Dofetilide, a new class III antiarrhythmic agent, is moderately effective in cardioverting AF or AFl to SR and significantly effective in maintaining SR for 1 year. In-hospital initiation and dosage adjustment based on QTc and Cl(Cr) are necessary to minimize a small but nonnegligible proarrhythmic risk.

1) Radiofrequency energy applied to a critical area in the atrial flutter reentrant circuit, inferior or posterior to the coronary sinus ostium, will terminate and prevent arrhythmia reinduction. 2) Long-term follow-up in a larger series of patients will be required to confirm efficacy of this technique, although short-term results look promising.

Background— There has been growing concern that linear ablation is associated with an increased risk of iatrogenic arrhythmias in patients undergoing ablation for atrial fibrillation (AF). Therefore, we compared circumferential pulmonary vein ablation plus left atrial linear ablation (CPVA+LALA) with segmental pulmonary vein isolation (PVI)in patients with paroxysmal AF. Methods and Results— Sixty-six consecutive patients with paroxysmal AF were prospectively randomly assigned to receive PVI versus CPVA+LALA (consisting of encircling lesions around the pulmonary veins), a roof line, and a mitral isthmus line with documentation of bidirectional mitral isthmus block. All patients were seen at 1, 3, 6, and every 12 months after ablation, with 14-day continuous ECG monitoring every 6 months. At 16.4±6.3 months after 1 ablation procedure, 19 patients (58%) remained free of atrial arrhythmias after PVI versus 17 patients (51%) after CPVA+LALA ( P =0.62). After PVI, 14 patients had recurrent paroxysmal AF, whereas after CPVA+LALA, 8 patients had recurrent AF, 6 had atypical left atrial flutter (LAFL), and 2 had both AF and LAFL ( P =0.32 between PVI versus CPVA+LALA for AF but P =0.002 for LAFL). Twenty-eight patients (85%) remained arrhythmia-free after 1.3±0.5 PVI procedures versus 28 patients (85%) after 1.4±0.6 CPVA+LALA procedures ( P =NS). Fluoroscopy time was longer after CPVA+LALA versus PVI (91 versus 73 minutes, P =0.04). Conclusions— As an initial ablation approach in patients with paroxysmal AF, more LAFL occurred after CPVA+LALA and fluoroscopy times were longer compared with segmental PVI.

There is a close interrelationship between atrial fibrillation (AF) and atrial flutter (AFL). Atrial fibrillation of variable duration precedes the onset of AFL in almost all instances; during AF, the functional components needed to complete the AFL re-entrant circuit, principally a line of block (LoB) between the vena cavae, are formed; if this LoB does not form, classical AFL does not develop. In contrast, there seems to be a spectrum of atrial re-entrant circuits (drivers) of short cycle lengths (CLs) (i.e., AFL). When the CL of the AFL re-entrant circuit is so short that it will only activate portions of the atria in a 1:1 manner, the rest of the atria will be activated rapidly but irregularly (i.e., via fibrillatory conduction), resulting in AF. In short, there are probably several mechanisms of AF, 1 of which is due to a very rapid AFL causing fibrillatory conduction. All of these interactions of AF and AFL have important clinical implications.

HF-1 b, an SP1 -related transcription factor, is preferentially expressed in the cardiac conduction system and ventricular myocytes in the heart. Mice deficient for HF-1 b survive to term and exhibit normal cardiac structure and function but display sudden cardiac death and a complete penetrance of conduction system defects, including spontaneous ventricular tachycardia and a high incidence of AV block. Continuous electrocardiographic recordings clearly documented cardiac arrhythmogenesis as the cause of death. Single-cell analysis revealed an anatomic substrate for arrhythmogenesis, including a decrease and mislocalization of connexins and a marked increase in action potential heterogeneity. Two independent markers reveal defects in the formation of ventricular Purkinje fibers. These studies identify a novel genetic pathway for sudden cardiac death via defects in the transition between ventricular and conduction system cell lineages.

Rate control in AF is possible in the majority of patients with AF. Beta-blockers were the most effective drugs. To achieve the goal of adequate rate control in all patients, frequent medication changes and drug combinations were needed.

Background-Left atrial linear ablation for atrial fibrillation (AF) may be proarrhythmic, leading to left atrial macro-reentrant tachycardia (LAT). Whether due to failure to achieve block initially or to recovery of conduction after ablation is unknown. This study was designed to evaluate the frequency of recovery of mitral isthmus (MI) conduction compared with cavo-tricuspid isthmus (CTI) conduction, and the relationship between recovery of MI conduction and postablation LAT. Methods and Results-Of 163 patients with AF who underwent circumferential pulmonary vein ablation plus left atrial linear ablation, in whom MI and CTI ablation produced bidirectional conduction block, 52 underwent repeat ablation for recurrent atrial arrhythmias (AF or LAT). Of these 52 patients, coronary sinus ablation was required in 48 to achieve bidirectional MI block at the index ablation. During repeat ablation, MI and CTI conduction was assessed in sinus rhythm. At repeat ablation, MI conduction had recovered in 38 of 52 patients, as compared with CTI conduction which recovered in only 12 of 52 patients (Pϭ0.001). At repeat ablation, the recurrent clinical arrhythmia in 12 patients was MI-dependent LAT. Recovery of MI conduction was associated with development of MI-dependent LAT (Pϭ0.01). Conclusions-Despite using bidirectional conduction block as a procedural end point, recovery of MI conduction is common and may lead to LAT after left atrial linear ablation for AF. The reason for greater recovery of MI versus CTI conduction is unknown but could be due to differences in isthmus anatomy or lower power used for ablation in the left versus right atrium. (Circ Arrhythm Electrophysiol. 2011;4:832-837.)

Introduction Most trials evaluating the efficacy of atrial fibrillation ablation report follow-up periods of 1–2 years. Long term results (> 5 years) following segmental pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) are largely unreported. Objective To evaluate the long-term efficacy of segmental PVI for the treatment of symptomatic, medically refractory, PAF. Methods Patients with paroxysmal atrial fibrillation who underwent pulmonary vein isolation at the University of California, San Diego Medical Center were evaluated retrospectively to determine the outcome of the index procedure. Of one hundred and eighteen segmental pulmonary vein isolation procedures preformed at UCSD Medical Center between January 1, 2002 and August 31, 2003, seventy-one patients who had long-term follow-up data were included. The five year outcomes were determined by last clinic encounter and telephone encounter at or after five years from the index procedure. Patients had routine clinic visits with EKGs and underwent cardiac monitoring for any complaints of symptoms suggestive of recurrent arrhythmia. Results Seventy-one patients (60±10 years, 56 male) were followed for > 5 years. After one procedure, with 12 months of follow up, sixty-one (86%) of patients were free from symptomatic atrial fibrillation (AF). After 24 months, fifty-six (79%) of patients remained free of AF. At the end of a follow up period of 63±5 months, only forty patients (56%) remained free from symptomatic atrial fibrillation after one procedure. In sixteen patients (22.5%), atrial fibrillation recurred after the second year post-ablation, with four patients recurring during the third year, four patients during the fourth year, and eight patients having their first recurrence of atrial fibrillation greater than 48 months after their index ablation procedure. Thirty-one patients underwent more than one ablation procedure (average 1.9±0.9 procedures per patient). After multiple procedures, sixty patients (84%) were arrhythmia free off medication at 63±5 months after their initial procedure. In patients who underwent more than one ablation procedure, the mean duration of follow up after the last ablation procedure was 7.5±2.1 months. Conclusions Overall five-year outcomes after segmental PVI for PAF are consistent with previously reported shorter term follow-up (≤ 2 years); however, late recurrences (>2 years) after a successful initial ablation procedure are not infrequent, and repeat ablation procedures are often required to maintain freedom from symptomatic arrhythmias. Continued long-term follow-up of patients with PAF after initially successful ablation may be warranted, especially in those patients in whom anticoagulation is discontinued.