Results
Prevalence and Variables Associated With AF History in Patients Admitted for AFL Ablation
A total of 356 patients (31.8%) were diagnosed with at least 1 episode of sustained AF (>1 minute) before AFL ablation (Table 1).
The characteristics of patients with and without AF history prior to AFL ablation were compared (n = 765, 68.2%). Patients with and without previously diagnosed AF had similar ages (65 ± 11 vs. 64 ± 12 years). In univariable analysis, patients with previously diagnosed AF were more likely to be female (27.8% vs. 21.6%), and less likely to have chronic lung disease (3.7% vs. 11.0%) or an associated HD (40.7% vs. 49.9%), especially congenital HD (1.7% vs. 4.8%). Patients with previously diagnosed AF were more likely to be treated with a class I AAD (45.5% vs. 7.7%), either isolated or associated with beta-blockers (data not shown), and more likely tended to be treated with amiodarone (36.5% vs. 31.2%, P = 0.08).
The multivariable analysis indicated that female gender was associated with a higher risk of AF history prior to AFL ablation (OR = 1.35, CI = 1.00–1.83, P = 0.05), and that chronic lung disease, congenital HD, and ischemic HD (OR = 0.27, CI = 0.15–0.50, P < 0.001; OR = 0.27, CI = 0.11–0.67, P = 0.01; and OR = 0.63, CI = 0.43–0.92, P = 0.02, respectively) were all independently associated with a lower risk of AF history (Table 1).
Risk of Events and Electrophysiological Data in Patients with and without AF History Prior to AFL Ablation
Patients with AF history were more likely to have at least 1 episode of 1/1 AFL (10.4% vs. 7%; P < 0.03) or to suffer from a major complication following AFL ablation (2.8% vs. 0.8%; P = 0.01). However, after adjustment on age, gender, and antiarrhythmic treatments, AF history was not significantly associated with 1/1 AFL (OR = 1.13, CI = 0.64–2.01, P = 0.67). In contrast, after a backward selection of variables significantly associated with major complications, AF history was retained as an independent predictor of major complication (OR = 3.64, CI = 1.29–10.26, P = 0.02).
AFL ablation failure was as frequent in patients with and without AF history (38/356, 10.7% vs. 81/765, 10.6%). AFL ablation failures were due to the development of AF or left atrial tachycardia in 50 patients, which occurred mostly after the interruption of AFL. Arrhythmia was induced by atrial pacing used to control isthmus block in 35 of them and was spontaneous in 15. Ablation was interrupted in 4 patients for intense drug-resistant chest pain and in 2 patients for complete AV block. In the remaining 63 patients, complete isthmus block could not be obtained.
Patients with AF history had a similar risk of cardiac death and pacemaker implantation during follow-up than patients without AF history but were at greater risk of AF episodes (31.5% vs. 19.3%, P < 0.001).
Factors Associated With AF Occurrence After AFL Ablation in the Entire Study Population
In univariable analysis, AF history and female gender were the only significant predictors of AF occurrence (Table 2). In the multivariable model, AF history prior to ablation (OR = 1.90, CI = 1.42–2.54, P < 0.001) and female gender (OR = 1.77, CI = 1.29–2.42, P < 0.001) were significantly associated with a higher risk of AF occurrence after ablation independently of age (Table 2).
Factors Associated With AF Occurrence After AFL Ablation in Patients With and without AF History Prior to AFL Ablation
In patients without prior AF, class I AAD and amiodarone were systematically stopped after ablation. We consequently studied the association between AAD taken prior to ablation and AF recurrence. Patients who experienced AF during follow-up were more likely to have taken class I AAD (12.2% vs. 6.6%, P = 0.02, data not shown) or amiodarone (37.8% vs. 29.7%, P = 0.05) prior to AFL ablation in comparison with patients who had no AF occurrence during follow-up. Beta-blockers either prior to or after AFL ablation were not associated with AF occurrence during follow-up (both P > 0.6, data not shown).
In multivariable analysis (Table 3), class I AAD and amiodarone prior to ablation were independently associated with a higher risk of AF after ablation (OR = 2.11, CI = 1.15–3.88, P = 0.02 and OR = 1.60, CI = 1.08–2.36, P = 0.02, respectively). Female gender was also an independent factor of risk of AF (OR 1.93, CI = 1.29–2.89, P = 0.0001).
Among patients with a history of AF prior to AFL ablation, age was the only independent predictor of AF occurrence after ablation (OR = 0.97, CI = 0.95–0.99, P = 0.01). Female gender tended to be associated with higher risk of AF recurrence (OR = 1.53, CI = 0.93–2.54, P = 0.09) in the multivariable model.
Embolic Risk of Patients After AFL Ablation
Age >65, female gender, and hypertension were frequent both in the whole population and in patients with AF occurrence after ablation (Table 4). In these 2 groups, more than half of the patients had a CHADS score ≥1 and most patients had a CHA2DS2-VASc score ≥1 (Table 4). CHA2DS2-VASc score of patients with and without AF occurrence after AFL ablation was similar (1.47 ± 1.17 vs. 1.46 ± 1.18, P = 0.99 and CHA2DS2-VASc ≥1 in 77.3% vs. 75.9%, P = 0.65). A total of 171 patients with AF prior to AFL ablation had a CHA2DS2-VASc score ≥2 (15.3% of the complete population).
During follow-up, 2 strokes occurred in patients with AF history (0.6%) and none occurred in patients without AF history. These 2 patients were not treated by anticoagulants at the time of this complication despite atrial tachycardia or AF recurrence was documented in both patients prior to stroke occurrence. In these patients, anticoagulants were stopped because of poor compliance in spite of CHADS scores equal to 2 in both patients. Of note, only 170 patients with AF history at the time of AFL ablation had a CHA2DS2-VASc score ≥2. Consequently, in this subset of patients, 2/170 patients had a stroke during the follow-up (1.2%).
In addition to these permanent cerebrovascular accidents, a transient ischemic attack occurred soon after AFL ablation in a 44-year-old man referred for a spontaneous 1:1 AFL. The patient returned in sinus rhythm after amiodarone treatment but was treated by anticoagulants for only 2 weeks before AFL ablation.
Management of AF After AFL Ablation
AF remained paroxysmal in most patients (225/260, 86.5%). AF was initially persistent in 35 patients (13.5%) and became permanent during follow-up in 92 patients (35.4%). Among the 260 patients with AF after AFL ablation, 18 patients required electric cardioversion (6.9%), 38 patients required AF ablation (14.6%), and 18 older patients (6.9%) required the implantation of a pacemaker associated with a latter His bundle ablation. Remaining patients were treated by AAD (n = 169, 65.0%) or only beta-blockers (n = 17, 6.5%). Pacemaker implantation was further indicated in 38 (14.6%) of these patients to use AAD without adverse events.