The Study Of Ablation Strategy For The Treatment Of Paroxysmal Atrial Fibrillation

Part I:Prospective randomized Comparative study of Pulmonary Vein Antrum Isolation versus Complex Fractionated Electrogram Ablation for Paroxysmal Atrial Fibrillation Introduction: There are two mayor ablation strategies for paroxysmal atrial fibrillation (PAF), one is pulmonary vein antrum isolation, the other one is mapping and ablation of complex fractionated electrogram (CFE). However, no randomized study comparing the clinical efficacy of PV antrum isolation ablation versus CFEs ablation as a primary strategy in patients with paroxysmal AF has been performed.Methods: We prospectively studied 118 patients (79 men, age 56.0±11.2 years) with symptomatic paroxysmal AF who underwent circumferential antrum PV isolation or CFE ablation. Patients were then randomly assigned to CFE ablation group and PV antrum isolation group (PVAI) after atrial fibrillation being induced. Patients with inducible AF followed the first step, will cross over the other ablation strategy. Patients who only had CFE ablation with subsequent AF noninducibility were classified into group one (G1), and those with single PVAI which rendered AF noninducible were classified into group two (G2). Cross-over patients who had both ablation strategies were assigned to group three (G3).Results: All the study patients were randomly assigned to CFE group (58 patients) and PVAI group (60 patients). There was no difference in baseline characteristics including age, gender, left atrial diameter, ejection fraction, structural heart disease and history of AF between both groups. AF became non-inducible in 24 patients (41%) after CFE ablation (G1), which included 2 patients with mitral isthmus dependent flutter, 1 with anterior wall focal AT and 2 with cavo-tricuspid isthmus dependent flutter developed during defragmentation ablation. These ATs were later successfully eliminated by ablation in the same procedure. The remaining 34 patients were cross-over to PVAI and rendered AF non-inducible in 20 patients. Additional cavo-tricuspid isthmus ablation was done in three patients. 14 patients still had inducible AF and one patient need DC cardioversion because of AF persistency. PVAI was successful in 60 patients except one due to cardiac temponade. AF was non-inducible in 35 patients (59%) after PVAI (G2). The acute incidence of AF noninducibility after single PVAI was much higher than that after single CFE ablation (59% vs. 41%, P=0.052). The remaining 24 patients had additional CFE ablation and rendered AF non-inducible in 16 patients. Additional cavo-tricuspid isthmus ablation was done in 9 patients because of clinical atrial flutter documentation or occurrence during the procedure. A focal AT arising from left anterior septal developed during CFE ablation and was successfully ablated. Left accessory pathway was found in one patient and was abolished. After a mean follow up of 22.6±6.4 months, the total success rate of CFE group is much lower than that of PVAI group (57% vs. 73%, P=0.075). Further subgroup analysis revealed that the proportion of AF recurrence patients in G2 is the highest (17.1%), followed by G1 (12.5%), G3 is the lowest (8.6%), but the statistically difference has not been reached (P=0.469). Post ablation AT occurred very commonly in patients who received CFE ablation, with the rate of 50% (12/24) in G1, 22% (13/58) in G3, but only 6% (2/35) in G1 (P<0.001). This makes the total success rate of G1 (38%) dramatically lower than that of G2 (77%)( P=0.002) and G3 (69%) unexpectedly lower than G2 (P=0.395). As to those highly selected patients in G3 who had noninducible AF (S1) and those who still had inducible AF (S2) after ablation, the follow up result of AF free proportion, AT occurrence and total success rate shows no significant difference Conclusions: Our findings suggest that PVAI, rather than CFE should be the initial ablation approach in patients with paroxysmal AF due to higher ocurrence rate of AT after CFE ablation. Part II: Prevalence and Long-term Clinical Implication of the Dissociated Pulmonary Vein Activities after Pulmonary Vein antrum Isolation in Patients with Paroxysmal Atrial FibrillationIntroduction: Dissociated pulmonary vein (PV) electrical activities were frequently observed after PV ablation for paroxysmal atrial fibrillation (AF). However, the incidence and clinical implication of dissociated PV electrical activities after circumferential PV antrum isolation remains unclear.Methods and Results: We prospectively studied 196 patients with symptomatic paroxysmal AF who underwent circumferential PV antrum isolation. Dissociated PV electrical activities was observed in 101 patients (51.5%, Group 1), but absence in the remaining 95 patients (48.5%, Group 2). There were no significant differences in the baseline clinical characteristics between them, except that Group 2 patients had a higher prevalence of hypertension (30 vs. 44%, P=0.04). After 15.8±7.9 months of follow-up, 148 (76%) had no recurrence of AF after the initial ablation procedure. AF recurrence rate was significantly higher in Group 2 patients than in Group 1 patients (Hazard Ratio 1.90, 95% confidence interval 1.10-3.56, P=0.023). Relapse of PV conduction was the major cause of AF recurrence in both groups (16/16 vs. 19/23, P=0.08), and the overall procedural success rate after the redo ablation procedure was similar in two groups (90% vs. 86%, P=0.44). However, the total number of patients with non-PV foci was significantly higher in Group 2 patients than in Group 1 (12/95 vs. 2/101, P<0.01).Conclusions: Dissociated PV electrical activities were observed in 52% of patients after ablation for paroxysmal AF, which may identify a subgroup of patients with PV foci as dominant mechanism of AF and higher initial procedural success with circumferential PV antrum isolation procedure. Part III:The follow-up study of sinus node function after catheter ablation of paroxysmal atrial fibrillation with prolonged sinus pauses Purpose To follow-up the sinus node function and long-term clinical outcome in patients with prolonged sinus pauses after termination of atrial fibrillation who underwent catheter ablation of paroxysmal atrial fibrillation(PAF)and to further discuss its probable mechanisms.Methods Eighteen patients(12 men; mean age 56.8±11.7 years, range 37～72 years) with PAF and prolonged sinus pauses(≥3 seconds) after termination of atrial fibrillation were included in this study. The mean PAF history of the study patients was 69.7±72.1months(range2～276)months. Circumferential PV antrum isolation was first performed guided by 3-D mapping system and the circulan catheter; then aggressive high right atrium programmed stimulation and burst pacing were done both before and after isoproterenol infusion. If other triggered foci could be found or other sustained tachycardias could be induced, additional ablation should be performed at these particular areas. Sinus node function was assessed the first week , 1, 3, and 6 months post ablation, by 24-hour ambulatory monitoring.Results Eleven patients had a sigle ablation procedure. 5 had redo procedure and 2 had ablation for 3 times. During the first procedure, typical atrial flutter was induced in three patients, and cavotricuspid isthmus bidirectional block was achieved by linear lesions, a vagal response was observed in 3 patients. One non-PV triggers of AF was found at the posterior left atrium in one patients during the third session. Three recurrent cases refused to accept the second procedure. Among then, one requiring pacemaker implantation, 1 had asymptomatic with the AF, and the remaining one had a history of pacemaker implantation. the mean follow-up time was 22.1±7.5months. 15 patients had no recurrence of AF, with no symptoms attributable to bradycardia or sinus pauses on ambulatory monitoring After the last ablation session. heart rate variability attenuation was detectable for up to 3 month, and returned to preablation levels at 6 months in12 patients which suitable for the analysis.Conclusions Atrial fibrillation may suppress the sinus node function, which manifests prolonged sinus pauses post paroxysmal atrial fibrillation termination. But this surppression can be eliminated by curative ablation of AF. This is accompanied by improvement in parameters of sinus node function, suggesting the reversible electrical remodeling of the sinus node.