[Arrhythmia and muscular exercise intolerance revealing lamin genetic defect in a young adult]. / Troubles du rythme et intolérance musculaire à l'effort chez un adulte jeune révélant une laminopathie.

INTRODUCTION: Arrhythmic disorders are infrequent in young adult and should evoke myopathy associated cardiomyopathy, even though muscular symptoms are moderate or absent. CASE REPORT: We report a 25-year-old woman who developed severe supraventricular rhythm disturbances with exercise intolerance and elevated serum creatine kinase level. Initially the echocardiography showed normal ventricular function. Mutation in the lamin gene (LMNA) was identified. During the disease course, arrhythmia and ventricular function worsened and required cardioverter defibrillator implantation. CONCLUSION: Laminopathies are genetic disorders among which dilated cardiomyopathy associated with skeletal muscular involvement is the most frequent phenotype, usually like Emery-Dreifuss muscular dystrophy. Other phenotypes are progeria, lipodystrophic syndromes and peripheral neuropathy. Cardiac involvement is responsible for syncope, thromboembolic events and sudden death and often requires early cardioverter defibrillator implantation.

Prevalence, causes of reappearance of symptoms or preexcitation syndrome after ablation of accessory pathway and management.

AIM: The purpose of the study was to look for the prevalence, significance and management of preexcitation syndrome (PS) or symptoms reappearance after accessory pathway (AP) ablation. AP ablation actually is the first treatment of PS. METHODS: Successful AP ablation was performed in 261 patients; reappearance of symptoms or PS on ECG occurred in 47 patients (18%) from 20minutes to several years. Their data were compared with remaining patients. RESULTS: Recurrences were more frequent in patients with spontaneous malignant form (34 vs. 21%), in congenital heart disease (4.2 vs. 0%) (P<0.002), in case of complication (11 vs. 2%) (P<0.007) and of a longer duration of applications (304±209 vs. 188±182sec) (P<0.019). Forty percent of patients had the same symptoms and electrophysiological data as before ablation. Twenty-four percent had an improvement of symptoms and/or electrophysiological data. However, 3 initially asymptomatic patients became symptomatic after ablation. Twenty-six percent had another AP or another rhythm disorder. We recommend transesophageal electrophysiological study for the control because only 40% of patients required second ablation. CONCLUSIONS: Reappearance of symptoms or a PS on ECG after AP ablation was not rare (18%) and was inconsistently associated with the reappearance of all initial AP electrophysiological properties. Only 40% of patients required a second AP ablation. Another arrhythmia was possible. Non-invasive second evaluation should be preferred. However, asymptomatic patients before ablation could become symptomatic.

Sex-related differences in peri- and post-ablation clinical data for patients with atrial flutter.

UNLABELLED: Sex-related differences were not reported for the atrial flutter (AF). The purpose of the study was to look for the influence of gender on indications, clinical data and long-term results of AFl ablation. METHODS: 985 patients, [227 females (23%)] were referred for radiofrequency AFl ablation. Clinical history, echocardiography were collected. Patients were followed from 3 months to 10 years. RESULTS: Age of women and men was similar (65.5 ± 12 vs 64 ± 11.5 years). Underlying heart disease (HD) was as frequent in women as men (77.5 vs 77%), but women had more congenital HD (10 vs 2%;p<0.001), valvular HD (18 vs 10%;p<0.002), hypertensive HD (24 vs 18%;p<0.05), and less chronic lung disease (5 vs 10%;p<0.01), and ischemic HD (5 vs 20%;p<0.001). Atrial fibrillation (AF) history was more frequent in women (36 vs 27%;p<0.001). AFl-related tachycardiomyopathy (4.5 vs 8%;p<0.03) was more frequent, but 1/1 AFl (10 vs 6%;p=NS) as frequent. Failure of ablation (16 vs 10%;p<0.01), ablation-related major complications (3.5 vs 0.9%;p<0.005) were more frequent in women. After 3 ± 3 years, AFl recurrences were as frequent in women and men (10 vs 14%), AF occurrence more frequent in women (34 vs 19.5%; p<0.001). After excluding patients with previous AF, AF risk remained higher in women (19 vs 12%; p<0.004). CONCLUSIONS: In patients admitted for ablation, AFL was less common in women than in men, despite similar age and similarly prevalent HD. More than men, women had frequent AF history, a higher risk of failure of ablation and AFl ablation-related major complications and a higher risk of AF after ablation.

Influence of the time on the prevalence of drug-related resuscitated sudden death during these past 20 years.

UNLABELLED: The use of drugs is the subject of numerous recommendations. The purpose of this study was to evaluate the prevalence of drug-related sudden deaths (SD) and the possible changes during these past 20 years. METHODS: 271 patients, 205 men, 66 women aged from 12 to 88 years (mean 59 ± 15) were admitted after SD resuscitation outside the acute phase of myocardial infarction, 146 before 2000 (group I), 125 between 2000 and 2010 (group II). Complete check-up was performed. RESULTS: Ischemic HD (41%) vs (37%), idiopathic dilated cardiomyopathy (12%) vs (11%), various HD (5%) vs (8%) were as frequent in groups I and II. Valvular HDs were more frequent in group I than II (12%) vs 6% (p<0.01). Abnormalities at ECG (preexcitation syndrome, conduction disturbance, atrial fibrillation or ion channel disorders) were less frequent in group I than II (8%) vs (18%) (p<0.02). Drug-facilitated or related SD's did not change in groups I and II: 54 patients presented a drug-related ventricular fibrillation or asystole, 16% in group I and 24% (NS) in group II. SD was caused by hypokalemia, QT interval increase or conduction disturbance. HD or abnormal ECG was present in 42 patients. Digoxin, diuretics, calcium inhibitors, betablockers, antiarrhythmic drugs alone or in association were mainly implicated. CONCLUSION: Drug-related arrhythmias continue to explain or favour at least 20% of SDs. Despite numerous recommendations on the use of drugs, the prevalence of fatal events that may be attributed to a cardiovascular drug does not decrease between the years before 2000 and after 2000.

Prevalence of atrial fibrillation in patients with history of paroxysmal supraventricular tachycardia.

OBJECTIVES: This study was performed to evaluate the prevalence of atrial fibrillation (AF) in patients seen for paroxysmal supraventricular tachycardia (PSVT) and to identify factors favoring AF. AF incidence is increased in patients with PSVT, but AF risk factors are unknown. POPULATION: 1187 patients, mean age 50 ± 19 years, were consecutively studied for spontaneous PSVT confirmed by electrophysiological study (EPS). Patients with anterograde conduction through an accessory pathway were excluded. METHODS: Clinical factors, age, gender, heart disease (HD) and electrophysiological data were noted. Patients with and without AF were compared. Mean follow-up was 4.48 ± 4.9 years. RESULTS: 61 patients developed documented paroxysmal or permanent AF or atrial flutter (5%). They were older than patients without AF (59 vs 49 years, p<0.0005), were more frequently men (59% vs 37%) (p<0.002), had more frequently prior AF (24.5% vs 0.5%) (p<0.0001) and associated HD (18% vs 5%) (p<0.004). There were no differences at EPS concerning the mechanism of re-entry. AF induction or occurrence during EPS was more frequent in patients with AF (31%) than in patients without AF (9%) (p<0.001). Multivariate analysis showed age, male gender, prior AF, HD and atrial vulnerability during EPS were independent predictors of AF. Univariate comparison between both groups suggests no effect of PSVT ablation on the incidence of AF. CONCLUSIONS: The prevalence of AF in our population was only 5%. The risk of AF was correlated with the classical risk factors of AF and atrial vulnerability during electrophysiological study. Patients with these risk factors should be followed.

[Accessory pathway ablation in children: indications and results]. / Ablation d'un faisceau accessoire chez les enfants : indications et résultats.

INTRODUCTION: Radiofrequency ablation of accessory pathways (AP) has become a first-line treatment, except in young children where the indications are discussed because of radiation risks and complications of catheterization. The purpose of the study was to evaluate the indications and results of radiofrequency AP ablation in children and teenagers. METHODS: Electrophysiological study (EPS) was performed in 145 patients aged from 5 to 18 years (13.5±3) with a preexcitation syndrome (PS). RESULTS: AP ablation was indicated in 66 children (group 1); others represent the group I. Group I was older and less frequently asymptomatic. All children with a spontaneous malignant form had an ablation. Group 1 has a faster conduction through the AP than group 2. The induction of reentrant tachycardia (RT), atrial fibrillation and the presence of a malignant form is more common in group 1. Failures or reappearances of WPW after ablation were frequent (20, 26%) related to a younger age (15±3 vs 17±4) (<0.05). In group 2, one 18-year-old teenager with untreated RT died before ablation. Asymptomatic children are well with disappearance of PS in two. Medically treated symptomatic children are well. CONCLUSION: If spontaneous malignant forms, symptoms with drugs or practice of competitive sport are indications of AP ablation, it is recommended to wait for adolescence in other children.

Pharmacological testing in the diagnosis of arrhythmias.

Pharmacological testing has several indications in the diagnosis of arrhythmia. It is used for the diagnosis of bradycardia-related syncope either during non invasive tests as adenosine triphosphate (ATP) for the diagnosis of vasovagal syncope, but also for the diagnosis of sick sinus syndrome or isoproterenol infusion during the head up tilt test to induce a vasovagal syncope or during electrophysiological study to look for infrahisian AV block or organic sick sinus syndrome after injection of Ajmaline or to know if sick sinus syndrome or suprahisian AV block are reversible after atropine and are vagal-related. It is used for the diagnosis of supraventricular and ventricular tachycardia; isoproterenol is largely used generally during electrophysiological study. The infusion of isoproterenol is required in exercise-related arrhythmias, in arrhythmogenic right ventricular cardiomyopathy, in idiopathic ventricular tachycardia and in idiopathic dilated cardiomyopathy. ATP can be used to induce a vagal-related atrial fibrillation and may help to differentiate a reentry through accessory pathway or AV nodal re-entrant tachycardia. It is used for the detection and the evaluation of prognosis of some diseases at risk of sudden death. Isoproterenol infusion is required in the preexcitation syndrome to look for the shortening of accessory refractory period. Ajmaline or flecaïnide injection is mandatory in the family of a patient with a Brugada syndrome to detect the disease.

Does syncope require rhythmic and non-rhythmic evaluation in patients with previous MI?

BACKGROUND: Multiple factors, in addition to left ventricular ejection fraction (LVEF) influence the risk of mortality in coronary artery disease. The purpose of this study was to evaluate the main causes of syncope after myocardial infarction (MI) and to propose an algorithm of management. METHODS: 356 patients consecutively admitted for syncope and history of MI (>1 month), without ventricular tachycardia (VT), underwent echocardiography, Holter monitoring, head-up tilt test, exercise testing, signal-averaged ECG, electrophysiological study (EPS) and evaluation of coronary status. The mean follow-up was 4±2 years. RESULTS: Monomorphic VT, ventricular flutter or fibrillation (VF) and supraventricular tachyarrhythmia were respectively induced at EPS in 87, 63 and 39 patients; conduction disturbances were noted in 23 patients, and 57 patients had several abnormalities. Among the 144 patients with negative EPS, coronary ischaemia was identified in 37 patients, and hypervagotonia in 27 patients. All studies remain negative in 84 patients (23.6%), more frequently women (p<0.001). Four patients died suddenly during follow-up. A longer QRS duration, a lower LVEF and grade IVa,b of Lown on Holter ECG were associated with the induction of VT. LVEF<40% and VT/VF induction were predictors of cardiac mortality, VT was a predictor of sudden death, and low LVEF and advanced age were predictors of death by heart failure. CONCLUSION: Myocardial ischaemia, hypervagotonia, conduction abnormalities, ventricular or supraventricular tachyarrhythmias were identified in 76% of patients with syncope after MI. Several factors of syncope were found in 57 patients (16%). Non-invasive rhythmological and systematic coronary status assessment should be recommended in patients with syncope following MI.

[Complete electrophysiological study remains necessary in symptomatic advanced cardiomyopathy]. / Une étude électrophysiologique complète reste nécessaire dans une cardiopathie évoluée symptomatique.

Multiple mechanisms can explain a tachycardia associated or not with a heart disease. It is important to establish its origin, particularly if advanced heart disease is present, for the treatment. Complete electrophysiological study remains an important means of diagnosis. We report the case of a 39-year old man, who had a dilated cardiomyopathy since the age of 25 years and who complained of tachycardia. These symptoms were shown to be related to atrioventricular nodal re-entrant tachycardia at electrophysiological study and a specific treatment was indicated.

The management of arrhythmic sincope.

Arrhythmic syncope explains 5% to 20% of the causes of syncope and its incidence increases with age. In patients with arrhythmic syncope, a poor prognosis can be expected if syncope is misdiagnosed, particularly when arrhythmias occur in a patient with advanced heart disease. Arrhythmic causes are due either to bradycardia (diagnosed by surface electrocardiography, 24-hour Holter monitoring and electrophysiologic study in patients with bundle-branch block) or to supraventricular or ventricular tachycardia (diagnosed by electrophysiologic study and/or long-term event recording). Arrhythmic syncope can be easily prevented with antiarrhythmic drugs or, more frequently, with non-medical treatments such as radiofrequency ablation of tachycardia, and pacemaker or defibrillator implantation.

[Comparison of patients with paroxysmal junctional tachycardia and syncope with those without syncope]. / Comparaison des sujets ayant des tachycardies jonctionnelles paroxystiques et des syncopes avec des sujets sans syncopes.

INTRODUCTION: The purpose of the study was to determine the possible mechanisms of presyncope in patients who have paroxysmal junctional tachycardias (PJT) and a normal surface ECG between tachycardias. METHODS: Among 419 patients consecutively recruited for PJT, aged from 10 to 88 years (47+/-19), 78 of them had presented at least one syncope; they had a normal ECG in sinus rhythm. Transesophageal programmed atrial stimulation was performed using one and two atrial extrastimuli delivered in control state and if necessary after infusion of 20-30 microg of isoproterenol; arterial blood pressure was monitored; vagal maneuvers and tilt test (n=25) were performed; echocardiogram was systematic. RESULTS: Age, sex, method of induction, tachycardia mechanism and the mean heart rate in tachycardia were similar in patients with and without syncope. Syncope was related to a vagal reaction induced by the PJT in 31 patients, to a fast rate during PJT in 15 patients, to a sinus node dysfunction in six patients, to a coronary ischemia in five patients, to a tetany induced by PJT in three patients, to an advanced age in three patients, to multiple causes in three patients and remained unexplained in eight patients. Radiofrequency ablation of reentrant circuit, performed in 28 patients, suppressed syncope in 26 of them. CONCLUSION: Presyncope or syncope occurred in 18% of patients who had a history of paroxysmal junctional tachycardia. Several mechanisms were implicated; the most frequent causes were coronary ischemia or sick sinus syndrome in old patients, vasovagal reaction or fast rate in tachycardia or tetany in patients of all ages.

[Which therapy for which patient? In daily practice]. / Quel traitement pour quel patient ? En Pratique.

Although the important progress in the curative treatment of atrial fibrillation, the indications of the regularisation of the first episode and of the preventive treatment remain difficult. Without real proofs on the interest of maintain in sinus rhythm, the indications depend on the age of the patient, the clinical tolerance and the objective impact on left ventricular ejection fraction.

[Transesophageal electrophysiological study in non sedated children younger than 11 years with a Wolff-Parkinson-White syndrome]. / Etude électrophysiologique par voie transoesophagienne chez des enfants de moins de 11 ans, non sédatés, ayant un syndrome de Wolff-Parkinson-White.

UNLABELLED: The electrophysiological evaluation of Wolff-Parkinson-White syndrome (WPW) is recommended in children aged more than five years to detect a risk of life-threatening arrhythmia. The purposes of the study were to determine the feasibility of transesophageal EPS in a child between six and 10 years in out-patient clinic. METHODS: Electrophysiological study (EPS) was indicated in 22 children, aged six to 10 years, with a manifest WPW either for no documented tachycardia (n=7), unexplained dizziness (n=2) or for a sportive authorization in 10 asymptomatic children. Two of the last children had a history of permanent tachycardia after the birth but were asymptomatic since the age of one year without drugs. RESULTS: EPS was performed in all children. The main difficulty lied in passing the catheter through the mouth. Programmed stimulation at cycle length of 380 ms was performed in all children to avoid high rates of pacing when the conduction through the accessory pathway (AP) and normal AV system was evaluated. Isoproterenol was not required in five children, because they developed a catecholaminergic sinus tachycardia. The AP refractory period was determined in all children between 200 and 270 ms. Orthodromic reentrant tachycardia (RT) was induced in 11 children, three asymptomatic children (27%), seven complaining of tachycardia and one with syncope. Rapid antidromic tachycardia was induced in this last child with dizziness. Atrial fibrillation was never induced. CONCLUSIONS: Esophageal EPS can be performed without sedation in a young child six to 10-year-old with a shortened protocol of stimulation, which was capable to clearly evaluate the WPW-related risks.

[Relationships between age and accessory pathway location in Wolff-Parkinson-White syndrome]. / Rapports entre l'âge et l'incidence d'une voie accessoire atrioventriculaire de localisation antéroseptale dans le syndrome Wolff-Parkinson-White.

BACKGROUND: Radiofrequency ablation of atrioventricular accessory pathway (AP) which is currently used, remains associated with a risk of complete AV block in the case of anteroseptal (AS) location and its indication remains debatable. The purpose of the study was to evaluate the frequency of AS location in Wolff-Parkinson-White syndrome (WPW) and the clinical and electrophysiological data of these patients. METHODS: Electrophysiologic study (EPS) was performed in 503 pts aged from six to 85 years (35+/-17), 297 men, 206 women, recruited for a patent WPW syndrome. The location of AP was determined on a 12 lead ECG during atrial pacing at maximal preexcitation according to classical criteria. The location was confirmed at EPS. Eleven pts were excluded because the location remained not clearly defined. EPS was indicated for suspected or documented tachycardias (n=264), syncope (n=68) or was systematic in asymptomatic patients (n=171). RESULTS: AS AP location was identified in 34 patients aged eight to 48 years (7%). Their mean age was younger than the age of remaining population (25+/-13 versus 36+/-17, p<0.001). According to the age, the prevalence of AS location was significantly higher in children and adolescents (14%) than after 40 years (3%) (p<0.01). There was no AS location among 108 patients aged more than 50 years. The maximal rate conducted over AP was lower in patients with AS location than in other locations either in control state (174+/-60 per minute versus 197+/-63 per minute) (p<0.01) or after isoproterenol (206+/-71 versus 248+/-69) (p<0.01). The number of induced reciprocating tachycardia (47% versus 57.5%), atrial fibrillation (15% versus 21%) and malign forms (12% versus 17%) did not differ significantly in patients with AS location and in other patients. Anterograde conduction disappeared spontaneously in three of six patients followed 8+/-1.5 years, and significantly increased in two other patients. CONCLUSIONS: AS AP location in WPW syndrome was more frequent in children than in adults. The maximal rate conducted over the AP was lower than in other locations. The incidence decreased after 40 years. AS AP location was never noted after 50 years in our population. This disappearance with age should be taken into account for the indications of AS AP ablation.

Clinical characteristics and management of paroxysmal junctional tachycardia in the elderly.

BACKGROUND: The proportion of elderly subjects is in progress. While atrial fibrillation is the most frequent arrhythmia after the age of 70 years, other tachycardias also occur in the elderly. AIMS: The aim of this study is to assess the clinical and electrophysiological characteristics of paroxysmal junctional tachycardia (PJT) in patients older than 70 years. METHODS: Eight hundred sixteen patients aged from 8 to 93 years have been consecutively recruited for PJT. Among them, 141 (17%) were older than 70 years. The clinical, electro-physiology and therapeutic data were studied. RESULTS: Forty-eight men and 93 women with an age range from 70 to 93 years (mean 76+/-5) were admitted for recurrent PJT. They were associated to cardiac decompensation in 10 cases, syncope in 26 cases, acute coronary syndrome in 14 cases and unexplained acute vascular event in 5 cases. The electro-physiological mechanism of the PJT was similar to the younger patients with a majority of nodal reentrant tachycardia (73%). Atypical nodal tachycardias were more frequent than in the youth (15 versus 4%). PJT ablation was indicated more frequently in elderly patients than in younger patients (79 versus 57%), but complications (7% versus 2.5%) and failures, especially related to atrial fibrillation induction (19% versus 5%) were more frequent in elderly patients. CONCLUSION: Junctional tachycardias are not rare in the elderly and should not be missed. A cautious medical treatment can be impeded by the presence of conduction troubles or comorbidities. If this approach is not efficacious, these subjects might take benefit from curative ablation, with still a 10% failure rate.

Wolff-Parkinson-White syndrome in the elderly: clinical and electrophysiological findings.

BACKGROUND: Screening for Wolff-Parkinson-White (WPW) syndrome is recommended in children and young adults. The aim of this study was to evaluate the clinical and electrophysiological characteristics of patent WPW syndrome in subjects > or =60 years of age. METHODS: Four-hundred and fifty-nine consecutive patients with WPW syndrome, aged 8-80 years, were recruited; 32 (7%) of these patients were > or =60 years of age. The clinical, electrophysiological and therapeutic data for these patients were evaluated. RESULTS: Sixteen men and 16 women, aged 60-81 years (67+/-4.5), were admitted for resuscitated sudden death (1), rapid atrial fibrillation (4), syncope (4), or junctional tachycardia (13); 10 patients were asymptomatic (10). Left lateral bundles of Kent were detected more frequently in patients over 60 years (56%) than in those<60 years of age (40.5%). Reciprocal tachycardia was induced in 58% of subjects<60 years of age and 53% of those > or =60 years old (difference not significant); atrial fibrillation was more frequent in subjects > or =60 years of age (37.5% vs. 19%) (p<0.05). The incidence of malignant forms of WPW syndrome was identical in older and younger subjects. Ablation of the accessory pathway was indicated 18 times; effective ablation of a left bundle of Kent required a second intervention more often in patients > or =60 years of age (22% vs. 5%) (p<0.05). CONCLUSION: WPW syndrome is not uncommon in subjects over 60 years of age (7%). Left lateral accessory pathways, that have similar conduction properties to those in much younger subjects, are common. Ablation of the bundle of Kent is often difficult but is indicated in symptomatic subjects or those with more serious forms of WPW syndrome.

[Dilated cardiomyopathy and syncope: management]. / Cardiomyopathie dilatée et syncope: conduite à tenir.

Syncope occurring in patients with primary dilated cardiac disease has several causes: ventricular tachycardia (VT), a major severe cause of this diagnosis, occurring however only in one third of cases. The other causes are supraventricular tachycardia, bradycardia and vagal hyperactivity. The management depends on the etiology of syncope in one hand and the severity of the cardiac disease and other comorbidities in the other hand. In 2007, a patient with life expectancy exceeding one year, without irreducible heart failure but with a known and stable altered left ventricular ejection fraction (LVEF)<30%, will probably benefit of non-drug technology for the treatment of syncope (defibrillator with or without resynchronization), possibly in association with the treatment of another identified etiology, such as ablation or anti-arrhythmic treatment of a supraventricular tachycardia. In a patient with LVEF>30%, the electrophysiology exploration remains the most reliable recommended investigation for identifying the cause of syncope prior to discuss the implantation of a portable Holter device, indicated when the electrophysiology study is negative and syncope repeating.

[Bi-tachycardia and ischemic cardiopathy (following myocardial infarction)]. / Bitachycardies et cardiopathies d'origine ischémique (antécédent d'infarctus du myocarde).

OBJECTIVE: The association of supraventricular tachycardia (SVT) and ventricular tachycardia (VT) is not common. The aim of this study was to evaluate its incidence and possible predisposing factors in patients with a history of myocardial infarction (MI), in order to correct them. METHODS: Out of 359 patients consecutively recruited for spontaneous VT occurring at least one month after the acute phase of an MI, 33 were noted to have a possible association of SVT with VT. These patients underwent the following investigations: Holter recording, left ventricular ejection fraction (LVEF) measurement, and electrophysiological studies including programmed atrial and ventricular pacing. RESULTS: The LEVF was 37.5+/-11%. An SVT was induced in 21 patients and a VT in 31 patients. Following investigation, the presumed factor predisposing to the two tachycardias was considered to be initiation of an SVT associated with rapid nodal conduction to the ventricle (Wenckebach point 210+/-23/mn) in 12 patients, branch to branch re-entry in 4 patients, reversible rhythmic dilated cardiomyopathy in 4 patients, an ischemic factor in 8 patients, post-operative period in 1 subject, infundibular VT in 1 subject, and an undetermined mechanism in 3 patients. The specific treatment of each of the identified etiologies usually prevented the recurrence of VT with the exception of one patient who had further VT during defibrillator recording, independent of any SVT. CONCLUSION: The association of SVT with VT is rare because it was only noted in 9% of subjects who presented with spontaneous VT following myocardial infarction; This incidence is debatable, and could be an underestimate due to the fact that diagnosis is difficult. Several presumed predisposing factors are implicated and should be actively sought.

Interest of non-invasive and semi-invasive testings in asymptomatic children with pre-excitation syndrome.

AIMS: To determine the feasibility and the results of exercise testing (ET) and electrophysiological study (EPS) in outpatient asymptomatic children with a Wolff-Parkinson-White (WPW) syndrome. METHODS AND RESULTS: Exercise testing and transesophageal EPS were performed in 55 outpatient asymptomatic children aged 6 to 19 years old (14 +/- 3) with WPW. Wolff-Parkinson-White persisted during maximal exercise. Isoproterenol was not required in five children younger than 10 years old, because they developed a catecholaminergic sinus tachycardia. Maximal rate conducted through accessory pathway (AP) was higher in children younger than 16 years old than in teenagers (P < 0.05). Atrioventricular re-entrant tachycardia (AVRT) was induced in six children; atrial fibrillation (AF) in 12 children. The induction of tachycardias and the dangerous forms (18%) were not influenced by age. After 5 +/- 1 years, one child, 12 year old with inducible rapid AF, had a sudden cardiac arrest; two children became symptomatic after ablation. CONCLUSIONS: Transesophageal EPS was required to determine the prognosis of asymptomatic WPW in children. The maximal rate conducted in AP was higher in children younger than 16 years old than in teenagers; other data did not differ. AVRT was rare; 71% of children had no inducible arrhythmia and were authorized to resume physical activities.