The Impact of Left Atrial Size on Long-Term Outcome of Catheter Ablation of Chronic Atrial Fibrillation

Background: The left atrial (LA) size is an important predictor of atrial fibrillation (AF) procedural termination and the long-term outcome. We sought to evaluate the long-term outcome in regard to the LA size and procedural termination.
Methods: Eighty-seven consecutive chronic AF patients (72 males, 53 ± 10 years) underwent 3D mapping (NavX) and ablation. A stepwise approach including circumferential pulmonary vein (PV) isolation, linear ablation, and continuous complex-fractionated electrogram (CFE) ablation (targeting fractionation intervals of < 50 ms). Electrical cardioversion was applied to those without any procedural termination. The freedom from AF was defined as the maintenance of sinus rhythm without the use of any class I or III antiarrhythmic drugs after the blanking period.
Results: Among the 87 patients, all received a circumferential PV isolation, 93% a linear ablation, and 59% a continuous CFE ablation. Those with AF procedural termination (n = 30) had a better long-term outcome when compared with those without termination during a follow-up of 21 ± 12 months. Moreover, a Kaplan-Meier analysis showed that in those with an LA diameter of less than 45 mm (n = 49), the freedom from AF rate was higher when procedural termination was achieved (P = 0.004). On the contrary, the outcome was comparable in those with an LA diameter of ≥ 45 mm (n = 38), whether AF procedural termination occurred or not (P = 0.658).
Conclusions: AF procedural termination was related to the long-term success during chronic AF ablation, especially in those with an LA diameter of less than 45 mm. The favorable effect of termination decreased when the LA diameter was ≥ 45 mm.     

Predictive Value of Thromboembolic Risk Scores Before an Atrial Fibrillation Ablation Procedure

Risk Scores for Atrial Fibrillation Ablation Introduction: It is not clear whether transesophageal echocardiography (TEE) should be performed prior to a planned atrial fibrillation (AF) ablation in all patients. Methods and Results: The objectives of this study were to determine in 681 consecutive patients: (i) the relationship between the CHADS2 and CHA2DS2‐VASc scores, the presence of a thrombogenic milieu and left atrial (LA) volume; (ii) the need for TEE in patients with low and intermediate thromboembolic risk assessed; and (iii) the predictive accuracy of the these 2 scores for the presence of thrombi in the LA/LAA (LA appendage) before a planned AF ablation. The prevalence of thrombi was 1%. All patients with thrombi had LA dilatation, a CHADS2 score ≥1 and a CHA2DS2‐VASc score ≥2. CHADS2 or CHA2DS2‐VASc scores <2 had an almost maximal negative predictive capability of excluding the presence of a thrombus (99.8% and 100%, respectively; 95% CI: 99–100). A CHADS2 score ≥2 had a sensitivity and specificity of 86% (95% CI: 42–100) and 82% (95% CI: 79–85), respectively, to predict the presence of a thrombus in the LA/LAA, while a CHA2DS2‐VASc score ≥2 had a sensitivity and specificity of 100% (95% CI: 59–100) and 67% (95% CI: 63–70). The area under the curve for CHADS2 and CHA2DS2‐VASc scores ≥2 was 0.928 (95% CI: 0.906–0.946) and 0.933 (95% CI: 0.912–0.951), respectively. Conclusion: Not all patients undergoing planned endocardial pulmonary vein isolation need preprocedural TEE. Both scores <2 had an almost maximal negative predictive capability of excluding the presence of a thrombus in the LA/LAA. (J Cardiovasc Electrophysiol, Vol. 24, pp. 139‐145, February 2013)     

Home Monitoring in Patients with Implantable Cardiac Devices: Is There a Potential Reduction of Stroke Risk? Results from a Computer Model Tested Through Monte Carlo Simulations

Introduction: Patients with pacemakers and implantable defibrillators (ICD) may experience asymptomatic atrial fibrillation (AF), detected with a delay depending on the in-person follow-up schedule. Home monitoring (HM) remote control with automatic alerts for AF may drive early anticoagulation, potentially reducing stroke risk.
Methods and Results: A sample of 136 pacemaker (103) and ICD (33) patients with or without cardiac resynchronization therapy not taking anticoagulation at implant were monitored remotely with HM. Upon HM alerts for AF, patients were recalled to update therapy. Two-year data were entered in a computer Monte Carlo model, simulating 4,000 virtual subjects with the same AF and CHADS₂ stroke risk distribution of our real population. Simulations reproduced a 2-year follow-up. Two thousand subjects were supposed to be followed with HM (HM group) and 2,000 with standard in-person follow-up (SF group) at 3, 6, 9, or 12 months.
Two-year Kaplan-Meier cumulative probability of ≥24-hour AF was 15.6% (95%CI 8.5–23.3%); the AF-related symptom rate was 27% and the median CHADS₂ score was 2. As a result of simulations, stroke incidence in case of AF was 2.3 ± 1.1% in the HM group and 2.4 ± 1.1%, 2.5 ± 1.2%, 2.7 ± 1.2%, and 2.9 ± 1.3% in the SF group with 3-, 6-, 9-, and 12-month follow-up programs, with odds ratios of 0.97 (95%CI 0.93–1.01), 0.91 (0.88–0.95), 0.87 (0.84–0.90), and 0.82 (0.79–0.85) (HM better if odds ratios <1), respectively.
Conclusions: Daily HM potentially reduces the stroke risk by 9% to 18% with respect to SF with intervisit intervals of 6 to 12 months.     

Routine preprocedural transesophageal echocardiography might not be necessary for stroke prevention evaluation in AF patients on anticoagulation therapy

Background

Preprocedural transesophageal echocardiography (TEE) is used to reduce the stroke during atrial fibrillation (AF) ablation. This study evaluated whether routine preprocedural TEE in addition to multidetector computed tomography (MDCT) is necessary to prevent periprocedural stroke in AF ablation.

Methods

Each patient underwent MDCT and TEE (group 1, n = 247) or MDCT alone (group 2, n = 103) for the initial evaluation before AF ablation. In group 2, TEE was performed only in patients who had left atrial (LA) thrombus or blood stasis in MDCT.

Results

There was no difference in sex, CHADS₂ score, or LA dimension between the two groups. In group 1, a thrombus was detected in 12 (5%) and 6 (2%) patients by the MDCT and TEE, respectively. All (100%) patients, who were revealed to have thrombus in TEE, also had a thrombus in MDCT. In group 2, 3 (3%) patients exhibited LA thrombus in MDCT, among whom thrombus was observed in only one patient (1%) in TEE. AF ablation was not performed in patients with thrombus. While one patient had a periprocedural stroke in group 1, no patient had in group 2 (P = 0.52).

Conclusion

The overall periprocedural stroke rate was low (0.3%) in AF patients on anticoagulation therapy. The preprocedural MDCT detected all patients with the LA thrombus. In AF patients with low CHADS2 score, optimal anticoagulation and relatively preserved left ventricular ejection fraction, routine preprocedural TEE in addition to the MDCT might not be necessary to decrease the periprocedural stroke rate.     

Body mass index, obstructive sleep apnea, and outcomes of catheter ablation of atrial fibrillation

Background: Obesity and obstructive sleep apnea (OSA) are associated with atrial fibrillation (AF). The effects of a large body mass index (BMI) and OSA on the results of radiofrequency catheter ablation (RFA) of AF are unclear.
Objective: To evaluate the effect of BMI and OSA on the efficacy of RFA for AF.
Methods: RFA was performed in 324 consecutive patients (mean age = 57 ± 11 years) with paroxysmal (234) or chronic (90) AF. OSA was diagnosed by polysomnography in 32 of 324 patients (10%) prior to ablation. Among the 324 patients, 18% had a normal BMI (<25 kg/m²), 39% were overweight (BMI ≥ 25 kg/m² and <30 kg/m²), and 43% were obese (≥30 kg/m²). RFA was performed to eliminate complex fractionated atrial electrograms (CFAE) in the pulmonary vein antrum and left atrium.
Results: At 7 ± 4 months after a single ablation procedure, 63% of patients without OSA and 41% with OSA were free from recurrent AF without antiarrhythmic drug therapy (P = 0.02). Multivariate analysis including variables of age, gender, type and duration of AF, OSA, BMI, left atrial size, ejection fraction, and hypertension demonstrated that OSA was the strongest predictor of recurrent AF (OR = 3.04, 95% CI: 1.11–8.32, P = 0.03). There was no association between BMI and freedom from recurrent AF. A serious complication occurred in 3 of 324 patients, with no relationship to BMI.
Conclusions: OSA is a predictor of recurrent AF after RFA independent of its association with BMI and left atrial size. Obesity does not appear to affect outcomes after radiofrequency catheter ablation of AF.     

Comparison of contrast enhanced 64-slice computed tomography and transesophageal echocardiography in detection of left atrial thrombus in patients with atrial fibrillation

BACKGROUND AND OBJECTIVE: Recent advances in multi-slice computed tomography (MSCT) have allowed an improved analysis of left atrial (LA) and left atrial appendage (LAA) anatomy prior to catheter ablation of atrial fibrillation (AF). However, data regarding the ability of MSCT to identify LA/LAA thrombus are limited. This prospective study compared the efficacy of 64-slice contrast-enhanced computed tomography (64CCT) with transesophageal echocardiography (TEE) of the heart in the identification of LA/LAA thrombus. MATERIALS AND METHODS: One-hundred and seventy consecutive patients scheduled for first-time catheter ablation of paroxysmal (n = 120) or persistent (n = 50) AF were enrolled for study. Each patient underwent non-gated 64CCT and TEE of the heart for exclusion of LA/LAA thrombus prior to ablation procedure. RESULTS: Fourteen cases (8.2%) of LA/LAA thrombi were interpreted by 64CCT (ten false-positive, four true positive), whereas 11 actual thrombi (6.5%) were detected by TEE (seven false-negative by 64CCT) in the same population. Maximal dimension of TEE identified thrombi did not differ between the false-negative by 64CCT group and the true-positive group (17 +/- 6 vs. 18 +/- 5 mm P = 0.677). Results indicated 64CCT sensitivity = 36.4%, specificity = 93.7%, positive predictive value = 28.6%, and negative predictive value = 95.5% in the detection of LA/LAA thrombus. The Kappa value in evaluating the agreement between 64CCT and TEE for detection of LA/LAA thrombus was 0.267. CONCLUSION: Compared to gold standard TEE, 64CCT was shown to be less reliable in the detection of LA/LAA thrombus prior to catheter ablation in patients with AF.     

Prevalence of Left Atrial Thrombus in Anticoagulated Patients With Atrial Fibrillation

BackgroundThe prevalence of left atrial (LA) thrombus in patients with atrial fibrillation (AF) or atrial flutter (AFL) on guideline-directed anticoagulation is not well known, yet this may inform transesophageal echocardiogram (TEE) use before cardioversion or catheter ablation.ObjectivesThe purpose of this study was to quantify LA thrombus prevalence among patients with AF/AFL on guideline-directed anticoagulation and to identify high-risk subgroups.MethodsEMBASE, MEDLINE, and CENTRAL were systematically searched from inception to July 2020 for studies reporting on LA thrombus prevalence among patients with AF/AFL undergoing TEE following at least 3 weeks of continuous therapeutic oral anticoagulation with vitamin K antagonists (VKAs) or direct oral anticoagulants (DOACs). Meta-analysis was performed using random effects models.ResultsThirty-five studies describing 14,653 patients were identified. The mean-weighted LA thrombus prevalence was 2.73% (95% confidence interval [CI]: 1.95% to 3.80%). LA thrombus prevalence was similar for VKA- and DOAC-treated patients (2.80%; 95% CI: 1.86% to 4.21% vs. 3.12%; 95% CI: 1.92% to 5.03%; p = 0.674). Patients with nonparoxysmal AF/AFL had a 4-fold higher LA thrombus prevalence compared with paroxysmal patients (4.81%; 95% CI: 3.35% to 6.86% vs. 1.03%; 95% CI: 0.52% to 2.03%; p < 0.001). LA thrombus prevalence was higher among patients undergoing cardioversion versus ablation (5.55%; 95% CI: 3.15% to 9.58% vs. 1.65%; 95% CI: 1.07% to 2.53%; p < 0.001). Patients with CHA₂DS₂-VASc scores ≥3 had a higher LA thrombus prevalence compared with patients with scores ≤2 (6.31%; 95% CI: 3.72% to 10.49% vs. 1.06%; 95% CI: 0.45% to 2.49%; p < 0.001).ConclusionsLA thrombus prevalence is high in subgroups of anticoagulated patients with AF/AFL, who may benefit from routine pre-procedural TEE use before cardioversion or catheter ablation.     

Prevalence and Clinical Characteristics Associated With Left Atrial Appendage Thrombus in Fully Anticoagulated Patients Undergoing Catheter‐Directed Atrial Fibrillation Ablation

LAA Thrombus Among Anticoagulated AF Patients. Introduction: Catheter‐directed atrial fibrillation (AF) ablation is contraindicated among patients with left atrial appendage (LAA) thrombus. The prevalence of LAA thrombus among fully anticoagulated patients undergoing AF ablation is unknown. Methods and Results: We retrospectively evaluated the prevalence of LAA thrombus among 192 consecutive patients undergoing AF ablation between July 2006 and January 2009. Seven of 192 patients (3.6%) had evidence of thrombus on transesophageal echocardiogram (TEE) despite being fully anticoagulated on warfarin (international normalized ratio [INR] 2–3) for 4 consecutive weeks prior to echocardiogram. Univariate analysis demonstrated that structural heart disease, large left atrial dimension, and number of AF ablations were associated with thrombus. Three patients with thrombus had paroxysmal AF with normal LV function. Conclusion: Despite full anticoagulation, 3.6% of patients undergoing AF ablation had LAA thrombus. We recommend that all patients, regardless of LV function or left atrial size, should undergo preprocedural TEE to exclude the presence of LAA thrombus. (J Cardiovasc Electrophysiol, Vol. 21, pp. 849‐852, August 2010)     

Trombo Atrial Esquerdo e Contraste Espontâneo Denso no Uso de Anticoagulante Oral de Ação Direta em Fibrilação Atrial: Visão de Centro Referenciado

BackgroundIn the treatment of atrial fibrillation (AF), the most frequently sustained arrhythmia, with catheter ablation (CA) or electrical cardioversion (ECV), the periprocedural period is one of the most critical phases. Currently, the use of new direct action oral anticoagulants (DOAC) is increasingly frequent; however, in the real world, there are still few data on studies on the thrombus incidence in the left atrium (TrLA) or dense spontaneous contrast (DSC) on transesophageal echocardiogram (TEE).ObjectiveTo evaluate the prevalence of events and association with risk factors in patients using DOACs. Primary objective: to analyze the prevalence of thrombus in the LA by TEE in patients using DOAC undergoing ECV/CA. Second, evaluate the association of comorbidities with the presence of thrombi and DSC.MethodsRetrospective cohort, single-center study with patients followed at the Arrhythmia Outpatient Unit (InCor-HCFMUSP). Patients indicated for procedures and using DOACs were selected, and their clinical/echocardiographic data were analyzed. A significance level of 5% was considered.Results354 patients were included, a total of 400 procedures, from March 2012-March 2018. Thrombus in the LA was found in 11 patients (2.8%), associated with advanced age (p=0.007) and higher CHA2DS2-VASc (p<0.001) score. DSC in the LA before TEE was found in 29 patients (7.3%), with lower LVEF (p<0.038) and greater LA dimension (p<0.0001).ConclusionThe incidence of LA thrombus and DSC in patients using DOC in the context of AF ECV/CA, although small, is not negligible. Patients with higher CHA2DS2-VASc scores, especially older and with larger LA diameter, are more prone to these echocardiographic findings.     

Does Left Atrial Volume and Pulmonary Venous Anatomy Predict the Outcome of Catheter Ablation of Atrial Fibrillation?

Introduction: Preprocedural factors may be helpful in selecting patients with atrial fibrillation (AF) for treatment with catheter ablation and in making an assumption regarding their prognosis. The aims of this study were to investigate whether left atrial (LA) volume and pulmonary venous (PV) anatomy, evaluated by computed tomography (CT) prior to ablation, will predict AF recurrence following catheter ablation.
Methods and Results: We included 146 patients (mean age 57 ± 11 years, 83% male) with symptomatic AF (55% paroxysmal, 18% persistent, 27% long-standing persistent). All patients underwent CT scanning prior to catheter ablation to evaluate LA volume and PV anatomy. Circumferential PV isolation was performed guided by Cartomerge electroanatomical mapping. The outcome was defined as complete success, improvement, or failure.
After a mean follow-up of 19 ±7 months, complete success was achieved in 59 patients (40%), and 38 patients (26%) demonstrated improvement. LA volume was found to be an independent predictor of AF recurrence with an adjusted OR of 1.14 for every 10-mL increase in volume (95% CI 1.00–1.29, P = 0.047). PV variations were equally distributed among the different outcomes of the ablation procedure, and therefore univariate analysis did not identify PV anatomy as a predictor of outcome.
Conclusion: LA volume is an independent predictor of AF recurrence after catheter ablation. Additionally, PV anatomy did not have any effect on the outcome. These findings suggest that an assessment of LA volume may be incorporated into the preprocedural evaluation of patients being considered for AF ablation.     

Prevalence of Fever in Patients Undergoing Left Atrial Ablation of Atrial Fibrillation Guided by Barium Esophagraphy

Background: Real-time esophageal imaging is critical in avoiding esophageal injury. However, the safety of esophageal imaging with barium has not been specifically explored.
Methods: Three hundred seventy consecutive patients underwent left atrial (LA) ablation of atrial fibrillation (AF) under conscious sedation. One hundred eighty-five patients (50%) underwent the ablation procedure with, and 185 patients (50%) underwent the procedure without administration of barium. Fever, as a surrogate for aspiration, was defined as a maximal temperature ≥100°F within the first 24 hours following the ablation procedure.
Results: Thirty of the 370 patients (8%) developed fever within 24 hours after LA ablation. The prevalence of fever was 9% (17/185) among patients who received barium and 7% (13/185) among those who did not receive barium (P = 0.6). Evaluation revealed the following causes of fever in 14 of the 30 patients (47%) with no difference in prevalence between the 2 groups: pericarditis, venous thromboembolism, hematoma, and infiltrate on chest radiography. Multivariate analysis failed to reveal any factors associated with development of fever. None of the patients experienced serious complications such as respiratory failure or atrioesophageal fistula.
Conclusions: Fever may occur in approximately 10% of patients undergoing LA ablation of AF. Administration of barium is not associated with fever or other complications such as aspiration pneumonia. Real-time imaging of the esophagus with barium administration in conjunction with conscious sedation appears to be safe.     

Periprocedural anticoagulation for atrial fibrillation ablation

Background: Catheter ablation for atrial fibrillation (AF) can increase risk of left atrial (LA) thrombi and stroke. Optimal periprocedural anticoagulation has not been determined.
Objective: We report the role of administering warfarin and aspirin without low molecular weight heparin in patients undergoing AF ablation.
Methods: A total of 207 patients underwent ablation for AF. Transesophageal echocardiography (TEE) guided transseptal puncture and ruled out clot in the LA. After first puncture, the sheath was flushed with heparin (5,000 Units/mL). After second puncture, a bolus of 80 units/kg of heparin was given, followed by an infusion to maintain activated clotting time (ACT) around 300–350 seconds. Warfarin was stopped and aspirin was started (325 mg/day) 3 days preprocedure. Warfarin was restarted on the day of the procedure. Both medications were continued for 6 weeks postablation. Warfarin was continued for 6 months in patients with prior history of persistent or recurrent AF. Thirty-seven patients who showed smoke in the LA on TEE were given low molecular weight heparin postprocedure until international normalized ratio (INR) was therapeutic.
Results: Thirty-two patients had persistent and 175 had paroxysmal AF; 87 were cardioverted during ablation. Two patients had transient ischemic attack (TIA) on the sixth and eighth days, respectively, following ablation, with complete recovery. Both had subtherapeutic INRs.
Conclusion: In patients without demonstrable clot or smoke in the LA, starting aspirin 3 days prior and warfarin immediately post-radiofrequency ablation, without low molecular weight heparin, with meticulous anticoagulation during the procedure, appears to be a safe mode of anticoagulation.     

Atrial fibrillation ablation in patients with known sludge in the left atrial appendage

Purpose

Transesophageal echocardiography (TEE) is routinely used to assess for thrombus in the left atrium (LA) and left atrial appendage (LAA) in patients undergoing atrial fibrillation (AF) ablation. However, little is known about the outcome of AF ablation in patients with documented LAA sludge. We hypothesize that AF ablation can be performed safely in a proportion of patients with sludge in the LAA and may have a significant benefit for these patients.

Methods

We performed a retrospective analysis of all patients undergoing AF ablation at New York University Langone Medical Center (NYULMC) from January 1st 2011 to June 30, 2013. Patients with sludge found on their TEE immediately prior to AF ablation were identified and followed for stroke, AF recurrence, procedural complications, major bleeding, or death.

Results

Among 1,076 patients who underwent AF ablation, 8 patients (mean age 69?±?13 years; 75 % men) with sludge were identified. Patients with sludge in their LAA had no incidence of early or late occurrence of stroke during mean follow-up of 10 months. One patient had a left groin hematoma, and two patients had atrial tachycardias that needed a repeat ablation. TEE at the time of repeat ablation demonstrated the presence of spontaneous echo contrast (smoke) and resolution of sludge. There were no deaths.

Conclusion

In a cohort of eight patients with LAA sludge who underwent AF ablation, no significant thromboembolic events occurred during or after the procedure. AF ablation can be performed safely and may be beneficial in these patients. Larger studies are warranted to better determine the most appropriate management route.     

Warfarin Is Not Needed in Low-Risk Patients Following Atrial Fibrillation Ablation Procedures

Background: The recently published HRS/EHRA/ECAS AF Ablation Consensus Statement recommended that warfarin should be used for at least 2 months following an AF ablation in all patients regardless of stroke risk factors. The objective of the study was to assess outcomes based upon anticoagulation practice after atrial fibrillation (AF) ablation to determine relative risk of a strategy of aspirin only in low-risk patients.
Methods: A total of 630 consecutive patients who underwent 934 ablation procedures using an open irrigated tip catheter for symptomatic AF were evaluated. Outcomes were compared between patients treated with warfarin (goal INR: 2–3) versus aspirin only (325 mg/day) in CHADS2 0–1 patients after ablation.
Results: Of the 690 patients, 123 (20%) were treated with aspirin and 507 (80%) with warfarin. Prevalences of the CHADS2 scores of patients on aspirin were (0: 40.7%, 1: 59.3%) and on warfarin (0: 13.6%, 1: 31.6%, ≥2: 54.8%), P < 0.0001. Patients in the warfarin group were older, had on average a lower ejection fraction, and had higher rates persistent/permanent AF, repeat ablations, hypertension, prior stroke/TIA, and diabetes. The 1-year survival free of AF for the total study population was 71.6%. There were no strokes/TIA in the aspirin group and 4 events (4 strokes, 0 TIAs) in the warfarin group. Two patients in the warfarin group died of fatal hemorrhage (1 intracranial, 1 gastrointestinal).
Conclusion: Select low-risk patients with a low CHADS2 (0–1) score who undergo left atrial ablation with an aggressive anticoagulation strategy with heparin and use of an open irrigated tip catheter with low CHADS2 scores can safely be discharged following their procedure on aspirin alone.     

Efficacy of Additional Ablation of Complex Fractionated Atrial Electrograms for Catheter Ablation of Nonparoxysmal Atrial Fibrillation

Background: The efficacy of ablation of complex fractionated atrial electrograms (CFEs) in the single ablation procedure for nonparoxysmal atrial fibrillation (AF) patients is not well demonstrated. The aim of this study was to compare the ablation strategies of pulmonary vein isolation (PVI) plus linear ablation with and without additional ablation of CFEs in these patients.
Methods: Consecutive 60 patients (49 ± 11 years old, 50 male, 10 female) with nonparoxysmal AF underwent catheter ablation guided by a NavX mapping system. A stepwise approach included a circumferential PVI and left atrial (LA) linear ablation followed by either the additional ablation of continuous CFEs in the LA/coronary sinus (the first 30 patients) or not (the second 30 patients), detected by an automatic algorithm.
Results: There was no difference in the baseline characteristics between the two groups. Complete PVI eliminated some continuous CFEs and altered the distribution of CFEs. Following PVI and linear ablation, the remaining continuous CFEs were identified in 7.9 ± 10% mapping sites of the LA and CS, and were ablated successfully with a procedural AF termination rate of 53%. With a follow-up of 19 ± 11 months, a Kaplan–Meier analysis showed that the patients with additional ablation of the CFEs had a higher rate of sinus rhythm maintenance. Multivariate analysis showed the single procedure success could be predicted by the procedural AF termination and the additional ablation of continuous CFEs in the LA/CS.
Conclusions: Ablation of continuous CFEs after PVI and LA linear ablation had a better long-term efficacy based on the results of single-ablation procedure.     

Transesophageal Echocardiography for the Prevention of Embolic Complications After Catheter Ablation for Atrial Fibrillation

Background: Thromboembolic complications during left-sided ablations range between 1.5 and 5.4%. Preprocedural TEE has been used to exclude the presence of left atrial thrombi in order to minimize risk. The use of TEE is empiric and it has not been evaluated in contemporary practice.
Methods and Results: A multicenter national survey describing the practice at 11 Canadian teaching hospitals. A total of 2,225 patients underwent elective catheter ablation for symptomatic AF. Transesophageal echocardiography (TEE) was used either routinely or selectively as a preablative strategy in patients. There were 996 patients in a routine preprocedure TEE strategy and 1,190 in a selected TEE strategy; 1 center (n = 39 patients) did not perform TEE. Twelve of 996 (1.2%) in the routine unselected cohort had thrombi identified. TEEs were performed in 200 of 1,190 in the selected cohort; 4 (2.0%) left atrial thrombi were observed; there was no significant difference in the prevalence of thrombi (P = 0.34). A total of 11 embolic events occurred inclusive of all groups. There was no difference in event rates between the 2 strategies (0.6% and 0.4%, P = 0.54). Events were unrelated to AF duration (persistent vs paroxysmal, r = 0.03, N = 2,225, P = 0.9).
Conclusion: The selection criteria employed to perform TEEs did not increase the chance of identifying LA thrombi in a patient cohort with primarily nondilated left atria and paroxysmal AF. The overall thromboembolic event rate was low (0.49%) and was not significantly different between the 2 TEE strategies.     

Dilated left atrium and pulmonary veins in patients with calcified coronary artery: a potential contributor to the genesis of atrial fibrillation

Introduction: Coronary artery disease (CAD) is an important etiology of atrial fibrillation (AF). Coronary artery calcification is a marker of coronary atherosclerosis and coronary events. The purpose of this study was to investigate whether larger left atrium (LA) and pulmonary veins (PVs) were seen by multidetector computed tomography (MDCT) scans in those patients with higher coronary calcium scores.
Methods and Results: A total of 166 patients undergoing MDCT for general check-up (n = 128, 77%) or suspected CAD (n = 38, 23%) were enrolled and divided into a control (calcium score = 0, n = 60), medium calcium score (calcium score = 100∼400, n = 47), and high calcium score (calcium score >400, n = 59) groups. Diameters and areas of the LA, left atrial appendage (LAA), and PVs were measured by MDCT. The high calcium score group had significantly larger PVs diameters, LAA orifice area (1.9 ± 1.4 cm², 0.9 ± 0.5 cm², 0.8 ± 0.4 cm², P < 0.005), LA anterior-posterior distance (32.2 ± 6.8 mm, 30.4 ± 6.5 mm, 27.3 ± 6.0 mm, P < 0.05), and transverse distance (52.6 ± 7.3 mm, 50.2 ± 9 mm, 49.5 ± 4.6 mm, P < 0.05) than the medium calcium score and control groups. Six (3.6%) patients with paroxysmal AF had higher calcium scores and larger diameters of LA, LAA, and PVs than those (96.4%) without paroxysmal AF. Two patients in the high calcium score group had calcified PVs localized to the right upper and left upper PVs. The incidence of calcified PVs was 1.2% for the total patients and 3.3% for the high calcium score patients.
Conclusion: In the presence of high calcium scores in this patient population, the LA, LAA, and PVs were enlarged.     

Low incidence of left atrial or left atrial appendage thrombus in patients with paroxysmal atrial fibrillation and normal EF who present for pulmonary vein antrum isolation procedure

Introduction: The incidence of left atrial appendage (LAA) thrombus in patients with paroxysmal atrial fibrillation (PAF) who present for pulmonary vein antrum isolation procedure (PVAI) is unknown.
Methods and Results: All consecutive patients from January 2000 to June 2004 who underwent a PVAI received a computed tomography (CT) to evaluate LAA thrombus before the procedure and 3 months post-PVAI. All patients were followed prospectively. One thousand two hundred twenty-one patients received a PVAI during the study dates. All patients received a CT pre-PVAI at 3 months, and 601 (49%) received a transesophageal echocardiography (TEE) pre-PVAI. Per protocol, all patients who had CT scans that were positive for LAA thrombus received a TEE. There were 9 patients who had LAA thrombus on CT scan, but only 3 had LAA thrombus on TEE. Using TEE as the gold standard, only 3 patients had an LAA thrombus before PVAI; of these patients, 2 had chronic AF with average ejection fraction (EF) of 48% and 1 patient had PAF with EF 25%. No patients with PAF and normal EF had LAA thrombus. Patients with LAA thrombus pre-PVAI had lower EF than patients without LAA thrombus (40% vs. 53%, P = 0.007) but had similar LA size (5.0 vs. 4.5 cm, P = 0.77). No other differences in baseline characteristics were noted.
Conclusions: In this registry of 1,221 patients, we did not observe LA thrombus in PAF patients with normal EF who present for PVAI. Prescreening CT alone is likely to be sufficient in paroxysmal AF patients with normal EF, and the use of TEE may not be needed.     

Atrial Fibrosis Helps Select the Appropriate Patient and Strategy in Catheter Ablation of Atrial Fibrillation: A DE‐MRI Guided Approach

MRI for AF Patient Selection and Ablation Approach. Introduction: Left atrial (LA) fibrosis and ablation related scarring are major predictors of success in rhythm control of atrial fibrillation (AF). We used delayed enhancement MRI (DE‐MRI) to stratify AF patients based on pre‐ablation fibrosis and also to evaluate ablation‐induced scarring in order to identify predictors of a successful ablation. Methods and Results: One hundred and forty‐four patients were staged by percent of fibrosis quantified with DE‐MRI, relative to the LA wall volume: minimal or Utah stage 1; <5%, mild or Utah stage 2; 5–20%, moderate or Utah stage 3; 20–35%, and extensive or Utah stage 4; >35%. All patients underwent pulmonary vein (PV) isolation and posterior wall and septal debulking. Overall, LA scarring was quantified and PV antra were evaluated for circumferential scarring 3 months post ablation. LA scarring post ablation was comparable across the 4 stages. Most patients had either no (36.8%) or 1 PV (32.6%) antrum circumferentially scarred. Forty‐two patients (29%) had recurrent AF over 283 ± 167 days. No recurrences were noted in Utah stage 1. Recurrence was 28% in Utah stage 2, 35% in Utah stage 3, and 56% in Utah stage 4. Recurrence was predicted by circumferential PV scarring in Utah stage 2 and by overall LA wall scarring in Utah stage 3. No recurrence predictors were identified in Utah stage 4. Conclusions: Circumferential PV antral scarring predicts ablation success in mild LA fibrosis, while posterior wall and septal scarring is needed for moderate fibrosis. This may help select the proper candidate and strategy in catheter ablation of AF. (J Cardiovasc Electrophysiol, Vol. 22, pp. 16‐22, January 2011)     

Increased intensity of anticoagulation may reduce risk of thrombus during atrial fibrillation ablation procedures in patients with spontaneous echo contrast

INTRODUCTION: A 10% incidence of left atrial (LA) thrombus formation has been detected using intracardiac echocardiography (ICE) imaging monitoring during LA ablation for atrial fibrillation (AF). The aim of this study was to determine if the intensity of anticoagulation reduces LA thrombus formation during pulmonary vein isolation procedure in patients with AF and spontaneous echo contrast (SEC). METHODS AND RESULTS: We studied 511 patients (age 56 +/- 10 years) undergoing pulmonary vein ostial isolation/ablation using radiofrequency energy. SEC was detected in 179 of 511 patients with ICE imaging before dual transseptal catheterization. All patients were anticoagulated with heparin to achieve activated clotting time (ACT) 250-300 seconds (group I) or >300 seconds (group II) confirmed at 30-minute intervals. SEC was detected in 49/294 (16.7%) patients in group I versus 130/217 (59.9%) in group II (P < 0.0001). LA thrombus was observed in 33/294 (11.2%) patients in group I versus 6/217 (2.8%) in group II (P < 0.05). For those patients with SEC, LA thrombus was observed in 22/49 (44.9%) in group I versus 2/61 (4.6%) in group II (P < 0.0001). There were no significant differences in age, number of unsuccessful drugs, persistent AF, left ventricular ejection fraction, and LA diameter between the two groups. No clinical embolic event was observed with withdrawal of LA thrombus to the RA. CONCLUSION: ICE-diagnosed SEC before transseptal catheterization identifies an increased risk of LA thrombus. Increased intensity of heparin anticoagulation (ACT >300 seconds) during LA ablation for AF may prevent LA thrombus formation especially in patients with SEC.