Management of patients with atrial fibrillation: different therapeutic options and role of electrophysiology-guided approaches.

At present the approach to atrial fibrillation treatment is based on the electrophysiological patterns of atrial fibrillation (on the basis of multiple intra-atrial recordings or sophisticated new mapping techniques) only in a restricted minority of patients, those who are candidate to ablation of the substrate and/or of the triggers. Atrial fibrillation has a broad spectrum of clinical presentations and a heterogeneous electrophysiological pattern. The treatment of this arrhythmia, both with drugs and non pharmacological treatments, has been based, classically, on empirical basis and on a clinically-guided staged-approach. The limitations of pharmacological treatment led in recent years to the development of a wide spectrum of non pharmacological treatments. This implies a change in the approach to atrial fibrillation and the need to identify potentially ideal candidates to complex and expensive treatments. In this view it is currently under investigation the possibility to identify potential responders to a definitive treatment or a combination of treatments (both pharmacological and non-pharmacological) on the basis of the electrophysiological pattern

Transvenous low energy internal cardioversion for atrial fibrillation: A review of clinical applications and future developments

Low energy internal atrial cardioversion can be performed by delivering biphasic shocks between transvenous catheters positioned within the cardiac chambers or great vessels. Delivery of shocks results in effective cardioversion at energies < 6-10 J and the procedure can be effective even when external cardioversion has failed. Shock induced discomfort varies from patient to patient, but the procedure can be usually performed without general anesthesia and eventually under mild sedation. Nevertheless, tolerability has to be improved by obtaining a substantial reduction in defibrillating thresholds. With regard to safety, delivery of shocks for defibrillating the atria implies a potential risk of inducing ventricular fibrillation; to minimize this risk, shock delivery must be synchronous to the QRS and should be avoided during rapid RR cycles (< 300 ms). Presently, transvenous low energy cardioversion is an investigational procedure, but a widening of indications is expected in the near future. The cost of the procedure, which remains invasive and requires a brief hospital stay must be balanced with the benefit of restoring sinus rhythm and the possibility of maintaining sinus rhythm for the medium- to long-term. Experimental and clinical investigations of low energy internal cardioversion have resulted in the development of devices for atrial defibrillation whose clinical role and cost-benefit ratio is currently under evaluation

Internal atrial cardioversion in atrial fibrillation

N/

Cardioverter-defibrillators after MADIT-II: the balance between weight of evidence and treatment costs.

The possibility of using implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden death in selected high-risk patients has prompted a series of prospective controlled studies. Recently, the MADIT II study highlighted the possibility of effective primary prevention of sudden death in patients with coronary artery disease selected by straightforward clinical data and without expensive screening (electrophysiological study). For patients with previous myocardial infarction and low left ventricular ejection fraction (</=30%), ICD implantation may reduce mortality risk by approximately 31% in the following 2 years. Implementation of this therapeutic strategy threatens to impact on public health-care spending. Possible cost-limiting mechanisms include price cuts because of increasing usage (market forces); identification of subgroups at higher risk of sudden death and use of cheaper devices with limited diagnostic and therapeutic options. Further long-term evaluation of the cost-effectiveness and cost-utility of ICDs should identify subgroups of patients for whom implantation is affordable despite current economic constraints. For heart failure patients, randomized controlled trials are currently evaluating the effects on overall survival of both conventional ICDs and devices with biventricular pacing capabilities. In this perspective, data from the COMPANION trial are expected to stimulate the use of devices with defibrillation back-up in candidates for biventricular pacing

Predictors of atrial defibrillation threshold in internal cardioversion

This study examined the clinical, echocardiographic, and electrophysiological factors influencing the atrial defibrillation threshold (ADFT) in patients with chronic, persistent AF undergoing transvenous, low energy, atrial cardioversion. Twenty-two patients (age 57 +/- 15 years) with a mean AF duration of 7.8 +/- 7.1 months (range 2-32 months) underwent internal cardioversion with catheters placed in the right atrium and coronary sinus. Biphasic shocks (3/3 ms) were delivered in a step-up protocol. ADFT was defined as the lowest energy shock that converted AF to sinus rhythm. All patients were successfully cardioverted at a mean ADFT of 5.62 +/- 2.82 J (range 2.6-12.9 J). Fifteen variables, including clinical characteristics (age, body mass index, AF duration, etiology), echocardiographic measurements (atrial diameter and volumes, interdexes of ventricular performance), hemodynamic measurements, and mean atrial cycle during AF were analyzed as possible predictors of ADFT. in univariate regression analysis, AF duration, mean RR interval, and cardiac index correlated with ADFT. In multivariate regression analysis, AF duration remained as the only significant predictor of ADFT (B coefficient 0.311, P < 0.002; 95% confidence interval [CI] 0.194-0.427). AF duration was the most powerful predictor of ADFT. It should be considered when planning internal CV of AF to limit the number of shocks delivered. Furthermore, long intervals between AF onset and CV should be avoided

Increase in QT/QTc dispersion after low energy cardioversion of chronic persistent atrial fibrillation.

The effects of atrial internal cardioversion on QT interval and QT dispersion (parameters associated with increased risk of ventricular tachyarrhythmias) are unknown. We investigated changes in QT interval, QTc and QT dispersion immediately after shock delivery for internal cardioversion in patients with chronic persistent atrial fibrillation

Efficacy of internal cardioversion for chronic atrial fibrillation in patients with and without left ventricular dysfunction.

Internal cardioversion can restore sinus rhythm with energies below 6-10 J, often without anaesthesia/sedation. We investigated its safety and short-/medium-term efficacy in patients with persistent atrial fibrillation (AF) with left ventricular dysfunction (defined as ejection fraction < or = 40%). Among 34 patients with persistent AF who agreed to receive internal cardioversion, 16 had left ventricular dysfunction and 18 did not (the groups were similar as regards age, duration of AF and pretreatment with amiodarone). Internal CV was performed delivering 3.0/3.0-ms biphasic shocks between coil catheters using a step-up protocol. Sinus rhythm was always restored. General anaesthesia (administered only when discomfort was not tolerated) was required only in 2 of the 16 (12.5%) patients with left ventricular dysfunction. The defibrillation threshold was similar in patients with and without left ventricular dysfunction (10.2+/-6.9 vs. 8.4+/-4.9 J; p=0.37). Short-term (within 72 h) AF recurrence rates in the presence and absence of left ventricular dysfunction were 19% (3/16) and 6% (1/18), respectively (p=0.51). After cardioversion, all patients received antiarrhythmic drugs (mostly amiodarone in patients with left ventricular dysfunction and class IC agents in the remainder). With mean follow-up periods of about 220 days, AF recurrence rates among patients with and without left ventricular dysfunction were 50% (8/16) and 28% (5/18), respectively (p=0.328). We conclude that even in patients with left ventricular dysfunction, internal CV is safe and effective, minimizing risks from anaesthesia. Although these patients may have a higher risk of short- or medium-term AF recurrence, 6-month maintenance of sinus rhythm is possible in about 50% of cases