The creation of linear contiguous lesions in the atria with an expandable loop catheter

Radiofrequency ablation to achieve durable pulmonary vein isolation

Pulmonary vein isolation (PVI) by radiofrequency (RF) ablation is an important alternative to antiarrhythmic drugs in the treatment of symptomatic atrial fibrillation. However, the inability to consistently achieve durable isolation of the pulmonary veins hampers the long-term efficacy of PVI procedures. The large number of factors involved in RF lesion formation and the complex interplay of these factors complicate reliable creation of durable and transmural ablation lesions. Various surrogate markers of ablation lesion formation have been proposed that may provide information on RF lesion completeness. Real-time assessment of these surrogates may aid in the creation of transmural ablation lesions, and therefore, holds potential to decrease the risk of PV reconnection and consequent post-PVI arrhythmia recurrence. Moreover, titration of energy delivery until lesions is transmural may prevent unnecessary ablation and subsequent adverse events. Whereas several surrogate markers of ablation lesion formation have been described over the past decades, a 'gold standard' is currently lacking. This review provides a state-of-the-art overview of ablation strategies that aim to enhance durability of RF-PVI, with special focus on real-time available surrogates of RF lesion formation in light of the biophysical basis of RF ablation.

Lesion Sequence and Catheter Spatial Stability Affect Lesion Quality Markers in Atrial Fibrillation Ablation

OBJECTIVES

This study sought to analyze high-frequency catheter excursion in relation to lesion quality markers in 20 consecutive patients undergoing first-time radiofrequency (RF) ablation for paroxysmal atrial fibrillation (AF).

BACKGROUND

Ablation therapy for AF requires the delivery of durable lesions. The extent to which lesion sequence, catheter spatial stability, and anatomic location influence lesion formation during RF ablation of AF is not well understood.

METHODS

Three-dimensional spatial excursion of the ablation catheter sampled at 60 Hz during pre-specified pairs of RF lesions was extracted from the CARTO3 System (Biosense Webster Inc., Irvine, California) and analyzed by using custom-developed MATLAB software (MathWorks, Natick, Massachusetts) to define precise catheter spatial stability during RF ablation. Ablation parameters including bipolar electrogram amplitude reduction, impedance decline and transmurality-associated unipolar electrogram (TUE) as evidence of lesion transmurality during lesion placement were recorded and analyzed.

RESULTS

We collected 437,760 position data points during lesion placement. Ablation catheter spatial stability and lesion formation parameters varied considerably by anatomic location. Lesions placed immediately had similar bipolar electrogram amplitude reduction, smaller impedance decline, but higher likelihood of achieving TUE compared to delayed lesions. Greater catheter spatial stability correlated with lesser impedance decline.

CONCLUSIONS

Lesion sequence, ablation catheter spatial stability, and anatomic location are important modifiers of RF lesion formation. Lesions placed immediately are more likely to exhibit TUE. Greater ablation catheter stability is associated with lesser impedance decline but greater likelihood of TUE.

Electrogram voltage and pacing threshold before ablation, measured by mini-electrodes, predict parameters indicative of transmural lesions in the human atrium

PURPOSE

An important attenuation of the atrial signal recorded with mini-electrodes (ME) embedded in an 8-mm tip was associated with a transmural radiofrequency lesion. Our aim was to assess if parameters obtained from ME or conventional bipoles before applications predict successful atrial lesions.

METHODS

We prospectively included 33 consecutive patients undergoing cavotricuspid isthmus (CTI) ablation. Electrogram voltages and pacing thresholds were measured with ME and conventional bipoles before and after radiofrequency (RF) applications. The time before the loss of capture during applications was recorded. Lesions were considered successful, in accordance with preclinical data, if ME voltage decreased > 54%.

RESULTS

Of 207 applications, 107 could be analyzed. During applications, voltages decreased more in the ME than in the conventional bipoles (66.8 ± 26.1% vs 37.5 ± 42.5%, P = 0.001). Likewise, pacing threshold increased significantly more using the ME (86.3 ± 22.9% ME, 52.6 ± 35.6% conventional, P = 0.001). ME pre-ablation voltages were significantly higher and pacing thresholds significantly lower in successful lesions (voltage 0.88 ± 0.71 vs 0.26 ± 0.18 mV, P = 0.0001; threshold 1.6 ± 1.7 vs 2.8 ± 3.0, P = 0.04). Neither of these parameters with conventional bipoles nor time to loss of capture showed differences. A ME voltage > 0.33 mV and a pacing threshold < 1.5 mA predicted a successful lesion with 0.78 and 0.6 sensitivity and 0.78 and 0.59 specificity.

CONCLUSIONS

Certain pre-ablation parameters derived from ME such as electrogram voltage and pacing threshold differ from those obtained by a conventional configuration and can predict a successful atrial lesion.

Intrapulmonary Vein Ablation Without Stenosis: A Novel Balloon-Based Direct Current Electroporation Approach

Background

Current thermal ablation methods for atrial fibrillation, including radiofrequency and cryoablation, have a suboptimal success rate. To avoid pulmonary vein (PV) stenosis, ablation is performed outside of the PV, despite the importance of triggers inside the vein. We previously reported on the acute effects of a novel direct current electroporation approach with a balloon catheter to create lesions inside the PVs in addition to the antrum. In this study, we aimed to determine whether the effects created by this nonthermal ablation method were associated with irreversible lesions and whether PV stenosis or other adverse effects occurred after a survival period.

Methods and Results

Initial and survival studies were performed in 5 canines. At the initial study, the balloon catheter was inflated to contact the antrum and interior of the PV. Direct current energy was delivered between 2 electrodes on the catheter in ECG‐gated 100 μs pulses. A total of 10 PVs were treated demonstrating significant acute local electrogram diminution (mean amplitude decrease of 61.2±19.8%). After the survival period (mean 27 days), computed tomography imaging showed no PV stenosis. On histologic evaluation, transmural, although not circumferential, lesions were seen in each treated vein. No PV stenosis or esophageal injury was present.

Conclusions

Irreversible, transmural lesions can be created inside the PV without evidence of stenosis after a 27‐day survival period using this balloon‐based direct current ablation approach. These early data show promise for an ablation approach that could directly treat PV triggers in addition to traditional PV antrum ablation.

Catheter ablation of persistent atrial fibrillation : Circumferential pulmonary vein ablation: beneficial effect of an additional linear lesion at the roof of the left atrium on the long-term outcome

BACKGROUND

Circumferential pulmonary vein ablation is still the standard approach in patients with persistent atrial fibrillation. However, the results are not very favourable and more complex ablation strategies are the subject of current controversy. Therefore, we have evaluated the effect of an additional linear lesion at the roof of the left atrium on the long-term outcome.

METHODS

A total of 125 patients with symptomatic persistent atrial fibrillation underwent a circumferential pulmonary vein ablation procedure in combination with an additional linear lesion at the roof of the left atrium (group A). The long-term follow-up data was compared to 125 patients with similar clinical characteristics who underwent circumferential pulmonary vein ablation without an additional linear lesion at the roof of the left atrium (group B).

RESULTS

The ablation procedure could be performed as planned in all 250 patients. Three years after catheter ablation, the success rate was 72.0% (no arrhythmia recurrence in 90 out of 125 patients) in group A and 63.2% in group B (no arrhythmia recurrence in 79 out of 125 patients; P = 0.04). There were no major complications.

CONCLUSIONS

Catheter ablation of persistent atrial fibrillation comprising a circumferential pulmonary vein ablation and an additional linear lesion at the roof of the left atrium provides more favourable long-term results than circumferential pulmonary vein ablation alone.

Catheter ablation of atrial fibrillation facilitated by preprocedural three-dimensional transesophageal echocardiography: Long-term outcome

AIM

To evaluate the long-term outcome of catheter ablation of atrial fibrillation (AF) facilitated by preprocedural three-dimensional (3-D) transesophageal echocardiography.

METHODS

In 50 patients, 3D transesophageal echocardiography (3D TEE) was performed immediately prior to an ablation procedure (paroxysmal AF: 30 patients, persistent AF: 20 patients). The images were available throughout the ablation procedure. Two different ablation strategies were used. In most of the patients with paroxysmal AF, the cryoablation technique was used (Arctic Front Balloon, CryoCath Technologies/Medtronic; group A2). In the other patients, a circumferential pulmonary vein ablation was performed using the CARTO system [Biosense Webster; group A1 (paroxysmal AF), group B (persistent AF)]. Success rates and complication rates were analysed at 4-year follow-up.

RESULTS

A 3D TEE could be performed successfully in all patients prior to the ablation procedure and all four pulmonary vein ostia could be evaluated in 84% of patients. The image quality was excellent in the majority of patients and several variations of the pulmonary vein anatomy could be visualized precisely (e.g., common pulmonary vein ostia, accessory pulmonary veins, varying diameter of the left atrial appendage and its distance to the left superior pulmonary vein). All ablation procedures could be performed as planned and almost all pulmonary veins could be isolated successfully. At 48-mo follow-up, 68.0% of all patients were free from an arrhythmia recurrence (group A1: 72.7%, group A2: 73.7%, group B: 60.0%). There were no major complications.

CONCLUSION

3D TEE provides an excellent overview over the left atrial anatomy prior to AF ablation procedures and these procedures are associated with a favourable long-term outcome.

Catheter ablation of paroxysmal atrial fibrillation: circumferential 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 paroxysmal atrial fibrillation. Circumferential pulmonary vein ablation is still the standard approach in these patients. The occurrence of an atrioesophageal fistula is a rare but life-threatening complication after such ablation procedures. This is due to the fact that the esophagus does frequently have a very close anatomical relationship to the left or right pulmonary vein ostia. The aim of our study was to evaluate whether the exclusion of areas adjacent to the esophagus does have a significant effect on the success rate after circumferential pulmonary vein ablation.

METHODS

Two hundred consecutive patients [121 men, 69 women; mean age 59.1 years (SD ± 11.3 years)] with symptomatic paroxysmal atrial fibrillation underwent a circumferential pulmonary vein ablation procedure (using the CARTO- or the NAVX-system). In 100 patients, a complete circumferential pulmonary vein ablation was attempted regardless of the anatomical relationship between the ablation sites and the esophagus (group A). In the remaining 100 patients, the esophagus was marked by a special EP catheter and areas adjacent to the esophagus were excluded from the ablation procedure. After discharge, patients were scheduled for repeated visits at the arrhythmia clinic at 1, 3, 6, 9, 12, 24 and 36 months after the ablation procedure.

RESULTS

The ablation procedure could be performed as planned in all 200 patients. In group A, all pulmonary veins could be isolated successfully in 88 out of 100 patients (88%). A mean number of 3.9 pulmonary veins (SD ± 0.37 PVs) were isolated per patient. The 12 cases of an incomplete pulmonary vein isolation were due to poorly accessible pulmonary vein ostia. In group B, all pulmonary veins could be isolated successfully in only 58 out of 100 patients (58%; P < 0.01). A mean number of 3.5 PVs (SD ± 0.6 PVs) were isolated per patient (P < 0.01). This was mostly due to a close anatomical relationship to the esophagus. The ablation strategy had to be modified in 46/100 patients in group B because of a close anatomical relationship between the right (n = 25) or left (n = 21) pulmonary vein ostia and the esophagus. One year after the ablation procedure, 87% of patients in group A (87/100) and 79% of patients in group B (79/100) were free from an arrhythmia recurrence (P = 0.19). Three years after catheter ablation, the success rate was 80% (no arrhythmia recurrence in 80 out of 100 patients) in group A and 66% in group B (no arrhythmia recurrence in 66 out of 100 patients; P = 0.04). There were no major complications during long-term follow-up.

CONCLUSIONS

The exclusion of areas adjacent to the esophagus results in a markedly higher percentage of incompletely isolated pulmonary veins after circumferential pulmonary vein ablation procedures. This results in a significantly higher arrhythmia recurrence rate during long-term follow-up.

Catheter ablation of persistent atrial fibrillation : Beneficial effect of a short-term adjunctive amiodarone therapy on the long-term outcome

BACKGROUND

Catheter ablation has become the first line therapy in patients with symptomatic, recurrent, drug-refractory atrial fibrillation. Circumferential pulmonary vein ablation is still the standard approach in these patients. However, the results are not very favorable (especially in patients with persistent atrial fibrillation). Therefore, more complex ablation strategies and the usefulness of (short-term) adjunctive antiarrhythmic drug therapy are a matter of discussion. The aim of this study was to analyze whether short-term amiodarone therapy after catheter ablation (3 months) has a positive effect on the success rates after circumferential pulmonary vein ablation in patients with persistent atrial fibrillation.

METHODS

A total of 230 consecutive patients with symptomatic persistent atrial fibrillation underwent a circumferential pulmonary vein ablation procedure (using the NAVX or CARTO system). Catheter ablation of the right or left atrial isthmus and a linear lesion in the roof of the left atrium were only performed in selected patients with documented episodes of atrial fibrillation. In 115 patients, a short-term adjunctive antiarrhythmic drug therapy with amiodarone was initiated immediately prior to the ablation procedure (for the first 3 months group A). In the remaining 115 patients, no antiarrhythmic drug therapy was administered except for beta blockers (group B).

RESULTS

Out of 115 patients 19 (16.5%) in group A and 34 (29.6%) in group B experienced an arrhythmia recurrence within the first 3 months after ablation requiring electrical cardioversion (P = 0.03; blanking period). One year after the ablation procedure 81.7% of patients in group A (94/115) and 73.0% of patients in group B (84/115) were free from further arrhythmia recurrences (P = 0.16). The success rate 2 years after catheter ablation was 76.5% (no arrhythmia recurrence in 88/115 patients) in group A and 63.5% in group B (no arrhythmia recurrence in 73/115 patients; P = 0.04). There were no major complications during long-term follow-up.

CONCLUSION

Adjunctive short-term amiodarone therapy improves the success rate after catheter ablation of persistent atrial fibrillation during long-term follow-up. This might be due to a decreased incidence of early arrhythmia recurrences after catheter ablation of atrial fibrillation and an improved reverse remodelling process.

Catheter ablation of persistent atrial fibrillation : Long-term results of circumferential pulmonary vein ablation in combination with a linear lesion at the roof of the left atrium

BACKGROUND

Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug-refractory atrial fibrillation. However, catheter ablation of persistent atrial fibrillation is still a challenge. Various relatively complex ablation strategies exist and their results are not very favorable. Therefore, the aim of our study was to evaluate a well-defined reasonable approach to catheter ablation of persistent atrial fibrillation. The strategy consisted of a circumferential pulmonary vein ablation in combination with a linear lesion at the roof of the left atrium.

METHODS

A total of 150 patients with symptomatic persistent atrial fibrillation were enrolled in this study. All patients underwent catheter ablation of persistent atrial fibrillation using the abovementioned approach.

RESULTS

The ablation procedure could be performed as planned in all 150 patients. Five years after catheter ablation, the success rate was 71.3% (no arrhythmia recurrence in 107 out of 150 patients). There were no major complications during long-term follow-up.

CONCLUSION

Catheter ablation of persistent atrial fibrillation can be performed safely and effectively using this ablation strategy providing favorable long-term follow-up results.

Radiofrequency catheter ablation for redo procedures after pulmonary vein isolation with the cryoballoon technique : Long-term outcome

BACKGROUND

Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug-refractory atrial fibrillation (AF). Cryoablation has been shown to be a safe and effective technique for pulmonary vein (PV) isolation. However, the arrhythmia recurrence rate is high after cryoablation procedures. Radiofrequency catheter ablation has been shown to be an effective strategy for redo procedures in these patients and to provide a favourable outcome during midterm follow-up. The aim of this study was to analyse whether the strategy also provides favourable results during long-term follow-up (5 years).

METHODS

In this study 30 patients (paroxysmal AF: 22 patients, persistent AF: 8 patients) underwent a redo procedure after initially successful circumferential PV isolation with the cryoballoon technique (Arctic Front Balloon, Medtronic). The redo ablation procedures were performed using a segmental approach or a circumferential ablation strategy (CARTO; Biosense Webster, Diamond Bar, CA, USA) depending on the intraprocedural findings.

RESULTS

During the repeat procedure, a mean number of 2.9 reconnected PV (SD ± 1.0) were detected. In 20 patients, a segmental approach was sufficient to eliminate the residual PV conduction because only a few PV fibres were recovered (1-3 reconnected PV; group A). In the remaining 10 patients, a circumferential ablation strategy was used because of a complete recovery of the pulmonary vein - left atrial (PV-LA) conduction (group B). All reconnected PV were isolated successfully again. A third or fourth ablation procedure had to be performed in 4 (3 and 1, respectively) patients (13.3%). At 5‑year follow-up, 66.7% of all patients were free from an arrhythmia recurrence (20 out of 30). There were no major complications during long-term follow-up.

CONCLUSION

In patients with an initial circumferential PV isolation using the cryoballoon technique, a repeat ablation procedure can be safely and effectively performed using radiofrequency catheter ablation providing good long-term follow-up results.

Catheter ablation of atrial fibrillation: Radiofrequency catheter ablation for redo procedures after cryoablation

AIM: To evaluate the effectiveness of two different strategies using radiofrequency catheter ablation for redo procedures after cryoablation of atrial fibrillation.

METHODS: Thirty patients (paroxysmal atrial fibrillation: 22 patients, persistent atrial fibrillation: 8 patients) had to undergo a redo procedure after initially successful circumferential pulmonary vein (PV) isolation with the cryoballoon technique (Arctic Front Balloon, CryoCath Technologies/Medtronic). The redo ablation procedures were performed using a segmental approach or a circumferential ablation strategy (CARTO; Biosense Webster) depending on the intra-procedural findings. After discharge, patients were scheduled for repeated visits at the arrhythmia clinic. A 7-day Holter monitoring was performed at 3, 12 and 24 mo after the ablation procedure.

RESULTS: During the redo procedure, a mean number of 2.9 re-conducting pulmonary veins (SD ± 1.0 PVs) were detected (using a circular mapping catheter). In 20 patients, a segmental approach was sufficient to eliminate the residual pulmonary vein conduction because there were only a few recovered pulmonary vein fibres. In the remaining 10 patients, a circumferential ablation strategy was used because of a complete recovery of the PV-LA conduction. All recovered pulmonary veins could be isolated successfully again. At 2-year follow-up, 73.3% of all patients were free from an arrhythmia recurrence (22/30). There were no major complications.

CONCLUSION: In patients with an initial circumferential pulmonary vein isolation using the cryoballoon technique, a repeat ablation procedure can be performed safely and effectively using radiofrequency catheter ablation.

Catheter ablation of persistent atrial fibrillation: anatomically based circumferential pulmonary vein ablation in combination with a potential-guided segmental approach to achieve complete pulmonary vein isolation

BACKGROUND

Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug-refractory atrial fibrillation. However, catheter ablation of persistent atrial fibrillation is still a challenge. Various rather complex ablation strategies exist and their results are not very favorable. Therefore, the aim of our study was to evaluate a well-defined reasonable approach to catheter ablation of persistent atrial fibrillation. The strategy consisted of a circumferential pulmonary vein ablation in combination with a potential-guided segmental approach to achieve complete pulmonary vein isolation and a linear lesion at the roof of the left atrium.

METHODS

A total of 43 patients (30 men, 13 women; mean age 55 years (SD ± 9 years)) with symptomatic persistent atrial fibrillation were enrolled in this study. All patients underwent catheter ablation of persistent atrial fibrillation using the above-mentioned approach (with the CARTO or the NAVX system). Additionally, catheter ablation of the mitral isthmus and the right atrial isthmus was performed in selected cases. In all patients, cardiac MRI or multi-detector spiral computed tomography was performed prior to the ablation procedure and a surface rendered model of the left atrium was created. After discharge, patients were scheduled for repeated visits at the arrhythmia clinic at 1, 3, 6, 9, and 12 months after the ablation procedure.

RESULTS

The ablation procedure could be performed as planned in all 43 patients. Nine patients had to undergo a repeat ablation procedure, so that a total of 52 procedures were evaluated. An additional linear lesion was created at the mitral isthmus in three patients (7%) during the initial procedure and in one patient (2.3%) during the second procedure. Catheter ablation of the right atrial isthmus was performed in 11 patients (25.6%) during the first procedure and in four additional patients during the redo procedure (9.3%). Twenty-four out of 43 patients (55.8%) experienced an arrhythmia recurrence within the first 3 months after ablation requiring an electrical cardioversion. At 1-year follow-up, analysis of a 7-day Holter monitoring revealed no evidence for an arrhythmia recurrence in 26 of 43 patients (60.5%). In nine of 43 patients (20.9%), only short episodes of paroxysmal atrial fibrillation were documented. In eight patients (18.6%), a recurrence of persistent atrial fibrillation (>48 h) was revealed by the long-term recordings. A duration of persistent atrial fibrillation >3 months was the most powerful predictor for arrhythmia recurrences at 1-year follow-up. A subgroup analysis revealed a markedly higher rate of stable sinus rhythm at 1-year follow-up in patients with a short duration of atrial fibrillation (≤ 3 months) compared to patients with a longer duration of AF (>3 months) prior to the procedure (72.0% versus 44.4%). There were no major complications.

CONCLUSIONS

Catheter ablation of persistent atrial fibrillation can be performed safely and effectively using this ablation strategy (especially in patients with short-lasting persistent atrial fibrillation (≤ 3 months)).

An Update on the Energy Sources and Catheter Technology for the Ablation of Atrial Fibrillation

The ablation of atrial fibrillation (AF) is an area of intense research in cardiac electrophysiology. In this review, we discuss the development of catheter-based interventions for AF ablation. We outline the pathophysiologic and anatomic bases for ablative lesion sets and the evolution of various catheter designs for the delivery of radiofrequency (RF), cryothermal, and other ablative energy sources. The strengths and weaknesses of various specialized RF catheters and alternative energy systems are delineated, with respect to efficacy and patient safety.

Catheter ablation of atrial fibrillation using the Navx-/Ensite-system and a CT-/MRI-guided approach

BACKGROUND

Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug refractory atrial fibrillation. However, catheter ablation of atrial fibrillation is still a challenge. This is partially due to the high degree of variability with regard to the individual anatomy. Nevertheless, 3D imaging systems (CT, MRI) provide detailed information about the individual left atrial and pulmonary vein morphology. A 3D CT or MRI reconstruction of the left atrium can be displayed in the Navx-/Ensite-system in a synchronised way during the ablation procedure, thereby facilitating the intervention. This study summarizes our preliminary experience with different strategies of AF ablation using the Navx-/Ensite-system and a CT-/MRI-guided approach.

METHODS

In a total of 41 patients, cardiac MRI (n = 7) or multi-detector spiral computed tomography (n = 34) was performed prior to an ablation procedure. Catheter ablation was performed for paroxysmal atrial fibrillation in 31 patients and for persistent atrial fibrillation in 10 patients. A 3D MRI or high resolution spiral CT data acquisition was performed and a surface rendered model of the LA was created. This model was displayed in the Navx-/Ensite-system throughout the ablation procedure.

RESULTS

Catheter ablation was performed using the Navx-system (n = 38) or the Ensite-system (n = 3). Three strategies were used depending on the type of atrial fibrillation: segmental isolation of the pulmonary veins (facilitated by a 3D real-time visualization of the ablation catheter and a circumferential mapping catheter; group A: 20 patients), linear lesions (group C: 3 patients) and a combined approach (group B; 18 patients). The CT-/MRI-models provided an excellent overview over the pulmonary veins and the left atrial appendage. They revealed a high degree of variability with regard to the individual anatomy (e.g. dimensions of the left atrial appendage, pulmonary vein ostia). The CT scans provided a more detailed reconstruction of the left atrial anatomy than the MRI scans (especially in patients who were in atrial fibrillation at the time of the data acquisition). In some patients, the CT-/MRI-models revealed a very small diameter of some pulmonary veins or side branches close to the ostium (e.g. right inferior pulmonary vein). Therefore, no attempt was made to achieve complete pulmonary vein isolation in some patients. In group A, 16/20 (80%) patients had no arrhythmia recurrence [mean follow-up 359 days (SD +/- 317 days)]. Twelve out of eighteen (67%) patients in group B [mean follow-up 452 days (SD +/- 311 days)] and 2/3 (67%) patients in group C did not experience an arrhythmia recurrence [mean follow-up 1,000 days (SD +/- 34 days)]. There were no major complications.

CONCLUSIONS

The information derived from 3D CT- or MRI-reconstructions facilitates AF ablations performed with the Navx-/Ensite-mapping system and enhances the safety of these procedures. Furthermore, the availability of an additional impedance-based 3D real-time visualization of the ablation catheter and the circular mapping catheter placed in the pulmonary veins represents a major advantage of the Navx system.

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 degrees 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.

Feasibility of noncontact intracardiac ultrasound ablation and imaging catheter for treatment of atrial fibrillation

Atrial fibrillation (AF) affects 1% of the population and results in a cost of 2.8 billion dollars from hospitalizations alone. Treatments that electrically isolate portions of the atria are clinically effective in curing AF. However, such minimally invasive catheter treatments face difficulties in mechanically positioning the catheter tip and visualizing the anatomy of the region. We propose a noncontact, intracardiac transducer that can ablate tissue and provide rudimentary imaging to guide therapy. Our design consists of a high-power, 20 mm by 2 mm, 128-element, transducer array placed on the side of 7-French catheter. The transducer will be used in imaging mode to locate the atrial wall; then, by focusing at that location, a lesion can be formed. Imaging of previously formed lesions could potentially guide placement of subsequent lesions. Successive rotations of the catheter will potentially enable a contiguous circular lesion to be created around the pulmonary vein. The challenge of intracardiac-sized transducers is achieving high intensities (300-5000 W/cm2) needed to raise the temperature of the tissue above 43 degrees C. In this paper, we demonstrate the feasibility of an intracardiac-sized transducer for treatment of atrial fibrillation. In simulations and proof-of-concept experiments, we show a 37 degrees C temperature rise in the lesion location and demonstrate the possibility of lesion imaging.

Atrial linear lesions: feasibility using cryoablation

BACKGROUND

Long linear lesions are created in the left atrium to modify the atrial substrate, thereby curing atrial fibrillation. The creation of long linear left atrial lesions using radiofrequency (RF) ablation is time consuming and difficult. Furthermore, it might result in significant complications. Cryoablation might overcome some of the disadvantages of RF ablation. Therefore, the aim of our study was to assess whether the creation of a long linear lesion is possible using cryotherapy.

METHODS

A right atrial septal linear lesion was created in six pigs (median weight: 50 kg; range: 40-60 kg). The ablation procedure was performed with a 7-F Freezor cryocatheter. The nonfluoroscopic mapping system LocaLisa was used as a navigation tool. At each point, freezing was maintained at the lowest attainable temperature (-75 degrees C) for 4 minutes. The CARTO system was used for the evaluation of the linear lesions. Furthermore, all animals were sacrificed immediately after the ablation procedure and a postmortem examination of the lesions was performed. Additionally, an analysis of the amplitudes of the intracardiac electrograms registered via the ablation catheter was performed before and after the ablation procedure.

RESULTS

A right atrial septal linear lesion could be created successfully in all six pigs. For the performance of this ablation line, a median number of 16 cryoapplications (range, 11-26) was necessary. The amplitudes of the intracardiac electrograms registered via the ablation catheter decreased significantly after ablation. The CARTO bipolar voltage map revealed very low potentials along the ablation line and showed a sharply demarcated ablation area at the septum in all pigs. Further analysis of the CARTO map revealed an incomplete conduction block in all cases. Most of the pigs had a small gap close to the fossa ovalis. The postmortem examination of 2,3,5-triphenyl-tetrazolium chloride-stained specimens showed sharply demarcated lesions without any ulcerations. There were no major complications during the procedure.

CONCLUSIONS

The creation of long linear lesions using cryoablation is feasible and safe. Lesion characteristics are different and more favorable than those created by RF. However, the aim of creating a transmural lesion and a complete conduction block remains an unsolved problem even with current cryoablation techniques. Nevertheless, growing experience and technical improvements might overcome some of the current limitations of this new technique.

Percutaneous Catheter Ablation Procedures for the Treatment of Atrial Fibrillation

In light of the significant morbidity and mortality from atrial fibrillation (AF), there has been significant interest in the development of percutaneous catheter ablation procedures for the suppression of AF. Given the success of the surgical Maze procedure, initial catheter-based approaches involved creation of linear atrial lesions. Success rates were low and utility was limited by a high complication rate and long procedural times. The recent discovery that AF is often initiated by atrial ectopic beats has resulted in therapies designed to target the ectopic sources, particularly those within the pulmonary veins. Experience and technological advances have improved the efficacy and safety of such procedures. This article will review catheter ablation procedures for the maintenance of sinus rhythm in patients with AF.

Ring electrode for radio-frequency heating of the cornea: modelling and in vitro experiments

Radio-frequency thermokeratoplasty (RF-TKP) is a technique used to reshape the cornea curvature by means of thermal lesions using radio-frequency currents. This curvature change allows refractive disorders such as hyperopia to be corrected. A new electrode with ring geometry is proposed for RF-TKP. It was designed to create a single thermal lesion with a full-circle shape. Finite element models were developed, and the temperature distributions in the cornea were analysed for different ring electrode characteristics. The computer results indicated that the maximum temperature in the cornea was located in the vicinity of the ring electrode outer perimeter, and that the lesions had a semi-torus shape. The results also indicated that the electrode thickness, electrode radius and electrode thermal conductivity had a significant influence on the temperature distributions. In addition, in vitro experiments were performed on rabbit eyes. At 5 W power, the lesions were fully circular. Some lesions showed non-uniform characteristics along their circular path. Lesion depth depended on heating duration (60% of corneal thickness for 20 s, and 30% for 10 s). The results suggest that the critical shrinkage temperature (55-63 degrees C) was reached at the central stroma and along the entire circular path in all the cases.

Catheter ablation therapy for atrial fibrillation

The past several years have witnessed a significant growth in the number of institutions offering catheter ablation for atrial fibrillation (AF). This growth has been a result of a better understanding of pathophysiology of AF and use of instruments and approaches that made catheter ablation of AF a safe and an effective alternative to the drug therapy. The procedure increasingly is becoming a therapy of choice for a select group of symptomatic, drug-refractory patients without structural heart disease, and it is being offered to a rapidly widening patient pool. This article reviews the procedural aspects and clinical evidence supporting this wider use of AF ablation. In addition, new techniques and technologies for AF ablation and new avenues of research in this area are explored.

Left atrial flutter after segmental ostial radiofrequency catheter ablation for pulmonary vein isolation

Segmental ostial ablation to electrically isolate pulmonary veins has been performed for atrial fibrillation. Left atrial flutter that utilized a critical isthmus adjacent to the ostium of the left superior pulmonary vein was diagnosed and successfully ablated in a patient 3 months after a successful pulmonary vein isolation procedure. Documenting the cause of symptoms after pulmonary vein isolation in patients with atrial fibrillation is critical in guiding therapy.

New cryotechnology for electrical isolation of the pulmonary veins

INTRODUCTION

Creation of radiofrequency lesions to isolate the pulmonary veins (PV) and ablate atrial fibrillation (AF) has been complicated by stenosis of the PVs. We tested a cryoballoon technology that can create electrical isolation of the PVs, with the hypothesis that cryoenergy will not result in PV stenosis.

METHODS AND RESULTS

Lesions were created in 9 dogs (weight 31-37 kg). Cryoenergy was applied to the PV-left atrial (LA) interface. Data collected before and after ablation included PV orifice size, arrhythmia inducibility, electrogram activity, and pacing threshold in the PVs. Tissue examination was performed immediately after ablation in 3 dogs and after 3 months (4.8 +/- 1.0) in 6 dogs. After ablation there was no localized P wave activity in the ablation zone and no LA-PV conduction. Before ablation, the pacing threshold was 1.9 +/- 1.1 mA in each PV. After ablation, the pacing threshold increased significantly to 7.2 +/- 1.8 mA, or capture was not possible. Burst pacing did not induce any sustained arrhythmias. Most dogs had hemoptysis during the first 24 to 48 hours. Acute tissue examination revealed hemorrhagic injury of the atrial-PV junction that extended into the lung parenchyma. After recovery, the lesions were circumferential and soft with no PV stenosis. Histologic examination revealed fibrous tissue with no PV-LA interface thickening.

CONCLUSION

This new cryoballoon technology effectively isolates the PVs from LA tissue. No PV stenosis was noted. Acute tissue hemorrhage and hemoptysis are short-term complications of this procedure. After 3 months of recovery, cryoablated tissue exhibits no collagen or cartilage formation.

Identification of transmural necrosis along a linear catheter ablation lesion during atrial fibrillation and sinus rhythm

BACKGROUND

Determining whether a linear catheter radio frequency (RF) ablation lesion is transmural may be difficult, especially during atrial fibrillation. We hypothesized that changes in pacing thresholds and electrogram amplitude during atrial fibrillation and sinus rhythm could be used to assess whether a radiofrequency ablation resulted in transmural necrosis.

METHODS

A hexapolar, linear, RF ablation catheter was positioned between the caval veins in the right atrium of seven sheep. Pacing thresholds and electrogram amplitudes during atrial fibrillation and sinus rhythm were measured before and after the application of RF energy. Sites along the linear lesion were assessed histologically.

RESULTS

The electrogram amplitude in atrial fibrillation decreased significantly more at transmural sites (unipolar recording: 33 +/- 11% transmural vs. 22 +/- 13% non-transmural, p < or = 0.01; bipolar recording: 62 +/- 9% transmural vs. 43 +/- 15% non-transmural, p < or = 0.01). The electrogram amplitude in sinus rhythm decreased significantly more at transmural sites (unipolar recording: 49 +/- 18% transmural vs. 15 +/- 20% non-transmural, p < 0.001; bipolar recording: 63 +/- 17% transmural vs. 42 +/- 19% non-transmural, p = 0.002). The pacing threshold increased significantly more at sites with transmural necrosis (unipolar: increased by 378 +/- 103% transmural vs. 207 +/- 93% non-transmural, p < 0.001; bipolar: 370 +/- 80% transmural vs. 259 +/- 60% non-transmural, p < 0.001).

CONCLUSIONS

The amplitude of the atrial electrogram from an ablation catheter can be used to discriminate areas with transmural necrosis from those without transmural necrosis during either atrial fibrillation or sinus rhythm. Termination of atrial fibrillation may not be necessary to estimate the histologic characteristics of an ablation lesion.

Simultaneous creation and evaluation of linear radiofrequency lesions

BACKGROUND

Catheter based "maze" procedures for atrial fibrillation have been hampered by difficult creation and evaluation of continuous and transmural linear lesions. Our aim was to develop an online evaluation method for effective lesion creation based on conventional techniques and using the multipolar ablation catheter, already in place.

METHODS AND RESULTS

We created 15 linear lines in right atria of 13 anesthetized sheep using three multipolar catheter designs (8 x 4 mm 7 Fr, 4 x 6 mm 7 Fr, 8 x 4 mm 3.7 Fr). The lesions were placed on the right posterolateral wall between the orifices of the superior and inferior vena cava. Radiofrequency energy was applied in the temperature-controlled mode to prespecified endpoints (electrogram amplitude decrease to < or = 50%; pacing threshold increase by > or = 100%; split potentials indicating conduction block). Macroscopically transmural and continuous lesions were achieved in only 3 experiments (29 +/- 12 mm x 5 +/- 1 mm), all created by 3.7 Fr octapolar catheters inserted through long sheaths. Preset temperature was reached in 96% of the electrodes (vs. 64% in the non-effective experiments; p < 0.01). Electrogram amplitude decrease (to < or = 50%) and pacing threshold increase (by > or = 100%) did not predict effectiveness. The only criterion that could reliably predict transmural continuous necrosis at histology was the development of split potentials (p < or = 0.05).

CONCLUSIONS

Effective creation of linear lesions is difficult. Pliable catheters that conform to the endocardial contour give the best results. The only endpoint that reliably predicted histological transmural continuous necrosis was development of split potentials indicating conduction block.

Comparison of the temperature profile and pathological effect at unipolar, bipolar and phased radiofrequency current configurations

With a multi-electrode catheter, phased radiofrequency (RF) delivers current between each electrode and a backplate as well as between adjacent electrodes. This study compared the tissue heating and lesion dimensions created by phased and standard RF. Ablation was performed on the in vivo thigh muscles in 5 pigs. Six lesions were created on each thigh muscle using phase angle 0 degrees RF, 127 degrees RF, 180 degrees RF with and without a backplate, and standard RF in bipolar and sequential unipolar configurations. Two plunge needles, each with 6 thermocouples 1 mm apart, were inserted into the tissue with one needle beside an electrode and the other midway between electrodes for tissue temperature measurement. The 0 degrees RF created lower tissue temperatures and smaller lesions between electrodes than those beside electrode. With 127 degrees and 180 degrees RF, tissue temperature and lesion dimensions between electrodes were similar to beside electrode, while the 127 degrees RF created higher tissue temperature and deeper lesions than 180 degrees RF (both with and without a backplate) at both sites. Standard RF bipolar ablation created similar tissue temperatures and lesion depths at both sites, but required greater power than the 127 degrees RF. Standard RF sequential unipolar ablation created only a slight temperature increase and no lesions between electrodes 3 and 4. As judged by tissue temperature, lesion depth and uniformity, and RF power requirement, 127 degrees RF may be a better energy configuration for linear ablation than the other RF modalities tested.

Linear lesion radiofrequency ablation in canine vagal atrial fibrillation: effects of special catheters designed for efficiency, and the critical role of lesions from the crista terminalis to the superior vena cava

OBJECTIVE

To determine whether specially devised catheters could be used to place radiofrequency (RF) linear lesions quickly and efficiently for termination and/or prevention of atrial fibrillation (AF).

METHODS

Two versions of 2 different types of ablating catheters were used in 12 canines with AF induced by rapid pacing during vagal stimulation. 1) Modified basket catheters in two versions, one designed to produce caudo-cranial linear lesions through extended bare electrode-splines in contact with the atrial wall; and the other designed to produce horizontal linear lesions by revolving within the atrium. Together these would form "longitude and latitude" grids in the atrium. 2) The second catheter type was 2 versions of coil electrodes with thermocouples centered under each of the large-area coil electrodes. One version of these deflectable coil electrodes was intended to produce lesions in the tricuspid valve annulus-inferior vena cava (IVC) isthmus; and along the crista terminalis from the superior vena cava (SVC) to the IVC. A different type of deflection angulation on the second version was intended to produce more horizontal lesions from the crista to the tricuspid annulus. Guidance was fluoroscopic, and by electrograms and transesophageal echo. Gross pathologic examinations followed each experiment. Prior to use in canines, all electrode configurations were tested in vitro on fresh bovine preparations suspended in saline at 37 degrees C.

RESULTS

The bare spline and coil electrode catheter configurations produced discrete non-perforating non-charring lesions in the in vitro preparations. One dog died of exsanginating hemorrhage. Post mortem examination revealed the lesions to be extremely variable, ranging from no evidence of effective RF delivery to deep lesions with perforation. Seven clinical successes were achieved (6 complete), with the coil electrode catheters accounting for 5 of the 7, although the procedure times were shorter with the baskets. Critical lesions were those from the crista to the SVC. Planned trans-isthmus lesions were not done, but may be needed to prevent atrial flutter not seen prior to effective AF ablation.

CONCLUSIONS

Special basket and coil-electrode catheters may be useful but require refinement. The finding that lesions between the crista terminalis and the SVC were critical to success may be applicable to some cases of AF in humans.

Ablation of atrial fibrillation in the rapid pacing canine model using a multi-electrode loop catheter

OBJECTIVES

This investigation details our experience using a loop catheter to ablate atrial fibrillation (AF) in dogs.

BACKGROUND

Atrial fibrillation is the most common arrhythmia and has significant morbidity. Maintenance of normal sinus rhythm (NSR) after conversion in many patients is still a challenge.

METHODS

A multi-electrode loop catheter was used to create linear atrial lesions to ablate AF in a rapid atrial pacing model in 29 dogs. Rhythm status was assessed over a six-month recovery period, after which tissue analysis was performed.

RESULTS

Acute conversion to NSR or atrial tachycardia (AT) was achieved in 90% of cases. Six of 26 conversions occurred after only left atrial (LA) lesions, and two after just right atrial lesions. Sixteen (62%) of 26 lesions that resulted in AF conversion were in the LA, and 11 of these 16 conversions occurred during a lesion connecting the mitral ring to the pulmonary veins. Acute conversion rate was similar with ring and coil electrodes, but AT was more frequent with coil electrodes (63% vs. 31%). At six months 80% of dogs were in NSR, 14% were in AT, and 7% remained in AF. There was an average reduction in P-wave amplitude of 64 +/- 26% after power application. Tissue analysis revealed transmural contiguous lesions when final outcome was NSR, and nontransmural/noncontiguous lesions where AF persisted.

CONCLUSIONS

Multi-electrode loop catheters can create contiguous transmural lesions in either atrium to safely and effectively ablate AF and provide a stable long-term rhythm outcome in this dog model. The left atrium appears to be the dominant chamber that sustains AF. Atrial tachycardia is a frequent acute outcome with coil electrodes.

Catheter ablation for cardiac arrhythmias

The safety and efficacy of catheter ablation for treatment of most types of cardiac arrhythmias are well established. These arrhythmias and arrhythmia substrates include AVNRT, accessory pathways, focal atrial tachycardia, atrial flutter, idiopathic ventricular tachycardia, and bundle-branch re-entry. Catheter ablation is considered as an alternative to pharmacologic therapy in the treatment of these cardiac arrhythmias.

Linear lesions in myocardium created by Nd:YAG laser using diffusing optical fibers: in vitro and in vivo results

BACKGROUND AND OBJECTIVE

Linear lesions may be necessary for successful catheter ablation of cardiac arrhythmias such as atrial fibrillation. This study uses laser energy delivered through diffusing optical fibers as an alternative to radiofrequency energy for the creation of linear lesions in cardiac tissue in a single application.

STUDY DESIGN/MATERIALS AND METHODS

Samples of canine myocardium were placed in a heated, circulating saline bath and irradiated with a 1.06-microm, continuous-wave Nd:YAG laser during in vitro studies. Laser ablation was then performed in vivo on the epicardial surface of the right ventricle during an open-chest procedure by using similar ablation parameters. Laser energy was delivered to the tissue by being diffused radially through flexible optical fiber tips oriented parallel to the tissue surface. Histology and temperature measurements verified transmurality, continuity, and linearity of the lesions.

RESULTS

Peak tissue temperatures measured in vitro remained low (51 +/- 1 degrees C at the endocardial surface, 61 +/- 6 degrees C in the mid-myocardium, and 55 +/- 6 degrees C at the epicardial surface) with no evidence of tissue charring or vaporization. Lesion dimensions produced in vitro and in vivo were similar (depth, 6 mm; width, 8-10 mm; length, 16-22 mm), demonstrating that tissue perfusion in vivo did not significantly alter the heating.

CONCLUSION

Long linear lesions, necessary for duplication of the surgical maze procedure during catheter ablation of atrial fibrillation, may be created by using laser radiation delivered through flexible diffusing optical fiber tips. Further development of steerable catheters for endocardial atrial ablation and studies correlating thermal damage zones with electrophysiologic indicators of irreversible conduction block are warranted.

[Characteristics of atrial electrograms recorded in radiofrequency induced block lines in an experimental model]

AIM

To analyze and quantify atrial electrogram modifications following the induction of linear lesions in the atrial wall using radiofrequency ablation procedures.

METHODS

An epicardial multiple electrode (221 unipolar electrodes) was used in 12 Langendorff perfused rabbit hearts to analyze atrial activation before and after radiofrequency induction of a linear lesion in the left atrial wall. After confirming the existence of conduction blockade in the lesion zone by epicardial mapping and propagation vector analysis, six electrodes each were selected in the lesioned and non-lesioned zones in all experiments, comparing the amplitude, maximum negative slope and morphology of the electrograms in both zones, before (control) and after radiofrequency delivery.

RESULTS

Analysis of the reproducibility of the measurements in two consecutive cycles showed a variation of 1 +/- 5% for amplitude (NS) and 1 +/- 9% for maximum negative slope (NS). In the non-damaged zone, amplitude (105 +/- 22%) and slope (92 +/- 16%) (values normalized with respect to those recorded before radiofrequency) did not vary significantly following radiofrequency, and simple electrograms were the most frequent recordings (82 vs 83% in control; NS). Amplitude (19 +/- 7%, p < 0.001) and slope (24 +/- 11%; p < 0.001) decreased significantly in the lesion zone, as did the percentage of simple electrograms (6 vs 86% in control; p < 0,001). In this same zone the morphology could not be determined in 12% of the recordings, while multiple electrograms were obtained in 15% (vs 2% in control; p < 0.01), and the most frequent type corresponded to double electrograms (67 vs 12% in control, p < 0.001), with both components coinciding in time with atrial activation in the zones proximal and distal to the lesion line.

CONCLUSIONS

Electrograms recorded directly in radiofrequency induce block lines show a significant decrease in amplitude and maximum negative slope. Double electrograms predominate in these recordings, both components of which represent activation on either side of the lesion. In a small proportion of cases simple and multiple electrograms can also be recorded in the block line.

Prospective randomized comparison of antiarrhythmic therapy versus first-line radiofrequency ablation in patients with atrial flutter

BACKGROUND

Despite the high success rate of radiofrequency (RF) ablation, pharmacologic therapy is still considered the standard initial therapeutic approach for atrial flutter.

OBJECTIVE

We prospectively compared the outcome at follow-up of patients with atrial flutter randomly assigned to drug therapy or RF ablation.

METHODS

Patients with at least two episodes of symptomatic atrial flutter in the last four months were randomized to regimens of either antiarrhythmic drug therapy or first-line RF ablation. After institution of therapy, end points included recurrence of atrial flutter, rehospitalization and quality of life.

RESULTS

A total of 61 patients entered the study, 30 of whom were randomized to drug therapy and 31 to RF ablation. After a mean follow-up of 21 +/- 11 months, 11 of 30 (36%) patients receiving drugs were in sinus rhythm, versus 25 of 31 (80%) patients who underwent RF ablation (p < 0.01). Of the patients receiving drugs, 63% required one or more rehospitalizations, whereas post-RF ablation, only 22% of patients were rehospitalized (p < 0.01). Following RF ablation, 29% of patients developed atrial fibrillation which was seen in 53% of patients receiving medications (p < 0.05). Sense of well being (pre-RF 2.0 +/- 0.3 vs. post-RF 3.8 +/- 0.5, p < 0.01) and function in daily life (pre-RF 2.3 +/- 0.4 vs. post-RF 3.6 +/- 0.6, p < 0.01) improved after ablation, but did not change significantly in patients treated with drugs.

CONCLUSION

In a selected group of patients with atrial flutter, RF ablation could be considered a first-line therapy due to the better success rate and impact on quality of life, the lower occurrence of atrial fibrillation and the lower need for rehospitalization at follow-up.