Progress in Nonpharmacologic Therapy of Atrial Fibrillation

Characterization of pulmonary vein reconnection post Cryoballoon ablation

Background

The Arctic Front Cryoballoon System is a technology in which substrate alterations in patients with atrial fibrillation (AF) recurrence have not been well characterized. In this study, we evaluated sites of pulmonary vein (PV) reconnections and the accuracy of the Achieve™ circular mapping catheter in detecting these reconnections after cryoablation.

Methods

This study included 15 patients undergoing redo AF ablation after a prior single cryoablation procedure. PV reconnection sites were determined by measuring PV signals and high output pacing from 4 vectors of the Achieve catheter. The results were compared with a roving mapping catheter guided by rotational intracardiac echocardiography (ICE) in the left atrium.

Results

All patients had PV reconnections (2.1 ± 0.8 veins/patient). The left superior PV was most commonly reconnected (n = 11), whereas the right inferior PV was least likely (n = 3). Both carinas (left: n = 11; right: n = 7) and left atrial appendage ridge (n = 11) were also frequently reconnected. Mapping with the Achieve catheter showed a positive predictive value (PPV) 100% and negative predictive value (NPV) 96% when compared with ICE guided mapping. In 2 patients, right superior PV reconnection was not identified by the Achieve.

Conclusion

During redo AF ablation after index cryoablation, multiple PVs are usually reconnected, with both carinas and left atrial appendage ridge being common sites of reconnection. The Achieve mapping catheter was able to identify reconnection with high positive and negative predictive values.

Reversal of pulmonary vein remodeling after catheter ablation of atrial fibrillation

Background

Pulmonary veins (PV) and the atria undergo electrical and structural remodeling in atrial fibrillation (AF). This study aimed to determine PV and left atrial (LA) reverse remodeling after catheter ablation for AF assessed by chest computed tomography (CT).

Methods

PV electrophysiologic studies and catheter ablation were performed in 63 patients (68% male; mean ± SD age: 56 ± 10 years) with symptomatic AF (49% paroxysmal, 51% persistent). Chest CT was performed before and 3 months after catheter ablation.

Results

At baseline, patients with persistent AF had a greater LA volume (91 ± 29 cm³vs. 66 ± 27 cm³; P = 0.003) and mean PV ostial area (241 ± 43 mm²vs. 212 ± 47 mm²; P = 0.03) than patients with paroxysmal AF. There was no significant correlation between the effective refractory period and the area of the left superior PV ostium. At 3 months of follow-up after ablation, 48 patients (76%) were AF free on or off antiarrhythmic drugs. There was a significant reduction in LA volume (77 ± 31 cm³ to 70 ± 28 cm³; P < 0.001) and mean PV ostial area (224 ± 48 mm² to 182 ± 43 mm²; P < 0.001). Patients with persistent AF had more reduction in LA volume (11.8 ± 12.8 cm³vs. 4.0 ± 11.2 cm³; P = 0.04) and PV ostial area (62 mm²vs. 34 mm²; P = 0.04) than those who have paroxysmal AF. The reduction of the averaged PV ostial area was significantly correlated with the reduction of LA volume (r = 0.38, P = 0.03).

Conclusions

Catheter ablation of AF improves structural remodeling of PV ostia and left atrium. This finding is more apparent in patients with persistent AF treated by catheter ablation.

Impact of atrial fibrillation ablation on left ventricular filling pressure and left atrial remodeling

BACKGROUND

Left ventricular (LV) diastolic dysfunction is associated with new-onset atrial fibrillation (AF), and the estimation of elevated LV filling pressures by E/e' ratio is related to worse outcomes in patients with AF. However, it is unknown if restoring sinus rhythm reverses this process.

OBJECTIVE

To evaluate the impact of AF ablation on estimated LV filling pressure.

METHODS

A total of 141 patients underwent radiofrequency (RF) ablation to treat drug-refractory AF. Transthoracic echocardiography was performed 30 days before and 12 months after ablation. LV functional parameters, left atrial volume index (LAVind), and transmitral pulsed and mitral annulus tissue Doppler (e' and E/e') were assessed. Paroxysmal AF was present in 18 patients, persistent AF was present in 102 patients, and long-standing persistent AF in 21 patients. Follow-up included electrocardiographic examination and 24-h Holter monitoring at 3, 6, and 12 months after ablation.

RESULTS

One hundred seventeen patients (82.9%) were free of AF during the follow-up (average, 18 ± 5 months). LAVind reduced in the successful group (30.2 mL/m(2) ± 10.6 mL/m(2) to 22.6 mL/m(2) ± 1.1 mL/m(2), p < 0.001) compared to the non-successful group (37.7 mL/m(2) ± 14.3 mL/m(2) to 37.5 mL/m(2) ± 14.5 mL/m(2), p = ns). Improvement of LV filling pressure assessed by a reduction in the E/e' ratio was observed only after successful ablation (11.5 ± 4.5 vs. 7.1 ± 3.7, p < 0.001) but not in patients with recurrent AF (12.7 ± 4.4 vs. 12 ± 3.3, p = ns). The success rate was lower in the long-standing persistent AF patient group (57% vs. 87%, p = 0.001).

CONCLUSION

Successful AF ablation is associated with LA reverse remodeling and an improvement in LV filling pressure.

Cryoballoon ablation of pulmonary veins for paroxysmal atrial fibrillation: first results of the North American Arctic Front (STOP AF) pivotal trial

OBJECTIVES

This study sought to assess the safety and effectiveness of a novel cryoballoon ablation technology designed to achieve single-delivery pulmonary vein (PV) isolation.

BACKGROUND

Standard radiofrequency ablation is effective in eliminating atrial fibrillation (AF) but requires multiple lesion delivery at the risk of significant complications.

METHODS

Patients with documented symptomatic paroxysmal AF and previously failed therapy with ≥ 1 membrane active antiarrhythmic drug underwent 2:1 randomization to either cryoballoon ablation (n = 163) or drug therapy (n = 82). A 90-day blanking period allowed for optimization of antiarrhythmic drug therapy and reablation if necessary. Effectiveness of the cryoablation procedure versus drug therapy was determined at 12 months.

RESULTS

Patients had highly symptomatic AF (78% paroxysmal, 22% early persistent) and experienced failure of at least one antiarrhythmic drug. Cryoablation produced acute isolation of three or more PVs in 98.2% and all four PVs in 97.6% of patients. PVs isolation was achieved with the balloon catheter alone in 83%. At 12 months, treatment success was 69.9% (114 of 163) of cryoblation patients compared with 7.3% of antiarrhythmic drug patients (absolute difference, 62.6% [p < 0.001]). Sixty-five (79%) drug-treated patients crossed over to cryoablation during 12 months of study follow-up due to recurrent, symptomatic AF, constituting drug treatment failure. There were 7 of the resulting 228 cryoablated patients (3.1%) with a >75% reduction in PV area during 12 months of follow-up. Twenty-nine of 259 procedures (11.2%) were associated with phrenic nerve palsy as determined by radiographic screening; 25 of these had resolved by 12 months. Cryoablation patients had significantly improved symptoms at 12 months.

CONCLUSIONS

The STOP AF trial demonstrated that cryoballoon ablation is a safe and effective alternative to antiarrhythmic medication for the treatment of patients with symptomatic paroxysmal AF, for whom at least one antiarrhythmic drug has failed, with risks within accepted standards for ablation therapy. (A Clinical Study of the Arctic Front Cryoablation Balloon for the Treatment of Paroxysmal Atrial Fibrillation [Stop AF]; NCT00523978).

Atrial Coronary Arteries in Areas Involved in Atrial Fibrillation Catheter Ablation

Background—

The proximity to vascular structures is a limiting factor during radiofrequency ablation. However, little or no attention has been given to the atrial arterial circulation during the development of atrial fibrillation (AF) catheter ablation techniques.

Methods and Results—

We examined the atrial arterial circulation in areas involved in AF ablation in 24 heart specimens by colored resin injection and careful dissection. The sinus node artery (SNA) arose from the circumflex artery in 42% of case; proximal to the LA appendage in 29%, crossing the left atrium (LA) anterior wall; and after the LA appendage in the remaining 13%, crossing the mitral isthmus and passing close to the left pulmonary veins (PVs), the LA roof, and the right superior PV. In 58%, the SNA arose from the right coronary artery. Major arteries (≥1 mm in external diameter) were found in the mitral isthmus in 54%, at the LA roof in 54%, and at the LA anterior wall in 29%. Around the left PV ostia, there were areas with major arteries in up to 37% (at the roof and inferior segments) and around the right PV ostia in up to 29% (at the roof segment).

Conclusions—

Major atrial coronary arteries, including the SNA, were commonly found in the areas involved in AF ablation and could cause difficulties in obtaining transmural lesions and electric isolation or even lead to ischemic sinus node or atrial dysfunction.

Ion channel trafficking: a new therapeutic horizon for atrial fibrillation

Atrial fibrillation (AF) is a common cardiac arrhythmia with potentially life-threatening complications. Drug therapies for treatment of AF that seek long-term maintenance of normal sinus rhythm remain elusive due in large part to proarrhythmic ventricular actions. Kv1.5, which underlies the atrial specific I(Kur) current, is a major focus of research efforts seeking new therapeutic strategies and targets. Recent work has shown a novel effect of antiarrhythmic drugs where compounds that block Kv1.5 channel current also can alter ion channel trafficking. This work further suggests that the pleiotropic effects of antiarrhythmic drugs may be separable. Although this finding highlights the therapeutic potential for selective manipulation of ion channel surface density, it also reveals an uncertainty regarding the specificity of modulating trafficking pathways without risk of off-target effects. Future studies may show that specific alteration of Kv1.5 trafficking can overcome the proarrhythmic limitations of current pharmacotherapy and provide an effective method for long-term cardioversion in AF.

A practical approach to the management of patients with atrial fibrillation

Atrial fibrillation is the most commonly encountered clinical arrhythmia and continues to grow in incidence. Current management involves highly individualised therapies based on underlying concomitant disease processes and symptoms. Moreover, there are numerous therapeutic permutations involving anticoagulation, rate-limitation and antiarrhythmic strategies. This review serves to update the clinician with a practical approach to each patient population and on current advances in management.

Atrial fibrillation: mechanistic insights and treatment options

Atrial fibrillation (AF) remains the most common clinically encountered arrhythmia. Unlike supraventricular arrhythmias that use a defined mechanism, AF involves a wide spectrum of arrhythmias from lone AF to paroxysmal to chronic AF. AF is an arrhythmia that may develop in several ways. Mechanical remodeling manifests as decreased atrial contractility and increased atrial compliance which leads to a stretch of the atrial myocardium. Atrial remodeling may also increase in atrial fibrosis which can slow conduction velocity and can shorten the refractory period in atria with long-standing AF. It is still unclear whether initiation of AF activates direct inflammatory effects or whether the presence of a pre-existing systemic inflammatory state promotes further persistence of AF. Currently, the patient population undergoing AF ablation has greatly expanded. Patients are older and have larger left atrial size and are more likely to have persistent/permanent AF. It is likely that AF comprises a spectrum of disease with no single mechanism adequate enough to comprehensively explain AF and its variability. The management of patients with AF involves elements of anticoagulation, rate control and rhythm control and such treatment strategies are not necessarily mutually exclusive of each other.

Trends in catheter ablation for atrial fibrillation in the United States

BACKGROUND

There are few data on the use of catheter ablation for atrial fibrillation (AF) in the United States. We analyzed data from the National Hospital Discharge Survey (NHDS) to examine trends in the rate of catheter ablation for hospitalized patients with AF over a 15-year period.

OBJECTIVE

To examine rates of catheter ablation in patients with AF over time.

DESIGN

All adult patients in the NHDS with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code for AF from the years 1990 to 2005 were identified and assessed for the presence of a cardiac catheter ablation procedure code. Clinical characteristics associated with ablation were identified and multivariable logistic regression used to determine trends in the rate of ablation therapy over time.

RESULTS

We identified 269,471 adults with AF. The rate of catheter ablation in AF patients increased from 0.06% in 1990 to 0.79% in 2005 (P < 0.001 for trend). Compared to those not undergoing ablation, ablated patients were younger (mean age 66 versus 76 years; P < 0.001), more likely to be male (57% versus 43%; P < 0.001), have private insurance (22% versus 11%; P < 0.001), and have a none of the following stroke risk factors: congestive heart failure, hypertension, age >75 years, diabetes mellitus, or stroke/transient ischemic attack (37% versus 16%; P < 0.001). Catheter ablation in AF patients increased by 15% per year over the time period (95% confidence interval [CI], 13%-16%) and across all age groups, including in patients age > or =80 years (0.0% in 1990 and 0.26% in 2005; P < 0.001 for trend).

CONCLUSIONS

The rate of catheter ablation in patients with AF is increasing significantly over time, even in the oldest patients. Medicine.

An event-driven distributed processing architecture for image-guided cardiac ablation therapy

Medical imaging data is becoming increasing valuable in interventional medicine, not only for preoperative planning, but also for real-time guidance during clinical procedures. Three key components necessary for image-guided intervention are real-time tracking of the surgical instrument, aligning the real-world patient space with image-space, and creating a meaningful display that integrates the tracked instrument and patient data. Issues to consider when developing image-guided intervention systems include the communication scheme, the ability to distribute CPU intensive tasks, and flexibility to allow for new technologies. In this work, we have designed a communication architecture for use in image-guided catheter ablation therapy. Communication between the system components is through a database which contains an event queue and auxiliary data tables. The communication scheme is unique in that each system component is responsible for querying and responding to relevant events from the centralized database queue. An advantage of the architecture is the flexibility to add new system components without affecting existing software code. In addition, the architecture is intrinsically distributed, in that components can run on different CPU boxes, and even different operating systems. We refer to this Framework for Image-Guided Navigation using a Distributed Event-Driven Database in Real-Time as the FINDER architecture. This architecture has been implemented for the specific application of image-guided cardiac ablation therapy. We describe our prototype image-guidance system and demonstrate its functionality by emulating a cardiac ablation procedure with a patient-specific phantom. The proposed architecture, designed to be modular, flexible, and intuitive, is a key step towards our goal of developing a complete system for visualization and targeting in image-guided cardiac ablation procedures.

Contemporary management of atrial fibrillation: update on anticoagulation and invasive management strategies

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Its increasing prevalence, particularly among the elderly, renders it one of the most serious current medical epidemics. Several management questions confront the clinician treating a patient with AF: Should the condition be treated? Is the patient at risk of death or serious morbidity as a result of this diagnosis? If treatment is necessary, is rate control or rhythm control superior? Which patients need anticoagulation therapy, and for how long? This review of articles obtained by a search of the PubMed and MEDLINE databases presents the available evidence that can guide the clinician in answering these questions. After discussing the merits of available therapy, including medications aimed at controlling rate, rhythm, or both, we focus on the present status of ablative therapy for AF. Catheter ablation, particularly targeting the pulmonary veins, is being increasingly performed, although the precise indications for this approach and its effectiveness and safety are being actively investigated. We briefly discuss other invasive options that are less frequently used, such as pacemakers, defibrillators, left atrial appendage closure devices, and the surgical maze procedure.

The place of hybrid therapies with drugs to supplement nonpharmacological therapies in atrial fibrillation

Atrial fibrillation (AF) is one of the most common cardiac arrhythmias, and its prevalence continues to rise as the aged population increases. Comparative studies of rhythm control and rate control have been equivocal; however, the benefits of rhythm control may have been offset by the limitations of antiarrhythmic drugs. More recently, nonpharmacological therapies have emerged that provide hope of more effective rhythm control. Catheter ablation techniques have gained favour with high success rates in specialized centers, although these techniques are not without complications and require considerable expertise. Pacing therapies designed to reduce harmful right ventricular pacing and increase physiological pacing have shown benefit in AF patients with bradycardia. Despite this progress, no single modality confers benefit for all patients. Strategies to combine these treatment modalities in a hybrid approach has shown increasing promise for subgroups of AF patients.

[Pulmonary vein isolation in treatment of atrial fibrillation--strategies, results and complications]

Atrial fibrillation is a relevant challenge for health care systems in Europe and North America. Interventional treatment of atrial fibrillation in terms of ablation of atrial structures including isolation of the pulmonary veins is nowadays established as an alternative to drug therapy, especially if treatment with antiarrhythmic drugs has been ineffective. Recently published European and North American guidelines support this strategy. This article describes different techniques of atrial fibrillation ablation including intracardiac echo-guided pulmonary vein isolation. Potential complications, success rates and different follow-up strategies are specified. Furthermore interventional treatment of atrial fibrillation of heart failure patients is discussed.

Catheter ablation of atrial fibrillation

Atrial fibrillation is a common arrhythmia associated with significant morbidity including angina, heart failure and stroke. Medical therapy remains suboptimal with significant side effects and toxicities, as well as a high recurrence rate. Catheter ablation or modification of the atrio-ventricular node with pacemaker implantation provides rate control but subjects the patient to the risks of an implantable device and does nothing to reduce the risk of stroke. Pulmonary vein antrum isolation offers a nonpharmacologic means of restoring sinus rhythm, thereby eliminating the morbidity of atrial fibrillation and the need for anti-arrhythmic drugs.

Radiofrequency ablation of atrial fibrillation: is the persistence of all intraprocedural targets necessary for long-term maintenance of sinus rhythm?

BACKGROUND

Several approaches have been developed for radiofrequency catheter ablation of atrial fibrillation, but the correct intraprocedural end point is still under debate, and few data exist about the destiny of ablation lesions over time. The aim of the present study was to evaluate the long-term maintenance of intraprocedural end points of ablation procedures.

METHODS AND RESULTS

Inclusion criteria were (1) a previous ablation procedure of pulmonary vein (PV) encircling performed for drug-refractory persistent atrial fibrillation; (2) a "complete" intraprocedural end point, which consisted of voltage abatement inside the lesions, PV disconnection, and exit-block pacing from inside the lesions, attained in all PVs; and (3) stable sinus rhythm documented during a minimum follow-up of 2.5 years after the procedure. Twenty volunteers were selected (12 males, mean age 59+/-7 years) and underwent a repeat electrophysiological study. After a follow-up of 36.4+/-4.7 months, complete voltage abatement was maintained around 32 PVs (40.0%), PV disconnection persisted in 12 (37.5%) of the previously isolated PVs, and exit block was present in 39 PVs (48.7%). Ten patients who underwent a redo ablation procedure because of recurrences of atrial fibrillation were used as the control group. Differences in intraprocedural end-point maintenance between the 2 groups were not statistically significant.

CONCLUSIONS

Common intraprocedural end points such as voltage abatement, PV disconnection, and exit block persist only in a limited number of patients, even when the outcome is favorable during follow-up. Further investigation will be required to determine whether such data will have implications for ablation strategies.

Impact of Transforming Growth Factor-β1 on Atrioventricular Node Conduction Modification by Injected Autologous Fibroblasts in the Canine Heart

Background— Atrioventricular (AV) nodal ablation for management of atrial fibrillation (AF) is irreversible and requires permanent pacemaker implantation. We hypothesized that as an alternative, implantation of autologous fibroblasts in the perinodal region would focally modify AV nodal conduction and that this modulation would be enhanced by pretreatment with transforming growth factor-β1 (TGF-β1), a stimulant of fibroblasts.

Methods and Results— Skin biopsies were taken from 12 mongrel dogs, and derived fibroblasts were dissociated and grown in culture for 2 weeks. Multiple injections (0.25 mL) were made through an 8F NOGA catheter along the fast/slow AV nodal pathways as guided by an electroanatomic mapping system. Seven dogs received fibroblasts alone (1×10 6 cells/mL), 7 dogs received TGF-β1 (5 μg), 4 dogs received fibroblasts and TGF-β1 (1×10 6 cells/mL+5 μg), and 4 dogs received saline only. AV node function was assessed at baseline and after 4 weeks. Saline (80 mL) with assigned therapy (0.25 mL per injection) was injected into the peri-AV nodal region in each dog. At baseline, the AH interval (66±3 ms) and the average RR interval (331±17 ms) in pacing-induced AF were similar in each cohort. The increase in AH interval in normal sinus rhythm was longer after fibroblast (23±4 versus 5±5 ms; P =0.05) and fibroblast plus TGF-β1 (50±5 versus 5±5 ms; P <0.001) injections than with saline alone, with similar findings during high right atrium and distal coronary sinus pacing. The AH interval was not significantly increased after TGF-β1 injections. The AH interval was significantly longer after fibroblast plus TGF-β1 injections than with either therapy (TGF-β1 or fibroblasts) alone. The RR interval during AF was increased in dogs that received fibroblasts alone (110±36 versus −41±34 ms) and to a greater extent with the addition of TGF-β1 (294±108 versus −41±34 ms). No AV block was seen in any cohort at 4 weeks. Labeled fibroblasts that expressed vimentin were identified in all dogs that received cell injections at 4 weeks.

Conclusions— AV nodal modification can be achieved with injected fibroblasts without the creation of AV block. The effect on AV node conduction is substantially enhanced by pretreatment of fibroblasts with TGF-β1. These data have therapeutic potential for the management of rapid ventricular rate during AF without pacemaker implantation.

A perspective on antiarrhythmic drug therapy to treat atrial fibrillation: there remains an unmet need

Because presently available antiarrhythmic drugs are neither as highly efficacious nor as safe as desirable for the prevention of atrial fibrillation (AF), rate control-versus-rhythm control trials for the treatment of AF were evaluated. They demonstrated that rate control is not simply a therapeutic fallback option if rhythm control should fail, but rather, it is a legitimate primary therapeutic option. Nevertheless, there remain many reasons to consider maintenance of sinus rhythm (rhythm control) over AF (rate control) if only there were antiarrhythmic agents that could provide this treatment more effectively and safely. In fact, an important analysis of the AFFIRM trial data indicated that rhythm control offers a significant survival advantage over rate control if it could be safely achieved. Therein lie an important clinical dilemma and an unmet need. Sinus rhythm is good, but we need better ways to maintain it effectively and safely.

Outcomes After Cardiac Perforation During Radiofrequency Ablation of the Atrium

BACKGROUND

Perforation during catheter procedures in either the atrium or ventricle is relatively uncommon, but potentially fatal if tamponade ensues. This study analyzes the occurrence and outcomes of cardiac perforation during catheter-based radiofrequency ablation procedures in the left atrium.

METHODS

All patients with a periprocedure perforation who have undergone radiofrequency ablation for atrial fibrillation (AF) or tachycardia were included.

RESULTS

Of 632 procedures performed from January 1999 to October 2004, 15 (2.4%) were complicated by perforation requiring pericardiocentesis. The perforation site was left atrium in 9 (60.0%), right atrium in 1 (6.7%), and right ventricle in 5 (33.3%). Intracardiac echocardiography was used in 13 (86.7%) and revealed an effusion before overt instability in 11 (73.3%). Thirteen (86.7%) patients developed a blood pressure <60 mmHg. The pressure stabilized in all patients after pericardiocentesis (hypotension to intervention: 10.1 +/- 5.1 minutes). The total blood volume removed was 848 +/- 880 mL (left atrium/right atrium: 1,074 +/- 1,002 vs right ventricle: 396 +/- 266, P = 0.168). Two patients required surgery to close left atrium dome perforations. The ablation was completed in 7 (46.7%) patients. Ten (66.7%) later developed early reoccurrence of AF. All patients were neurologically intact at hospital discharge. During a 1.5 +/- 1.1 year follow-up, AF was eliminated (n = 4) or controlled (n = 1) in 5 (71.4%) patients with complete procedures, and 2 (20.0%) patients underwent successful repeat ablation.

CONCLUSION

The incidence of perforation during ablation of the left atrium is low. Most perforations occur in the left atrium; however, few require surgical closure. Although less than with uncomplicated procedures, the majority of patients with complete ablations achieve long-term elimination of AF.

Rate versus rhythm control in the management of patients with atrial fibrillation

The management of patients with atrial fibrillation involves three main areas: anticoagulation, rate control and rhythm control. Importantly, these are not mutually exclusive of each other. Anticoagulation is necessary for patients who are at a high risk of stroke; for example, those who are older than 75 years, or those who have hypertension, severe left ventricular dysfunction, previous cerebrovascular events, or diabetes. It is now clear that patients who are at a high risk of stroke require long-term anticoagulation with warfarin regardless of whether a rate-control or rhythm-control strategy is chosen. One possible exception might be patients who are apparently cured with catheter ablation. Several published trials comparing rate-control and rhythm-control strategies for the treatment of patients with atrial fibrillation have shown no difference in mortality between these approaches. The patients enrolled in these studies were typically over 65 years of age. Data comparing rate and rhythm strategies in patients who are younger than 60 years of age are limited. For more elderly patients, it seems reasonable to consider rate control as a primary treatment option and to reserve rhythm control for those who do not respond to rate control. For younger patients, we prefer to start with a rhythm-control approach and to reserve rate-control approaches for patients in whom antiarrhythmic drugs, ablation, or both, do not ameliorate the symptoms.

Survey of physician experience, trends and outcomes with atrial fibrillation ablation

OBJECTIVE

We evaluated the prevalence, trends, outcomes and the general experience of physicians performing atrial fibrillation ablation (AF-ABL) in the United States (US).

BACKGROUND

AF-ABL is a non-pharmacological and potentially curative therapy for AF. Success rates for AF-ABL have been reported to be between 80 and 90%. Although there are numerous clinical trial addressing this therapy little is known about the general status of AF-ABL in clinical practice.

METHODS

We administered a mailed survey to the physician members of a professional arrhythmia society (Heart Rhythm Society, formerly known as the North American Society of Pacing and Electrophysiology) who practiced in the US (n = 1843).

RESULTS

There were 304 responses, 66% (n = 204) performed ABL and 30% (n = 92) performed AF-ABL. The study group performed a total of 5,592 AF-ABL from 2000 to 2003, out of 72,575 total ABL procedures during the same time period. There was a four-fold increase in the number of AF-ABL between 2000 and 2003 (2000: 628 vs. 2003: 2,575). In the same period, the self-reported short and long-term success rates of AF-ABL improved an average of 18 +/- 4% (p < or = 0.001). In 2003 the average self-reported one-month, one-year, and two-year success rates were: 71 +/- 4%, 66 +/- 5%, 63 +/- 6% respectively. The predicted five-year success was 60 +/- 4%. The average procedure took 4.5 +/- 0.4 hours. Physicians reported that approximately 29 +/- 4% of their patents were potential candidates for AF-ABL.

CONCLUSIONS

AF-ABL is becoming a much more common procedure in the US. Over the last four years the perceived short and long term success rates of AF-ABL have improved. Success rates in this survey are 10 to 20% lower than those reported in the recent clinical trials.

Pulmonary vein ablation of atrial fibrillation: beyond the traditional

The present review aims at giving a synthesis on the evolution in the last decade of the catheter-based ablative treatments for atrial fibrillation (AF). We report the rationale of current pulmonary vein (PV) ablation techniques: segmental PV isolation and circumferential PV ablation. The endpoint is the electrical isolation of the PVs from the left atrium, as they house foci triggering AF in 80% to 95% of cases and seem to play a key role in arrhythmia maintenance. Recurrence rates of AF after these PV ablation strategies are very encouraging. Two recent randomized trials, AFFIRM and RACE, showed no significant difference in outcomes between a strategy of pharmacological heart rate control and that of restoration and maintenance of sinus rhythm with antiarrhythmic drugs. However, multicenter randomized trials comparing PV ablation with drug therapy are required. Future refinements in catheter technology and navigation systems should provide simpler and faster procedures and render PV ablation more widespread and accepted from the scientific and medical communities.

Prevention of iatrogenic atrial tachycardia after ablation of atrial fibrillation: a prospective randomized study comparing circumferential pulmonary vein ablation with a modified approach

BACKGROUND

Circumferential pulmonary vein ablation (CPVA) is effective in curing atrial fibrillation (AF), but new-onset left atrial tachycardia (AT) is a potential complication. We evaluated whether a modified CPVA approach including additional ablation lines on posterior wall and the mitral isthmus would reduce the incidence of AT after PV ablation.

METHODS AND RESULTS

A total of 560 patients (291 men, 52%; age, 56.5+/-7.3 years) entered the study; 280 were randomized to CPVA alone (group 1) and 280 to modified CPVA (group 2). The primary end point was freedom from AT after the procedure. In group 1, 28 patients (10%) experienced new-onset AT, and 41 (14.3%) experienced recurrent AF. In group 2, 11 patients (3.9%) experienced AT, and 36 (12.9%) had recurrent AF. Group 1 was more likely to experience AT than group 2 (P=0.005). Freedom from AF after ablation was similar in both groups (P=0.57). Among those in group 1, gap-related macroreentrant AT was documented in 23 of the 28 patients (82%), and focal AT was found in 5 (18%). In group 2, gap-related macroreentrant AT was found in 8 of the 11 patients (73%), and focal AT was seen in 3 (27%). Two patients in group 1 and 1 patient in group 2 had both AT and AF. The strongest predictor of AT was the presence of gaps (P<0.001).

CONCLUSIONS

Modified CPVA is as effective as CPVA in preventing AF but is associated with a lower risk of developing incessant AT.

Left atrial tachycardia after circumferential pulmonary vein ablation for atrial fibrillation

OBJECTIVES

The purpose of this study was to evaluate the electroanatomic characteristics of left atrial tachycardia (AT) in a series of patients who underwent circumferential pulmonary vein ablation (CPVA) and to describe the ablation strategy and clinical outcome.

BACKGROUND

Circumferential pulmonary vein ablation is an effective treatment for atrial fibrillation. A potential midterm complication is the development of left AT. There are only isolated reports describing mapping and ablation of such arrhythmias.

METHODS

Thirteen patients (age 57.4 +/- 8.9 years, five female) underwent mapping and ablation of 14 left ATs via an electroanatomic mapping system a mean of 2.6 +/- 1.6 months after CPVA.

RESULTS

Three patients were characterized as having focal AT (cycle length: 266 +/- 35.9 ms). Of 11 macro-re-entrant tachycardias studied in the remaining 10 patients (cycle length: 275 +/- 75 ms), 5 showed single-loop and 6 dual-loop circuits. Re-entrant circuits used the mitral isthmus, the posterior wall, or gaps on previous encircling lines. Such gaps and all three foci occurred anterior to the left superior pulmonary vein or at the septal aspect of the right pulmonary veins. Thirteen of 14 tachycardias (93%) were successfully ablated.

CONCLUSIONS

Left AT after CPVA can be due to a macro-re-entrant or focal mechanism. Re-entry occurs most commonly across the mitral isthmus, the posterior wall, or gaps on previous ablation lines. Such gaps and foci occur most commonly at the anterior aspect of the left superior pulmonary vein and at the septal aspect of the right pulmonary veins. These arrhythmias can be successfully mapped and ablated with an electroanatomic mapping system.