Eric Good

Catheter Ablation for Paroxysmal Atrial Fibrillation Segmental Pulmonary Vein Ostial Ablation Versus Left Atrial Ablation

Background—Segmental ostial catheter ablation (SOCA) to isolate the pulmonary veins (PVs) and left atrial catheter ablation (LACA) to encircle the PVs both may eliminate paroxysmal atrial fibrillation (PAF). The relative efficacy of these 2 techniques has not been directly compared. Methods and Results—Of 80 consecutive patients with symptomatic PAF (age, 52±10 years), 40 patients underwent PV isolation by SOCA and 40 patients underwent LACA to encircle the PVs. During SOCA, ostial PV potentials recorded with a ring catheter were targeted. LACA was performed by encircling the left- and right-sided PVs 1 to 2 cm from the ostia and was guided by an electroanatomic mapping system; ablation lines also were created in the mitral isthmus and posterior left atrium. The mean procedure and fluoroscopy times were 156±45 and 50±17 minutes for SOCA and 149±33 and 39±12 minutes for LACA, respectively. At 6 months, 67% of patients who underwent SOCA and 88% of patients who underwent LACA were free of symptomatic PAF when not taking antiarrhythmic drug therapy (P =0.02). Among the variables of age, sex, duration and frequency of PAF, ejection fraction, left atrial size, structural heart disease, and the ablation technique, only an increased left atrial size and the SOCA technique were independent predictors of recurrent PAF. The only complication was left atrial flutter in a patient who underwent LACA. Conclusions—In patients undergoing catheter ablation for PAF, LACA to encircle the PVs is more effective than SOCA.

Risk of Thromboembolic Events After Percutaneous Left Atrial Radiofrequency Ablation of Atrial Fibrillation

Background— In patients with atrial fibrillation (AF), the risk of thromboembolic events (TEs) is variable and is influenced by the presence and number of comorbid conditions. The effect of percutaneous left atrial radiofrequency ablation (LARFA) of AF on the risk of TEs is unclear. Methods and Results— LARFA was performed in 755 consecutive patients with paroxysmal (n=490) or chronic (n=265) AF. Four hundred eleven patients (56%) had ≥1 risk factor for stroke. All patients were anticoagulated with warfarin for ≥3 months after LARFA. A TE occurred in 7 patients (0.9%) within 2 weeks of LARFA. A late TE occurred 6 to 10 months after ablation in 2 patients (0.2%), 1 of whom still had AF, despite therapeutic anticoagulation in both. Among 522 patients who remained in sinus rhythm after LARFA, warfarin was discontinued in 79% of 256 patients without risk factors and in 68% of 266 patients with ≥1 risk factor. Patients older than 65 years or with a history of stroke were more likely to remain anticoagulated despite a successful outcome from LARFA. None of the patients in whom anticoagulation was discontinued had a TE during 25±8 months of follow-up. Conclusions— The risk of a TE after LARFA is 1.1%, with most events occurring within 2 weeks after the procedure. Discontinuation of anticoagulant therapy appears to be safe after successful LARFA, both in patients without risk factors for stroke and in patients with risk factors other than age >65 years and history of stroke. Sufficient safety data are as yet unavailable to support discontinuation of anticoagulation in patients older than 65 years or with a history of stroke.

Radiofrequency Catheter Ablation of Chronic Atrial Fibrillation Guided by Complex Electrograms

Background— Radiofrequency catheter ablation of atrial fibrillation (AF) guided by complex fractionated atrial electrograms has been reported to eliminate AF in a large proportion of patients. However, only a small number of patients with chronic AF have been included in previous studies. Methods and Results— In 100 patients (mean age, 57±11 years) with chronic AF, radiofrequency ablation was performed to target complex fractionated atrial electrograms at the pulmonary vein ostial and antral areas, various regions of the left atrium, and the coronary sinus until AF terminated or all identified complex fractionated atrial electrograms were eliminated. Ablation sites consisted of ≥1 pulmonary vein in 46% of patients; the left atrial septum, roof, or anterior wall in all; and the coronary sinus in 55%. During 14±7 months of follow-up after a single ablation procedure, 33% of patients were in sinus rhythm without antiarrhythmic drugs, 38% had AF, 17% had both AF and atrial flutter, 9% had persistent atrial flutter, and 3% had paroxysmal AF on antiarrhythmic drugs. A second ablation procedure was performed in 44% of patients. Pulmonary vein tachycardia was found in all patients in both previously targeted and nontargeted pulmonary veins. There were multiple macroreentrant circuits in the majority of patients with atrial flutter. At 13±7 months after the last ablation procedure, 57% of patients were in sinus rhythm without antiarrhythmic drugs, 32% had persistent AF, 6% had paroxysmal AF, and 5% had atrial flutter. Conclusions— Modest short-term efficacy is achievable with radiofrequency ablation of chronic AF guided by complex fractionated atrial electrograms, but only after a second ablation procedure in >40% of patients. Rapid activity in the pulmonary veins and multiple macroreentrant circuits are common mechanisms of recurrent atrial arrhythmias.

A Randomized Assessment of the Incremental Role of Ablation of Complex Fractionated Atrial Electrograms After Antral Pulmonary Vein Isolation for Long-Lasting Persistent Atrial Fibrillation

OBJECTIVES This study sought to determine whether ablation of complex fractionated atrial electrograms (CFAEs) after antral pulmonary vein isolation (APVI) further improves the clinical outcome of APVI in patients with long-lasting persistent atrial fibrillation (AF). BACKGROUND Ablation of CFAEs has been reported to eliminate persistent AF. However, residual pulmonary vein arrhythmogenicity is a common mechanism of recurrence. METHODS In this randomized study, 119 consecutive patients (mean age 60 +/- 9 years) with long-lasting persistent AF underwent APVI with an irrigated-tip radiofrequency ablation catheter. Antral pulmonary vein isolation resulted in termination of AF in 19 of 119 patients (Group A, 16%). The remaining 100 patients who still were in AF were randomized to no further ablation and underwent cardioversion (Group B, n = 50) or to ablation of CFAEs in the left atrium or coronary sinus for up to 2 additional hours of procedure duration (Group C, n = 50). RESULTS Atrial fibrillation terminated during ablation of CFAEs in 9 of 50 patients (18%) in Group C. At 10 +/- 3 months after a single ablation procedure, 18 of 50 (36%) in Group B and 17 of 50 (34%) in Group C were in sinus rhythm without antiarrhythmic drugs (p = 0.84). In Group A, 15 of 19 patients (79%) were in sinus rhythm. A repeat ablation procedure was performed in 34 of 100 randomized patients (for AF in 30 and atrial flutter in 4). At 9 +/- 4 months after the final procedure, 34 of 50 (68%) in Group B and 30 of 50 (60%) in Group C were in sinus rhythm without antiarrhythmic drugs (p = 0.40). CONCLUSIONS Up to 2 h of additional ablation of CFAEs after APVI does not appear to improve clinical outcomes in patients with long-lasting persistent AF.

Relationship between burden of premature ventricular complexes and left ventricular function

BACKGROUND Frequent idiopathic premature ventricular complexes (PVCs) can result in a reversible form of left ventricular dysfunction. The factors resulting in impaired left ventricular function are unclear. Whether a critical burden of PVCs can result in cardiomyopathy has not been determined. OBJECTIVE The objective of this study was to determine a cutoff PVC burden that can result in PVC-induced cardiomyopathy. METHODS In a consecutive group of 174 patients referred for ablation of frequent idiopathic PVCs, the PVC burden was determined by 24-hour Holter monitoring, and transthoracic echocardiograms were used to assess left ventricular function. Receiver-operator characteristic curves were constructed based on the PVC burden and on the presence or absence of reversible left ventricular dysfunction to determine a cutoff PVC burden that is associated with left ventricular dysfunction. RESULTS A reduced left ventricular ejection fraction (mean 0.37 +/- 0.10) was present in 57 of 174 patients (33%). Patients with a decreased ejection fraction had a mean PVC burden of 33% +/- 13% as compared with those with normal left ventricular function 13% +/- 12% (P <.0001). A PVC burden of >24% best separated the patient population with impaired as compared with preserved left ventricular function (sensitivity 79%, specificity 78%, area under curve 0.89) The lowest PVC burden resulting in a reversible cardiomyopathy was 10%. In multivariate analysis, PVC burden (hazard ratio 1.12, 95% confidence interval 1.08 to 1.16; P <.01) was independently associated with PVC-induced cardiomyopathy. CONCLUSION A PVC burden of >24% was independently associated with PVC-induced cardiomyopathy.

Delayed-Enhanced Magnetic Resonance Imaging in Nonischemic Cardiomyopathy: Utility for Identifying the Ventricular Arrhythmia Substrate

OBJECTIVES The purpose of this study was to assess the value of delayed-enhanced magnetic resonance imaging (DE-MRI) to guide ablation of ventricular arrhythmias in patients with nonischemic cardiomyopathy (NIC). BACKGROUND In patients with NIC, ventricular arrhythmias often are associated with scar tissue. DE-MRI can be used to precisely define scar tissue. METHODS DE-MRI was performed in 29 consecutive patients (mean age 50 +/- 15 years) with NIC (mean ejection fraction 37 +/- 9%) referred for catheter ablation of ventricular tachycardia (VT) or premature ventricular complexes (PVCs). Scar was extracted from DE-MRIs and was then integrated into the electroanatomic map. Mapping data were correlated with respect to the localization of scar tissue. RESULTS Scar was identified by DE-MRI in 14 of 29 patients. Nine of these patients had VT and 5 had PVCs. In 5 of the patients there was predominantly endocardial scar, and mapping and ablation of arrhythmias was effectively performed from the endocardium in all 5 patients. In 2 patients scar was either intramural or epicardial with extension to the endocardium. In both patients with partial endocardial scar extension, the ablation was effective in eliminating some but not all arrhythmias. In 2 patients most of the scar tissue was confined to the epicardium; mapping identified and eliminated an epicardial origin in both patients. No effect on arrhythmias could be achieved in the other 5 patients with predominantly intramural scar. CONCLUSIONS DE-MRI in patients without prior infarctions can help to identify the arrhythmogenic substrate; furthermore, it helps to plan an appropriate mapping and ablation strategy.

Computed Tomographic Analysis of the Anatomy of the Left Atrium and the Esophagus. Implications for Left Atrial Catheter Ablation

Background—During left atrial (LA) catheter ablation, an atrioesophageal fistula can develop as a result of thermal injury of the esophagus during ablation along the posterior LA. No in vivo studies have examined the relationship of the esophagus to the LA. The purpose of this study was to describe the topographic anatomy of the esophagus and the posterior LA by use of CT. Methods and Results—A helical CT scan of the chest with 3D reconstruction was performed in 50 patients (mean age, 54±11 years) with atrial fibrillation before an ablation procedure. Consecutive axial and sagittal sections of the CT scan were examined to determine the relationship, size, and thickness of the tissue layers between the LA and the esophagus. The mean length and width of the esophagus in contact with the posterior LA were 58±14 and 13±6 mm, respectively. The esophagus had a variable course along the posterior LA. The esophagus was close (10±6 mm from the ostia) and parallel to the left-sided pulmonary veins (PVs) in 56% of patients and had an oblique course from the left superior PV to the right inferior PV in 36% of patients. The mean thicknesses of the posterior LA and anterior esophageal walls were 2.2±0.9 and 3.6±1.7 mm, respectively. In 98% of patients, there was a fat layer between the esophagus and the posterior LA. However, this layer was often discontinuous. Conclusions—The esophagus and posterior LA wall are in close contact over a large area that may often lie within the atrial fibrillation ablation zone, and there is marked variation in the anatomic relationship of the esophagus and the posterior LA. Both the esophageal and atrial walls are quite thin. However, a layer of adipose tissue may serve to insulate the esophagus from thermal injury, explaining why atrioesophageal fistulas are rare.

Noninducibility of Atrial Fibrillation as an End Point of Left Atrial Circumferential Ablation for Paroxysmal Atrial Fibrillation A Randomized Study

Background—An anatomic approach of left atrial radiofrequency circumferential ablation (LACA) to encircle the pulmonary veins is often effective in eliminating paroxysmal atrial fibrillation (AF). However, no electrophysiological end points other than voltage abatement and/or conduction slowing or block across ablation lines have been used. It has been unclear whether noninducibility of AF is a clinically useful end point. Methods and Results—In 100 patients with paroxysmal AF (mean age, 55±10 years), LACA to encircle the left- and right-sided pulmonary veins was performed during AF, with additional ablation lines in the posterior left atrium and mitral isthmus, with an 8-mm-tip catheter. After completion of this lesion set, sinus rhythm was present, and AF lasting >60 seconds was not inducible in 40 patients (40%; group 1). The 60 patients in whom AF was still present or who still had inducible AF were randomly assigned to no further ablation (group 2; 30 patients) or to additional ablation lines along the left atrial septum, roof, and/or anterior wall where there were fractionated electrograms (group 3; 30 patients). In group 3, AF was rendered noninducible in 27 of 30 patients (90%). At a 6-month follow-up, 67% of patients in group 2 were free of AF without drug therapy compared with 86% of patients in group 3. (P=0.05, log-rank test). Left atrial flutter occurred in 17% and 27% of patients in each group, respectively (P=0.3). Conclusions—After LACA in patients with paroxysmal AF, AF usually can be rendered noninducible by additional ablation at sites of fractionated electrograms. Noninducibility of AF attained by additional electrogram-guided left atrial ablation may be associated with a better midterm clinical outcome than when AF is still inducible after LACA alone.

A Tailored Approach to Catheter Ablation of Paroxysmal Atrial Fibrillation

Background— Because the genesis of atrial fibrillation (AF) is multifactorial and variable, an ablation strategy that involves pulmonary vein isolation and/or a particular set of ablation lines may not be equally effective or efficient in all patients with AF. A tailored strategy that targets initiators and drivers of AF is a possible alternative to a standardized lesion set. Methods and Results— Catheter ablation was performed in 153 consecutive patients (mean age, 56±11 years) with symptomatic paroxysmal AF with the use of an 8-mm tip radiofrequency ablation catheter. The esophagus was visualized with barium. The pulmonary veins and left atrium were mapped during spontaneous or induced AF. Arrhythmogenic pulmonary veins were isolated or encircled. If AF was still present or inducible, complex electrograms in the left atrium, coronary sinus, and superior vena cava were targeted for ablation. The end point of ablation was absence of frequent atrial ectopy and spontaneous AF during isoproterenol infusion and noninducibility of AF. Routine energy applications near the esophagus were avoided. During follow-up, left atrial flutter developed in 19% of patients and was still present in 10% at >12 weeks of follow-up. A repeat ablation procedure was performed in 18% of patients. During a mean follow-up of 11±4 months, 77% of patients were free from AF and/or atrial flutter without antiarrhythmic drug therapy. Pericardial tamponade or transient neurological events occurred in 2% of procedures. Conclusions— A tailored ablation strategy that only targets triggers and drivers of AF is feasible and eliminates paroxysmal AF in ≈80% of patients.

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.