Radiofrequency Ablation of Drivers of Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice, accounts for one-third of arrhythmia hospitalizations and is associated with an increased risk of stroke, heart failure, and all-cause mortality. Moreover, there is an increasing AF prevalence due to aging of the population, a rising prevalence of chronic heart disease, and increased survival. Unfortunately, medications aimed at suppressing AF and maintaining sinus rhythm or at controlling ventricular rate are only marginally effective and may cause serious adverse effects. The limitations of pharmacologic treatment patterns have fuelled the development of new interventional strategies. Current techniques of AF ablation can achieve a 60-80% improvement in highly selected patients with medically refractory AF. However, the procedure is not without risk, is long-lasting and recurrence rates are still high. Moreover, the results in persistent AF patients are far from optimal, require the creation of extensive atrial lesions and repeated procedures. The main reason that explains the current situation is the incomplete understanding of mechanisms underlying AF maintenance despite many years of research and speculation. The incremental value of ablation of high frequency sources following circumferential PV isolation has not been assessed. There is no prospective data available as to the safety and benefit of such a combined approach in patients with paroxysmal and persistent AF. Such information would be very important in helping guide the future direction of ablative therapy for AF as well as helping to answer important questions about the role of high frequency sites in persistent AF treatment.

Inclusion criteria

• Patients age 18 or older.
• Patients with paroxysmal AF symptomatic and refractory to at least one antiarrhythmic medication.
• In patients with paroxysmal AF, at least one episode of AF must have been documented by ECG or Holter within 12 months of randomization in the trial.
• Patients with persistent AF defined as a sustained episode that had been present for more than seven days without intervening spontaneous episodes of sinus rhythm and that recurred within seven days after cardioversion.
• Patients with persistent AF must be on continuous anticoagulation with warfarin (INR 2-3) for> 4 weeks prior to ablation. In patients with paroxysmal AF no continuous anticoagulation therapy with warfarin for > 4 weeks prior to ablation will be needed provided a transesophageal echocardiogram performed prior to ablation exclude the presence of thrombi or other abnormalities that discourage performing the procedure.
• Patients must be able and willing to provide written informed consent to participate in the clinical trial.

Exclusion criteria

• Patients with AF secondary to reversible causes.
• Patients with inadequate anticoagulation levels as defined in the inclusion criteria.
• Patients with left atrial thrombus, tumor, or another abnormality which precludes catheter introduction on TEE prior to the procedure.
• Patients with contraindications to systemic anticoagulation with heparin or coumadin.
• Patients who have previously undergone atrial fibrillation ablation, either by surgery or by percutaneous catheter.
• Patients with left atrial size > 55 mm.
• Patients who are or may potentially be pregnant.
• Patients with hyperthyroidism or hypothyroidism.
• Current enrollment in another investigational drug or device study.
• Pacemaker or Implantable Cardioverter Defibrillator.