Frontier of catheter ablation for atrial fibrillation

The sudden evolution of catheter ablation (CA) therapy for atrial fibrillation (AF) was brought by the discovery of a new insight into the triggering mechanism of AF by Haïssaguerre et al. in 1998. This discovery opened a new era of evolution of ablation therapy of paroxysmal AF (PAF). At the frontier of AF ablation, technical development of CA for long-standing persistent AF (CAF) has been done enthusiastically, although the detailed electrophysiologic mechanism and anatomical substrate of persistent AF remain unknown. Stepwise ablation composed of multiple procedures, circumferential pulmonary vein isolation (PVI), biatrial defragmentation, and anatomical linear ablation with the endpoint of AF termination has been the most widely accepted method, because the efficacy of this method was reported to be surprisingly high during a relatively short duration of follow-up. Recently, they showed this strategy has a significant limitation in efficacy for CAF with long AF duration (>7 years), enlarged left atrium (>50 mm in left anterior descending artery), short AF cycle length (AFCL) (<130 ms) and impaired cardiac function. For cases associated with these clinical, anatomical, and electrophysiological parameters, AF termination as an endpoint might be abandoned if peak prolongation of AFCL, reduction of intra-/inter-atrial AFCL gradient, and low defibrillation threshold are attained after predetermined lesion set is completed. Prolonged procedure with massive tissue ablation to attain AF termination should be avoided, because it potentially increases adverse events during and immediately after the procedure and causes extensive scar-formation in both atria with atrial mechanical dysfunction.     

Approach to the catheter ablation technique of paroxysmal and persistent atrial fibrillation: a meta-analysis of the randomized controlled trials

Review of the Catheter Ablation Technique in AF. Background: Several randomized controlled trials (RCTs) have been published to investigate the optimal techniques for atrial fibrillation (AF) ablation. Many of these are small in number and include both paroxysmal and persistent AF; however, the techniques for each of these types of AF may differ. Method and Results: We searched MEDLINE, EMBASE, and the Cochrane Controlled Trials Register for RCTs evaluating AF ablation for either paroxysmal or persistent AF. The primary endpoint was freedom from AF after a single procedure. A total of 35 unique randomized controlled trials were found to fulfill the criteria. A significant degree of heterogeneity was present given the differing sample sizes, populations studied, and outcomes. Radiofrequency ablation (RFA) was found to be favorable in prevention of AF over antiarrhythmic drugs (AADs) in either paroxysmal (5 studies, RR 2.26; 95% CI 1.74, 2.94) or persistent AF (5 studies, RR 3.20; 95% CI 1.29, 8.41). When comparing specific techniques, wide‐area PVI appeared to offer the most benefit for both paroxysmal (6 studies, RR 0.78; 95% CI 0.63, 0.97) and persistent AF (3 studies, RR 0.64; 95% CI 0.43, 0.94). CFE ablation provided only benefit for persistent AF when combined with antral PVI (4 studies, RR 0.55; 95% CI 0.34, 0.87). Conclusions: Despite significant methodological limitations, it appears that additional ablations beyond PVI are necessary for persistent AF but not proven for paroxysmal AF. The optimal technique for persistent AF, however, deserves a further study, in the setting of a large, randomized controlled trial . (J Cardiovasc Electrophysiol, Vol. 22, pp. 729‐738, July 2011)     

Incidence of asymptomatic cerebral microthromboembolism after atrial fibrillation ablation guided by complex fractionated atrial electrogram

Cerebral Microthromboembolism After CFAE Ablation . Background: The incidence of cerebral thromboembolism after pulmonary vein isolation (PVI) ranges from 2% to 14%. This study investigated the incidence of cerebral thromboembolism after complex fractionated atrial electrogram (CFAE) ablation with or without PVI. Methods: One hundred consecutive atrial fibrillation (AF) patients (50 paroxysmal and 50 persistent, including 10 longstanding) who underwent CFAE ablation combined with (n = 41, PVI+CFAE group) or without (n = 59, CFAE group) PVI were studied. Coronary angiography (CAG) was conducted with AF ablation in 5 cases in which coronary artery stenosis was suspected on 3D‐computed tomography. PVI was performed before CFAE ablation without circular catheter during AF. After termination of AF, additional ablation was performed to complete PVI with a circular catheter. All patients underwent cerebral magnetic resonance imaging (MRI) including diffusion‐weighted MRI and T2‐weighted MRI the day after ablation. Results: New thromboembolism was detected in 7.0%, and there was no significant difference between the 2 strategies (7.3% in PVI+CFAE group, 6.8% in CFAE group). CHADS2 score (1.6 ± 1.0 vs 0.8 ± 0.9, P < 0.05), left atrial volume (LAV; 83.8 ± 27.1 vs 67.8 ± 21.8, P < 0.05), and left ventricular ejection fraction (LVEF, 53.1 ± 9.2 vs 65.1 ± 9.7, P < 0.01) were significantly different when comparing patients with or without thromboembolism. In multivariate analysis, LVEF (odds ratio [OR], 0.92; 95% confidence interval [CI], 0.84–0.99; P < 0.05) and concomitant CAG (OR 18.82; 95% CI, 1.77–200.00; P < 0.05) were important predictors of new cerebral thromboembolism. Conclusions: The incidence of cerebral microthromboembolism after CFAE ablation was not greater than previous reports in PVI. Cautious management is required during AF ablation, especially in the patients with low LVEF. (J Cardiovasc Electrophysiol, Vol. 23, pp. 567–573, June 2012)     

Left atrial flutter after radiofrequency catheter ablation of focal atrial fibrillation

We report an arrhythmic complication in two patients in whom a procedure directed at isolating one or two pulmonary veins had been performed. The complication was related to pulmonary vein disconnection scars after ablation. Both patients developed new clinical tachycardia (atypical atrial flutter) secondary to a reentrant phenomena in the vicinity of a previously ablated pulmonary vein.     

The efficacy of high-power short-duration radiofrequency for atrial fibrillation ablation: A protocol for systematic review and meta-analysis

Background:Studies comparing data between the high-power short-duration radiofrequency (HPSR) and low power longer duration therapy were limited and inconsistent. Therefore, we conduct a high-quality systematic review and meta-analysis to assess the efficacy and safety of HPSR on outcomes for patients with atrial fibrillation (AF).Methods:The online literature is searched using the following combination of medical subject heading terms: “high-power” OR “high power” AND “radiofrequency” AND “atrial fibrillation.” MEDLINE (PubMed), EMBASE (OVID), Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science (ISI database) will be searched without any language restrictions. All clinical trials to assess the efficacy and safety of HPSR in the treatment of atrial fibrillation will be considered eligible for analysis. The present study will be performed by Review Manager Software (RevMan Version 5.3, The Cochrane Collaboration, Copenhagen, Denmark). Ethical approval and patient consent are not required because this study is a literature-based study.Results:This study expects to provide credible and scientific evidence for the efficacy and safety of HPSR on outcomes for patients with AF.Registration number:10.17605/OSF.IO/WAEBN.     

Ablation of perimitral flutter following catheter ablation of atrial fibrillation: impact on outcomes from a randomized study (PROPOSE)

MVI Block vs Trigger Ablation in PMFL . Introduction: Patients with previous ablation for atrial fibrillation (AF) may experience recurrence of perimitral flutter (PMFL). These arrhythmias are usually triggered from sources that may also induce AF. This study aims at determining whether ablation of triggers or completing mitral valve isthmus (MVI) block prevents more arrhythmia recurrences. Methods and Results: Sixty‐five patients with recurrent PMFL after initial ablation of long standing persistent AF were included in this study. Thirty‐two patients were randomized to MVI ablation only (Group 1) and 33 were randomized to cardioversion and repeat pulmonary vein (PV) isolation plus ablation of non‐PV triggers (Group 2). MVI bidirectional block was achieved in all but 1 patient from Group 1. In Group 2, reconnection of 17 PVs was detected in 14 patients (42%). With isoproterenol challenge, 44 non‐PV trigger sites were identified in 28 patients (85%, 1.57 sites per patient). At 18‐month follow‐up, 27 patients (84%) from Group 1 had recurrent atrial tachyarrhythmias, of whom 15 remained on antiarrhythmic drug (AAD); however, 28 patients from Group 2 (85%, P < 0.0001 vs Group 1) were free from arrhythmia off AAD. The ablation strategy used in Group 2 was associated with a lower risk of recurrence (hazard ratio = 0.10, 95% CI 0.04–0.28, P < 0.001) and an improved arrhythmia‐free survival (log rank P < 0.0001). Conclusion: In patients presenting with PMFL after ablation for longstanding persistent AF, MVI block had limited impact on arrhythmia recurrence. On the other hand, elimination of all PV and non‐PV triggers achieved higher freedom from atrial arrhythmias at follow‐up. (J Cardiovasc Electrophysiol, Vol. 23, pp. 137‐144, February 2012)     

阵发性心房颤动经导管消融治疗40例报告

目的探讨经导管消融治疗阵发性心房颤动(房颤)的有效性和安全性。方法自2002年7月至2004年9月，对40例药物治疗无效的反复发作的阵发性房颤患者进行导管消融治疗。同步记录高位右心房、冠状静脉窦及肺静脉电图。采用3种不同的方法(节段性消融肺静脉电隔离术，Carto三维空间标测系统指导下肺静脉电隔离术，超声球囊肺静脉电隔离术)进行肺静脉电位的消融隔离。结果术后随访3—18个月。40例中27例(67．5％)经消融成功，3例(7．5％)有效，10例(25％)失败。Carto标测可减少X线曝光时间。消融过程中出现严重并发症为1例急性心脏压塞，经抢救存活。结论经导管消融治疗阵发性房颤是可行的，对大部分患者有效。     

Left atrial strain,intervendor variability,and atrial fibrillation recurrence after catheter ablation: A systematic review and meta-analysis

The aim of this systematic review and meta-analysis is to investigate the capacity of preinterventional left atrial strain (LAS) to predict AF recurrence (AFR) after catheter ablation by using all relative published data. Intervendor variability regarding different ultrasound stations and strain analysis software suites was taken into consideration. The research was performed according to PRISMA guidelines. The Cochrane database, MEDLINE, and EMBASE were searched for studies assessing echocardiography LAS prior to catheter ablation of AF cases. The systematic research yielded 10 studies (2 retrospective and 8 prospective, 880 patients in total). LAS differed significantly between the patients with AFR and those with no AF recurrence (nAFR) during the follow-up period (LAS_AFR: 17.5 ± 8.7% vs. LAS_nAFR: 24.1 ± 9.5%, p < 0.00001). A pooled cutoff value of 21.9% for LAS was extracted for the prediction of ablation success. Regarding intervendor variability, subgroup analyses were able to be performed for studies using GE and TomTec software. The difference in LAS_AFR and LAS_nAFR remained significant (p < 0.00001 and p < 0.0001 for TomTec and GE, respectively), while significant intervendor difference in absolute strain values was also detected (p < 0.0001 for both AFR and nAFR groups). LAS prior to catheter ablation is consistently lower in patients who experience AF recurrence. Its incorporation in clinical practice would assist physicians detect patients who require closer follow-up. Intervendor variability appears to be considerable and steps must be taken to document it thoroughly and mitigate it if possible.     

Randomized comparison between pulmonary vein antral isolation versus complex fractionated electrogram ablation for paroxysmal atrial fibrillation

Catheter Ablation of Paroxysmal AF. Introduction: Circumferential pulmonary vein antral isolation (PVAI) and atrial complex fractionated electrograms (CFEs) are both ablative techniques for the treatment of paroxysmal atrial fibrillation (PAF). However, data on the comparative value of these 2 ablation strategies are very limited. Methods and Results: We randomized 118 patients with drug‐refractory PAF to receive PVAI ablation (n = 60) or CFE ablation (n = 58). For CFE group, spontaneous/induced AF was mapped using validated, automated software to guide ablation until all CFE areas were eliminated. For PVAI group, all 4 pulmonary vein antra were electrically isolated as confirmed by circular mapping catheter. Patients with spontaneous/inducible AF after the initial ablation procedure were crossed over to the other arms. After initial ablation procedure, AF persisted/inducible in 24/59 patients (41%), and 34/58 patients (59%) assigned to PVAI and CFE ablation, respectively (P = 0.05). Then 58 patients underwent PVAI + CFE ablation. After 22.6 ± 6.4 months, PVAI ablation group was more likely than CFE ablation group to achieve control of any AF/atrial tachycardia (AT) off drugs (43/60, 72% vs 33/58, 57%, P = 0.075) and lower recurrence rate of AT (11.9% vs 34.5%, P = 0.004). Patients who received CFE ablation alone (38%) had significantly lower overall success rate to achieve control of AF/AT off drugs compared with patients who received PVAI ablation (77%, P = 0.002) alone or PVAI + CFE ablation (69%, P = 0.008) due to higher recurrence rate of AT (50% vs 6% vs 13%, P < 0.01). Conclusions: CFE ablation in PAF patients was associated with higher occurrence rate of postprocedure AT compared with PVAI ablation, whereby making it less likely to be a sole ablation strategy for PAF patients. (J Cardiovasc Electrophysiol, Vol. 22, pp. 973‐981, September 2011)     

心房颤动冷冻消融方法的应用进展

肺静脉隔离是心房颤动(房颤)导管消融的基石,冷冻球囊是专门为肺静脉解剖结构设计的工具,应用冷冻球囊导管进行肺静脉隔离(PVI)的有效性和安全性获得了临床研究证实,国内外指南都已将冷冻球囊消融作为房颤消融PVI的标准疗法.冷冻球囊消融具有持久肺静脉隔离、安全性高、操作简便、患者感受好、学习曲线短等优势,因此,近10年在临...     

慢性心房颤动导管消融:碎裂电位消融和线性消融的比较

目的评价环肺静脉隔离(CPVI)基础上采用心房碎裂电位(CFAEs)消融或(和)线性(Linear)消融进行心房基质改良的疗效。方法回顾性分析156例慢性心房颤动(简称房颤)消融病例,房颤病程2.5±2.3年,左房内径42.4±4.5 mm。根据消融术式改进分为三组CPVI+CFAEs、CPVI+linear和CPVI+CFAEs+Linear组。比较消融术中房颤终止比例及随访疗效。结果三组消融总时间有显著性差异(160±14 min vs 178±9 min vs 241±8min,P<0.01)。CPVI+CFAEs组终止房颤/转变房性心动过速(简称房速)的比例(52.7%)显著高于CPVI+Line-ar组(18.4%),但低于CPVI+CFAEs+Linear组(73.1%)。术后3.1±1.2个月,三组二次消融比例47.3%、51%、38.5%,P=0.43。术后平均随访9.5±1.8个月,三组无房性快速性心律失常复发例数分别为39例(70.9%)、33例(67.3%)和41例(78.8%),P=0.41(服用抗心律失常药物比例25.6%、24.2%和22%,P=0.96)。结论 CP-VI基础上CFAEs消融的房颤终止比例高于单纯线性消融,但低于联合应用CFAEs消融和Linear消融。尽管如此,三组术后二次消融比例和随访成功率无显著性差异。     

肺静脉电隔离术联合碎裂电位消融治疗持续性房颤疗效观察

目的：观察肺静脉电隔离术（ pulmonary vein isolation , PVI ）联合碎裂电位（ complex fractionated atrial electrograms , CFAE）消融对持续性房颤的疗效。方法对比观察23名于本院行房颤射频消融术的持续性房颤患者,所有患者均行PVI及左房顶部线性消融,其中12例联合CFAE消融,术后随访1年;观察两组手术时间、X线曝光时间、消融时间、手术并发症、左房大小、左房血栓、一次手术成功率等指标。结果联合CFAE消融组总手术时间（252±35） min、X线曝光时间（42±9．1）min、消融时间（94±11）min,单纯行PVI 组分别为（176±22）min、（34±7．6）min、（63±8）min,联合CFAE消融组手术各时间均明显延长（P＜0．01）;两组手术并发症、对左房大小及左房血栓的影响比较差异均无统计学意义;联合CFAE消融组一次手术成功率（75％）明显高于单纯行PVI组（64％）（ P＜0．05）。结论 PVI联合CFAE消融治疗持续性房颤虽增加手术、消融及X线曝光时间,但并不会提高并发症发生率,可提高房颤消融的一次手术成功率。     

Spectral profiles of complex fractionated atrial electrograms are different in longstanding and acute onset atrial fibrillation atrial electrogram spectra

Spectral Profiles of CFAE. Background: Spectral analysis of complex fractionated atrial electrograms (CFAE) may be useful for gaining insight into mechanisms underlying paroxysmal and longstanding atrial fibrillation (AF). The commonly used dominant frequency (DF) measurement has limitations. Method: CFAE recordings were acquired from outside the 4 pulmonary vein ostia and at 2 left atrial free wall sites in 10 paroxysmal and 10 persistent AF patients. Two consecutive 8s‐series were analyzed from recordings >16s in duration. Power spectra were computed for each 8s‐series in the range 3–12 Hz and normalized. The mean and standard deviation of normalized power spectra (MPS and SPS, respectively) were compared for paroxysmal versus persistent CFAE. Also, the DF and its peak amplitude (ADF) were compared for pulmonary vein sites only. Power spectra were computed using ensemble average and Fourier methods. Results: No significant changes occurred in any parameter from the first to second recording sequence. For both sequences, MPS and SPS were significantly greater, and DF and ADF were significantly less, in paroxysmals versus persistents. The MPS and ADF measurements from ensemble spectra produced the most significant differences in paroxysmals versus persistents (P < 0.0001). DF differences were less significant, which can be attributed to the relatively high variability of DF in paroxysmals. The MPS was correlated to the duration of uninterrupted persistent AF prior to electrophysiologic study (P = 0.01), and to left atrial volume for all AF (P < 0.05). Conclusions: The MPS and ADF measurements introduced in this study are probably superior to DF for discerning power spectral differences in paroxysmal versus longstanding CFAE. (J Cardiovasc Electrophysiol, Vol. 23, pp. 971‐979, September 2012)     

Hybrid dual stage closed chest ablation of persistent atrial fibrillation

The hybrid ablation (HABL) of atrial fibrillation which combines endoscopic, minimally invasive, closed chest epicardial ablation with endocardial CARTO-guided accuracy was introduced to overcome limitations of current therapeutic options for patients with persistent (PSAF) and long-standing persistent atrial fibrillation (LSPAF). The purpose of this single-centre, prospective clinical registry was to evaluate procedural safety and feasibility as well as effectiveness of the HABL in patients with PSAF and LSPAF 1-year post-procedure. From 07.2009 to 12.2014, ninety (n = 90) patients with PSAF (n = 39) and LSPAF (n = 51) underwent HABL. Mean AF duration was 4.5 ± 3.7 years. At 6 months post-procedure 78% patients were in SR. At 12 months post-procedure 86% patients were in SR and 62.3% in SR and of class I/III AADs. These results suggest that combination of epicardial and endocardial RF ablation should be considered as a treatment option for patients with persistent and long-standing persistent atrial fibrillation as it is safe and effective in restoring sinus rhythm.