Catheter ablation of paroxysmal atrial fibrillation using a 3D mapping system

Three-dimensional computed tomography overlay for pulmonary vein antrum isolation: Follow-up and clinical outcomes

BACKGROUND

To facilitate the creation of circumferential lines in pulmonary vein (PV) antrum isolation, three-dimensional (3D) navigation systems are used widely. Alternatively, 3D reconstructions of the left atrium (LA) can be superimposed directly on fluoroscopy to guide ablation catheters and to mark ablation sites.

METHODS

In 71 atrial fibrillation patients circumferential PV ablation was performed. 3D reconstructions of the LA were derived from contrast cardiac-computed tomography and circumferential PV isolation was performed. In subsequent ablation procedures, veins were re-isolated, and defragmentation or linear lesions were performed if necessary.

RESULTS

Adequate 3D reconstructions were formed and registered to fluoroscopy in all patients. All veins, except 2 in one single patient, could be isolated, resulting in freedom of AF in 45 patients (63 %). In 19 patients a second procedure was performed, in which 2.7 ± 1.1 PV per patient were re-isolated; in 3 patients a third procedure was performed. After follow-up of 15 ± 8 months, 51 (91 %) of patients with paroxysmal and 10 (67 %) with persistent AF were free of AF.

CONCLUSIONS

The results of 3D overlay for circumferential PV isolation are good, although the reconduction rate and need for subsequent ablations remains high, and the outcomes of this technique appear to be equivalent to other mapping techniques.

AF Ablation: Do You Need a Mapping System for Ablation?

Radiofrequency ablation has become a mainstay in the therapy for atrial fibrillation (AF). Although there are many different techniques for achieving adequate results, the cornerstone of AF remains pulmonary vein isolation. Three-dimensional (3D) electroanatomical mapping systems play an important role in the reduction of fluoroscopy and the identification of electrical and anatomic landmarks and are used commonly in AF ablation procedures. In this article, the authors discuss the advantages and limitations of 3D mapping systems and try to answer the question: Are they needed for successful AF ablation?

2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design

This is a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation, developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology and the European Cardiac Arrhythmia Society (ECAS), and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). This is endorsed by the governing bodies of the ACC Foundation, the AHA, the ECAS, the EHRA, the STS, the APHRS, and the HRS.

Effect of repeated radiofrequency catheter ablation on left atrial function for the treatment of atrial fibrillation

Radiofrequency catheter ablation (RFCA) is a potential curative treatment for atrial fibrillation (AF) by eliminating the arrhythmia and inducing left atrial (LA) reverse remodeling. However, the effect on LA function, especially after repeated procedures, has scarcely been studied. The aim of this study was to evaluate the impact of RFCA on LA size and function in patients with AF after a first and a repeated procedure. RFCA was performed in 154 patients with symptomatic drug-refractory AF. LA volumes and function were assessed with real-time 3-dimensional echocardiography before and 6 months after the procedure. Recurrence of the arrhythmia was defined as any atrial tachyarrhythmia lasting >30 seconds, clinically documented or by 24-hour Holter recording, after the first 6 months after ablation. Of the 154 patients, 104 (67%) required only a first ablation, and 50 (33%) required redo RFCA. LA volume was reduced after first RFCA (from 60 ± 19 to 52 ± 17 ml for 3-dimensional LA maximum volume, p <0.001, and from 38 ± 18 to 33 ± 15 ml for 3-dimensional LA minimum volume, p <0.000) without impairment of LA contractile function, measured as the active emptying percentage of total volume (39 ± 25% vs 43 ± 26%, p = NS). After repeated RFCA procedures, 3-dimensional LA maximum volume was reduced (from 57 ± 18 to 52 ± 18 ml, p = 0.04), also without further LA contractile function impairment (active emptying percentage of total volume) (36 ± 24% vs 36 ± 25% of total volume, p = NS). This effect was similar in paroxysmal and persistent AF. In conclusion, RFCA induces reductions in LA volumes without a deleterious impact on contractile function, even after repeated ablation.

Incidental extracardiac findings in cardiac computed tomography performed before radiofrequency ablation of atrial fibrillation

BACKGROUND

Radiofrequency ablation has became a validated therapeutic technique for symptomatic drug refractory atrial fibrillation (AF). Cardiac computed tomography (CT) is used to evaluate left atrial (LA) anatomy in order to improve AF ablation. The analysis of noncardiac structures during cardiac CT may identify clinically significant incidental findings (IFs). The objective of this study was to determine the prevalence of IF in patients undergoing AF catheter ablation.

METHODS

Between February 2008 and March 2010, all patients planned for a first procedure of AF or LA tachycardia (LAT) ablation underwent a cardiac CT scan and were retrospectively included in this study. Extracardiac IFs were considered to be present if an abnormality was identified without previous clinical suspicion or known disease.

RESULTS

Two hundred and fifty patients (55.2 ± 9.6 years of age, 82.4% men) were enrolled (133 paroxysmal, 43 persistent, 58 permanent AF, and 16 LAT). Fifty-eight patients (23.2%) had a total of 76 IFs. Patients with IF were significantly older (59.5 ± 8.2 vs 53.8 ± 9.7 years old, P < 0.001). No relationship existed between the type of arrhythmia and IF existence. The majority of IFs were pulmonary (50%), with 15.8% of pulmonary emphysema. Two cases of lung cancer and of pulmonary fibrosis, 15 mediastinal adenopathies, and three congenital coronary arteries anomalies were found.

CONCLUSIONS

Cardiac CT scan is a useful tool to evaluate LA morphology before AF ablation. However, as a considerable prevalence of IF was found in our study, extracardiac structures should be routinely analyzed to detect unknown conditions, which could require specific management.

CARTO-guided vs. NavX-guided pulmonary vein antrum isolation and pulmonary vein antrum isolation performed without 3-D mapping: effect of the 3-D mapping system on procedure duration and fluoroscopy time

PURPOSE

Pulmonary vein antrum isolation (PVAI) guided by intracardiac echocardiography and a roaming circular mapping catheter is an effective treatment modality for atrial fibrillation. Unfortunately, the complexity of this technique leads to long procedure times and high fluoroscopy exposure. This study examined the effect of two different mapping systems on the procedural characteristics and clinical outcomes of PVAI for atrial fibrillation.

METHODS

Referred patients underwent PVAI using a magnetic-based 3-dimensional (3-D) mapping (CARTO® System; group 1), a current-based system (EnSite NavX™; group 2), or fluoroscopy without 3-D mapping (group 3) between February 2004 and November 2009.

RESULTS

Data were analyzed from 71 patients in group 1, 165 patients in group 2, and 197 patients in group 3. Baseline characteristics and measured long-term outcomes did not differ between the groups. Although patients in group 1 were more likely to undergo a concurrent flutter ablation (P = 0.01), they had significantly shorter procedure time, fluoroscopy time, and radiofrequency energy delivery time compared with group 2 and 3 patients. No difference was detected among the groups with respect to recurrence, mean time to recurrence, or number of PVAI procedures.

CONCLUSIONS

Use of a magnetic-based 3-D mapping system, which allows precise spatial localization of the ablation catheter, was associated with significantly lower procedure time, fluoroscopy duration, and radiofrequency energy delivery time during catheter ablation for atrial fibrillation compared with a current-based system and ablation performed without 3-D mapping, although measured short- and long-term clinical outcomes were similar.

The impact of catheter-tracking technologies on efficacy and safety in cardiac electrophysiology

Usage of nonfluoroscopic mapping systems is increasingly common in invasive cardiac electrophysiology. Novel technologies have resulted in numerous systems potentially leading to improved outcomes of the procedures. Apart from the improvement in procedural outcomes, usage of these systems is associated with a significant reduction in x-ray exposure.

Minimally invasive radiofrequency ablation of lone atrial fibrillation by monolateral right minithoracotomy: operative and early follow-up results

BACKGROUND

Although an increasing number of symptomatic patients with atrial fibrillation (AF) are being treated with percutaneous radiofrequency ablation, the actual long-term success rate of this procedure remains uncertain. The increasing availability of minimally invasive techniques has made surgery progressively more appealing, especially because of its superior capacity to create transmural lesions.

METHODS

In a group of 46 patients with paroxysmal or persistent "lone" AF, who were refractory to medical treatment or had arrhythmia recurrences after a transcatheter procedure, we performed epicardial radiofrequency ablation by a minimally invasive, monolateral thoracoscopic approach. Mean operative time was 85 +/- 35 minutes, and intensive care unit and hospital stays were, respectively, 18.7 +/- 5.1 hours and 4.1 +/- 1.4 days. There were no deaths and only 1 serious complication due to severe bleeding requiring conversion to median sternotomy.

RESULTS

At the 6-month follow-up (Holter monitoring), 40 patients (87%) were in stable sinus rhythm. Of the 6 recurrences that we observed, 5 occurred in patients with persistent AF and 1 in a patient with paroxysmal AF (p < 0.01).

CONCLUSIONS

Minimally invasive monolateral thoracoscopic radiofrequency ablation is safe and apparently effective. If these findings are confirmed on larger populations followed for longer periods, this procedure may become a viable proposal for treating refractory lone AF.

Very late recurrences of atrial fibrillation after pulmonary vein isolation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, accounting for approximately one-third of all hospitalizations from cardiac rhythm disturbances. Over the past decade, catheter ablation (predominantly in the form of pulmonary vein isolation [PVI]) has become an important therapy in the treatment of patients with symptomatic, drug-refractory AF. Despite the improvements in technology, operator experience, and advances in methodology that have led to higher success rates and a reduction in complications, the recurrence rate of AF after PVI is still relatively high. Published studies suggest that approximately 33% to 86% of patients undergoing catheter ablation of AF have freedom from recurrent AF, with 30% to 40% requiring a second procedure. Although most studies looking at the efficacy of PVI are limited by relatively short follow-up, recent data suggest that patients with an initially favorable procedural response may have very late recurrences of AF, even years after PVI. It is likely that the mechanism behind very late recurrences of AF is multifactorial, involving both recurrent pulmonary vein triggers and progressive remodeling of left atrial substrate over time, making it more vulnerable to triggering. These recurrences have important clinical implications in the care of patients, specifically with regard to the increased risk of stroke associated with AF.

Circumferential pulmonary vein ablation: does use of a circular mapping catheter improve results? A prospective randomized study

BACKGROUND

The best method for performing atrial fibrillation (AF) ablation is still under debate. The importance of using a circular mapping (CM) catheter for assessing isolation of the pulmonary vein (PV) antrum on the outcome of the procedure has not been clearly established.

OBJECTIVE

The purpose of this study was to evaluate whether use of a CM catheter improves the arrhythmia-free proportion after circumferential pulmonary vein ablation (CPVA).

METHODS

A series of 146 consecutive patients (83% males, age 53 +/- 10 years, 53% paroxysmal AF) were randomized to two ablation strategies. In both groups, ipsilateral PV encirclement was performed until disappearance or dissociation of the local electrogram within the surrounded area. In the first group, only the radiofrequency catheter was used to both map and ablate (CPVA group, n = 73). In the other group, a CM catheter was added to assess the electrical activity of the PV antrum (CPVA-CM group, n = 73). An ablation line along the left atrial roof was also created in all patients.

RESULTS

Procedural and fluoroscopic times were longer in the CPVA-CM group (P <.05). Severe procedure-related complications occurred in 1 (1.4%) patient in the CPVA group and in 3 (4.1%) patients in the CPVA-CM group (P = .317). After mean follow-up of 9 +/- 3 months, 31 (42.5%) patients in the CPVA group and 47 (64.4%) patients in the CPVA-CM group were arrhythmia-free without antiarrhythmic medication (P = .008).

CONCLUSION

Use of a CM catheter to ensure isolation of the PV antrum improved the success of CPVA but increased some procedural requirements.

Three-dimensional electroanatomic mapping systems in catheter ablation of atrial fibrillation

Atrial fibrillation (AF) is the most common tachyarrhythmia, with a prevalence of 5% in people over the age of 65. Catheter ablation of AF has emerged as an important management choice for drug-refractory symptomatic paroxysmal or persistent AF. Three-dimensional (3D) electroanatomic mapping systems were introduced into catheter ablation of AF more than a decade ago. The 3D tool has the benefit of reducing the radiation exposure time, as well as voltage and fractionation mapping in order to identify the critical substrate during the ablation, prevent the formation of gaps, guide the ablation of post-ablation atrial tachycardia or flutter, and integrate images to improve the safety and long-term success rate. The 3D systems successfully enable safe and tailored radiofrequency ablation of AF in individual patients. (Circ J 2010; 74: 18 - 23).

Cost-Effectiveness Of Catheter Ablation Treatment For Patients With Symptomatic Atrial Fibrillation

Background: Atrial Fibrillation is the most common cardiac arrhythmia. It increases the risk of thromboembolic events and many atrial fibrillation patients suffer quality of life impairment due to disturbed heart rhythm. Pulmonary vein isolation using radiofrequency catheter ablation treatment is aimed at maintaining sinus rhythm ultimately improving quality of life. Randomized clinical trial have shown that catheter ablation is more effective than antiarrhythmic drugs for the treatment of atrial fibrillation, but its impact on quality of life and cost-effectiveness has not been widely studied. Aims: To assess the cost-effectiveness of radiofrequency ablation (RFA) vs. antiarrhythmic drug (AAD) treatment, among symptomatic atrial fibrillation patients not previously responding to AAD. Methods: A decision-analytic Markov model was developed to assess costs and health outcomes in terms of quality adjusted life years (QALYs) of RFA and AAD over a lifetime time horizon. We conducted a literature search and used data from several sources as input variables of the model. One-year rates of atrial fibrillation with RFA and AAD, respe tively, were available from published randomized clinical trials. Other data sources were published papers and register data. Results: The RFA treatment strategy was associated with reduced costs and an incremental gain in QALYs compared to the AAD treatment strategy. The results were sensitive to whether long-term quality of life improvement is maintained for the RFA treatment strategy and the risk of stroke in the different atrial fibrillation health states. Conclusion: This study shows that the short-term improvement in atrial fibrillation associated with RFA is likely to lead to long-term quality of life improvement and lower costs indicating that RFA is cost-effective compared to AAD.

Prevalence and causes of fatal outcome in catheter ablation of atrial fibrillation

OBJECTIVES

The purpose of this study was to provide a systematic multicenter survey on the incidence and causes of death occurring in the setting of or as a consequence of catheter ablation (CA) of atrial fibrillation (AF).

BACKGROUND

CA of AF is considered to be generally safe. However, serious complications, including death, have been reported.

METHODS

Using a retrospective case series, data relevant to the incidence and cause of intra- and post-procedural death occurring in patients undergoing CA of AF between 1995 and 2006 were collected from 162 of 546 identified centers worldwide.

RESULTS

Thirty-two deaths (0.98 per 1,000 patients) were reported during 45,115 procedures in 32,569 patients. Causes of deaths included tamponade in 8 patients (1 later than 30 days), stroke in 5 patients (2 later than 30 days), atrioesophageal fistula in 5 patients, and massive pneumonia in 2 patients. Myocardial infarction, intractable torsades de pointes, septicemia, sudden respiratory arrest, extrapericardial pulmonary vein (PV) perforation, occlusion of both lateral PVs, hemothorax, and anaphylaxis were reported to be responsible for 1 death each, while asphyxia from tracheal compression secondary to subclavian hematoma, intracranial bleeding, acute respiratory distress syndrome, and esophageal perforation from an intraoperative transesophageal echocardiographic probe were causes of 1 late death each.

CONCLUSIONS

Death is a complication of CA of AF, occurring in 1 of 1,000 patients. Knowledge of possible precipitating causes is key to operators and needs to be considered during decision making with patients.

Predictors of Success After a First Circumferential Pulmonary Vein Isolation For Atrial Fibrillation

Background: To identify and characterise pre-procedural and procedural parameters which predict maintenance of sinus rhythm after a first circumferential pulmonary vein isolation (CPVI) for recurrent atrial fibrillation (AF). Methods: 100 patients (54±10 yrs) undergoing CARTO-guided CPVI for symptomatic drug refractory, paroxysmal or shortstanding persistent AF were studied. The endpoint was complete electrical isolation within the encircled regions. 3D left atrial (LA) volume was measured by CARTO geometry. Follow-up examinations (symptoms, ECG, 24-hour ECG recording) were performed at 1 and 3 months and every 3 months thereafter. Results: After the first CPVI, 71 patients (71%) were free of AF without antiarrhythmic drug therapy (follow up:28±11 months). The only independent and significant predictors for freedom of AF after the first CPVI were duration of AF history and 3D LA volume (p<0.05). However, a significant overlap in durations of AF history and 3D LA volumes between failures and successes was observed. Conclusions: (1) Using the "circumferential pulmonary vein isolation" approach, the first catheter ablation leads to resolution of arrhythmia in ≈ 70% of symptomatic AF patients. (2) Independent predictors for freedom of AF after initial CPVI are duration of AF history and 3D LA volume. (3) Due to considerable overlap between failures and successes, these parameters can not be used to identify patients who should not undergo CPVI or in whom an additional ablation beyond CPVI is required. On the other hand, our results do suggest that an ablation strategy early in the course of AF disease can influence successful outcome.

Effectiveness of catheter ablation versus antiarrhythmic drug therapy for atrial fibrillation

PURPOSE OF REVIEW

The optimal treatments for atrial fibrillation have long been sought among rhythm control and rate control strategies. Unfortunately, rhythm control strategies with antiarrhythmic drugs have proven to be a disappointment. Catheter ablation techniques, however, have been rapidly advancing and have the potential to offer a permanent cure. Rhythm control with catheter ablation may in fact be a superior treatment modality for atrial fibrillation. The purpose of this review is to examine the evidence in favor of this argument.

RECENT FINDINGS

The dissatisfaction with poorly performing antiarrhythmic drug therapies for the treatment of atrial fibrillation has fueled the development of alternative therapies for rhythm control. Catheter ablation has emerged as a viable, efficacious, and safe alternative. In fact, in head to head comparisons with antiarrhythmic drugs, catheter ablation continues to come out on top with often markedly superior performances. In addition to efficacy and safety, catheter ablation also seems to be a fiscally viable alternative.

SUMMARY

On the basis of the outstanding performance of catheter ablation compared with antiarrhythmic drug therapy, it is not surprising to see its widespread adoption and ever expanding indications.

Feasibility and safety of remote-controlled magnetic navigation for ablation of atrial fibrillation

Radiofrequency ablation for atrial fibrillation (AF) involves complex catheter manipulation resulting in prolonged procedure time and fluoroscopy exposure. Remote magnetic navigation (RMN) represents a novel approach toward improving the ability to perform complex ablation. Forty patients underwent ablation for AF, 20 using RMN (NIOBE II, Stereotaxis, Inc) with a 4-mm-tip magnetic catheter (Celsius, Biosense Webster) and 20 using a conventional 8-mm-tip bidirectional ablation catheter (Blazer, Boston Scientific). All patients underwent a combined wide area circumferential ablation and segmental pulmonary vein (PV) isolation using a circular mapping catheter and cavotricuspid isthmus ablation for right atrial flutter. The procedural end point was PV entrance block. There was no difference in atrial size, left ventricular systolic function, or type of AF between groups. PV entrance block was achieved in all patients. Mean procedure time was 279 +/- 60 minutes in the conventional group versus 209 +/- 56 minutes in the RMN group (p <0.001). Mean fluoroscopy time in the conventional group was 58.6 +/- 21 minutes versus 19.5 +/- 9.8 in the RMN group (p <0.001). At 1 year there were 15 patients in the conventional group and 16 in the RMN group free from clinical AF and off antiarrhythmic drugs (p = NS). There were 2 additional ablations performed for atypical atrial flutter in the conventional group and 3 in the RMN group (p = ns). Ablation catheter char formation was not observed. There were no procedural complications. In conclusion, radiofrequency ablation of AF performed with RMN is safe and feasible. Compared with conventional hand-navigated ablation, RMN ablation results in similar clinical outcomes with decreased fluoroscopy and procedure times.

Innovation focus: the patient with arrhythmia

Great strides have been made over the last two decades in the management of patients with rhythm disorders. Despite this, however, the remaining critical problems of stroke related to atrial fibrillation or as a result of radiofrequency ablation require innovative solutions to fully realize the potential of these recent advances. Similarly, implanted cardiac devices have revolutionized the care of patients with bradyrhythmias and tachyarrhythmias. Dyssynchronus ventricular pacing associated with present devices; however, results in heart failure, tricuspid regurgitation, and inappropriate device therapy once again create a demand for creative solutions. While not technically an arrhythmia, epilepsy management today is riddled with many of the problems that plagued cardiac arrhythmia management previously, and thus an appreciation of the similarities in requirement for investigative solutions may yield groundbreaking solutions. In this paper, we describe some novel methods to reduce complications associated with rhythm disorders and their treatment and apply the lessons learned from cardiovascular arrhythmia management to the brain. These include: a method to reduce coagulum formation and thus subsequent thromboembolism with indwelling catheters specifically during radiofrequency ablation procedures; a technique to ligate the left atrial appendage through percutaneous subxiphoid pericardial access; development and testing of a novel intramyocardial pace-sense lead, particularly used in a unique anatomic location (the atrioventricular septum) to allow pacing the ventricles in a relatively synchronous manner without crossing the tricuspid valve or entering the coronary sinus; finally, novel modifications of the cardiovascular mapping and ablation techniques used for the management of the central nervous system disorders primarily via the venous drainage of the brain. Innovative and potential solutions to treat the patient with arrhythmia are presented.

Myocardial electrical impedance as a predictor of the quality of RF-induced linear lesions

Production of complete (i.e. continuous and transmural) cardiac lesions by radiofrequency (RF) ablation can cure certain cardiac arrhythmias. However, a predictor of lesion completeness that is reliable and can be measured intraoperatively is needed in order to maximize effectiveness of ablation therapy. Predictors that require membrane excitation or response to stimulation are not always practical. This study tested whether changes of myocardial impedance across the lesion can predict completeness. RF energy was applied epicardially on perfused rabbit ventricles to produce linear lesions that were complete (n = 25) or incomplete (noncontinuous or nontransmural, n = 25). Before and after creation of each lesion, the magnitude and phase of impedance at 1 kHz were measured with a four-electrode epicardial array across the lesion. For 16 of the lesions, the translesion stimulus-excitation delay was also measured. Lesion completeness was evaluated with 2,3,5-triphenyltetrazolium chloride stain. Complete lesions increased resistivity by 26 Omega cm (21% of the preablation value, p = 0.0007, n = 17) when the inactive RF electrode remained on the epicardium during impedance measurements. When the RF electrode was removed during measurements, the rise of resistivity by complete lesions increased to 58 Omega cm (30% of the preablation value, p = 0.022, n = 8). For incomplete lesions, resistivity did not change significantly. Ablation did not significantly alter the phase of impedance. Accuracies of predictions of lesion completeness by the change in resistivity or the change in translesion stimulus-excitation delay were comparable (Youden's index 0.75 and 0.625, respectively, n = 16). Thus, RF ablation increases myocardial resistivity. The resistivity can predict lesion completeness and may provide an alternative to predictors based on excitation.

Effect of presenting rhythm on image integration to direct catheter ablation of atrial fibrillation

INTRODUCTION

Magnetic resonance (MR) imaging of the left atrium (LA) can be integrated with electroanatomic mapping systems to guide catheter ablation of atrial fibrillation (AF). The usefulness of this technique is dependent on the accuracy of image integration.

OBJECTIVE

The aim of this study is to determine the effect of heart rhythm at the time of pre-procedure MR imaging and heart rhythm at the time of ablation on integration error.

METHODS

Fifty-two consecutive patients who underwent catheter ablation for AF were included. All patients underwent MR imaging of LA and pulmonary veins and image integration with real-time electroanatomic mapping. The rhythm at the time of MR imaging and on the day of ablation was recorded. CARTO-Merge software (Biosense-Webster) was used to calculate the average accuracy of integration of electroanatomic points with MR-derived reconstructions.

RESULTS

There was no significant difference in integration error between patients who were in AF at the time of their MR vs. those who were in sinus rhythm at the time of their MR (1.76 +/- 0.26 vs. 1.88 +/- 0.31 mm, p = 0.15). There was also no significant difference in integration error between patients who were in concordant vs. discordant rhythms at the time of MR vs. day of ablation (1.81 +/- 0.23 vs. 1.89 +/- 0.32 mm, p = 0.40). There was a trend toward less integration error between patients who were in AF on the day of ablation vs. those in sinus rhythm (1.74 +/- 0.26 vs. 1.89 +/- 0.31 mm, p = 0.07).

CONCLUSIONS

Image integration can be performed to direct catheter ablation of AF regardless of the rhythm at the time of imaging and ablation.

Preventive ablation strategies in a biophysical model of atrial fibrillation based on realistic anatomical data

Ablation strategies to prevent episodes of paroxysmal atrial fibrillation (AF) have been subject to many clinical studies. The issues mainly concern pattern and transmurality of the lesions. This paper investigates ten different ablation strategies on a multilayered 3-D anatomical model of the atria with respect to 23 different setups of AF initiation in a biophysical computer model. There were 495 simulations carried out showing that circumferential lesions around the pulmonary veins (PVs) yield the highest success rate if at least two additional linear lesions are carried out. The findings compare with clinical studies as well as with other computer simulations. The anatomy and the setup of ectopic beats play an important role in the initiation and maintenance of AF as well as the resulting therapy. The computer model presented in this paper is a suitable tool to investigate different ablation strategies. By including individual patient anatomy and electrophysiological measurement, the model could be parameterized to yield an effective tool for future investigation of tailored ablation strategies and their effects on atrial fibrillation.

Left atrial contractility is preserved after successful circumferential pulmonary vein ablation in patients with atrial fibrillation

INTRODUCTION

Circumferential pulmonary vein ablation (CPVA) for atrial fibrillation (AF) consists of creating extensive lesions in the left atrium (LA). The aim of the study was to evaluate changes in LA contractility after ablation and their relationship with procedure outcome.

METHODS AND RESULTS

A series of 90 consecutive patients underwent cardiac magnetic resonance imaging (MRI) before and 4-6 months after CPVA. Only patients in sinus rhythm during both imaging acquisitions were included in the study to measure LA end-diastolic (LAmax) and LA end-systolic (LAmin) volumes. Fifty-five patients were finally analyzed (41 men, 52 +/- 11 years, 74% paroxysmal AF). During a mean follow-up of 12 +/- 7 months and after 1.2 +/- 0.3 ablation procedures, 38 patients (69%) were arrhythmia-free (group I), and the remaining 17 patients had recurrences (group II). There was a significant decrease in mean LAmax volume in both groups, whereas mean LAmin volume only decreased in group I. Mean LA ejection fraction (EF) was preserved after CPVA in group I (40 +/- 11% vs 38 +/- 10%; P = 0.27) but decreased in patients with arrhythmia recurrences (37 +/- 10% vs 27 +/- 10%; P < 0.001). In fact, LA EF remained stable or increased in 68% of patients without arrhythmia recurrences.

CONCLUSIONS

LAmax volume reduction following CPVA occurs regardless of the clinical efficacy of the procedure, whereas mean LAmin volume only decreased in patients without recurrences. LA EF was preserved or even increased in most patients with successful CPVA.

Thoracoscopic microwave ablation of atrial fibrillation

The aim of the study was to assess the safety and efficacy of thoracoscopic microwave ablation in treating atrial fibrillation (AF). AF predisposes to embolic complications and may cause heart failure. The treatment of AF is still challenging in spite of the promising results of endocardial radiofrequency approach. The present study is a follow-up study of 22 patients (mean age 45 years, range 21-59) with disabling paroxysmal (n=10) or persistent (n=12) AF who underwent a thoracoscopic microwave isolation of pulmonary veins. The patients had a lone AF. All the patients had suffered from severely disabling AF for >1 year (range 1-16 years) without any response to antiarrhythmic medication. The patients have been followed-up on an average of 11 months (range 3-22 months). During the follow-up, 13 (60%) patients have become asymptomatic without any documentation of AF since at least two months, six (27%) patients with anti-arrhythmic medication have clinically improved. Because of major intrathoracic bleeding and because of liver damage the thoracoscopy wound had to be expanded to open thoracotomy in two patients. Thoracoscopic AF microwave ablation seems to be a promising alternative to endocardial ablation in the treatment of highly symptomatic paroxysmal and persistent AF.

Cost Comparison of Catheter Ablation and Medical Therapy in Atrial Fibrillation

INTRODUCTION

There is emerging evidence for clinical superiority of catheter ablation over rate and rhythm control strategies in paroxysmal atrial fibrillation (PAF). The objective of this study was to compare costs related to medical therapy versus catheter ablation for PAF in Ontario (Canada).

METHODS

Costs related to medical therapy in the analysis included the cost of anticoagulation, rate and rhythm control medications, noninvasive testing, physician follow-up visits, and hospital admissions, as well as the cost of complications related to this management strategy. Costs related to catheter ablation were assumed to include the cost of the ablation tools (electroanatomic mapping or intracardiac echocardiography-guided pulmonary vein ablation), hospital and physician billings, and costs related to periprocedural medical care and complications. Costs related to these various elements were obtained from the Canadian Registry of Atrial Fibrillation (CARAF), government fee schedules, and published data. Sensitivity analyses looking at a range of initial success rates (50-75%) and late attrition rates (1-5%), prevalence of congestive heart failure (CHF) (20-60%), as well as discounting varying from 3% to 5% per year were performed.

RESULTS

The cost of catheter ablation ranged from $16,278 to $21,294, with an annual cost of $1,597 to $2,132. The annual cost of medical therapy ranged from $4,176 to $5,060. Costs of ongoing medical therapy and catheter ablation for PAF equalized at 3.2-8.4 years of follow-up.

CONCLUSION

Catheter ablation is a fiscally sensible alternative to medical therapy in PAF with cost equivalence after 4 years.

Recent insights into the pathophysiology of atrial fibrillation

Although the problem of atrial fibrillation is now widely appreciated, the fundamental mechanisms that lead to arrhythmia onset and persistence have been difficult to elucidate. As a result, available pharmacologic therapies have focused more on modifying ion channel activity than on the underlying mechanisms. Recent studies suggest an important role for alterations in autonomic regulation, neurohormonal activation, and a systemic inflammatory state in the genesis and persistence of atrial fibrillation. The relative contributions of these distinct pathways to atrial fibrillation likely vary from patient to patient, and within a patient, as a function of age. Tailored therapies, together with patient-specific ablative interventions, may increase the success with which atrial fibrillation is treated and minimize the occurrence of life-threatening thromboembolic complications.

Catheter ablation as first-line therapy for patients with symptomatic atrial fibrillation

Atrial fibrillation (AF) is a common clinical problem that is associated with an impaired quality of life, thromboembolism, heart failure and death. Medical treatment of AF remains suboptimal and is associated with potentially serious side effects. The disappointing outcomes with medical therapy have spurred the age of catheter ablation of AF. In the last 10 years, catheter ablation of AF has evolved dramatically and has been shown to be superior to medical therapy in multiple studies. As a result, catheter ablation may be offered to the symptomatic patient as first-line therapy in lieu of antiarrhythmic medications, which have limited efficacy and are associated with significant toxicity.