[Chloroquine cardiotoxicity in long-term lupus therapy in two patients]. / Cardiotoxicité après un traitement au long cours par chloroquine chez deux patientes lupiques.

BACKGROUND: The antimalarial compounds chloroquine and hydroxychloroquine are widely used in the treatment of connective tissue diseases and are usually well tolerated. We report two cases of chloroquine cardiotoxicity. PATIENTS AND METHODS: Two women (aged 43 and 48 years) were treated for 5 years for lupus. They developed severe conduction disturbances requiring a pacemaker. Plasma chloroquine concentrations were abnormally high in both cases. In one case, a genetic polymorphism modulating the activity of a cytochrome involved in chloroquine metabolism (CYP2C8) was identified. DISCUSSION: Since 1965, 60 cases of occasionally severe cardiotoxicity have been reported following long-term treatment with chloroquine in most cases, but also with hydroxychloroquine. This toxicity must be detected early and close cardiac assessment is required.

High prevalence of ventricular repolarization abnormalities in people carrying TGFßR2 mutations.

Mutations in the TGFßR2 gene have been associated with a life threatening risk of aortic dissection but no arrhythmic death has been previously reported. Two young females carrying a TGFßR2 mutation, initially diagnosed as Marfan syndrome or Loeys Dietz syndrome, presented sudden death with autopsy ruling out dissection. The ECGs of the 2 Sudden Cardiac Deaths revealed profound ventricular repolarization abnormalities with a sinusoidal T-U morphology associated with normal left ventricular ejection fraction. These data strongly suggest sudden cardiac arrhythmic deaths and prompted us to systematically study the repolarization pattern in the patients with TGFßR2 mutations. ECG findings from 58 mutation carriers patients (TGFßR2 group) were compared with those of 46 non-affected first degree relatives (control group). TGFßR2 mutation was associated with ventricular repolarization abnormalities in 47% of patients (p < 0.001 vs. controls), including a 19.6 ms (95%CI 8.7; 30.5) QTc interval prolongation compared to the non-affected first degree relatives (p < 0.001), higher prevalence of abnormal U waves (16% vs. 2%), and sinusoidal T-U morphology (10% vs. 0%). TGFßR2 mutations can be associated with abnormal ventricular repolarization pattern, longer QT interval than non-carrier relatives and an increased risk for sudden death.

[The best of arrhythmia in 2006]. / L'essentiel de 2006 en rythmologie.

Even though the year 2006 did not bring any major publication reporting therapeutic trials in the field of arrhythmia, it has been marked by the publication of important international guidelines on atrial fibrillation (AF), the treatment of ventricular arrhythmia and the prevention of sudden death, as well as studies on AF ablation, the external automatic defibrillator, the risk factors of ventricular fibrillation in the acute phase of myocardial infarction, and genetic aspects of the arrhythmogenic right ventricular dysplasia.

[The Jervell and Lange-Nielsen syndrome. Natural history, molecular basis and clinical outcome]. / Syndrome de Jervell et Lange-Nielsen. Histoire naturelle, bases moléculaires et devenir clinique.

UNLABELLED: Data on the Jervell and Lange-Nielsen syndrome (JLN), the long QT syndrome (LQTS) variant associated with deafness and caused by homozygous or compound heterozygous mutations on the KCNQ1 or on the KCNE1 genes encoding the IKs current, are still largely based on case reports. We analyzed data from 186 JLN patients obtained from the literature (31%) and from individual physicians (69%). Most patients (86%) had cardiac events and 50% were symptomatic already by age 3. Their QTc was markedly prolonged (557 +/- 65 ms). Most of the arrhythmic events (95%) were triggered by emotions or exercise. Females are at lower risk for cardiac arrest and sudden death (CA/SD). A QTc>550 ms and history of syncope during the first year of life are independent predictors of subsequent CA/SD. Most mutations (90.5%) are on the KCNQ1 gene; mutations on the KCNE1 gene are associated with a more benign course. beta-blockers have only partial efficacy as 51% of the patients had events despite therapy and 29% had CA/SD. CONCLUSIONS: JLN syndrome is a most severe variant of LQTS, with a very early onset, major QTc prolongation, and is not well responsive to beta-blockers. Subgroups at relatively lower risk for CA/SD are identifiable and include females, patients with a QTc pound550 ms, without events in the first year of life, and with mutations on KCNE1. Early therapy with ICDs has to be considered.

[Recommendations for sports participation in patients with arrhythmia]. / Recommandations sur la pratique de l'activité sportive en cas de pathologie rythmique.

Nowadays, sports are a wonderful mean for social success, and the high-level athlete is the symbol of a perfect hygiene of life. Despite this, the occurrence of unexplained sudden death (SD) is not exceptional, especially during training and competition. In this context, it is important to intensify medical controls for these athletes, especially in a very early phase, in order to detect subjects at risk. In case of detection of a cardiac disease prone to cardiovascular or arrhythmic event, the practice of any high-level sportive activity or even any sustained sportive activity must be forbidden without hesitation, with the aim of protecting these subjects. Even though a total interdiction of sports practice can be a tough decision to be accepted, it should prevail on the dramatic consequences of sudden death. Physicians' responsibility issues in the screening and management of competition or leisure-time sportsmen are of high importance since in case of sudden death, the physician and the medical community liabilities can be considered. As a consequence, the medical community set up recommendations on the screening, treatment and even interdiction of sportive activity for athletes, which should also be applied to leisure-time sportsmen. In the first part of this article, the different causes (especially the arrhythmia-related) of sudden death occurring in sportsmen are reviewed. In the second part, the recommendations on practice of high-level sports in case of arrhythmia or genetic arrhythmic cardiac disease are summarized.

Notched T waves on Holter recordings enhance detection of patients with LQt2 (HERG) mutations.

BACKGROUND: The 2 genes KCNQ1 (LQT1) and HERG (LQT2), encoding cardiac potassium channels, are the most common cause of the dominant long-QT syndrome (LQTS). In addition to QT-interval prolongation, notched T waves have been proposed as a phenotypic marker of LQTS patients. METHODS AND RESULTS: The T-wave morphology of carriers of mutations in KCNQ1 (n=133) or HERG (n=57) and of 100 control subjects was analyzed from Holter ECG recordings. Averaged T-wave templates were obtained at different cycle lengths, and potential notched T waves were classified as grade 1 (G1) in case of a bulge at or below the horizontal, whatever the amplitude, and as grade 2 (G2) in case of a protuberance above the horizontal. The highest grade obtained from a template defined the notch category of the subject. T-wave morphology was normal in the majority of LQT1 and control subjects compared with LQT2 (92%, 96%, and 19%, respectively, P:<0.001). G1 notches were relatively more frequent in LQT2 (18% versus 8% [LQT1] and 4% [control], P:<0.01), and G2 notches were seen exclusively in LQT2 (63%). Predictors for G2 were young age, missense mutations, and core domain mutations in HERG. CONCLUSIONS: This study provides novel evidence that Holter recording analysis is superior to the 12-lead ECG in detecting G1 and G2 T-wave notches. These repolarization abnormalities are more indicative of LQT2 versus LQT1, with G2 notches being most specific and often reflecting HERG core domain missense mutations.

Prognostic value of radionuclide angiography in patients with right ventricular arrhythmias.

BACKGROUND: The prognosis of patients with right ventricular (RV) arrhythmias remains uncertain. This study prospectively evaluated the prognostic value of RV and left ventricular (LV) involvement assessed by radionuclide angiography (RNA) as predictors for sudden death. METHODS AND RESULTS: Patients (n=188) with severe arrhythmias originating from the RV were followed up for a mean of 45+/-34 months. Data on clinical presentation, resting and stress ECG, signal-averaged ECG, 24-hour Holter monitoring, and programmed stimulation were collected along with RNA. Patients were classified as group I (n=82) with normal RNA or group II (n=106) with an abnormal RV suggestive of arrhythmogenic RV cardiomyopathy, classified as diffuse or localized disease, with or without associated LV abnormalities. During follow-up, 14 patients died suddenly, all in group II. None of the clinical and electrical data were predictive of death. An abnormal RNA study was a highly predictive factor for death (P<0.005), as well as the presence of LV abnormalities (P<0.01). CONCLUSIONS: The present study confirms that arrhythmogenic RV cardiomyopathy is a severe disease with a high risk for cardiac death. Evidence of RV abnormalities in patients presenting with RV arrhythmias is highly predictive for sudden death, as is its association with LV involvement.

Predictive value of electrophysiologic studies during treatment of ventricular tachycardia with the beta-blocking agent nadolol. The Working Group on Arrhythmias of the French Society of Cardiology.

Sixty patients with recurrent inducible sustained ventricular tachycardia were prospectively treated with nadolol (40 or 80 mg/day). Old myocardial infarction was present in 43 patients and dilated cardiomyopathy in 12. In group I (n = 36), nadolol was given alone, whereas in group II (n = 24), previously ineffective treatment with amiodarone was continued in combination with nadolol. Left ventricular ejection fraction was higher in patients in group I (0.40 +/- 0.12) than in group II (0.30 +/- 0.10, p less than 0.01) patients. Electrophysiologic study was repeated after short-term treatment with nadolol, which was continued regardless of the results of this test, according to the scheme of the parallel approach. Recurrence of spontaneous tachycardia or sudden death occurred in 21 patients after 10 +/- 9.2 months; sustained tachycardia was inducible in 19 on nadolol therapy. The remaining 39 patients (of whom 21 had inducible tachycardia while taking the drug) have had no recurrence of tachycardia after 27.8 +/- 9.3 months of follow-up study. Sensitivity, specificity and predictive value of a positive and negative test were 90.5%, 46%, 47.5% and 90%, respectively. The results differ between group I and group II patients, the latter having a high percent of false positive responses. This difference is even more obvious with respect to left ventricular ejection fraction: the predictive value of a positive test was 86% when ejection fraction was greater than 0.40 and 39% when it was less than 0.40.(ABSTRACT TRUNCATED AT 250 WORDS)

[Comparison between three-dimensional electro-anatomical mapping and conventional mapping in the ablation of atrial tachycardias]. / Comparaison entre la cartographie electro-anatomique tridimensionnelle et la cartographie conventionnelle dans l'ablation des tachycardies atriales.

In atrial tachycardias, catheter ablation using conventional mapping system is associated with high immediate success and low recurrence. Three-dimensional electroanatomical mapping system combined to catheter ablation of atrial tachycardias has reached, in small uncontroled series, success rates of 100%. However, limited data are available about rates of recurrence or complication using this approach. In order to compare both mapping systems, we have conducted a study of 65 consecutive patients (36 women and 29 men) that underwent both electrophysiologic study and catheter ablation for suspected atrial tachycardias. Pre-existing heart disease was noted in 43%, hypertension in 32% and a history of atrial fibrillation of flutter in 52%. Catheter ablation guided by conventional mapping was undertaken in 44 patients and by three-dimensional electroanatomical mapping in 21. Successful ablation was performed in 68% of patients with conventional mapping and in 90% with three-dimensional electroanatomical mapping. No complication and recurrence were observed with the latter approach, while 5 patients had a recurrence and 2 had immediate complication with conventional mapping. Catheter ablation of atrial tachycardias combined with three-dimensional electroanatomical mapping appeared to be effective and safe, however, conventional mapping system still remains a reliable approach that must be considered as the first choice for atrial tachycardias ablation.

[Value and limitations of programmed ventricular stimulation]. / Intérêts et limites de la stimulation ventriculaire programmée.

The electrocardiogramme and methods of prolonged ECG recording are sufficient for diagnosing most cardiac arrhythmias. They also provide some prognostic information and allow evaluation and follow-up of treatment. However, in some situations, endocavitary electrophysiological investigations are required when the diagnosis is uncertain, that more prognostic information is required or interventional techniques (endocavitary ablation) are envisaged. The aim of this report is to summarise the value and limitations of programmed ventricular stimulation. Many of its indications have been abandoned in terms of rhythm stratification in the face of more robust parameters, in particular the left ventricular ejection fraction. However, it retains a potential utility in terms of prognosis in arrhythmogenic right ventricular dysplasia, the Brugada syndrome and operated Tetralogy of Fallot. In any event, it is important to remember that studies resulting in diagnostic or therapeutic recommendations were performed with strict protocols of stimulation in selected patients and that these recommendations can only be applied when the evaluation protocols are respected. The indications of programmed ventricular stimulation will increase in the therapeutic field with the development of new techniques of 3D mapping, new systems of catheter guiding which should extend the indications of endocavitary ablation.

[Primary anomalies of ventricular repolarisation]. / Anomalies primaires de la repolarisation ventriculaire. Conséquences electrophysiologiques.

The duration of repolarisation is the main determinant of the refractory period and therefore plays a major electrophysiological role. Ventricular repolarisation can be influenced or modified by very many extrinsic factors responsible for so-called secondary changes or anomalies. On the contrary, primary anomalies of ventricular repolarisation correspond to intrinsic anomalies of ionic conduction which in turn affect repolarisation. Primary anomalies of ventricular repolarisation are the consequences of vascular disease, which is the origin of both electrocardiographic anomalies and rhythm disorders, and which can result in sudden death from ventricular fibrillation. Three clinical syndromes correspond with these definitions: long QT syndrome, short QT syndrome, and Brugada syndrome. Much of the experimental work seems to show that arrhythmogenic action results mostly from an increase in the heterogeneity of the refractory periods, whether this involves a prolonged, short or even normal repolarisation time. The various experimental models also give a better understanding of the repolarisation changes observed on the electrocardiogram. Knowledge of the mechanisms responsible for arrhythmias due to primary anomalies of ventricular repolarisation could provide a model for secondary anomalies.

[Catecholinergic ventricular tachycardia in children]. / Tachycardies ventriculaires catécholergiques chez l'enfant.

Catecholinergic ventricular tachycardia is an adrenergic induced polymorphic ventricular arrhythmia. It occurs in infancy and is responsible for syncope and sudden death in the absence of any morphological cardiac abnormality. Without treatment the mortality in catecholinergic ventricular tachycardia is very high. We report genetic and clinical data from 25 cases of catecholinergic ventricular tachycardia referred with syncope (n=19) or resuscitated sudden death during exercise (n=6). A family history from the 25 families identified 41 apparent subjects considered as being clinically affected, with an average age of 30 +/- 10 years (11 to 62 years). Analysis of the RyR2 gene showed mutations in 13 of the 25 cases and in 39 of apparent subjects. With betablocker treatment (nadolol: 1.6 +/- 0.15 mg/kg), 96% of patients remained asymptomatic over an average follow-up of between 7.5 +/- 1.5 years, although some of them continued to display polymorphic ventricular extrasystoles on exercise. Nevertheless, 12% of the cases suffered sudden death or further syncope during follow-up. An automatic defibrillator was implanted in 2 patients who had a RyR2 mutation. High dose betablockers are effective in preventing serious rhythm disturbance in children. In adolescence, implanting an automatic defibrillator should be discussed in cases with a history of syncope or resuscitated sudden death. We confirm the importance of genetic studies in these families at high risk of sudden death.

[AFFIRM: what we have learned ... and pending issues]. / AFFIRM: ce que nous avons appris ... et les questions en suspens.

During these last years, several therapeutic strategies trials have been performed in atrial fibrillation: the goal was to compare the rhythm control strategy (restoration and maintenance of sinus rhythm) to the rate control strategy (slowing of heart rate in atrial fibrillation). The most important of these different trials is the AFFIRM study. The main conclusion of this trial is that rate control can be chosen in first intention and not only in case of failure of the rhythm control strategy. These results can not be applied to 2 categories of patients: on one hand patients with heart failure and on the other hand young patients without cardiopathy in whom the strategy of rhythm control and sinus rhythm maintenance, mainly by class I antiarrhythmic drugs, remains the better choice.

Heterozygous mutation in the pore of potassium channel gene KvLQT1 causes an apparently normal phenotype in long QT syndrome.

Mutations in KvLQT1, a gene encoding a potassium channel, cause both the recessive Jervell and Lange-Nielsen (JLN) syndrome and the dominant Romano-Ward (RW) syndrome. These diseases are characterised by a prolonged QT interval on the ECG, syncopes and sudden death due to cardiac arrhythmias. The JLN syndrome is also associated with a congenital bilateral deafness. We report here a novel missense mutation, W305S, in the pore region of KvLQT1 identified by PCR-SSCP analysis in two consanguineous JLN families. In contrast to several missense mutations found in the same region of KvLQT1 in RW patients which are associated with severe cardiac phenotypes, the W305S mutation is responsible for an apparently normal phenotype in heterozygous JLN carriers.

Influence of amiodarone on genetically determined drug metabolism in humans.

Amiodarone has been shown to interact with the nongenetically determined hepatic elimination of several drugs, including phenytoin and digoxin. Its influence on genetically determined metabolic pathways has not been studied in humans. We examined the effects of oral amiodarone therapy on the genetically determined metabolism of isoniazid (N-acetyltransferase), mephenytoin (cytochrome P450MEPH), and dextromethorphan (CYP2D6). Eight patients with arrhythmias were studied before and 76 +/- 16 days after amiodarone (loading dose of 1000 mg/day for 10 days followed by a maintenance dose of 200 to 400 mg/day). Genetically determined enzyme activity was assessed indirectly by calculating the metabolic ratio (parent drug/metabolite in 8-hour urine for CYP2D6 and P450MEPH and N-acetylisoniazid/isoniazid in plasma for N-acetyltransferase) after oral administration of the parent compounds. At the time of phenotyping, plasma concentrations of amiodarone and N-desethylamiodarone were 0.66 +/- 0.35 micrograms/ml and 0.65 +/- 0.26 micrograms/ml, respectively. Amiodarone increased the log(metabolic ratio) of dextromethorphan from a median of -2.5 (range, -2.9 to -2.0) to a median of -1.9 (range, -2.5 to -1.5; p less than 0.02) but did not alter the metabolic ratio of mephenytoin or isoniazid. The amount of dextromethorphan excreted in urine increased from a median of 0.084 mumol/8 hours (range, 0.041 to 0.161 mumol/8 hours) to a median of 0.205 mumol/8 hours (range, 0.064 to 0.288 mumol/8 hours; p less than 0.02) and the amount of its metabolite (dextrorphan) tended to decrease from a median of 26 mumol/8 hours (range, 15 to 37 mumol/8 hours) to a median of 20 mumol/8 hours (range, 7 to 27 mumol/8 hours; p less than 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

Drug therapy for prevention of atrial fibrillation.

Atrial fibrillation is not a homogeneous entity, and many factors are responsible for a number of different behaviors, clinical consequences, and reactions to therapy. Therefore, the conventional evaluation of preventive treatments is not really adapted to provide the correct answers to difficult problems of therapeutic indications, as the 2 components of the benefit-risk ratio are not really known. Like ventricular fibrillation, atrial fibrillation may be primary or secondary to organized tachyarrhythmias, and reentrant flutter or automatic atrial tachycardia may well form the actual target for treatment. The automatic nervous system is never absent as a determinant of the onset of arrhythmia, and the vagal as well as the sympathetic action may predominate and explain why a treatment may or may not be effective in situations that are identical only in appearance. The electrophysiologic milieu formed by the atrial tissue probably accounts for the perpetuation of the process of atrial fibrillation or its self-termination, and drugs themselves may contribute to modify the milieu in a way that in the end may be favorable or not. Finally, the presence or the absence of heart disease and heart failure largely contributes to the state of the vagosympathetic balance, to the hemodynamic consequences of atrial fibrillation, and ultimately to the proper toxic effects of drugs. The overall consequence of these complex situations is that any precise therapeutic decision algorithm for atrial fibrillation is always simplistic and that any global evaluation of drug efficacy or toxicity is not really meaningful as long as the category of patients treated is not precisely determined: no drug appears better or worse than others, but simply more or less adapted to various situations.

Results of electrical fulguration in arrhythmogenic right ventricular disease.

Eleven patients with sustained ventricular tachycardia (VT) refractory to antiarrhythmic drugs due to right ventricular disease shown by angiography underwent fulguration. Seven patients always had VT with the same morphology, and 4 had clinical VT with 2 or 3 different QRS waveforms. Five patients underwent a single fulguration and the other 6 underwent from 2 to 5 procedures; 2 to 14 shocks (mean 6) of 150 to 250 J were used. No serious complications occurred. At 31.5 +/- 9 months of follow-up, the arrhythmia was controlled in 8 patients, with continuation of previously ineffective antiarrhythmic drug therapy in 6 of 8. The number of VT episodes the year before and after fulguration was 0.5 +/- 0.7 vs 3.5 +/- 1.7 (p less than 0.001). There was no statistically significant difference between the success rate and the degree of prematurity of the onset of the local electrogram during VT: -36 +/- 31 ms for successes and -38 +/- 13 ms for failures. In 7 patients with monomorphic VT, there were 6 successes and 1 failure, and in 4 patients with several morphologies of VT, there were 2 successes and 2 failures (1 due to the appearance of a "new" VT). Thus, electrical fulguration of VT in patients with right ventricular disease is safe and most often effective, particularly in patients with monomorphic VT, when combined with antiarrhythmic drugs. In these patients, the usually recommended endocardial mapping criteria for the determination of the optimal fulguration site were not predictive of outcome. Further studies are necessary to better define the optimal site for fulguration.

Surgery for the Wolff-Parkinson-White syndrome in 73 consecutive patients: what have we learnt from intraoperative mapping?

Intraoperative epicardial mapping data obtained in 73 consecutive patients operated upon for the Wolff-Parkinson-White syndrome were reviewed. Fifty-six patients had single and 17 patients had multiple accessory pathways. Except for right free wall pathways, all bypass tracts were divided using an endocardial approach. There were 2 operative deaths, 1 of which occurred after a concomitant mitral valve replacement. A total of 78 of the 87 pathways present in the 71 survivors were successfully ablated (90%). All failures occurred in patients with left posterior septal pathways. Epicardial mapping performed prior to bypass was found helpful in identifying multiple distinct accessory pathways which had been missed preoperatively. This occurred in 6 patients and led to appropriate combinations of classic operative approaches which resulted in all of these pathways being successfully divided. Further, by demonstrating that Kent bundles often presented as multiple closely-spaced or arborized accessory pathways, intraoperative mapping led to widening of the margins of surgical dissection, and in particular to an additional left atriotomy in all cases of left posterior septal accessory pathways which resulted in a substantial improvement in our rate of success.

[Prognostic factors for success in catheter ablation of the right Kent bundle: report of 27 patients]. / Factores pronóstico de éxito en la fulguración de los haces de Kent derechos: a propósito de una serie de 27 pacientes.

In 27 patients with atrial fibrillation and/or reciprocating tachycardia, ablation of right-sided Kent bundles (23 in the right posterior paraseptal region and four of the right free wall) was performed. The anterograde refractory period of the accessory pathways was 253 +/- 70 msec and the shortest R-R interval during atrial fibrillation 211 +/- 47 msec. Cumulative energies of 589 +/- 396 J per patient were used, with 3 +/- 2 shocks and 195 +/- 312 J per shock. Accessory pathway ablation was effective in 16/27 patients (59%) during an 11 +/- 8 months of follow-up (in 15/16 pre-excitation disappeared; in nine of them the anterograde and retrograde conductions were abolished and in the other six the anterograde and retrograde conductions were severely altered; ablation was partially ineffective in 1/16 patients who remained asymptomatic on medical treatment and without inducible reciprocal rhythm). Ablation was ineffective in 11/27 patients. Three hours after ablation a patient died from electromechanical dissociation; during ablation a 200 J shock cancelled preexcitation, not being possible to produce reciprocal rhythm. The emergency echocardiography only showed a minimum posterior pericardial effusion. Ablation was effective in 15/23 patients (65%) right posterior paraseptal. Overall success in 1989 (10/27 patients) was 70% (7/10 patients). The success in 1989 was 70% (6/8 patients) right posterior paraseptal. The shortest RP' interval (was 82 +/- 19 msec) during the reciprocal rhythm, where the ablation was performed, was 82 +/- 19 msec (74 +/- 17 msec with success and 99 +/- 19 msec with failure).(ABSTRACT TRUNCATED AT 250 WORDS)

[The surgical section of the bundle of Kent as an operative treatment of the Wolff-Parkinson-White syndrome: apropos a series of 82 operated cases]. / Sección quirúrgica del fascículo de Kent como tratamiento cruento del síndrome de Wolff-Parkinson-White: a propósito de una serie de 82 casos operados.

Eighty two patients diagnosed of the Wolff-Parkinson-White syndrome (WPW) underwent operation for the surgical section of the Kent-His bundle. In these cases, posteroseptal localization (PS) occurred in 32, left lateral (LL) in 25, right lateral (RL) in six, anteroseptal (AS) in one, posteroseptal and left lateral in 14, right and left posteroseptal in two, anteroseptal and left lateral in one, and left lateral and right and left posteroseptal in one. All of the patients presented an invalidating clinical of palpitations and/or loss of consciousness, and episodes of atrial fibrillation and/or reciprocal rhythm were registered in all cases. The mean anterograde refractory period in the accessory pathways was 244 +/- 60 msec, and the shortest RR in atrial fibrillation was 190 +/- 36 msec. A mitral commissurotomy was carried out in 3 patients during surgery, mitral prostheses were implanted in two, a double aorto-coronary bypass was made in three and an interventricular communication was closed in one. After a follow-up of 36 +/- 18 months, the surgical section of the Kent bundle was found to be effective in 77 out 82 patients (94%). (In 70 out of 77 cases, both anterograde and retrograde conduction were totally abolished and in seven out of 77 obtunded. All patients were asymptomatic during the follow-up period). In 5 out of 82 patients, surgical treatment was ineffective all five showed a PS Kent-His and two presented a second Kent-His fascicle (LL).(ABSTRACT TRUNCATED AT 250 WORDS)