Randomized Comparison Between Open Irrigation Technology and Intracardiac-Echo-Guided Energy Delivery for Pulmonary Vein Antrum Isolation: Procedural Parameters, Outcomes, and the Effect on Esophageal Injury

Role of oesophageal cooling in the prevention of oesophageal injury in atrial fibrillation catheter ablation: a systematic review and meta-analysis of randomized controlled trials

AIMS

To evaluate the efficacy of oesophageal cooling in the prevention of oesophageal injury in patients undergoing atrial fibrillation (AF) catheter ablation.

METHODS AND RESULTS

Comprehensive search of MEDLINE, EMBASE, and Cochrane databases through April 2022 for randomized controlled trials (RCTs) evaluating the role of oesophageal cooling compared with control in the prevention of oesophageal injury during AF catheter ablation. The study primary outcome was the incidence of any oesophageal injury. The meta-analysis included 4 RCTs with a total of 294 patients. There was no difference in the incidence of any oesophageal injury between oesophageal cooling and control [15% vs. 19%; relative risk (RR) 0.86; 95% confidence interval (CI) 0.31-2.41]. Compared with control, oesophageal cooling showed lower risk of severe oesophageal injury (1.5% vs. 9%; RR 0.21; 95% CI 0.05-0.80). There were no significant differences among the two groups in mild to moderate oesophageal injury (13.6% vs. 12.1%; RR 1.09; 95% CI 0.28-4.23), procedure duration [standardized mean difference (SMD) -0.03; 95% CI -0.36-0.30], posterior wall radiofrequency (RF) time (SMD 0.27; 95% CI -0.04-0.58), total RF time (SMD -0.50; 95% CI -1.15-0.16), acute reconnection incidence (RR 0.93; 95% CI 0.02-36.34), and ablation index (SMD 0.16; 95% CI -0.33-0.66).

CONCLUSION

Among patients undergoing AF catheter ablation, oesophageal cooling did not reduce the overall risk of any oesophageal injury compared with control. Oesophageal cooling might shift the severity of oesophageal injuries to less severe injuries. Further studies should evaluate the long-term effects after oesophageal cooling during AF catheter ablation.

Incidence and clinical relevance of upper gastrointestinal pathology during preprocedural endoscopy in patients undergoing pulmonary vein isolation

BACKGROUND

Reflux-induced esophagitis might facilitate ablation-induced esophageal lesions (ELs) following pulmonary vein isolation (PVI), and these may progress to atrio-esophageal fistula (AEF). In contrast, preexisting ELs are not prone to progression but may affect procedure planning.

OBJECTIVE

To study the incidence of preexisting esophageal and upper gastrointestinal (UGI) pathology in patients undergoing PVI, and the relation to ablation-induced ELs.

METHODS

From 08/2018 to 09/2021, consecutive patients undergoing (radiofrequency [RF] or cryoballoon [CB]) PVI were examined by esophagogastroscopy (EGD) before and following ablation. Postprocedural endoscopic ultrasound (EUS) was added in 2021.

RESULTS

412 patients (median age 67.5 [IQR 61.3-75.0] years, 56.1% male) were studied. Preprocedural EGD showed abnormalities in 226/399 patients, 15% in the lower third of the esophagus. Half (99/226) were relevant for PVI, 13 procedures were postponed, 6 due to pathological EGD results. A third of the patients with new esophageal injury following ablation had preexisting esophagitis which was associated with a trend for a higher incidence of ELs after RF ablation (12.5 vs. 6.9%, p = 0.232), and a six- and two-fold higher rate of food retention after CB-PVI (28.6 vs. 4.5%, p = 0.008) and RF ablation (8.3 vs. 4.4%, p = 0.279), respectively.

CONCLUSION

(1) EGD before PVI showed UGI abnormalities in > 50% of patients, one-fourth of these relevant for PVI. (2) Esophageal inflammation was associated with a higher incidence of post-ablation (peri)-esophageal injury. Whether having this information before ablation is able to reduce ELs or AEF remains to be shown.

Radiofrequency ablation for treatment of atrial fibrillation with the use of intracardiac echocardiography vs without intracardiac echocardiography: A meta-analysis of observational and randomized studies

AIMS

Intracardiac echocardiography (ICE) provides superior quality images and can monitor catheter location within the heart continuously. Given the limited evidence, we conducted the meta-analysis to evaluate outcomes with ICE in radiofrequency (RF) ablation of atrial fibrillation (AF).

METHODS AND RESULTS

PubMed/MEDLINE, Embase and Cochrane were searched for studies reporting RF ablation for treatment of AF with the use of ICE vs without ICE and 12 studies were included. Sensitivity analyses limiting studies to ablation with the use of contact force (CF) catheters were conducted and subgroup analyses were performed according to the published year. In main analyses, RF ablation with ICE for treatment of AF was associated with significant reduction in total X-ray time (MD, -9.80; 95% CI, -15.57 to -4.04; I² =99%; p <0.01), total procedure time (MD, -17.65; 95% CI, -30.22 to -5.09; I² =89%; p <0.01), and complications (RR, 0.90; 95% CI, 0.87 to 0.92; I² =20%; p<0.01) vs without ICE. The ICE-guided group tended to decrease total absorbed X-ray dose (SMD, -0.91; 95% CI, -1.86 to 0.04; I² =96%; p =0.06). Freedom from arrhythmia (RR, 1.06; 95% CI, 0.98 to 1.14; I² =0%; p =0.13) was comparable between the two groups.

CONCLUSION

In patients with AF, ICE-guided RF ablation is correlated with significant reductions in total X-ray time, total procedure time, and complications vs ablation without ICE. Total absorbed X-ray dose tends to reduce in the ICE group and freedom from arrhythmia is comparable between the two groups. This article is protected by copyright. All rights reserved.

Esophageal Thermal Injury after Catheter Ablation for Atrial Fibrillation with High-Power (50 Watts) Radiofrequency Energy

Background and Objectives

Data regarding the safety of atrial fibrillation (AF) ablation using high-power (50 W) radiofrequency (RF) energy in Asian populations are limited. This study was conducted to evaluate the incidence and pattern of esophageal injury after high-power AF ablation in an Asian cohort.

Methods

We searched the prospective AF ablation registry to identify patients who underwent AF ablation with 50 W RF energy using the smart touch surround flow catheter (Biosense Webster, Diamond Bar, CA, USA). Visitag™ (Biosense Webster) was used for lesion annotation with predefined settings of catheter stability (3 mm for 5 seconds) and minimum contact force (50% of time >5 g). All patients underwent upper gastrointestinal endoscopy at 1 or 3 days after the ablation.

Results

A total of 159 patients (mean age: 63±9 years, male: 69%, paroxysmal AF: 45.3%, persistent AF: 27.7%, long-standing persistent AF: 27.0%) were analyzed. Initially, 26 patients underwent pulmonary vein isolation with 50 W for 5 seconds at each point. The remaining 133 patients underwent prolonged RF duration (anterior 10 seconds and posterior 6 seconds). The incidence rates of esophageal erythema/erosion and superficial ulceration were 1.3% for each type of the lesion. Food stasis, a suggestive finding of gastroparesis, was observed in 25 (15.7%) patients. There were no cases of cardiac tamponade, stroke, or death.

Conclusions

In Asian patients, AF ablations using 50 W resulted in very low rates of mild esophageal complications.

Esophageal injury associated with catheter ablation for atrial fibrillation: Determinants of risk and protective strategies

Catheter ablation has become an important element in the management of atrial fibrillation. Several technical advances allowed for better safety profiles and lower recurrence rates, leading to an increasing number of ablations worldwide. Despite that, major complications are still reported, and esophageal thermal injury remains a significant concern as atrioesophageal fistula (AEF) is often fatal. Recognition of the mechanisms involved in the process of esophageal lesion formation and the identification of the main determinants of risk have set the grounds for the development and improvement of different esophageal protective strategies. More sensitive esophageal temperature monitoring, safer ablation parameters and catheters, and different energy sources appear to collectively reduce the risk of esophageal thermal injury. Adjunctive measures such as the prophylactic use of proton-pump inhibitors, as well as esophageal cooling or deviation devices, have emerged as complementary methods with variable but promising results. Nevertheless, as a multifactorial problem, no single esophageal protective measure has proven to be sufficiently effective to eliminate the risk, and further investigation is still warranted. Early screening in the patients at risk and prompt intervention in the cases of AEF are important risk modifiers and yield better outcomes.

Comparative study of strategies to prevent esophageal and periesophageal injury during atrial fibrillation ablation

OBJECTIVE

To compare the prevalence of esophageal and periesophageal thermal injury in patients undergoing radiofrequency (RF) atrial fibrillation (AF) ablation using 8 mm tip catheters during three different esophageal protection strategies.

METHODS

Forty-five consecutive patients with paroxysmal or persistent AF underwent first ablation procedure, besides esophagogastroduodenoscopy (EGD) combined with radial endosonography (EUS) performed before and after the pulmonary vein (PV) isolation. Before the procedure, patients were randomly assigned to one of three esophageal lesion protection strategies: group I-without any protective or monitoring dispositive and limiting RF applications to 30 W for 20 seconds, in left atrium posterior wall (LAPW); group II-power and time of RF delivery, up to 50 W for 20 seconds at LAPW, limited by esophageal temperature monitoring; group III-applications of RF in LAPW with fixed power application of 50 W for 20 seconds during continuous esophageal cooling.

RESULTS

Baseline characteristics of patients were similar in all groups. The four PVs were isolated in 14 (93.3%), 13 (86.7%), and 15 (100%) patients, respectively in groups I, II, and III. The mean RF power was significantly higher (P < .001) in the posterior side of PVs in group III. Post-AF ablation EGD and EUS revealed two esophageal wall ulcerations and two periesophageal mediastinal edemas only in the esophageal cooling group (P = .008).

CONCLUSION

Esophageal cooling balloon strategy resulted in a higher RF power energy delivery when ablating at the LA posterior wall, using 8 mm nonirrigated tip catheters under temperature mode control. Despite that, patients presented a relatively low incidence of esophageal and periesophaeal injuries.

The use of intracardiac echocardiography catheters in endocardial ablation of cardiac arrhythmia: Meta-analysis of efficiency, effectiveness, and safety outcomes

Aims

The optimal use of intracardiac echocardiography (ICE) may reduce fluoroscopy time and procedural complications during endocardial ablation of cardiac arrhythmias. Due to limited evidence in this area, we conducted the first systematic literature review and meta‐analysis to evaluate outcomes associated with the use of ICE.

Methods and Results

Studies reporting the use of ICE during ablation procedures vs without ICE were searched using PubMed/MEDLINE. A meta‐analysis was performed on the 19 studies (2186 patients) meeting inclusion criteria, collectively representing a broad range of arrhythmia mechanisms. Use of ICE was associated with significant reductions in fluoroscopy time (Hedges' g −1.06; 95% confidence interval [CI] −1.81 to −0.32; P < .01), fluoroscopy dose (Hedges' g −1.27; 95% CI −1.91 to −0.62; P < .01), and procedure time (Hedges' g −0.35; 95% CI −0.64 to −0.05; P = .02) vs ablation without ICE. A 6.95 minute reduction in fluoroscopy time and a 15.2 minute reduction in procedure time was observed between the ICE vs non‐ICE groups. These efficiency gains were not associated with any decreased effectiveness or safety. Sensitivity analyses limiting studies to an atrial fibrillation (AF) only population yielded similar results to the main analysis.

Conclusion

The use of ICE in the ablation of cardiac arrhythmias is associated with significantly lower fluoroscopy time, fluoroscopy dose, and shorter procedure time vs ablation without ICE. These efficiency improvements did not compromise the clinical effectiveness or safety of the procedure.

PV isolation guided by esophageal visualization with a tailored ablation strategy for the avoidance of esophageal thermal injury: a randomized trial

PURPOSE

Radiofrequency ablation along the posterior wall of the left atrium may lead to atrioesophageal fistula due to esophageal thermal injury. The purpose of our study was to prospectively investigate whether ablation guided by soluble contrast esophageal visualization (SCEV) reduces injury during atrial fibrillation (AF) ablation.

METHODS

Seventy-eight patients with paroxysmal AF undergoing circumferential pulmonary vein isolation (PVI) were randomized to a SCEV group (n = 39) and control group without visualization (n = 39). Cine imaging of the esophagus was performed during soluble contrast swallowing at the beginning of ablation, after adjacent ipsilateral PVI and at the end of the procedure. The ablation lesion set was modified to avoid radiofrequency delivery within the contrast esophagram boundaries. In the control group, a single final ingestion was performed at the end of the procedure. Esophageal injury was assessed by esophagogastroscopy within 24 h in all patients.

RESULTS

In the control group, the ablation lesion crossed over the esophagus in 46.2% of patients, whereas in SCEV group, the ablation line violated the boundaries of the esophagus unavoidably in 15.4% of patients (confidence interval (CI); 1.61-13.98, p = 0.003). The incidence of esophageal injury was significantly lower in patients that underwent ablation with SCEV (5.1% vs. 20.5%, CI; 0.04-1.06, p = 0.042). Regardless of randomization group, patients who received ablation which overlapped the esophagus had a higher incidence of esophageal injury compared with those without overlap (37.5 vs. 1.9%, CI; 3.73-271.37, p = 0.000).

CONCLUSIONS

Esophageal contrast visualization helps to reduce the potential for esophageal injury during paroxysmal AF ablation. This simple procedural adjunct has important implications to improve safety of paroxysmal AF ablation procedures globally.

Oesophageal Injury During AF Ablation: Techniques for Prevention

Atrial fibrillation remains the most common arrhythmia worldwide, with pulmonary vein isolation (PVI) being an essential component in the treatment of this arrhythmia. In view of the close proximity of the oesophagus with the posterior wall of the left atrium, oesophageal injury prevention has become a major concern during PVI procedures. Oesophageal changes varying from erythema to fistulas have been reported, with atrio-oesophageal fistulas being the most feared as they are associated with major morbidity and mortality. This review article provides a detailed description of the risk factors associated with oesophageal injury during ablation, along with an overview of the currently available techniques to prevent oesophageal injury. We expect that this state of the art review will deliver the tools to help electrophysiologists prevent potential oesophageal injuries, as well as increase the focus on research areas in which evidence is lacking.

Radiofrequency Catheter Ablation for Atrial Fibrillation Elicited "Jackhammer Esophagus": A New Complication Due to Vagal Nerve Stimulation?

Radiofrequency catheter ablation (RFCA) is a potentially curative method for treatment of highly symptomatic and drug-refractory atrial fibrillation (AF). However, this technique can provoke esophageal and nerve lesion, due to thermal injury. To our knowledge, there have been no reported cases of a newly described motor disorder, the Jackhammer esophagus (JE) after RFCA, independently of GERD. We report a case of JE diagnosed by high-resolution manometry (HRM), in whom esophageal symptoms developed 2 weeks after RFCA, in absence of objective evidence of GERD. A 65-year-old male with highly symptomatic, drug-refractory paroxysmal AF was candidate to complete electrical pulmonary vein isolation with RFCA. Prior the procedure, the patient underwent HRM and impedance-pH to rule out GERD or hiatal hernia presence. All HRM parameters, according to Chicago classification, were within normal limits. No significant gastroesophageal reflux was documented at impedance pH monitoring. Patient underwent RFCA with electrical disconnection of pulmonary vein. After two weeks, patient started to complain of dysphagia for solids, with acute chest-pain. The patient repeated HRM and impedance-pH monitoring 8 weeks after RFCA. HRM showed in all liquid swallows the typical spastic hypercontractile contractions consistent with the diagnosis of JE, whereas impedance-pH monitoring resulted again negative for GERD. Esophageal dysmotility can represent a possible complication of RFCA for AF, probably due to a vagal nerve injury, and dysphagia appearance after this procedure must be timely investigated by HRM.

High-volume lesions using a new second-generation open irrigation radiofrequency catheter are associated with the development of inhomogeneous lesions

BACKGROUND

After catheter ablation there is often a discrepancy between acute and chronic success rates. We aimed to evaluate major determinants for lesion quality and understand different manifestations of lesion structures.

METHODS

In a canine thigh muscle model radiofrequency (RF) current was delivered for 60 seconds at 30 W (n = 39) or 50 W (n = 18) with 15-g contact force. A second-generation 12-hole gold open irrigation catheter (SGIT) and a first-generation six-hole platinum-iridium catheter (FGIT; Biotronik, Berlin, Germany) were used. Electrode and tissue temperatures (at the surface and 3.5-mm and 7-mm depth) were recorded and lesion dimensions were measured. Lesions with steam pops were excluded. Histological examination was performed to evaluate homogeneity of the lesions. Inhomogeneity was defined as a visual multiband lesion pattern indicating different histological characteristics.

RESULTS

In total 57 lesions were created. Seventeen lesions were excluded (steam pops) and 40 lesions were analyzed. A total number of 11 homogeneous and 29 inhomogeneous lesions were identified. Using the SGIT catheter 16.7% of the lesions was homogeneous and 83.3% inhomogeneous; for FGIT it was 43.8% and 56.2% (P = 0.065), respectively. Homogeneous lesions had lower volumes as compared to inhomogeneous lesions (514.0 ± 198.8 vs 914.8 ± 399.1 mm, P = 0.003). Multiple logistic regression analysis indicated that the SGIT catheter is a significant predictor for inhomogeneous lesions (odds ratio 6.5, 95% confidence interval 1.1-38.8; P = 0.040) independent from power setting and flow rate.

CONCLUSIONS

The development of inhomogeneous lesions after acute RF ablation is associated with higher lesion volumes and the use of the second-generation irrigation gold-tip catheter.

Percutaneous catheter ablation of atrial fibrillation

Atrial fibrillation is the most common arrhythmia and is associated with important morbidity and mortality. Antiarrhythmic therapy is recommended as initial therapy but is associated with modest efficacy and significant side effects. Over the past several years, catheter ablation has been demonstrated to provide effective and safe curative therapy for atrial fibrillation. Future investigations will assess advances in catheter ablation technology and will help to define the precise role of catheter ablation relative to alternative therapies, such as rate-control and antiarrhythmic therapy.

Initial feasibility testing of limited field of view magnetic resonance thermometry using a local cardiac radiofrequency coil

The visualization of lesion formation in real time is one potential benefit of carrying out radiofrequency ablation under magnetic resonance (MR) guidance in the treatment of atrial fibrillation. MR thermometry has the potential to detect such lesions. However, performing MR thermometry during cardiac radiofrequency ablation requires high temporal and spatial resolution and a high signal-to-noise ratio. In this study, a local MR coil (2-cm diameter) was developed to investigate the feasibility of performing limited field of view MR thermometry with high accuracy and speed. The local MR coil allowed high-resolution (1 × 1 × 3 mm(3)) image acquisitions in 76.3 ms with a field of view 64 × 32 mm(2) during an open-chest animal experiment. This represents a 4-fold image acquisition acceleration and an 18-fold field of view reduction compared to that achieved using external MR coils. The signal sensitivity achieved using the local coil was over 20 times greater than that achievable using external coils with the same scan parameters. The local coil configuration provided fewer artifacts and sharper and more stable images. These results demonstrate that MR thermometry can be performed in the heart wall and that lesion formation can be observed during radiofrequency ablation procedures in a canine model.

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.

Catheter ablation for paroxysmal and persistent atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common cardiac arrhythmia seen in cardiovascular departments. Treatments include medical interventions and catheter ablation. Due to uncertainties in medical therapies for AF, and the need to continue sinus rhythm, ablation has been recently considered as a viable alternative. Many new ablation methods based on pulmonary vein isolation (PVI) have been developed.

OBJECTIVES

The primary objective of this review was to assess the beneficial and harmful effects of catheter ablation (CA) in comparison with medical treatment in patients with paroxysmal and persistent AF. The secondary objective was to determine the best regimen of CA.

SEARCH METHODS

Searches were run on The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library Issue 3 2009, MEDLINE (1950 to August 2009), EMBASE (1980 to August 2009), the Chinese Biomedical Literature Database (1978 to August 2009) and the CKNI Chinese Paper Database (1994 to 2009) . Several journals published in Chinese were also handsearched.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in people with paroxysmal and persistent AF treated by any type of CA method. Two reviewers independently selected the trials for inclusion.

DATA COLLECTION AND ANALYSIS

Assessments of risk of bias were performed by two reviewers, and relative risk (RR) and 95% confidence intervals (CI) were used for dichotomous variables. Meta-analysis were performed where appropriate.

MAIN RESULTS

A total of 32 RCTs (3,560 patients) were included. RCTs were small in size and of poor quality.CA compared with medical therapies: seven RCTs indicated that CA had a better effect in inhibiting recurrence of AF [RR 0.27; 95% CI 0.18, 0.41)] but there was significant heterogeneity. There was limited evidence to suggest that sinus rhythm was restored during CA (one small trial: RR 0.28, 95% CI 0.20-0.40), and at the end of follow-up (RR 1.87, 95% CI 1.31-2.67; I(2)=83%). There were no differences in mortality (RR, 0.50, 95% CI 0.04 to 5.65), fatal and non-fatal embolic complication (RR 1.01, 95% CI 0.18 to 5.68) or death from thrombo-embolic events (RR 3.04, 95% CI 0.13 to 73.43).Comparisons of different CAs; 25 RCTs compared CA of various kinds. Circumferential pulmonary vein ablation was better than segmental pulmonary vein ablation in improving symptoms of AF (p<=0.01) and in reducing the recurrence of AF (p<0.01). There is limited evidence to suggest which ablation method was the best.

AUTHORS' CONCLUSIONS

There is limited evidence to suggest that CA may be a better treatment option compared to medical therapies in the management of persistent AF. This review was also unable to recommend the best CA method.

Limiting esophageal temperature in radiofrequency ablation of left atrial tachyarrhythmias results in low incidence of thermal esophageal lesions

Background

Atrio-esophageal fistula formation following radiofrequency ablation of left atrial tachyarrhythmias is a rare but devastating complication. Esophageal injuries are believed to be precursors of fistula formation and reported to occur in up to 47% of patients. This study investigates the incidence of esophageal lesions when real time esophageal temperature monitoring and temperature limitation is used.

Methods

184 consecutive patients underwent open irrigated radiofrequency ablation of left atrial tachyarrhythmias. An esophageal temperature probe consisting of three independent thermocouples was used for temperature monitoring. A temperature limit of 40°C was defined to interrupt energy delivery. All patients underwent esophageal endoscopy the next day.

Results

Endoscopy revealed ulcer formation in 3/184 patients (1.6%). No patient developed atrio-esophageal fistula. Patient and disease characteristics had no influence on ulcer formation. The temperature threshold of 40°C was reached in 157/184 patients. A temperature overshoot after cessation of energy delivery was observed frequently. The mean maximal temperature was 40.8°C. Using a multiple regression analysis creating a box lesion that implies superior- and inferior lines at the posterior wall connecting the right and left encircling was an independent predictor of temperature. Six month follow-up showed an overall success rate of 78% documented as sinus rhythm in seven-day holter ECG.

Conclusion

Limitation of esophageal temperature to 40°C is associated with the lowest incidence of esophageal lesion formation published so far. This approach may contribute to increase the safety profile of radiofrequency ablation in the left atrium.

Evaluation of the left atrial substrate in patients with lone atrial fibrillation using delayed-enhanced MRI: implications for disease progression and response to catheter ablation

BACKGROUND

Lone atrial fibrillation (AF) is thought to be a benign type or an early stage of the disease.

OBJECTIVE

This study sought to compare the left atrium (LA) substrate using delayed-enhanced magnetic resonance imaging (DE-MRI) in patients with lone AF versus those with comorbidities.

METHODS

Forty of 333 included patients met criteria for lone AF. All patients underwent DE-MRI to quantify atrial fibrosis as a marker for structural remodeling (SRM) and underwent catheter ablation. Based on the degree of SRM, patients were staged into 4 groups: Utah I (≤5% LA wall enhancement), Utah II (>5% to ≤20%), Utah III (>20% to ≤35%), or Utah IV (>35%).

RESULTS

Distribution in Utah I to IV was comparable in patients with lone AF and non-lone AF. In both groups, a number of patients showed extensive SRM. Mean enhancement (14.08 ± 8.94 vs. 16.94 ± 11.37) was not significantly different between the 2 groups (P = .0721). In the lone AF group, catheter ablation was successful in suppressing AF in all of Utah I, 81.82% of Utah II, 62.5% of Utah III, and none of Utah IV patients. Similar results were achieved in the non-lone AF group. Outcome after ablation was significantly dependent on the SRM of the LA (P < .001).

CONCLUSION

The degree of LA structural remodeling as detected using DE-MRI is independent of AF type and associated comorbidities. Selecting appropriate treatment candidates based on the quality and quantity of atrial fibrosis using DE-MRI would improve procedural outcome and avoid unnecessary intervention.

Evaluation of left atrial lesions after initial and repeat atrial fibrillation ablation: lessons learned from delayed-enhancement MRI in repeat ablation procedures

BACKGROUND

We evaluated scar lesions after initial and repeat catheter ablation of atrial fibrillation (AF) and correlated these regions to low-voltage tissue on repeat electroanatomic mapping. We also identified gaps in lesion sets that could be targeted and closed during repeat procedures.

METHODS AND RESULTS

One hundred forty-four patients underwent AF ablation and received a delayed-enhancement MRI at 3 months after ablation. The number of pulmonary veins (PV) with circumferential lesions were assessed and correlated with procedural outcome. Eighteen patients with AF recurrence underwent repeat ablation. MRI scar regions were compared with electroanatomic maps during the repeat procedure. Regions of incomplete scar around the PVs were then identified and targeted during repeat ablation to ensure complete circumferential lesions. After the initial procedure, complete circumferential scarring of all 4 PV antrum (PVA) was achieved in only 7% of patients, with the majority of patients (69%) having <2 completely scarred PVA. After the first procedure, the number of PVs with complete circumferential scarring and total left atrial wall (LA) scar burden was associated with better clinical outcome. Patients with successful AF termination had higher average total left atrial wall scar of 16.4%+/-9.8 (P=0.004) and percent PVA scar of 66.2+/-25.4 (P=0.01) compared with patients with AF recurrence who had an average total LA wall scar 11.3%+/-8.1 and PVA percent scar 50.0+/-24.7. In patients who underwent repeat ablation, the PVA scar percentage was 56.1%+/-21.4 after the first procedure compared with 77.2%+/-19.5 after the second procedure. The average total LA scar after the first ablation was 11.0%+/-4.1, whereas the average total LA scar after second ablation was 21.2%+/-7.4. All patients had an increased number of completely scarred pulmonary vein antra after the second procedure. MRI scar after the first procedure and low-voltage regions on electroanatomic mapping obtained during repeat ablation demonstrated a positive quantitative correlation of R(2)=0.57.

CONCLUSIONS

Complete circumferential PV scarring difficult to achieve but is associated with better clinical outcome. Delayed-enhancement MRI can accurately define scar lesions after AF ablation and can be used to target breaks in lesion sets during repeat ablation.

Thermal esophageal lesions after radiofrequency catheter ablation of left atrial arrhythmias

OBJECTIVES

Radiofrequency catheter ablation in patients with left atrial arrhythmias may cause esophageal damage because of the close proximity between the posterior wall of the left atrium and the esophagus. The aim of this prospective study was to determine the incidence, endoscopic characterization, and endoluminal temperature dependency of esophageal thermal lesions after catheter ablation.

METHODS

In all, 185 consecutive patients with symptomatic atrial fibrillation or left atrial macro-re-entrant tachycardia who underwent left atrial radiofrequency catheter ablation were scheduled for upper gastrointestinal endoscopy. During the ablation procedure, a non-fluoroscopic three-dimensional system for catheter orientation, computed tomography (CT) image integration, and activation mapping was used. The esophagus was intubated with a temperature probe for visualization within the three-dimensional image and for real-time intraluminal temperature monitoring.

RESULTS

A total of 27 (14.6%) asymptomatic ulcer-like or hemorrhagic esophageal thermal lesions with a diameter of 2-16 mm were observed. Esophageal lesions did not occur below an intraluminal esophageal temperature of 41 degrees C. The maximal temperature in the esophagus was significantly higher in patients with thermal lesions than in patients without lesions (42.6+/-1.7 degrees C vs. 41.4+/-1.7 degrees C, P=0.003). For every 1 degrees C increase in endoluminal temperature, the odds of an esophageal lesion increased by a factor of 1.36 (95% confidence interval (CI) 1.07-1.74, P=0.012). No progression of the lesions was observed during follow-up endoscopies.

CONCLUSIONS

Localized esophageal ulcer-like lesion is a frequent event after left atrial catheter ablation and can be found in patients whose intraluminal temperature has reached at least 41 degrees C.

Late gadolinium enhancement of the esophagus is common on cardiac MR several months after pulmonary vein isolation: preliminary observations

BACKGROUND

Pulmonary vein isolation (PVI) as a treatment for atrial fibrillation (AF) is commonly performed. This procedure can damage the esophagus. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) offers noninvasive assessment of scar. We sought to examine the prevalence of esophageal hyperenhancement on LGE-CMR prior to and following PVI.

METHODS

Seventy-four patients underwent LGE-CMR prior to and 1.7 +/- 1.9 months post PVI for AF. Transmural esophageal hyperenhancement was visually assessed. The pre- and post PVI esophageal position was measured, relative to the vertebral body.

RESULTS

Prior to PVI, 3% (2/74) of patients had esophageal LGE on CMR. At post-PVI follow-up, 30% (23/74) of the studies demonstrated new esophageal hyperenhancement adjacent to an ablation site. Most (74%, 17/27) positive esophageal LGE studies were performed >30 days after PVI, while no (0/9) studies performed >2 months post PVI were positive for esophageal hyperenhancement. The presence of post-procedural esophageal hyperenhancement was not associated with longer ablation time (P = 0.42), use of an irrigated catheter (74% with LGE vs 47% without, P = 0.16), right-sided esophageal location (56% with LGE vs 39% without, P = 0.17), size of left atrium cavity (58 +/- 8 mm with LGE vs 61 +/- 10 mm without, P = 0.15), or the timing of the LGE-CMR study after PVI (36 +/- 10 days with LGE vs 60 +/- 66 days without, P = 0.09).

CONCLUSION

Though rare before PVI, new esophageal LGE is seen in almost one-third of patients after PVI. The clinical implications to remain to be explored, but clinicians should be aware of this frequent imaging finding.

Magnetic resonance imaging-confirmed ablative debulking of the left atrial posterior wall and septum for treatment of persistent atrial fibrillation: rationale and initial experience

INTRODUCTION

Though pulmonary vein (PV) isolation has been widely adopted for treatment of atrial fibrillation (AF), recurrence rates remain unacceptably high with persistent and longstanding AF. As evidence emerges for non-PV substrate changes in the pathogenesis of AF, more extensive ablation strategies need further study.

METHODS

We modified our PV antrum isolation procedure to include abatement of posterior and septal wall potentials. We also employed recently described image-processing techniques using delayed-enhancement (DE) MRI to characterize tissue injury patterns 3 months after ablation, to assess whether each PV was encircled with scar, and to assess the impact of these parameters on procedural success.

RESULTS

118 consecutive patients underwent debulking procedure and completed follow-up, of which 86 underwent DE-MRI. The total left atrial (LA) radiofrequency delivery correlated with percent LA scarring by DE-MRI (r = 0.6, P < 0.001). Based on DE patterns, complete encirclement was seen in only 131 of 335 PVs (39.1%). As expected, Cox regression analysis showed a significant relationship between the number of veins encircled by delayed enhancement and clinical success (hazard ratio of 0.62, P = 0.015). Also, progressive quartile increases in postablation posterior and septal wall scarring reduced recurrences rates with a HR of 0.65, P = 0.022 and 0.66, P = 0.026, respectively.

CONCLUSION

Pathologic remodeling in the septal and posterior walls of the LA helps form the pathogenic substrate for AF, and these early results suggest that more aggressive treatment of these regions appears to correlate with improved ablation outcomes. Noninvasive imaging to characterize tissue changes after ablation may prove essential to stratifying recurrence risk.

Detection and quantification of left atrial structural remodeling with delayed-enhancement magnetic resonance imaging in patients with atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is associated with diffuse left atrial fibrosis and a reduction in endocardial voltage. These changes are indicators of AF severity and appear to be predictors of treatment outcome. In this study, we report the utility of delayed-enhancement magnetic resonance imaging (DE-MRI) in detecting abnormal atrial tissue before radiofrequency ablation and in predicting procedural outcome.

METHODS AND RESULTS

Eighty-one patients presenting for pulmonary vein antrum isolation for treatment of AF underwent 3-dimensional DE-MRI of the left atrium before the ablation. Six healthy volunteers also were scanned. DE-MRI images were manually segmented to isolate the left atrium, and custom software was implemented to quantify the spatial extent of delayed enhancement, which was then compared with the regions of low voltage from electroanatomic maps from the pulmonary vein antrum isolation procedure. Patients were assessed for AF recurrence at least 6 months after pulmonary vein antrum isolation, with an average follow-up of 9.6+/-3.7 months (range, 6 to 19 months). On the basis of the extent of preablation enhancement, 43 patients were classified as having minimal enhancement (average enhancement, 8.0+/-4.2%), 30 as having moderate enhancement (21.3+/-5.8%), and 8 as having extensive enhancement (50.1+/-15.4%). The rate of AF recurrence was 6 patients (14.0%) with minimal enhancement, 13 (43.3%) with moderate enhancement, and 6 (75%) with extensive enhancement (P<0.001).

CONCLUSIONS

DE-MRI provides a noninvasive means of assessing left atrial myocardial tissue in patients suffering from AF and might provide insight into the progress of the disease. Preablation DE-MRI holds promise for predicting responders to AF ablation and may provide a metric of overall disease progression.