Ablation Therapy of Type I Atrial Flutter May Eradicate Paroxysmal Atrial Fibrillation

Patients with typical right atrial flutter (AFL) may also have underlying atrial fibrillation (AF) or be at high risk of developing AF. Inducibility of AF among patients undergoing AFL ablation may be an important predictor of future occurrence of AF and may be useful in guiding management of this patient population.

This study aimed to determine whether inducibility of AF at the time of AFL ablation is independently associated with the risk of future AF.

Attempt at induction of AF by burst pacing was performed in consecutive patients who underwent AFL ablation. Time to incidence of AF after AFL ablation was examined using multivariable Cox proportional hazards models. All analyses were stratified by a history of AF.

A total of 175 patients were retrospectively evaluated over a median follow-up period of 482 days. In patients without a documented history of AF (n = 93), the incidence of AF after AFL ablation was 18.7 per 100 person-years. In these patients, inducible AF was strongly associated with the future development of AF (adjusted hazard ratio 15.99; 95% confidence interval 5.10–50.12). In contrast, in patients with a documented history of AF (n = 82), the incidence of AF after AFL ablation was 59.3 per 100 person-years and inducible AF was not associated with the future development of AF (adjusted hazard ratio 1.26; 95% confidence interval 0.74–2.14).

Inducibility of AF after AFL ablation is strongly and independently associated with the risk of future AF among patients without a history of AF but not among patients with a history of AF.

Similar predisposing factors are found in most types of atrial arrhythmias. The incidence of atrial fibrillation (AF) among patients with atrial flutter is high, suggesting similar outcomes in patients with those arrhythmias. We sought to investigate the long-term outcomes and prognostic factors of patients with AF and/or atrial flutter with contemporary management using radiofrequency ablation. In an academic institution, we retrospectively examined the clinical course of 8,962 consecutive patients admitted to our department with a diagnosis of AF and/or atrial flutter. After a median follow-up of 934 ± 1,134 days, 1,155 deaths and 715 stroke and/thromboembolic (TE) events were recorded. Patients with atrial flutter undergoing cavotricuspid isthmus ablation (n = 875, 37% with a history of AF) had a better survival rate than other patients (hazard ratio [HR] 0.35, 95% confidence interval [CI] 0.25 to 0.49, p <0.0001). Using Cox proportional hazards model and propensity score model, after adjustment for main other confounders, ablation for atrial flutter was significantly associated with a lower risk of all-cause mortality (HR 0.55, 95% CI 0.36 to 0.84, p = 0.006) and stroke and/or TE events (HR 0.53, 95% CI 0.30 to 0.92, p = 0.02). After ablation, there was no significant difference in the risk of TE between patients with a history of AF and those with atrial flutter alone (HR 0.83, 95% CI 0.41 to 1.67, p = 0.59). In conclusion, in patients with atrial tachyarrhythmias, those with atrial flutter with contemporary management who undergo cavotricuspid isthmus radiofrequency ablation independently have a lower risk of stroke and/or TE events and death of any cause, whether a history of AF is present or not.

The purpose of this study was to explore the mechanisms of conversion from atypical atrial flutter (AFL) to atrial fibrillation (AF), and the long-term results of cavotricuspid isthmus ablation in these patients. We retrospectively reviewed the records of 221 patients with typical AFL referred to our hospital for ablation. A total of 25 patients had atypical AFL, and cavotricuspid isthmus ablation was performed in 23 with isthmus-dependent atypical AFL, as well as in 180 patients with typical counterclockwise and/or clockwise AFL. In all, 13 spontaneous transitions from atypical AFL to AF were documented in 11 of 17 patients. Before AF, a pattern of lower loop reentry was observed in 11 of 13 patients (85%) and upper loop reentry in 3 (1 had both). Multiple early breaks along the tricuspid annulus during AFL were noted in 6 of 13 patients (46%). Among the 13 transitions, discrete atrial premature complexes before AF were found in 5 patients with lower loop reentry and in 1 with upper loop reentry (46%). In the remaining patients, a more rapid atrial rhythm was involved in the development of AF with a pulmonary venous focus in 2. In some cases, additional “breaks” in the functional line of block occurred before the development of AF. There was a significant increased incidence of AF (68%) in those with atypical AFL compared with those with typical AFL (38%) (p = 0.004). After a mean follow-up of 28 ± 9 months for the atypical group and 18 ± 11 months for the typical group, the AF recurrence rate was similar (57% vs 48%, p = 0.4). Discrete atrial premature complexes or atrial tachycardia may initiate AF either directly or by producing further breaks in lines of functional block. Bidirectional cavotricuspid isthmus block is associated with cure or control of AF in approximately 50% of patients with AFL.

Various nonpharmacologic interventions are available for patients with atrial fibrillation (AF) who are refractory to standard drug therapy. Atrioventricular junctional ablation and permanent pacing is a very effective therapy for patients with AF and a poorly controlled ventricular response. The surgical MAZE procedure has been performed on small numbers of patients but is remarkably successful in restoring and maintaining sinus rhythm. The role of permanent pacing as treatment for paroxysmal AF is undergoing evaluation and dual-site atrial pacing appears particularly promising in reducing the number of episodes of paroxysmal AF. Certainly the most exciting frontier in the treatment of AF is radiofrequency catheter ablation procedures. Our understanding of the mechanisms of paroxysmal AF and chronic AF has expanded enormously in the past 5 years. Radiofrequency lesions in pulmonary veins using standard technology will cure many cases of paroxysmal AF. However, catheter systems under development offer a great promise of treating most paroxysmal and chronic AF within the next few years. These developments will revolutionize our approach to this ever more prevalent clinical problem.