arrhythmias has been extensively evaluated in the scientific context, much less is known about clinical practice in this field. The previously published studies reflect results obtained in a small number of selected patients treated by well-experienced operators in high-volume single centres, and whether extrapolation of these results can be made in the ‘real world’ of daily practice remains unknown. The study by Kesek et al.6 reported in this issue of Europace provides a nation-wide database of RFA procedures in Sweden collecting data from all eight centres serving a country's population of 9.18 million inhabitants. The authors are to be congratulated on the rigorous and extensive nature of the registry representing the real-life practice evaluating both safety and efficacy of RFA procedures in Sweden in 2007. The Swedish registry gives us detailed information on RFA procedures performed in a whole country. The first relevant information is the total number of RFA interventions performed per year. This latter point is important since the number of procedures per million of inhabitants in individual countries is not well known. It can be expected that several factors other than medical ones like local practice traditions and national health policies may influence the total number of interventions performed in a given country. In the Swedish registry, the data covered 7018 ablations carried out in 5885 patients during 2004–07, with 2314 ablations procedures performed in 2007, representing 252 ablations per million of inhabitants.6 These findings are in agreement with other published European registries.6,7
During the last decade, catheter ablation procedures rates continued to grow with both increase in rates of success and decrease in rates of complications.1–5 Success rates of catheter ablation vary in the published literature but generally RFA of APs, AVRNT, atrio-ventricular junction (AVJ), and AFL can be performed with success rates >95%, low recurrence rates (
5%), and relatively low incidence of complications.1,2 It is well admitted that the probability of ablation success is higher among patients with AFL and AVJ, whereas it is lower in patients with AP and intermediate in the AVNRT group.4,5,8 Kesek et al.6 found that the primary success for AVNRT, AP, AFL, and ectopic atrial tachycardia were 96, 89, 87, and 71%, respectively. These rates of success are similar to those reported in recent published studies or other registries, except for AFL ablation.1–5,8 Indeed, primary success of AFL is expected to be close to 100%, mainly due to technical progress (8 mm tip and cooled-tip catheters use) and a better evaluation of the cavo-tricuspid isthmus bidirectional block.8,9 It is therefore quite strange to find an AFL primary success of only 87% in the Sweden registry,6 but the figure was based on only 50% of procedures analysis, which can be an explanation for such low success rates.6 Moreover, the proportion of patients treated for AFL appears to be low (18%) in the study by Kesek et al., 6 representing the fourth indication compared with AVNRT (24.6%), atrial fibrillation (AFib) (22.5%), and AP (18.5%) procedures. Was this low proportion of patients treated for AFL due to first intent medical treatment approach in agreement with national policies or was it due to a low prevalence of AFL in Sweden? In a recent prospective study published on the subject, RFA was associated with both fewer secondary effects and higher long-term success rate when compared with the first-line medical treatment supporting RFA even after the first AFL episode.8
In the Sweden registry, the authors found a 1.8% rate of complications.6 The first published European registry reported a higher rate of serious complications (5.1%), but these results were due to the initial training period of the majority of participating centres.2 With progress recently made in technology and operator growing experience, the rate of major complications decreased to 1.5%, for example, in the French registry.3 In 1999, Calkins et al.5 reported the largest prospective multicentre study in this field evaluating the safety of RFA in a large screened population including 1050 patients. In this latter study, the investigators found a 1.6% rate of major complications including 0.3% of death, 0.2% of stroke, 0.1% of myocardial infarction, and 1% of AV block requiring pacemaker implantation. Calkins et al.5 showed that the risk of AV block was related to the type of procedure, 1.3% in the AVNRT group compared with 1% of 500 patients who underwent ablation of an AP. Calkins et al.5 also reported a rate of 0.6% of tamponade and 0.2% of aortic valve injury but these complications were strangely classified in the less serious complications group. In this landmark study, three predictors of major complications were identified including age, presence of structural heart disease, and presence of multiple ablation targets.5 In particular, the risk of death was higher in the presence of an underlying structural heart disease or in patients with a low ejection fraction as well as in patients undergoing AVJ ablation.5 It might be interesting to know whether the authors of the Sweden registry found such predictors of complications.
Despite technology and operator experience improvements, the incidence of secondary effects has not significantly decreased in 2007 in the Swedish registry when compared with that reported 8 years earlier by Calkins et al.5,6 The changes over the time of substrates treated including macro-re-entrant atrial tachycardia, atypical flutter, ventricular tachycardia, and AFib requiring more complex RFA procedures may partially explain the absence of complications rates decrease when early periods of RFA are compared with more recent ones. Since its introduction into clinical practice, RFA aimed at curing AFib has become increasingly prevalent but remains the type of ablation with the largest rate of complications (particularly pericardial effusion) mainly because the technique used requires transseptal puncture and RFA application in the left atrium.10 The Sweden registry confirms this trend since AFib appears to be the second indication for RFA representing 22.5% of the total number of procedures with a 2.9% rate of complications in this peculiar subgroup of patients.6 Such a proportion of patients treated for AFib in Sweden seems however to be even higher than that reported in other European countries.7 For example, in Spain, AFib is only the fourth indication for RFA involving only 8% of the population.7 It might be interesting to know the reasons of such differences between countries. Atrial fibrillation prevalence might be higher in Sweden when compared with other European countries, or the treatment of AFib might be different in Sweden with more aggressive approach in this subset of patients.
The authors have to be congratulated for their work which emphasizes the importance of nation-wide registries to better evaluate the efficacy and safety of RFA in the real world of daily practice. In the future, such national registries might be taken into consideration in addition to randomized trials to adjust current international guidelines to an individual country for the treatment of patients suffering arrhythmias.
Footnotes
The opinions expressed in this article are not necessarily those of the Editors of Europace or of the European Society of Cardiology.
References
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[2] Hindricks G. The multicenter European radiofrequency survey (MERFS): complications of radiofrequency catheter ablation of arrhythmias. Eur Heart J (1993) 14:843–6.
[3] Le groupe de rythmologie de la société française de cardiologie. Complications of radiofrequency ablation: a French experience. Arch Mal Coeur (1996) 89:1599–605.
[4] Scheinman M, Calkins H, Gillette P, Klein R, Lerman BB, Morady F, et al. NASPE policy statement on catheter ablation: personnel, policy, procedures and therapeutic recommendations. Pace (2003) 26:789–99.
[5] Calkins H, Yong P, Miller JM, Olshanski B, Carlson M, Saul JP, et al. Catheter ablation of accessory pathways, atrioventricular nodal reentrant tachycardia, and the atrioventricular junction: final results of a prospective, multicenter clinical trial. Circulation (1999) 99:262–70.
[6] Kesek M. Ablation procedures in Sweeden during 2007: results from the Sweden Catheter Ablation Registry. Europace (2009) 11:152–154.
[7] Garcia-Bolao I, Macias-Gallego A, Diaz-Infante E. Spanish catheter registry. Sixth official report of the Spanish Society of Cardiology Working Group on Electrophysiology and Arrhythmias (2006). Rev Esp Cardiol (2007) 60:1188–96.[Medline]
[8] Da Costa A, Thévenin J, Roche F, Romeyer-Bouchard C, Abdellaoui L, Messier M, et al. Results from the LADIP Trial on atrial flutter, a multicentric prospective randomized study comparing amiodarone and radiofrequency ablation after the first episode of symptomatic atrial flutter. Circulation (2006) 114:1676–81.
[9] Anselme F, Savouré A, Cribier A, Saoudi N. Catheter ablation of typical atrial flutter. A randomized comparison of 2 methods for determining complete bi-directional isthmus block. Circulation (2001) 103:1434–9.
[10] Cappato R, Calkins H, Chen SA, Davies W, Iesaka Y, Kalman J, et al. Worlwilde survey on the methods, efficacy, and safety of catheter ablation for humans atrial fibrillation. Circulation (2005) 111:1100–5.
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Europace 2009 11: 152-154.[Abstract] [Full Text]
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