Catheter ablation of atrial fibrillation: long-term outcomes

The benefits of percutaneous coronary intervention (PCI) can be offset by periprocedural complications such as acute vessel closure and stent thrombosis in the absence of adequate antiplatelet and antithrombotic therapy. Additionally, conditions occurring after 30 days post-PCI, such as in-stent restenosis or late stent thrombosis can occur. Excess antithrombotic therapy, on the other hand, carries a risk of major gastrointestinal or intracranial bleeding as well as vascular access site bleeding complications. In this review, evidence related to the various pharmacological agents for reduction of stent thrombosis available to clinicians during and after PCI will be explored.     

Mapping and Isolation of the Pulmonary Veins Using the PVAC Catheter

Objectives: We aimed to investigate the feasibility, efficacy, and safety of the pulmonary vein ablation catheter (PVAC) catheter (a novel multielectrode catheter using duty‐cycled bipolar and unipolar radiofrequency energy, Medtronic, Minneapolis, MN, USA) to completely isolate the pulmonary veins (PVs). Methods: Twenty‐seven patients (60 ± 8 years) with paroxysmal atrial fibrillation (AF) underwent PV isolation with the PVAC catheter. PVAC was used for both mapping and isolation of the PVs (PVAC‐guided ablation). After PVAC ablation, presence/absence of PV potentials (PVP) was verified using a conventional circular mapping catheter. In case of residual PVP on the circular catheter, PVAC ablation was continued. Results: After PVAC‐guided ablation 99 of 106 PVs (93%) and 21 of 27 patients (78%) were proven to be isolated. Failure to isolate was due to a mapping failure in four right‐sided PVs and a true ablation failure in three right‐sided PVs. After continued PVAC ablation, 103 of 106 PVs (97%) and 25 of 27 patients (93%) were shown to be isolated. The total procedural time from femoral vein access to complete catheter withdrawal was 176 ± 25 minutes. The actual dwelling‐time of the PVAC within the left atrium was 102 ± 37 minutes. Esophageal T° rise to >38.5° occurred in nine of 19 monitored patients (47%). Conclusions: (1) PVAC‐guided ablation (i.e., mapping and ablation with a single catheter) results in isolation of all PVs in 73% of the patients. (2) An additional circular mapping catheter is required to increase complete isolation rate to 93% of the patients. (3) Given the esophageal T° rise in almost 50% of patients, safety precautions are needed. (PACE 2010; 33:168–178)     

Different clinical courses and predictors of atrial fibrillation occurrence after transisthmic ablation in patients with preablation lone atrial flutter, coexistent atrial fibrillation, and drug induced atrial flutter

The aim of this prospective study was to compare the long-term follow-up after transisthmic ablation of patients with preablation lone atrial flutter, coexistent AF, and drug induced atrial flutter to determine if postablation AF followed a different clinical course and displayed different predictors in these groups. The study evaluated 357 patients who underwent transisthmic ablation for typical atrial flutter. These were divided into four groups according to their preablation history. Group A included patients with typical atrial flutter and without preablation AF (n=120, 33.6%). Group B included patients with preablation AF and spontaneous atrial flutter (n=132, 37.0%). Group C patients had preablation AF and atrial flutter induced by treatment with IC drugs (propafenone or flecainide) (n=63, 17.6%) Group D included patients with preablation AF and atrial flutter induced by treatment with amiodarone (n=42, 11.8%). During a mean follow-up of 15.2 double dagger 10.6 months (range 6-55 months) AF occurred more frequently in groups B (56.1%) and C (57.1%) patients than in groups A (20.8%, P <0.0001) and D (31.0%, P <0.0001) patients. The results of multivariate analysis revealed that different clinical and echocardiographical variables were correlated with postablation AF occurrence in the different groups. Patients with atrial flutter induced by amiodarone have a significantly lower risk of postablation AF than patients with spontaneous atrial flutter and AF, and those with atrial flutter induced by IC drugs. Different clinical and echocardiographical variables predict postablation AF occurrence in different subgroups of patients.     

Relation Between Left Atrial Size and Secondary Atrial Arrhythmias After Successful Catheter Ablation of Common Atrial Flutter

Catheter ablation ptovides an effective cure for patients with typical atrial flutter. However, these patients may have the potential to develop atrial tachyarrhythmias other than common atrial flutter. This study examines clinical and echocardiographic predictors for the occurrence of uncommon atrial flutter or atrial fibrillation after abolition of common atrial flutter. The study population comprised 17 patients (12 men, 5 women, age 32–74 years) who underwent successful radiofrequency catheter ablation of common atrial flutter. Common atrial flutter did not recur in any patient during a median follow-up time of 8 (range 1–25) months. Within a median of 7 (range 1–223) days, however, symptomatic atrial tachyarrhythmias occurred in 8 of 17 patients (47%): uncommon atrial flutter (n = 4); atrial fibrillation (n = 3); and both uncommon atrial flutter and atrial fibrillation in one patient. Preablation left atrial volume was significantly larger in patients who developed secondary arrhythmias compared with patients who remained in sinus rhythm (57.9 ± 15.6 vs 43.7 ± 16.4 cm³, P < 0.05). Enlarged left atrial volume dichotomized at 51 cm³ independently predicted postablation atrial arrhythmias (x²=5.11, rel. risk = 5.3, P < 0.05). On Kaplan-Meier analysis, time to occurrence of postablation atrial arrhythmias was significantly shorter in patietits with enlarged left atrium (P < 0.02). In conclusion, symptomatic uncommon atrial flutter and atrial fibrillation develops in a substantial proportion of patients after successful ablation of common atrial flutter. Out of a series of clinical and echocardiographic parameters, preablation left atrial size is the best predictor for the occurrence of these postablation atrial arrhythmias.     

Noncavotricuspid isthmus-dependent right atrial tachycardia after paroxysmal atrial fibrillation ablation

Background: Atrial tachycardia (AT) is commonly encountered after atrial fibrillation (AF) ablation. But no study exclusively on noncavotricuspid isthmus‐dependent right AT (NCTI‐RAT) post‐AF ablation has been reported. The present study aims to describe its prevalence, electrophysiological mechanisms, and ablation strategy and to further discuss its relationship with AF. Methods: From July 2006 to November 2009, 350 consecutive patients underwent catheter ablation for paroxysmal AF. A total of seven patients (2.0%) developed NCTI‐RAT after left atrium ablation for AF. In these highly selected patients (two male, mean age 54 ± 11 years, mean left atrium diameter of 34 ± 7 cm), all had circumferential pulmonary vein isolation in their initial procedures and three of them had additional complex fractionated electrograms ablation in the left atrium and the coronary sinus. Results: Totally, nine NCTI‐RATs were mapped and successfully ablated in the right atrium with a mean cycle length of 273 ± 64 ms in seven patients. Five ATs in three patients were electrophysiologically proved to be macroreentry and the remaining four were focal activation. All the ATs were successfully abolished by catheter ablation. After a mean follow‐up of 29 ± 15 months post‐AT ablation, all patients were free of AT and AF off antiarrhythmic drugs. Conclusions: NCTI‐RAT is relatively less common post‐AF ablation. Totally, 2.0% of paroxysmal AF patients were revealed to have NCTI‐RAT. (PACE 2011; 34:391–397)     

Mechanism of spontaneous transition from typical atrial flutter to atrial fibrillation: role of ectopic atrial fibrillation foci

Paroxysmal AF has been known to be initiated by ectopic beats, especially in the pulmonary veins (PVs), and radiofrequency catheter ablation could cure it. We considered that the spontaneous transition from typical atrial flutter to AF also could be initiated by ectopic beats. Twenty patients (18 men, mean age 66 +/- 14 years) with episodes of spontaneous transition from typical atrial flutter to AF were included in this study. They underwent detailed mapping of both atria. All the patients had spontaneous AF initiated by ectopic beats, and all of them had typical atrial flutter and spontaneous transition from typical atrial flutter (12 patients with counterclockwise atrial flutter and 8 patients with clockwise atrial flutter) to AF. The transition was initiated by ectopic beats from the PVs (17 foci, 85%), crista terminalis (2 foci, 10%), and superior vena cava (1 focus, 5%). After successful ablation of AF foci, typical atrial flutter was induced again, but no spontaneous transition was found after at least 10 minutes of observation. We concluded that paroxysmal AF and spontaneous transition from typical atrial flutter to AF were initiated by ectopic beats, and successful catheter ablation of the ectopic foci can eliminate paroxysmal AF and spontaneous transition from typical atrial flutter to AF.     

Catheter Ablation for Paroxysmal Atrial Fibrillation: A Randomized Comparison between Multielectrode Catheter and Point‐by‐Point Ablation

Introduction: Catheter ablation for paroxysmal atrial fibrillation is widely used for patients with drug‐refractory paroxysms of arrhythmia. Recently, novel technologies have been introduced to the market that aim to simplify and shorten the procedure. Aim: To compare the clinical outcome of pulmonary vein (PV) isolation using a multipolar circular ablation catheter (PVAC group), with point‐by‐point PV isolation using an irrigated‐tip ablation catheter and the CARTO mapping system (CARTO group; CARTO, Biosense Webster, Diamond Bar, CA, USA). Methods: Patients with documented PAF were randomized to undergo PV isolation using PVAC or CARTO. Atrial fibrillation (AF) recurrences were documented by serial 7‐day Holter monitoring. Results: One hundred and two patients (mean age 58 ± 11 years, 68 men) were included in the study. The patients had comparable baseline clinical characteristics, including left atrial dimensions and left ventricular ejection fraction, in both study arms (PVAC: n = 51 and CARTO: n = 51). Total procedural and fluoroscopic times were significantly shorter in the PVAC group (107 ± 31 minutes vs 208 ± 46 minutes, P < 0.0001 and 16 ± 5 minutes vs 28 ± 8 minutes, P < 0.0001, respectively). The AF recurrence was documented in 23% and 29% of patients in the PVAC and CARTO groups, respectively (P = 0.8), during the mean follow‐up of 200 ± 13 days. No serious complications were noted in both study groups. Conclusions: Clinical success rates of PV isolation are similar when using multipolar circular PV ablation catheter and point‐by‐point ablation with a three‐dimensional (3D) navigation system in patients with PAF, and results in shorter procedural and fluoroscopic times with a comparable safety profile. (PACE 2010; 33:1039–1046)     

Incremental predictive value of pre-procedural N-terminal pro-B-type natriuretic peptide for short-term recurrence in atrial fibrillation ablation

The objective of this work was to assess the predictive value of pre-procedural N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels in patients undergoing atrial fibrillation (AF) ablation. Seventy-three consecutive patients with AF (paroxysmal n = 49, persistent n = 24) and preserved left ventricular (LV) systolic function (LV ejection fraction > 45%) were prospectively enrolled in this study. All of the enrolled patients underwent catheter ablation after a measurement of their plasma NT-proBNP levels, and an echocardiographic examination with assessment of their LV diastolic function and left atrial(LA) volume. Patients with AF recurrence at 3 months had more persistent AF (P = 0.001), a higher LA volume index (P = 0.002), lesser decelerating times (DT) of mitral inflow (P = 0.014), and higher NT-proBNP levels (P < 0.001), when compared with patients with sinus rhythm restoration. The baseline log NT-proBNP correlated significantly with age (r = 0.26, P = 0.025), LA volume index (r = 0.41, P = 0.001), E/E’ (r = 0.34, P = 0.007), DT (r = −0.34, P = 0.007), and E (r = 0.25, P = 0.04). The log NT-proBNP (HR 7.76, 95% CI 2.95–20.39, P < 0.001) was an independent predictor of AF recurrence. The measurement of NT-proBNP added incremental predictive value to standard indexes of LA size or diastolic function, including LA volume index and DT (P = 0.02). This study suggests the clinical utility of the level of NT-proBNP as an integrating marker of various risk factors, and as an incremental predictive marker for AF catheter ablation. Dr. Hwang and Dr. Son contributed equally to this work.     

心房颤动导管消融的地位和进展

心房颤动(房颤)是临床常见的心律失常之一,最大风险是血栓栓塞,常见是脑卒中。随着人口的老龄化,房颤人数持续增加,治疗问题也逐渐成为人们关注重点。房颤导管消融是其重要治疗方法之一,可明显改善房颤患者预后。且随着技术发展,消融方法也日趋成熟,故导管消融术治疗房颤地位正在逐步提升。但消融方法尚无固定术式,发生机制尚未完全明确,尤其对于持续房颤。因此房颤消融术仍存在一些问题有待进一步探索。     

Radiofrequency Catheter Ablation Using Long Coiled Electrodes: Impact of Irrigation on Lesion Dimensions and Incidence of Coagulum Formation

Ablation catheters with multiple long coiled electrodes have been recently developed to induce continuous linear lesions for the treatment of atrial fibrillation. The efficacy and safety of ablation catheters with multiple long coiled electrodes has not been evaluated. The aim of the present in vivo study was to investigate the influence of saline irrigation on lesion dimensions and coagulum formation during RF current ablation using those ablation catheters. In 14 anesthetized sheep, the thigh muscle was prepared as a cradle and filled with heparinized blood (37 degrees C). The quadripolar coiled ablation catheter (electrode length 7 mm, electrode distance 2 mm) was placed parallel to the muscle with standardized 10-g contact pressure. RF current energy was delivered sequentially temperature-(70 degrees C) or power-controlled (10, 20, 30, or 40 W) with additional irrigation of the electrode (10 mL/min normal saline) for 90 seconds. Forty-two of 129 RF current lesions were induced by temperature-controlled and 87 by irrigated ablation. Except for three lesions following low energy irrigated application (10 W), all lesions were continuous. Significantly larger lesions following irrigated RF current applications were produced with a power output of 30 W (depth 0.74 +/- 0.13 cm, width 0.78 +/- 0.13 cm) and 40 W (depth 0.75 +/- 0.16 cm, width 0.92 +/- 0.28 cm) as compared to 20 W (depth 0.47 +/- 0.13 cm, width 0.82 +/- 0.22 cm). Coagulum formation adherent to the electrode was exclusively observed following 18 of 42 nonirrigated RF current ablations. In conclusion, irrigated coiled ablation electrodes induce continuous linear lesions with a power output of 20-40 W. The risk of coagulum formation at the coiled electrode can be avoided by irrigation.     

Successful pulmonary vein isolation using transvenous catheter cryoablation improves quality-of-life in patients with atrial fibrillation

BACKGROUND: Recent studies have demonstrated that transvenous catheter cryoablation is a safe and effective technique for creating pulmonary veins (PVs) electrical isolation for the treatment of atrial fibrillation (AF). However, the impacts of this procedure on quality-of-life (QoL) have not been evaluated. METHODS AND RESULTS: We studied the effects of PV isolation using transvenous catheter cryoablation on QoL in 46 patients (34 men, mean age: 50 +/- 12 years) with drug-refractory AF. QoL was assessed by Medical Outcomes Study Short Form-36 (SF-36) and Symptom Checklist at baseline and 3-month after cryoablation, and compared with those in a sex-age matched normal control. At 3-month follow-up, 24 of 46 patients (52%) had no recurrence of AF, including 11 patients who were not taking antiarrhythmic drugs. At baseline, patients with AF had significantly lower QoL scores in overall and in 5/8 subscales of SF-36 than the sex-age matched control group (P < 0.05). In patients with successful outcome after cryoablation showed a significant improvement in overall and in 5/8 subscales of SF-36 QoL scores have significantly increased as compared with the baseline (P < 0.05). Furthermore, their QoL scores in overall and in 6/8 subscales of SF-36 were similar to the sex-age matched control group (P > 0.05). The Symptom Checklist also showed significant reduction in both the symptoms frequency scores and symptoms severity scores at 3-month follow-up as compared with baseline (P < 0.05). CONCLUSIONS: Successful PV isolation using transvenous catheter cryoablation is associated with significant reduction in the frequency and severity of AF symptoms and improvement in the general QoL, reaching the levels of normal controls.     

Segmental pulmonary vein ablation: success rates with and without exclusion of areas adjacent to the esophagus

Background: Catheter ablation has become the first line of therapy in patients with symptomatic recurrent, drug‐refractory atrial fibrillation (AF). The occurrence of an atrioesophageal fistula is a rare but serious complication after AF‐ablation procedures. This risk is even present during segmental pulmonary vein (PV) ablation procedures because the esophagus does frequently have a very close anatomical relationship to the right or left PV ostia. The aim of the present study was to analyze whether the exclusion of areas adjacent to the esophagus does have a significant effect on the success rates after segmental pulmonary vein ablation procedures. Methods: Forty‐three consecutive patients with symptomatic paroxysmal AF were enrolled in this study. In all patients, a segmental PV ablation procedure was performed. The procedures were facilitated by a 3D real‐time visualization of the circumferential mapping catheter placed in the pulmonary veins using the NavX? system (St. Jude Medical, St. Paul, MN, USA; open irrigated tip ablation catheter; 43°C; 30 W). In 21 patients, a complete ostial PV isolation was attempted regardless of the anatomical relationship between the ablation sites and the esophagus (group A). In the remaining 22 patients, the esophagus was marked by a stomach tube and areas adjacent to the esophagus were excluded from the ablation procedure (group B). After discharge, patients were scheduled for repeated visits at the arrhythmia clinic at 1, 3, and 6 months after the ablation procedure. Results: The segmental pulmonary vein ablation procedure could be performed as planned in all patients. In group A, all pulmonary veins could be isolated successfully in 14 out of 21 patients (67%). A mean number of 3.7 pulmonary veins (SD ± 0.5 PVs) were isolated per patient. The main reasons for an incomplete PV isolation were: small diameter of the PVs, side branches close to the ostium, or poorly accessible PV ostia. In group B, all PVs could be isolated successfully in only 12 out of 22 patients (55%; P = 0.54). A mean number of 3.2 PVs (SD ± 0.9 PVs) were isolated per patient (P = 0.05). This was mostly due to a close anatomical relationship to the esophagus. The ablation strategy had to be modified in 16/22 patients in group B because of a close anatomical relationship between the left (n = 10) or right (n = 6) PV ostia and the esophagus. After 3 months, the percentage of patients free from an AF recurrence was not significantly different between the two groups (90% vs 95%; P = 0.61). After 6 months, there was no significant difference between the success rates either (81% vs 82%; P = 1.0). There were no major complications in both groups. Conclusions: The exclusion of areas adjacent to the esophagus results in a moderately higher percentage of incompletely isolated PVs. However, it does not have a significant effect on the AF recurrence rate during short‐term and mid‐term follow‐up.     

经导管射频消融治疗阵发性心房颤动临床研究

[目的]探讨经导管射频消融治疗阵发性心房颤动的有效性与安全性.[方法]60例阵发性心房颤动患者药物治疗无效且反复发作,采用节段性消融肺静脉电隔离术、CARTO和EnSite 3000三维空间标测系统指导下肺静脉电隔离术3种不同的方法进行肺静脉电位经导管射频消融隔离治疗,术后随访3～41个月.[结果]60例患者中42例(70.0%)经消融成功,10例(16.7%)有效,8例(13.3%)失败,无严重并发症;CARTO和EnSite 3000三维空间标测系统指导肺静脉电隔离术可明显减少X线曝光时间.[结论]经导管射频消融治疗局灶性心房颤动是可行的,对大部分患者是有效的.     

Ostial PV Isolation:

Pulmonary vein (PV) isolation by elimination of spike potentials has been reported to cure drug refractory atrial fibrillation. Because of the heterogenous morphology of the PVs, sequential electroanatomic reconstruction of the PVs was performed in 39 patients (group A), who underwent subsequent PV isolation by interruption of all conductive myocardial fibers by distinct RF current applications using a "lasso" approach. In group B (157 patients), only biplane two-dimensional fluoroscopy was performed to guide the diagnostic and the ablation catheters. After reprocedures (in 7% of patients in group A and 22% of group B), which depicted a recurrence of a spike potential inside or at the ostium of  >1 previously isolated PV in all restudied patients, stable sinus rhythm was documented in 69% of patients in group A and 60% of patients in group B. Reasons for the relapse of the previously eliminated spike potentials include a temporary ablation effect and a too distal interruption of the conducting myocardial fiber. Detailed knowledge of the individual three-dimensional morphology enhanced the clinical success rate of PV isolation but is time-consuming using CARTO   (8.0 ± 1.7 vs 5.0 ± 1.6, P < 0.001)   . Further technical improvement to fuse the individual three-dimensional anatomy and the electrophysiological markers to a composed "electroanatomic" map may overcome this limitation in the future. (PACE 2003; 26[Pt. II]:1624–1630)     

Left Atrial Linear Ablation to Modify the Substrate of Atrial Fibrillation Using a New Nonfluoroscopic Imaging System

Linear left atrial ablation is performed in combination with pulmonary vein (PV) isolation to improve the clinical results of atrial fibrillation (AF) ablation. These procedures require long procedures and fluoroscopic exposure. The aim of the present study was to evaluate the performance of a new, nonfluoroscopic, real-time, three-dimensional navigation system for linear ablation at the left atrial roof and mitral isthmus. The study included 44 patients (54 ± 10 years of age, 5 women) with drug-refractory AF, who underwent roof line or mitral isthmus linear ablation after 4-PV isolation. In 22 patients, ablation was performed with the navigation system (test group), and in the remainders linear ablation was performed with fluoroscopic guidance alone (control group). Conduction block was achieved in 20 patients (91%) in test group, and 21 patients (95%) in the control group (ns). Use of the navigation system was associated with a shorter fluoroscopic exposure for roof line (5.6 ± 3.0 minutes vs 8.7 ± 5.0 minutes, P < 0.05), and a trend for mitral isthmus ablation (7.8 ± 7.8 minutes vs 12.1 ± 5.9 minutes). It was also associated with a trend toward shorter procedure times for roof line (15.3 ± 8.6 minutes vs 22.9 ± 16.8 minutes) and mitral isthmus line (20.2 ± 15.8 minutes vs 32.0 ± 7.6 minutes) but no difference in duration of radiofrequency delivery. There was no procedural complication. The use of this new nonfluoroscopic imaging system was associated with a shorter fluoroscopic exposure as well as a trend toward shorter duration of linear ablation procedures for AF.