H. Oddsson 1, N. Edvardsson and H. Walfridsson. Introduction

Transcription

1 Europace (2002) 4, doi: /eupc , available online at on Episodes of and atrial vulnerability after successful radiofrequency catheter ablation in patients with Wolff Parkinson White syndrome H. Oddsson 1, N. Edvardsson and H. Walfridsson Divisions of Cardiology, 1 O} rebro University Hospital and Sahlgrenska University Hospital, Göteborg, Sweden Episodes of occur in patients with WPW syndrome but frequently disappear after successful radiofrequency ablation. Aims To analyze the incidence of before and after successful ablation and the presence of increased atrial vulnerability. Methods and Results Fifty-four of 183 WPW patients had at least one documented episode of before ablation. During a follow-up of months 13/54 patients (24%) experienced. At baseline, the patients with were more often men (74% vs 53%, P=0 007), were older (45 15 vs years, P=0 0001), more often had pre-excitation during sinus rhythm (87% vs, 73%, P=0 04) and had increased atrial vulnerability (41% vs 18%, P<0 001). Only patients with before, developed after ablation. The 13 (of 54) patients who relapsed were also older (53 13 vs years, P=0 03), had increased atrial vulnerability at baseline (77% vs 29%, P=0 002), and were more symptomatic, (13 21 vs 1 3 arrhythmia attacks/month, P=0 001). No patient without before ablation developed after treatment. Conclusions The accessory pathway was important for the development of. Frequent tachycardias seem to promote an electrical remodelling and an increased atrial vulnerability to, whereas after successful ablation the majority of patients remain free of. (Europace 2002; 4: ) 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved. Key Words: Wolff Parkinson White syndrome, radiofrequency catheter ablation,, atrial vulnerability and follow-up. Introduction Orthodromic tachycardia is the most common paroxysmal tachycardia in the Wolff Parkinson White syndrome but paroxysmal is relatively common and may, occasionally, lead to ventricular fibrillation and sudden death in patients with WPW syndrome [1 3]. Radiofrequency catheter ablation of accessory pathways is an effective treatment with a high rate of initial success in eliminating the pathways and achieving Manuscript submitted 28 November 2000, and accepted after revision 10 January Correspondence: Hjörtur Oddsson, Department of Cardiology, O} rebro University Hospital, S O} rebro, Sweden. Hjortur.Oddsson@orebroll.se a permanent cure of reciprocating tachycardias [4]. Regarding the connection of the Wolff Parkinson White syndrome and episodes of, several issues remain to be defined [5,6]. Some patients continue to have recurrent after elimination of the pathway and the risk of showing this phenomenon after successful radiofrequency ablation is not well known. The relative importance of the accessory pathway and the electrophysiological properties of the atrial myocardium and the normal conduction system in initiating is also unknown [7 10]. The purpose of this study was to analyze the clinical and electrophysiological characteristics of WPW patients with and without documented episodes of atrial fibrillation before and after successful RF catheter ablation, and to relate these findings to documented relapses of during follow-up /02/ $35.00/ The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.

2 202 H. Oddsson et al. Table 1 Underlying structural heart disease Previous AF (54 pts) Material Patients The study group consisted of the first 183 patients with Wolff Parkinson White syndrome who underwent successful RF ablation in our hospital. Another 14 patients with documented recurrence of the accessory pathway were excluded from the study. The patients were classified according to the presence (n=54) or absence (n=129) of at least one documented episode of atrial fibrillation before RF ablation. Their mean age at the time of electrophysiological study and ablation was years (range 10 to 79 years). There were 108 men and 75 women. At the electrophysiological study pre-excitation during sinus rhythm was present in 141 patients while the other 42 patients had concealed WPW syndrome. Nine of the 54 patients (17%) with had structural heart disease vs 17 of 129 patients (13%) without atrial fibrillation (Table 1). Methods No previous AF (129 pts) Ischaemic heart disease 3 4 Hypertension 3 1 Ventricular septal defect 0 2 Endocardial fibrosis 0 1 Valvular heart disease 0 2 Aortic dilatation 0 1 Myocardial hypertrophy 3 6 9(17%) 17(13%) AF=; pts=patients. Before RF ablation all patients provided medical histories and underwent physical examination, 12-lead ECG and 2-D echocardiography with Doppler. A non-invasive electrophysiological investigation by means of transoesophageal stimulation including the determination of the Wenckebach point and atrial stimulation at 500 ms stimulation interval with introduction of single and double extra-stimuli was performed in order to confirm the presence of inducible tachycardias. The decision for radiofrequency ablation was based on the frequency and severity of symptoms and, in two asymptomatic patients because pre-excitation would have disqualified them from their choice of profession. At the invasive procedure multipolar catheters were placed in the coronary sinus, the right ventricular apex and the His bundle region. Depending on the location of the pathway, the ablation catheter was introduced via the retrograde approach into the left ventricle or into the right atrium, respectively. The stimulation protocol was not specifically intended to induce. Increased atrial vulnerability was defined as induced with one or two extrastimuli at the basic pacing cycle lengths of 500 and 400 ms or during incremental atrial pacing to 300 ms basic pacing cycle length. Successful ablation was defined as the confirmation of definite elimination of delta wave and/or retrograde pathway conduction that was maintained for at least 30 min after the successful energy application. One to three months after ablation the first 100 patients underwent routine clinical follow-up with history of tachycardia, physical examination and a 12-lead ECG. Transoesophageal atrial stimulation or invasive electrophysiological testing was performed routinely in the first 100 patients but after that only in patients with palpitations and/or a clinical suspicion of relapse. All patients received a questionnaire with questions about the follow-up period: duration of tachycardia episodes, symptoms during tachycardia, all documented arrhythmias, attack frequency and the presence of underlying cardiovascular diseases. The mean follow-up time was months (29 14 months in the group with and months in the group without atrial fibrillation before ablation). Three patients died at ages 64, 65 and 76 years. The causes of death were acute myocardial infarction, pulmonary carcinoma and brain haemorrhage, respectively, occurring 8 months to 3 years after ablation. Five patients were lost to follow-up, three of whom were confirmed to be alive according to the Swedish population registry and two were living abroad. The patients were further asked about symptoms: palpitations, type of palpitations (regular or irregular), visits to hospitals and physicians, history of cardioversion and treatment with antiarrhythmic drugs. Some answers had to be clarified by individual contacts. All patients with a history of palpitations or arrhythmias had their hospital records checked and the patients were interviewed. In 59 patients with some suspicion of tachycardia electrophysiological testing was performed in the 45 patients who agreed. Statistical analysis Statistical analysis was performed by means of the two-tailed Student s t-test for unpaired data and the χ 2 test for non-parametric data. Results Patient characteristics before ablation Fifty-four patients had a history of prior to ablation (30%). Seven had a history of atrial fibrillation without pre-excitation (13%) while 47 had pre-excited (87%).

3 Episodes of 203 Table 2 Baseline characteristics of patients with and without AF before RF ablation With n=54 (30%) Without n=129 (70%) P value Males, % Age, years Pre-excitation during SR, % Increased atrial vulnerability, % Structural heart disease, % ns Duration of symptoms, years ns RR interval during orthodromic tachycardia, ms ns (n=45) (n=117) ns=not significant; AF=; RF=radiofrequency; SR=sinus rhythm. In the group the location of the accessory pathway was in the left free wall (37 patients), in the posteroseptal area (13 patients), in the right free wall (one patient) while three patients had two different pathways. In the group without 91 pathways were located in the left free wall, 25 in the posterior septum and six in the right free wall. Five patients had two pathways. Forty-seven patients in the group (87%) had pre-excitation during sinus rhythm before ablation (Table 2). Six of them had pre-excited atrial fibrillation as the only documented spontaneous arrhythmia and in the invasive or transoesophageal investigation there was no inducible re-entry tachycardia. Four of these six had documented only during electrophysiological provocation (two at transoesophageal stimulation and two at invasive provocation). All six patients had complete ventriculoatrial block during ventricular stimulation before ablation and, therefore, were not capable of having orthodromic or antidromic tachycardias and none of them had atrial fibrillation after ablation. The mean age of these six patients was 37 (range years). The remaining 48 patients with prior to ablation also had symptomatic and documented reciprocating tachycardias. There was one survivor of resuscitated ventricular fibrillation: he had a right-sided posteroseptal pathway and was first treated surgically 3 years earlier. He had had episodes of prior to surgery but was free of symptoms after that until the ventricular fibrillation occurred. He was successfully treated with radiofrequency ablation. Of the 129 patients without 127 had orthodromic tachycardias, 16 of which were associated with rate dependent bundle branch block. The other two patients were asymptomatic and had neither documented nor inducible arrhythmias. The patients with were significantly older, more often men, and had increased atrial vulnerability but did not have a more rapid ventricular response during reciprocal tachycardia (Table 2). Pre-excitation, duration of symptoms, structural heart disease and the localization of accessory pathways were not different in the groups with and without atrial fibrillation. After successful ablation Atrial fibrillation reoccurred in 13 of 183 patients after a mean of 14 months ( 14 months) after successful ablation (7%). All 13 patients belonged to the group that had experienced prior to ablation. Thus the relapse rate was 24% among those who had documented before ablation. There was no single episode of documented after ablation in a patient without before ablation. The patients in whom recurred were older, had more frequent arrhythmias per month before ablation and increased atrial vulnerability (Table 3). All patients who had after ablation also had orthodromic tachycardias prior to ablation. Compared with the patients without after ablation those with were older, had longer duration of symptoms and were more prone to during EP study (Table 4). After ablation four patients were treated with electrical cardioversion because of. Seven patients had only one or two self-terminating episodes of atrial fibrillation. One patient developed chronic atrial fibrillation during the follow-up period. Discussion Episodes of were reported in 15 58% of patients with WPW syndrome referred for treatment of life-threatening arrhythmias with or without a history of resuscitation from sudden death [11 13]. After surgical ablation, the incidence was 5.4% which was in contrast with previous studies by Sharma et al. who did not observe any episodes of after surgical ablation in 50 patients [12,14]. Haïssaguerre et al. reported

4 204 H. Oddsson et al. Table 3 Baseline characteristics of patients with AF before RF ablation and who did or did not develop AF after ablation Pts with AF after RF n=13 Pts without AF after RF n=41 P value Males, % ns Age, years Pre-excitation, % ns Atrial vulnerability, % Duration of symptoms, years ns Attacks per month RR interval during AF, ms ns (n=9) (n=35) AF=; pts=patients; RF ablation=radiofrequency catheter ablation; ns=not significant. Table 4 Baseline characteristics of patients with both AF before and after ablation versus no AF before or after RF ablation With n=13 Without n=170 P value Males, % ns Age, years Pre-excitation, % ns Increased atrial vulnerability, % Duration of symptoms, years Previous AF 100% 24% AF=; RF ablation=radiofrequency catheter ablation; ns=not significant. a 9% recurrence after DC ablation during a mean follow-up of 34 months in 75 patients with previous [13]. They defined atrial vulnerability as induction of sustained (>1 min) using single or double atrial extrastimuli at two basic pacing cycle lengths. Among our patients there was only one patient with proven degeneration of pre-excited to ventricular fibrillation. We found a 30% incidence of which may be due to selection of particularly symptomatic patients in connection with the introduction of radiofrequency ablation in this hospital. Surprisingly many patients with concealed Wolff Parkinson White syndrome had (seven of 42 patients, 17%) which is different from a previous study in which had occurred spontaneously in 31 (54%) of the 57 patients with the Wolff Parkinson White syndrome and in one (3%) of the 33 with a concealed accessory pathway [15]. Atrial fibrillation reoccurred in one of our seven patients. Atrial fibrillation reoccurred in 24% of the patients with previous and all had had reciprocating tachycardias before ablation. Again, this figure is comparatively high and may possibly be explained by selection and a higher age than in other studies. The prevalence of in this age group in the normal population is <1% and cannot explain the differences between the groups [16]. Thus, curing these patients from the re-entrant tachycardias that are totally dependent on the accessory pathway does not eliminate the risk of. It may therefore be hypothesized that the arrhythmic state per se promotes the development of and that these properties either remain or need a longer period of time to subside. This theory seems to hold, regarding the differences in atrial vulnerability. Atrial fibrillation may develop via a shorter or longer period of fast reciprocating tachycardia, and seems to happen more often in patients with more than one pathway and also more often in patients with preexcitation than in concealed WPW. A short refractory period of the pathway also predisposed to [15]. One theory claimed that branching of the accessory pathway might be a substrate for micro-reentry and but has not been electrophysiologically proven. Patients with proven seem to be more easily inducible to by electrophysiological testing. We found no difference in the RR intervals during induced reciprocating tachycardias in patients with or without. This is in agreement with some previous studies [17,18] but not with all [12].

5 Episodes of 205 Atrial vulnerability has been defined differently [8,9,19]. It is tempting to suggest that an aggressive stimulation protocol would induce in many patients but that a protocol with a maximum of two supraventricular extrastimuli would probably have a higher clinical significance and higher specificity in predicting recurrence of [13]. Wathen et al. reported that the existence of an accessory pathway was not necessary for induction of atrial fibrillation and that it was just as easy to start atrial fibrillation before and immediately after ablation [9]. Tsuchioka et al. demonstrated that the atrial refractory periods and the potential minimal wavelength of an atrial impulse were significantly increased, after surgery. Fragmented atrial activity (an increase of 150% or more in the duration of the high right atrial electrogram) was observed in 80% of the patients before surgery and in 25% after surgery [20]. The difference between these two studies is the longer time between the surgical treatment and the electrophysiological control study. The results suggest that accessory pathways affect the properties of the atrial myocardium and atrial vulnerability directly or indirectly and that the reversibility of these changes may differ and need time. The older age of patients with might imply that they had structural abnormalities and that would more easily appear after successful RF ablation. In the present study, we did not find any difference in underlying heart disease between the groups with or without after ablation (Table 1). Atrial fibrillation was documented in 7% of all patients after ablation compared with 30% before treatment. This implies that the accessory pathway played a role in the development of but may not be the only explanation. Reciprocating tachycardias may initiate and long-lasting tachycardias may cause changes in electrophysiological properties predisposing to [21]. Patients who presented with almost always also had spontaneous or inducible re-entrant tachycardias [15]. In the present study six patients with as the only documented clinical arrhythmia all lacked ventriculoatrial conduction capabilities and had no recurrent during a follow-up period of 38 months. If the increased risk of depends on the symptomatic regular tachycardias as predisposing factors, one might expect some signs of reversibility after the tachycardias have ceased to occur. If signs of atrial vulnerability decrease this would be the result of reversed electrophysiological remodelling. Our results support such a hypothesis. If frequent regular tachycardias slowly change the substrate in favour of development of, this favours early intervention with radiofrequency catheter ablation in case of frequent attacks irrespective of symptomatology during the re-entrant tachycardias. The present study followed the recurrence of symptoms documented during episodes of during a follow-up period that was longer than in most previous studies of the WPW syndrome and atrial fibrillation. References [1] Montoya PT, Brugada P, Smeets J, et al. Ventricular fibrillation in the Wolff Parkinson White syndrome. Eur Heart J 1991; 12(2): [2] Klein GJ, Bashore TM, Sellers TD, Pritchett EL, Smith WM, Gallagher JJ. Ventricular fibrillation in the Wolff Parkinson White syndrome. N Engl J Med 1979; 301: [3] Attoyan C, Haïsaguerre M, Dartigues JF, Le Metayer P, Warin JF, Clementy J. Ventricular fibrillation in Wolff Parkinson White syndrome. Predictive factors. Arch Mal Coeur Vaiss 1994; 87: [4] Calkins H, Langberg J, Sousa J, et al. Radiofrequency catheter ablation of accessory atrioventricular connections in 250 patients. Abbreviated therapeutic approach to Wolff Parkinson White syndrome. Circulation 1992; 85: [5] Kuck K, Schluter M, Geiger M, Siebels J, Duckeck W. Radiofrequency current catheter ablation of accessory atrioventricular pathways. Lancet 1991; 337: [6] Jackman W, Wang X, Friday K, Roman C, Moulton K, Beckman K. Catheter ablation of accessory atrioventricular pathways (Wolff Parkinson White syndrome) by radiofrequency current. N Eng J Med 1991; 324: [7] Fujimura O, Klein GJ, Yee R, Sharma AD. Mode of onset of in the Wolff Parkinson White syndrome: how important is the accessory pathway? J Am Coll Cardiol 1990; 15: [8] Kalbfleisch SJ, el-atassi R, Calkins H, Langberg JJ, Morady F. Inducibility of before and after radiofrequency catheter ablation of accessory atrioventricular connections. J Cardiovasc Electrophysiol 1993; 4: [9] Wathen M, Natale A, Wolfe K, Yee R, Klein G. Initiation of in the Wolff Parkinson White syndrome: the importance of the accessory pathway. Am Heart J 1993; 125: [10] Tai C, Chen S, Chiang C, et al. Accessory atrioventricular pathways with only antegrade conduction in patients with symptomatic Wolff Parkinson White syndrome. Clinical features, electrophysiological characteristics and response to radiofrequency catheter ablation. Eur Heart J 1997; 18: [11] Fischell TA, Stinson EB, Derby GC, Swerdlow CD. Longterm follow-up after surgical correction of Wolff Parkinson White syndrome. J Am Coll Cardiol 1987; 9: [12] Chen PS, Pressley JC, Tang AS, Packer DL, Gallagher JJ, Prystowsky EN. New observations on before and after surgical treatment in patients with the Wolff Parkinson White syndrome. J Am Coll Cardiol 1992; 19: [13] Haïssaguerre M, Fischer B, Labbe T, et al. Frequency of recurrent after catheter ablation of overt accessory pathways. Am J Cardiol 1992; 69: [14] Sharma AD, Klein GJ, Guiraudon GM, Milstein S. Atrial fibrillation in patients with Wolff Parkinson White syndrome: incidence after surgical ablation of the accessory pathway. Circulation 1985; 72: [15] Della Bella P, Brugada P, Talajic M, et al. Atrial fibrillation in patients with an accessory pathway: importance of the conduction properties of the accessory pathway. J Am Coll Cardiol 1991; 17: [16] Kannel WB, Abbott RD, Savage DD, McNamara PM. Epidemiologic features of chronic : the Framingham study. N Engl J Med 1982; 306: [17] Konoe A, Fukatani M, Tanigawa M, et al. Electrophysiological abnormalities of the atrial muscle in patients

6 206 H. Oddsson et al. with manifest Wolff Parkinson White syndrome associated with paroxysmal. Pacing Clin Electrophysiol 1992; 15: [18] Fan W, Peter CT, Gang ES, Mandel W. Age-related changes in the clinical and electrophysiologic characteristics of patients with Wolff Parkinson White syndrome: comparative study between young and elderly patients. Am Heart J 1991; 122: [19] Asano Y, Kaneko K, Matsumoto K, Saito J, Yamamoto T, Dohi Y. Atrial fibrillation and atrial vulnerability in the Wolff Parkinson White syndrome. Jpn Circ J 1991; 55: [20] Tsuchioka Y, Karakawa S, Nagata K, et al. The role of the accessory pathway in the onset of in Wolff Parkinson White syndrome electrophysiological examination before and after surgical ablation. Jpn Circ J 1994; 58: [21] Muraoka Y, Karakawa S, Yamagata T, Matsuura H, Kajiyama G. Dependency on atrial electrophysiological properties of appearance of paroxysmal in patients with Wolff Parkinson White syndrome: evidence from atrial vulnerability before and after radiofrequency catheter ablation and surgical cryoablation. Pacing Clin Electrophysiol 1998; 21: