P1021Low incidence of atrial tachycardia following ablation of low voltage areas in sinus rhythm for persistent atrial fibrillation

.  Background: Dedicated ablation strategies for persistent atrial fibrillation (AF) have shown a limited success rate with frequent atrial tachycardia (AT) occurrence. Recent studies suggest that atrial arrhythmogenic sites are related to tissular heterogeneities and increased fibrosis can be identified as reduced bipolar voltage areas.

. Purpose: Targeting low voltage areas (LVA) in addition to PVI may represent an efficient strategy for the ablation of persistent AF, and may limit the risk of AT recurrence.

. Methods: We prospectively included consecutive patients with symptomatic persistent AF. The ablation strategy consisted of the following steps: circumferential pulmonary vein isolation (CPVI), Sinus rhythm restoration by electrical cardioversion, voltage map performed in sinus rhythm. Complementary RFA was guided by low voltage areas (0.2-0.4 mV). Success was defined as freedom from AF/ atrial flutter or atrial arrhythmia at 12 months or more.

. Results:  101 patients (mean age: 62.5 +/- 10.4 years, men 73%) were included with persistent AF or long standing AF (7%). Procedure time was: 154 ± 25 min and fluoroscopy time: 184 ± 90 sec. Time of RFA was 44.7 +/- 12 min. Mean LA volume was 182 +/- 38 mL. LVA were found in 50 patients (49.5%). The distribution of these areas was:  30 anterior wall 29.7%), 21 septum (20.7%), 19 roof (18.8%), 5 inferior (4.9%), 11 left appendage (10.8%), 6 posterior (5.9%), 3 mitral isthmus (3%). RF ablation was realized for all LVA and homogenisation was attempt. After a single procedure at a mean FU of 12 months, 72.3% of patients were free of symptomatic AF. 27 patients had recurrence of atrial AF: 7 permanent, 15 persistent and 5 paroxysmal AF. Predictive factors of recurrence of AF were: long standing persistent AF, large left atrial volume (> 205 mL), shorts AF cycle length (< 168 ms) and reduce LEVF (< 45%). Atrial tachycardia occurred in 5 patients (4,9%). Mechanisms of AT were: typical cavo-tricuspid flutter in one patient, peri-mitral flutter in 2 patients, and atrial focal tachycardia (close to pulmonary veins) in 2 patients.

. Conclusion: These results suggest that PVI with complementary RF ablation guided on low voltage areas is an efficient strategy for symptomatic persistent AF, and reduce the recurrence of AT following this ablation strategy.

[Long-term evaluation of endocavitary cryoablation of nodal reentry]

Radiofrequency ablation is the reference treatment of refractory nodal reentry. Cryoablation has the advantage of having more modulable effects and minimises the risk of permanent atrioventricular block (AVB). Its immediate efficacy seems comparable to that of radiofrequency ablation but the long-term results are not well known. Endocavitary cryoablation of the slow pathway was undertaken in 26 patients (18 women) with an average age of 47.7 +/- 72.8 years with re-entrant nodal tachycardia refractory to medical therapy. The primary success rate was 92% (24 out of 26). On average, 2.6 +/- 2.2 (1 to 10) cryoablations at - 70 degrees C were delivered and were preceded by 6.4 +/- 4.5 (1 to 16) cryomappings to locate the site of the slow pathway. During cryomapping, 8 episodes of AVB were observed in 6 patients (6 second or third degree), all of which were revertible on rewarming. No cases of permanent AVB were observed. An oesophageal stimulation test of inducibility was performed on the 4th day in 21 patients, 16 of which were not reinducible. During follow-up of 355 +/- 194 days, 22 of the 26 patients (85%) had no recurrence of the arrhythmia. Two of the 24 primary successes had a recurrence, in addition to the two primary failures. Two of the four recurrences occurred in a non-sustained form which was less disabilitating for the patient and the recurrences were controlled in the 4 patients by antiarrhythmic therapy. These results suggest that cryoablation may be a reliable and effective long-term treatment of re-entrant nodal tachycardias. If confirmed in larger series in terms of efficacy and safety, cryoablation could become the treatment of choice of re-entrant nodal tachycardia.

[Automobile driving and implantable defibrillators]

The consequences of implanting an automatic cardioverter defibrillator (ICD) on vehicle driving in France are poorly known. This retrospective study examined the behaviour at the wheel of ICD recipients who were recommended to abstain from driving for 3 to 6 months after device implantation. The study population included 98 patients (mean age = 59.5 +/- 14.8 years) followed for a mean of 24. +/- 23.9 months, who underwent ICD implant for ventricular tachycardia (65% of patients ventricular fibrillation (15%), syncope (8%), as part of a research protocol of myocardial cell transplantation 6%, or for primary prevention (5%). The underlying heart disease was ischemic in 59% of patients dilated cardiomyopathy in 11%,hypertrophic cardiomyopathy in 8%, valvular in 6%. Brugada syndrome in 4%, right ventricular arrhythmogenic cardiomyopathy in 2%, and miscellaneous disorders in 9% of patients. Five patients died without post mortem interrogation of the ICD. Only 28% of drivers remembered, and 13% observed, the recommended driving limitations. However, 45% (the oldest) claimed to drive prudently. During follow-up, 47% of patients received an ICD shock. Their mean it ventricular ejection fraction was 34 +/- 14%, versus 43 +/- 18% in patients who received no ICD therapy (p = 0.015). Syncope occurred in 16% who received ICD shocks. Shocks were delivered during driving in 6 patients, without consequent accident. Despite their non-observance of recommended driving limitations. ICD recipients suffered few traffic accidents. Legislation in France should reproduce the guidelines issued by European professional societies and enacted by the British laws.

[New energy sources for ablative methods]

Radiofrequency current is the reference energy source for endocavitary ablation of arrhythmias. It is particularly well adapted for the ablation of focal arrhythmogenic substrates such as accessory pathways or foyers of automatism. Technological advances have made the lesions larger but the extension of the indications of percutaneous ablation to more complex substrates such as atrial fibrillation have justified the evaluation of alternative energies. The production of linear transmural lesions or deeper lesions which respect the parietal myocardial architecture and endocardial structure are a challenge for these energies. The capacity of functional mapping specific to cryogenics has provided this energy source with a clinical application for ablation of high risk structures whereas other energies, despite the chronicity of their experimental evaluation, are still at the stage of preliminary clinical trials with the sophisticated catheters in special indications.

[1/1 nodo-ventricular conduction atrial flutter with amiodarone]

1/1 atrial flutter is a regularly described complication of class I anti-arrhythmics. It is, however, very rarely encountered with class III anti-arrhythmics because prolongation of the atrio-ventricular node refractory period prevents 1/1 nodo-ventricular conduction. There have only been seven cases of 1/1 atrial flutter with amiodarone reported in the literature. Here we describe a new case of 1/1 atrial flutter with amiodarone. Our case clearly illustrates not only the different pro-arrhythmic effects of amiodarone (prolongation of the flutter cycle, and infra-Hissian block) but also the pathophysiological mechanisms possible with 1/1 conduction (prolongation of the flutter cycle, considerable permeability of the AV node). It demonstrates the difficulties of diagnosing such a rhythm disturbance, and that it is sometimes poorly tolerated, as well as underlining the importance of early diagnosis (in this case by oesophageal recording). Preventive treatment of 1/1 flutter can include amiodarone, digitalis, a betablocker or a bradycardic calcium inhibitor.

[The choice of pacing sites: should we change our practice?]

For the past 45 years the sites used for elective pacing have been the apex of the right ventricle and the right atrium. Although the initial objective of pacing was the "simple" correction of a conduction disorder, a more recent evolution has been to achieve a favourable haemodynamic effect, considering left ventricular filling and synchronisation of ventricular contraction as essential. Demonstration of the benefit in terms of survival brought about by pacing in atrioventricular block has not required large trials. However, it is possible that this improvement in morbidity and mortality is in part offset by the altered haemodynamics due to pacing at the right ventricular apex. At the atrial level, the prevention of AF is the holy grail of atrial pacing, but is far from being attained, perhaps because the physiopathological bases are not clear and have not really been demonstrated, casting doubt on the final objective. The choice of pacing site is essential in this context, as much in the atrium as in the ventricle. The current problem regarding this choice is the same as for all medical treatment, where the risk/benefit ratio is evaluated: if the usual sites are potentially deleterious, is it possible to continue using them or is it necessary to change implantation practices, and what level of proof is needed?

[Prevention of recurrences of atrial fibrillation by cardiologists established in general office practice: data from the FAUVE observatory]

OBJECTIVES

Analyse the modalities of preventive therapy of recurrences of paroxysmal or persistent atrial fibrillation (AF) with Vaughan-Williams (VW) type IC antiarrhythmics.

METHODS

Observational study conducted with 326 French cardiologists established in general office practice, involving on the one hand an opinion survey among the cardiologists and on the other hand a cross-sectional observatory of usual medical practice. Each cardiologist was asked to include two patients aged less than 65 with non-permanent (paroxysmal or persistent) AF without left ventricle dysfunction (LVD) and initiated on treatment with a VW type IC antiarrhythmic after cardioversion to sinus rhythm.

RESULTS

The opinion survey among the cardiologists indicates that non-permanent AF constitutes 36.1% of AF cases, of which 57.8% concern LVD-free patients. Most cardiologists (85%) declare to institute a preventive therapy of AF recurrences in 70-100% of these patients after cardioversion to sinus rhythm, with a VW type IC antiarrhythmic in more than 50% of cases. Of the 633 patients included in the FAUVE observatory, mainly men, 409 (64.6%) had paroxysmal AF and 224 (35.4%) had persistent AF. Analysis of therapeutic management shows that both alteration of the previous treatment and the choice of a VW type IC antiarrhythmic are based chiefly on efficacy and on tolerability of the antiarrhythmic therapy.

CONCLUSION

VW type IC antiarrhythmics constitute a therapy of choice for the maintenance of sinus rhythm in non-aged and LVD-free patients with non-permanent AF.

[Predictive criteria of early recurrence of atrial arrhythmia after reduction by electrical cardioversion]

The management of atrial arrhythmias aims not only to restore sinus rhythm but also to maintain it. Ten to thirty per cent of patients have early recurrence of atrial arrhythmias, the treatment of which remains empiric. The aim of this study was to define factors predictive of early recurrence of atrial arrhythmias and the consequences on the length of hospital stay. A series of 131 patients who underwent reduction of atrial arrhythmias by electrical cardioversion was studied retrospectively. A recurrence within 24 hours was observed in 12.2% of the patients. These recurrences significantly increased the length of hospital stay (6.8+/-6.3 versus 3.6+/-3.8 days, p=0.005). This study confirms two previously reported results with respect to more long-term recurrences. In the "early recurrence" group, the duration of the atrial arrhythmia was longer (p=0.003) and there were fewer treatments with amiodarone (p=0.03). In addition, original results were obtained. In the "early recurrence" group, the patients were more often treated with furosemide (p=0.02), class Ic antiarrhythmics (p=0.007) or anaesthetised with thiopental (p=0.002) than patients without early recurrences. Experimental data explain these results. However, they require confirmation by a prospective randomised trial.

[External electrical cardioversion of atrial arrhythmia: predictive criteria of success]

AIM

Supraventricular arrhythmia is a major public health problem because of its prevalence and clinical consequences. The first step of the treatment usually consists in restoring sinusal rhythm. The aim of this study is to evaluate results and predictive factors of success of electrical cardioversion.

METHODS

We studied a series of 143 consecutive electric cardioversion preformed in 131 French patients.

RESULTS

The rate of successful direct current cardioversion was 91.2%. Negative predictive factors are the height body mass index and the age of arrhythmia. Atrial flutter is a predictive factor of success. These results agree with published results. Our study highlights the interest of some nonantiarrhythmic drugs received by the patient during the period before the direct current cardioversion. Thus, a spironolactone treatment appears to be a new predictive factor of the success of electrical cardioversion (success in patients treated with spironolactone: 100% vs 89% without, P = 0.04).

CONCLUSIONS

Our results agree with usual predictive factors of the success of cardioversion. Nevertheless, a new approach is that of the positive effect of spironolactone on cardioversion. A prospective randomized study is necessary to confirm this result.

[Electrophysiological remodeling induced by atrial fibrillation. An experimental curiosity or major factor in atrial fibrillation in man?]

Atrial fibrillation usually progresses from a paroxysmal to a permanent arrhythmia, even in the absence of underlying cardiac disease. The treatment is more difficult when the arrhythmia is chronic. This progression may be explained by the aggravation of underlying cardiac disease with time. Another explanation is that the arrhythmia induces functional and structural changes of the atrial tissues (remodelling) which promote the perpetuation of the arrhythmia and which make treatment less effective. Although the electrophysiological changes predisposing to atrial fibrillation have been known for over 15 years, it was only in 1995 that experimental studies showed the presence of atrial electrophysiological remodelling induced by the arrhythmia. This process of long term adaptation of the atrial myocytes to the tachycardia comprises marked changes of the parameters which sustain the arrhythmia: changes in refractory period (decreased duration, inadaptation to the heart rate, increased dispersion), reduced conduction speed and sinus dysfunction. Atrial remodelling also affects the contractile function by the structural changes. The calcium currents play a major role in its development. This mechanism has not yet been completely defined in the clinical setting and its importance in sustaining the arrhythmia has not been clearly evaluated. Atrial fibrillation remains one of the most difficult arrhythmias to treat. A better understanding of cellular mechanisms of remodelling could open up new therapeutic approaches to limit the natural history of the arrhythmia with progression to chronicity and structural changes responsible for the degradation of atrial contractility.

[Heart rate and mortality: review of the literature]

A great number of studies focussed on a wide variety of subjects have been concerned with the subject of morbi-mortality and the effect of heart rate. These studies show that there is a connection between high heart rate and arterial hypertension, and a significant coronary, cardiovascular, non-cardiovascular and overall mortality risk. Two explanations are possible for this. The increase in heart rate together with associated sympathetic hyperactivity can be considered a cardiovascular risk factor: or it could be viewed as an independent risk factor, associated with an increase in mechanical constraints.