[The best of arrhythmia in 2006]

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.

[Recommendations for sports participation in patients with arrhythmia]

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.

[Value and limitations of programmed ventricular stimulation]

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]

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.

[AFFIRM: what we have learned ... and pending issues]

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.

[Catecholinergic ventricular tachycardia in children]

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.

[Comparison between three-dimensional electro-anatomical mapping and conventional mapping in the ablation of atrial tachycardias]

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.

[Ventricular extrasystoles]

Ventricular extrasystoles result from premature excitation of the heart from a site beyond the bifurcation of the bundle of His, at the level of the conductive tissue or myocardial cells. In practice they represent a daily problem for cardiologists due to their frequent occurrence. They can be detected in symptomatic patients and also in asymptomatic subjects, for example during routine health checks. It is therefore important to distinguish benign ventricular extrasystoles from those which are potentially serious, so that a useless or even dangerous treatment is not undertaken and severe anxiety is not caused in patients who have become 'medicalised'. The decision about treatment is only made following electrocardiographic and echographic clinical investigation, with the presence of cardiopathy being one of the major deciding factors.

[Recent concepts of the Brugada syndrome, the long QT syndrome and adrenergic ventricular tachycardias]

The clinical syndromes responsible for sudden death have benefited from spectacular advances in recent years. The authors propose a brief review of the genetic, electrophysiological, physiopathological and clinical characteristics of the long QT syndrome, Brugada's syndrome, adrenergic ventricular tachycardias and the short QT syndrome. The initial concept of one gene responsible for one pathology has uncovered new zones of complexity within diseases considered to be monogenetic in origin. These new findings have impacted on diagnostic and therapeutic strategies of these conditions. However, the assessment of the arrhythmic risk and the choice of treatment in individual cases still remain almost exclusively the domain of clinical judgement. Similarly, the better understanding of the mechanisms of the arrhythmias in these syndromes has opened up new specific therapeutic approaches which require validation by clinical trial.

[A multicentre trial of the diagnostic value and cost of electrocardiography in symptoms suggesting arrhythmia with a new event recorder with transtelephonic transmission]

Events recorders are used for electrocardiographic documentation of symptoms of arrhythmia too sporadic and short lasting to be recorded by 24 hour Holter monitoring. However, there are no French studies comparing the value and cost of event recorders with conventional diagnostic methods. Recently, a new telediagnostic device has become available in France leading to an assessment of the technique. The aim of this study was to determine the value of this event recorder and the cost of diagnostic ECG in the assessment of presumed arrhythmic symptoms such as palpitations or rare tachycardia (<3 episodes per week) of short duration, compared with conventional techniques. Fifty-eight patients with these criteria were randomised, 30 to Survcard (Group I) and 28 to conventional diagnostic methods (Group II). The patients were comparable with respect to age, sex distribution, type of symptoms and associated cardiac disease. The ECG diagnosis of the symptoms was established in 20 cases (66.6%) of patients in Group I in 17 +/- 16 days, and in 14 cases (50.0%) of Group II in 23 +/- 28 days. The difference between the two groups was not statistically significant. The cost of a positive diagnosis for Group I (Survcard) varied from 0 to 228.47 Euro with an average of 71.22 +/- 117.02 Euro. The cost of positive diagnosis in Group II varied from 76.80 to 2340.41 Euro with an average of 480.39 +/- 797.41 Euro. In conclusion, this study showed that the percentage of patients with a positive diagnosis was comparable in the two groups but that the cost was 6 times higher in the group investigated by conventional methods than in the Survcard group because of more costly medical intervention.

[Bidirectional ventricular tachycardias]

Bidirectional tachycardias are rare arrhythmias. Nevertheless in the sixties and seventies these arrhythmias prompted much work relating to their mechanism. Discussions about the supposed supra-ventricular origin of certain bidirectional tachycardias essentially rested on presumptive arguments based on electrocardiographic analysis. All the electrophysiological investigations which could be performed in tachycardia showed a ventricular origin. The current hypotheses concerning the electrophysiological mechanism favour non-unifocal mechanisms as well as a very diverse aetiology: an automatic focus, or the triggered activities being associated with alternating conduction, or re-entry between the left hemibranches. Although the classic context is of excess digitalis with advanced cardiopathy, readily in atrial fibrillation with a poor prognosis as a corollary, the most recent description of catecholergic ventricular tachycardias with the very characteristic appearance of bidirectional tachycardias justifies updating the understanding of these unusual tachycardias.

[Characteristic electrocardiographic procedures of isthmic-dependent atrial flutter; influence of clinical and echocardiographic procedures]

The appearance of the F waves on the ECG is considered to be related to the type of circuit of the anti-clockwise flutters and the clockwise isthmic-dependant flutters. In the authors' experience, the usual ECG description of these two types of flutter is not always observed. This study was undertaken to analyse the different appearances of anti-clockwise and clockwise flutters and to try and explain the reasons for these differences. Over a 4 year period, 139 patients with an ECG of atrial flutter required electro-physiological studies and echocardiography of the 156 flutters analysed: 130 were anti-clockwise and 26 clockwise. Three types of anti-clockwise flutter were observed: type 1 with exclusively negative F waves in the inferior leads: type 2 and 3 with negative F waves in the inferior leads and a small (type 2) or large (type 3) positive terminal components. The types 2 and 3 were associated with a higher incidence of left atrial dilatation, cardiac disease and atrial fibrillation than type 1. Two types of clockwise flutter were observed: type 1 with positive notched F waves in the inferior leads with a return to the iso-electric line and type 2 with wide F waves in the inferior leads with two components, predominantly positive and negative, without return to the iso-electric line. There are different ECG appearances of anti-clockwise and clockwise flutter which seem to be correlated with structural cardiac abnormalities. The anti-clockwise flutters with a positive terminal component of the F waves in the inferior leads corresponds to a subgroup with a high probability of cardiac disease and left atrial dilatation.

[Left superior vena cava: a simple diagnosis by transthoracic echocardiography. A case report]

Persistent left superior vena cava is an anomaly of the systemic venous return occurring in 0.5% of the general population. We report the case of a patient with an incidental diagnosis made during a dyspnea while he had chronic pulmonary disease. The diagnosis was suspected by the presence of a markedly dilated coronary sinus and confirmed by a simple contrast injection into the left antecubital vein. Transesophageal echocardiography and magnetic resonance imaging confirmed the existence of 2 superior vena cava with the left superior vena cava draining into the coronary sinus. This congenital anomaly is of minimal hemodynamic significance when isolated. The diagnosis can be useful for placement of central catheters from left superior approach.

[Brugada syndrome]

The Brugada syndrome is characterised clinically by the occurrence of syncope or sudden death due to ventricular arrhythmias in patients with structurally normal hearts and electrocardiographic signs of right bundle branch block and ST elevation in the right precordial leads (V1 to V3). The transmission of the condition is autosomal dominant with variable penetration. Mutations have been identified in a gene coding for the alpha sub-unity of the sodium channel (SCN5A) on chromosome 3 in only 30% of cases. This mutation is responsible for a reduction of the density of the sodium current and explains the aggravation of the electrocardiographic anomalies by antiarrhythmic drugs which block the sodium channels. The prognosis is poor in symptomatic patients and depends on the prevention of sudden death by the implantation of an automatic defibrillator. The therapeutic decision is much more difficult in asymptomatic patients without a family history. The authors propose a decisional algorithm. The management may have to be modified in the months or years to come depending on advances in the understanding of this syndrome.

[Indications for implantable automatic defibrillators: critical analysis]

The implantable automatic defibrillator (IAD), invented in 1980, has revolutionised the management of patients with malignant ventricular arrhythmias resistant to medical treatment or ablation procedures. The number of devices implanted continues to increase in the industrialised countries and, based on the results of clinical trials, the indications for IAD are now well codified and increase as new clinical studies are published. However, the absolute number of implantations in France remains low (about 1200 to 2000, about 20 per million population) for a number of reasons: cost of IAD, absence of reimbursement by the health service which has restrained the implantation to public hospitals, and information of cardiologists for whom IAD may seem to be reserved for a few exceptional cases. Several factors suggest that the number of implantations will increase in the near future. First of all, the procedures of implantation have become much more simple due mainly to technical improvements. Then, the results of recent studies have validated prophylactic implantations of these devices in primary prevention in the post-infarction period (MADIT, MUSTT, MADIT II studies) and have demonstrated the superiority of IAD over antiarrhythmic drug therapy in terms of global survival in patients with severe ventricular arrhythmias (AVID, CIDS, CASH studies).

[Chloroquine cardiomyopathy revealed by complete atrio-ventricular block. A case report]

We describe a rare case of chloroquine cardiomyopathy occurring during long term (7 years) treatment for rheumatoid polyarthritis in a 42 year old woman. There was an isolated acute severe conduction defect, which is particularly rare. Histological study with the electron microscope allowed confirmation of this diagnosis. We report here the secondary cardiological effects of this frequently used synthetic antimalarial.