Kars Neven

Long-Term Results of Catheter Ablation in Paroxysmal Atrial Fibrillation Lessons From a 5-Year Follow-Up

Background— Paroxysmal atrial fibrillation (AF) naturally progresses toward chronic AF at an estimated rate of 15% to 30% over a 1- to 3-year period. Pulmonary vein (PV) isolation is increasingly performed for the treatment of drug-refractory paroxysmal AF. The long-term data on clinical outcome after circumferential PV isolation are limited. Methods and Results— From 2003 to late 2004, 161 patients (121 men; age, 59.8±9.7 years) with symptomatic paroxysmal AF and normal left ventricular function underwent circumferential PV isolation guided by 3-dimensional mapping and double Lasso technique. Right-sided and left-sided continuous circular lesions encircling the ipsilateral PVs were placed with irrigated radiofrequency energy. The procedure end point was the absence of all PV spikes for at least 30 minutes after PV isolation verified by 2 Lasso catheters placed within the ipsilateral PVs. Sinus rhythm was present in 75 patients (46.6%) after the initial procedure during a median follow-up period of 4.8 years (0.33 to 5.5 years). A second procedure was performed in 66 and a third procedure in 12 patients. Recovered PV isolation conduction was observed in 62 of 66 patients (94.0%) during the second and in 8 of 12 patients (66.7%) during the third procedure. After a median of 1 (1 to 3) procedure, stable sinus rhythm was achieved in 128 of 161 patients (79.5%), whereas clinical improvement occurred in an additional 21 of 161 patients (13.0%) during a median follow-up of 4.6 years (0.33 to 5.5 years). Four patients in stable sinus rhythm died during follow-up. Progression toward chronic AF was observed in 4 patients (2.4%); however, only 2 patients reported symptoms. Conclusion— In patients with paroxysmal AF and normal left ventricular function, circumferential PV isolation results in stable sinus rhythm in the majority of patients, and low incidence of chronic AF was observed after ablation during up to 5 years of follow-up.

Fatal End of a Safety Algorithm for Pulmonary Vein Isolation With Use of High-Intensity Focused Ultrasound

Background—High-intensity focused ultrasound (HIFU) can achieve pulmonary vein isolation (PVI), but there are safety concerns after severe complications. Therefore, we evaluated an esophageal temperature (ET)-guided safety algorithm to apply HIFU safely. Methods and Results—After standard left atrial access, HIFU was repeatedly applied until PVI was complete. A safety algorithm was used: ≤3 complete ablations per pulmonary vein (PV), early abortion when no effect after 50% of programmed time or when ET was ≥40.0°C, use of power modulation (PM) at ET 39.0°C: to reduce ablation temperature in surrounding tissue, acoustic power is switched on/off at 1 Hz; in all first ablations, use of PM after 50% of programmed time. Touch-up radiofrequency ablation was used when PVI failed. Periprocedural ET monitoring and endoscopy 2 days after ablation were performed. Twenty-eight patients (18 males; mean age at enrollment, 63 years), with paroxysmal atrial fibrillation (AF; n=19) and persistent AF (n=9) were included. In 84 of 109 PV (9 of 25 patients), PVI was achieved using HIFU only. In 9 of 109 PV, HIFU was aborted because of high ET. Mean ET at the end of the ablations with and without use of PM were 38.1±2.0°C and 37.4±1.0°C (P=0.0002). During endoscopy in 2 of 26 patients, a small thermal lesion was found. Other complications included 2 persistent phrenic nerve palsies, 1 ischemic stroke, 1 pericardial effusion 48 days after ablation, 1 unexplained death 49 days after ablation, and 1 lethal atrial-to-esophageal fistula 31 days after ablation. Conclusions—The safety algorithm failed to prevent lethal complications. Currently HIFU does not meet the safety standards required for treatment of atrial fibrillation.

Feasibility of circumferential pulmonary vein isolation using a novel endoscopic ablation system.

Background—Pulmonary vein isolation (PVI) is an established treatment option for patients with drug refractory paroxysmal atrial fibrillation. A novel compliant endoscopic ablation system housing a 980-nm-diode laser allows for discrete point-by-point ablation enabling a true circumferential ablation line design. We sought to determine the feasibility and safety of a circumferential ablation using endoscopic ablation system. Methods and Results—Thirty patients (17 female; mean age, 58±9 years) with a median paroxysmal atrial fibrillation history of 3 years (range, 1 to 17 years) were treated. PVI was achieved in 114 of 116 (98%) PVs (4 left common PVs), thereby achieving simultaneous PVI for separate ipsilateral PVs in 19 of 26 (73%) left PVs and 6 of 30 (20%) right PVs. The total procedure time was 250±62 minutes. Procedure time decreased from 310±59 to 220±37 minutes (P=0.0001) between the first 10 and the last 20 cases. Mean fluoroscopy time was 30±18 minutes. Twenty-seven patients underwent postoperative endoscopy showing no or minimal thermal lesions in the esophagus in 21 (78%) and 2 (7%), respectively. In 4 (15%) patients, an esophageal ulceration was found that healed without sequelae. One pericardial tamponade and 1 right-sided phrenic nerve palsy occurred. During a median follow-up of 168 days (113 to 203 days; q1-q3), 24 of 30 patients (80%) remained free of atrial fibrillation recurrence. Conclusions—Circumferential PVI using the novel compliant endoscopic ablation system was feasible in the majority of left PVs and minority of right PVs accompanied by a complication rate comparable to established approaches. To minimize the risk for thermal esophageal injury temperature monitoring is recommended.

Remote Robotic Navigation and Electroanatomical Mapping for Ablation of Atrial Fibrillation — Considerations for Navigation and Impact on Procedural Outcome

Background—Radiofrequency current ablation of atrial fibrillation (AF) requires high technical skills to achieve optimal catheter stability and is associated with an individually high x-ray exposure to both the patient and the operator. To facilitate catheter navigation and to reduce the operators x-ray burden, remote navigation (RN) systems have been developed. Considerations for navigation of a novel remote robotic navigation system in pulmonary vein isolation (PVI) procedures are reported. Methods and Results—In 65 patients with drug-refractory AF (43 paroxysmal, 22 persistent), complete circumferential PVI was performed using RN in conjunction with different electroanatomic mapping systems. Acute complete PVI using exclusively RN was achieved in 95%. The procedure time was 195±40 minutes. The operators x-ray exposure time was reduced by 6±4 minutes (35%) using RN. In 7 of 14 patients with persistent AF, conversion to sinus rhythm was achieved by radiofrequency current ablation. During a median follow-up period of 239 days (range, 184 to 314 days), 47 of 65 patients (73%) remained free of any documented atrial tachyarrhythmia recurrences after a single procedure. The relative proportion of patients remaining free of AF was 76% and 68% for paroxysmal and persistent AF, respectively. Conclusions—PVI using the novel RN system can be performed safely and effectively. One third of the operators fluoroscopy exposure time might be saved using RN. However, the questions of whether the overall fluoroscopy exposure is reduced by RN and whether RN improves PVI procedures needs to be assessed during a comparative trial between man and machine.Background— Radiofrequency current ablation of atrial fibrillation (AF) requires high technical skills to achieve optimal catheter stability and is associated with an individually high x-ray exposure to both the patient and the operator. To facilitate catheter navigation and to reduce the operator’s x-ray burden, remote navigation (RN) systems have been developed. Considerations for navigation of a novel remote robotic navigation system in pulmonary vein isolation (PVI) procedures are reported. Methods and Results— In 65 patients with drug-refractory AF (43 paroxysmal, 22 persistent), complete circumferential PVI was performed using RN in conjunction with different electroanatomic mapping systems. Acute complete PVI using exclusively RN was achieved in 95%. The procedure time was 195±40 minutes. The operator’s x-ray exposure time was reduced by 6±4 minutes (35%) using RN. In 7 of 14 patients with persistent AF, conversion to sinus rhythm was achieved by radiofrequency current ablation. During a median follow-up period of 239 days (range, 184 to 314 days), 47 of 65 patients (73%) remained free of any documented atrial tachyarrhythmia recurrences after a single procedure. The relative proportion of patients remaining free of AF was 76% and 68% for paroxysmal and persistent AF, respectively. Conclusions— PVI using the novel RN system can be performed safely and effectively. One third of the operator’s fluoroscopy exposure time might be saved using RN. However, the questions of whether the overall fluoroscopy exposure is reduced by RN and whether RN improves PVI procedures needs to be assessed during a comparative trial between man and machine. Received August 31, 2008; accepted December 17, 2008. # CLINICAL PERSPECTIVE {#article-title-2}

One-year clinical outcome after pulmonary vein isolation using the novel endoscopic ablation system in patients with paroxysmal atrial fibrillation.

BACKGROUND Pulmonary vein isolation (PVI) is an established treatment option for atrial fibrillation (AF). Recently the novel endoscopic ablation system (EAS) was introduced and proved potential for successful acute PVI. OBJECTIVE This study sought to investigate the 1-year follow-up results after EAS-based PVI. METHODS A total of 40 patients (20 female, age 57 ± 9 years) with a long history (5 ± 4 years) of drug-refractory (2 ± 1 antiarrhythmic drugs) paroxysmal AF were included into our analysis. PVI was performed using exclusively the novel EAS. Follow-up included regular telephonic interviews, Holter electrocardiographic (ECG) and transtelephonic ECG recordings. A symptomatic or documented AF episode >60 seconds after a blanking period of 3 months was defined as recurrence. RESULTS A total of 155 PVs were targeted; 153 of 155 (99%) PVs were isolated successfully using exclusively the novel EAS. During a median follow-up of 402 (331 to 478; quartile 1 to quartile 3) days, 24 of 40 patients (60%) remained free of any symptomatic or documented AF episode without antiarrhythmic drugs after a single procedure. Seven patients suffering from AF recurrence underwent radiofrequency current-based Re-PVI 203 ± 102 days after the index EAS-based procedure. Left atrium to pulmonary vein reconduction was found in 17 of 25 initially isolated PVs. No PV stenosis was detected based on magnetic resonance imaging 3 months postablation. CONCLUSION Patients after EAS-based PVI due to paroxysmal AF demonstrate 1-year single-procedure success rates similar to those of other ablation techniques and ablation energies. The major determinant for AF recurrence after EAS treatment seems to be reconnection of previously isolated PVs. More patients and longer follow-up periods are mandatory before final conclusions can be drawn regarding the efficacy and safety of the EAS.

Long-term clinical outcome following pulmonary vein isolation with high-intensity focused ultrasound balloon catheters in patients with paroxysmal atrial fibrillation

AIMS High-intensity focused ultrasound (HIFU) applied via a balloon catheter is a novel technology for pulmonary vein isolation (PVI) in patients with paroxysmal atrial fibrillation (PAF). The long-term success rate is unknown. METHODS AND RESULTS Thirty-two patients (22 male, age 60 +/- 9 years) with a long history [5 (4;9) years] of drug refractory [3 +/- 1 anti-arrhythmic drugs (AADs)], symptomatic PAF were included into the analysis. Pulmonary vein isolation was performed using the first- and second-generation HIFU balloon catheters (ProRhythm, Ronkonkoma, NY, USA). Follow-up (F/U) included regular telephonic interviews, trans-telephonic Holter ECG, and event recording. Recurrence was defined as a documented or symptomatic AF episode >30 s without a blanking period. In total 101/116 targeted PVs (87%) were acutely isolated exclusively using HIFU. During a median F/U of 1400 (930;1568) days, 18 patients (56%) were free of AF without AAD after a single HIFU procedure. In nine patients with AF recurrence, 20 PVs exhibited electrical reconduction and re-isolation was performed using irrigated radiofrequency current (RFC) ablation. CONCLUSION Patients treated with the first- and second-generation HIFU balloon catheters due to symptomatic PAF show long-term success rates similar to RFC-based PVI procedures. The major determinant of AF recurrence after HIFU treatment seems to be reconduction of previously isolated PVs. However, the favourable effectiveness is offset by the severe complications reported following HIFU treatment. This led to a halt of its clinical use.

Safety and Feasibility of Closed Chest Epicardial Catheter Ablation Using Electroporation

Background—Permanent coronary artery damage is a hazardous complication of epicardial radiofrequency ablation. Irreversible electroporation (IRE) is a promising nonthermal ablation modality able to create deep myocardial lesions. We investigated the effects of epicardial IRE on luminal coronary artery diameter and lesion depth. Methods and Results—In 5 pigs (60–75 kg), the pericardium was exposed using surgical subxiphoidal epicardial access. A custom deflectable octopolar 12-mm circular catheter with 2-mm ring electrodes was introduced in the pericardium via a steerable sheath. After coronary angiography (CAG), the proximal, mid, and distal left anterior descending, and circumflex coronary arteries were targeted with a single, cathodal 200 J application. CAG was repeated after IRE and after 3 months follow-up. Using quantitative CAG, the minimal luminal diameter at the lesion site was compared with the average of the diameters just proximal and distal to that lesion. Intimal hyperplasia and lesion size were measured histologically. CAG directly postablation demonstrated short-lasting luminal narrowing with normalization in the targeted area, suggestive of coronary spasm. After 3 months, all CAGs were identical to preablation CAGs: mean reference luminal diameter was 2.2±0.3 mm, mean luminal diameter at the lesion site was 2.1±0.3 mm (P=0.35). Average intimal hyperplasia in all arteries was 2±4%. Median lesion depth was 6.4±2.6 mm. Conclusions—Luminal coronary artery diameter remained unaffected 3 months after epicardial IRE, purposely targeting the coronary arteries. IRE can create deep lesions and is a safe modality for catheter ablation on or near coronary arteries.

Myocardial Lesion Depth With Circular Electroporation Ablation

Background—Recently, we demonstrated the feasibility and safety of circular electroporation ablation in porcine pulmonary vein ostia, but the relationship between the magnitude of the application and lesion dimensions is still unknown. Methods and Results—An in vivo porcine study was performed on left ventricular epicardium submerged under 10 mm of blood, using devices that mimic a 20-mm-diameter 7F circular ablation catheter. Model D contained 10 separate electrodes, whereas model M consisted of 1 circular electrode. Ablations were performed at 50, 100, and 200 J with model D and at 100 J with model M. Lesion dimensions were measured after 3-week survival. All applications resulted in smooth voltage waveforms demonstrating the absence of vapor globe formation, arcing, and a pressure wave. Applications up to 100 J with model D resulted in separate lesions under the electrodes. At 200 J, continuous deep circular lesions were created despite the use of separate electrodes. There was a significant relationship between applied current and median lesion depth, with a slope of 0.17 mm/A. At 100 J, there was no difference in lesion depth or width between models D and M. The electrodes and ablation site directly after ablation showed no signs of thermal damage. Conclusions—In an epicardial porcine model with blood around the application site, continuous circular lesions, deep enough for electric pulmonary vein isolation, were created with a single circular 200-J application. Lesions were continuous despite the use of separate electrodes. Lesion depth increased with the magnitude of the application.

Pulmonary vein stenosis after catheter ablation: electroporation versus radiofrequency.

Background— Radiofrequency ablation inside pulmonary vein (PV) ostia can cause PV stenosis. A novel alternative method of ablation is irreversible electroporation, but the long-term response of PVs to electroporation ablation is unknown. Methods and Results— In ten 6-month-old pigs (60–75 kg), the response of PVs to circular electroporation and radiofrequency ablation was compared. Ten consecutive, nonarcing, electroporation applications of 200 J were delivered 5 to 10 mm inside 1 of the 2 main PVs, using a custom-deflectable, 18-mm circular decapolar catheter. Inside the other PV, circular radiofrequency ablation was performed using 30 W radiofrequency applications via an irrigated 4-mm ablation catheter. PV angiograms were made before ablation, immediately after ablation, and after 3-month survival. PV diameters and heart size were measured. With electroporation ablation, PV ostial diameter decreased 11±10% directly after ablation, but had increased 19±11% after 3 months. With radiofrequency ablation, PV ostial diameter decreased 23±15% directly after ablation and remained 7±17% smaller after 3 months compared with preablation diameter despite a 21±7% increase in heart size during aging from 6 to 9 months. Conclusions— In this porcine model, multiple circumferential 200-J electroporation applications inside the PV ostia do not affect PV diameter at 3-month follow-up. Radiofrequency ablation inside PV ostia causes considerable PV stenosis directly after ablation, which persists after 3 months.Background—Radiofrequency ablation inside pulmonary vein (PV) ostia can cause PV stenosis. A novel alternative method of ablation is irreversible electroporation, but the long-term response of PVs to electroporation ablation is unknown. Methods and Results—In ten 6-month-old pigs (60–75 kg), the response of PVs to circular electroporation and radiofrequency ablation was compared. Ten consecutive, nonarcing, electroporation applications of 200 J were delivered 5 to 10 mm inside 1 of the 2 main PVs, using a custom-deflectable, 18-mm circular decapolar catheter. Inside the other PV, circular radiofrequency ablation was performed using 30 W radiofrequency applications via an irrigated 4-mm ablation catheter. PV angiograms were made before ablation, immediately after ablation, and after 3-month survival. PV diameters and heart size were measured. With electroporation ablation, PV ostial diameter decreased 11±10% directly after ablation, but had increased 19±11% after 3 months. With radiofrequency ablation, PV ostial diameter decreased 23±15% directly after ablation and remained 7±17% smaller after 3 months compared with preablation diameter despite a 21±7% increase in heart size during aging from 6 to 9 months. Conclusions—In this porcine model, multiple circumferential 200-J electroporation applications inside the PV ostia do not affect PV diameter at 3-month follow-up. Radiofrequency ablation inside PV ostia causes considerable PV stenosis directly after ablation, which persists after 3 months.

Two-year clinical follow-up after pulmonary vein isolation using high-intensity focused ultrasound (HIFU) and an esophageal temperature-guided safety algorithm

BACKGROUND AND OBJECTIVE High-intensity frequency ultrasound (HIFU) can achieve pulmonary vein isolation (PVI), but severe complications have happened. An esophageal temperature (ET)-guided safety algorithm was implemented. We investigated medium-term outcome. METHODS After left atrial access, HIFU was applied until complete PVI. The safety algorithm was as follows: ≤3 complete ablations per pulmonary vein, early abortion when ET ≥40.0°C, use of Power Modulation at ET >39.0°C or when after 20 to 30 seconds no change in PV electrograms: to reduce the ablation temperature in the surrounding tissue, acoustic power is switched on and off with a frequency of 1 Hz; in all first ablations, use of Power Modulation after 50% of programmed time. Touch-up radiofrequency ablation when PVI failed. Follow-up included interviews and Holter electrocardiograms. Recurrence was defined as atrial fibrillation (AF) >30 seconds without a blanking period. RESULTS A total of 28 symptomatic patients (18 males, age 63 years), with paroxysmal AF (n = 19) and persistent AF (n = 9) were included. After a median follow-up of 738 days, 22 of the 28 patients (79%) were free of AF without antiarrhythmic drugs. After 1 repeat procedure with radiofrequency ablation, 5 patients remained free of AF. The complications were as follows: 1 lethal atrial-to-esophageal fistula at day 31, 1 pericardial effusion at day 48, 1 unexplained death at day 49, and 2 persistent phrenic nerve palsies with full recovery within 12 months. CONCLUSIONS Two-year follow-up after PVI using HIFU and an ET-guided safety algorithm shows success rates similar to those of radiofrequency-based procedures but with higher complication rates. Importantly, the ET-guided safety algorithm failed to prevent severe complications. HIFU does not meet safety standards required for the treatment of AF, and this led to a halt of its clinical use.