Electroanatomic Mapping Techniques Research Articles

Registro español de ablación con catéter. XXIII informe oficial de la Asociación del Ritmo Cardiaco de la Sociedad Española de Cardiología (2023)

Introduction and objectivesWe report the results of the 2023 Spanish catheter ablation registry. MethodsProcedural data were collected and incorporated into the REDCap platform by all participating centers through a specific form. ResultsThere were 104 participating centers in 2023 compared with 103 in 2022. In 2023, the total number of ablation procedures was 26 207, indicating a stabilization of the increase observed in 2022 following the pandemic. The increase was mainly due to procedures for atrial fibrillation (AF), with a total of 9942 ablations, representing 38% of all substrates. Notably, pulse-field ablation represented 10.3% of all AF ablation procedures, leading single-shot ablation strategies to outnumber point-by-point AF ablation for the first time in the history of the registry. Cavotricuspid isthmus ablation remained the second most targeted substrate (19% of all substrates, n=5067). The overall acute success rate remained high (97%), with a downward trend in the complication rate (1.6% vs 1.8% in 2022) and mortality rate (0.03%; n=7). Compared with 2022, there was a significant increase in procedures performed using electro-anatomical mapping and zero-fluoroscopy techniques for cavotricuspid isthmus ablation (52% vs 26%), AV node re-entrant tachycardia (48% vs 34%), and accessory pathways (62% vs 22%). We registered 466 ablations in pediatric patients. ConclusionsThe data indicate a stabilization in the post-pandemic increase in ablation procedures, with an absolute and relative increase in AF as the predominant substrate. Success rates remained stable with a modest reduction in complication and mortality rates.

PO-04-110 MAPPING TRENDS IN AVNRT ABLATION: AN INTERNATIONAL ANALYSIS

Electroanatomic mapping (EAM) in AVNRT procedures is an ongoing area of interest due to AVNRT prevalence and safety considerations, particularly in pediatric populations. The utility of voltage mapping to identify the slow pathway has been documented. However, use of mapping techniques differs widely across geographies, and trends in clinical practice of these techniques and the acute outcomes have not been quantified. To assess mapping patterns in AVNRT procedures by geography. Acute observational data from 484 AVNRT procedures were prospectively collected from 125 centers in 12 countries in North and South America, Europe, and Australia. Choice of mapping and ablation strategy was left to physician discretion. Procedure data (mapping approach, catheter choice, and number of Ablation lesions required Before Consolidation (ALBC)) were compared to analyze acute outcomes and regional use trends. There was a significant difference in EAM use in AVNRT cases in the US vs. OUS (89.5% vs. 64.5%, respectively, p<.05). Low voltage bridge (LVB) mapping was the most frequently used technique globally; 37.7% of US and 52.7% of OUS cases (p<.05). Wavefront collision mapping (WFC) and Local Activation Time (LAT) mapping applying isochronal late activation mapping concepts saw high use in the US (WFC: 28.2%, LAT: 22.3%) but infrequently OUS (7.5%, p<.05; 4.3%, p<.05). Fractionation mapping was uncommon in all regions (US 1.4%, OUS 0%; p>.05) (Figure 1). There was a significant decrease in ALBC between procedures that used EAM and those that did not (4.39±5.5 and 6.6±9.0 ablation lesions, respectively, p=.01). ALBC was also significantly different by mapping catheter choice, with cases that used HD Grid requiring fewer ablation lesions than cases that mapped with ablation or linear catheters (3.7±3.9, 5.4±7.1, and 6.0±6.8, respectively, p=.02). There was a significant difference in mapping catheter choice in the US vs. OUS (Table 1). In all regions analyzed, LVB mapping was the most common EAM technique and ablation catheters were the most commonly used mapping catheter. There were significant regional differences in the rate of EAM use and technique. Procedures that used EAM required fewer ALBC, an effect further amplified in the cases using HD Grid. Therefore, use of both EAM and HD Grid may help to minimize ALBC in AVNRT, an important safety and efficiency consideration. Further analysis exploring long-term efficacy by approach in a protocol-driven cohort may be warranted.Tabled 1Table 1.USOUSAblation Catheter54.0% (n=122)58.1% (n=111)HD Grid30.1% (n=68)34.6% (n=66)Linear Mapping Catheter16.0% (n=36)7.3% (n=14)Prevalence of mapping catheter choices compared between cases in the US and OUS. All differences were significant (p<.05) Open table in a new tab

Comparison of combined substrate-based mapping techniques to identify critical sites for ventricular tachycardia ablation

Established electroanatomic mapping techniques for substrate mapping for ventricular tachycardia (VT) ablation includes voltage mapping, isochronal late activation mapping (ILAM), and fractionation mapping (FM). Omnipolar mapping (Abbott, Inc.) is a novel, optimized bipolar electrogram creation technique with integrated local conduction velocity annotation. The relative utilities of these mapping techniques are unknown. To evaluate the relative utility of various substrate mapping techniques for identification of critical sites for VT ablation. Electroanatomic substrate maps were created and retrospectively analyzed in 27 patients in whom 33 VT critical sites were identified. Both abnormal bipolar voltage and omnipolar voltage encompassed all critical sites and were observed over a median 66 (IQR: 41.3-86) cm2 and 52 (IQR 37.7-65.5) cm2, respectively. ILAM deceleration was observed over a median 9 (IQR 5.0, 11.1) cm2 and encompassed 22 (67%) critical sites, while abnormal omnipolar conduction velocity (OCV, <1mm/ms) was observed over 10 (IQR 5.3-16.6) cm2 and identified 22(67%) of critical sites, and fractionation mapping was observed over a median 4 (IQR 1.5, 7.6) cm2 and encompassed 20 (61%) critical sites. Mapping yield was greatest for Fractionation + OCV (2.1 critical sites / cm2), and least for bipolar voltage mapping (0.5 critical sites / cm2). OCV identified 100% of the critical sites in areas with a local point density >50 points/ cm2. ILAM, fractionation and omnipolar conduction velocity mapping each identified distinct critical sites and provided a smaller area of interest than voltage mapping alone. Sensitivity of novel mapping modalities improved with greater local point density.

PO-622-06 RELATIVE UTILITY OF OMNIPOLAR SUBSTRATE MAPPING FOR VENTRICULAR TACHYCARDIA ABLATION

EnSite Omnipolar mapping (Abbott, Abbott Park, IL, USA.) is a novel method of directionally optimized, high density, bipolar electrogram creation with integrated local conduction velocity annotation. Established electroanatomic mapping techniques for substrate mapping for ventricular tachycardia (VT) ablation includes voltage mapping, isochronal late activation mapping (ILAM), and fractionation mapping. The relative utilities of these mapping techniques is unknown.

Excision of a rare cardiac tumor aided by endocardial electroanatomical mapping

Glomus tumors are rare benign soft tissue lesions, most commonly found on the skin. They are an extremely rare cause of the cardiac tumor. We report a case of right atrial glomus tumor excised using a novel technique utilizing cardiac electroanatomical mapping techniques ordinarily used for arrhythmia surgery.

Ventricular conduction stability test: a method to identify and quantify changes in whole heart activation patterns during physiological stress.

Abnormal rate adaptation of the action potential is proarrhythmic but is difficult to measure with current electro-anatomical mapping techniques. We developed a method to rapidly quantify spatial discordance in whole heart activation in response to rate cycle length changes. We test the hypothesis that patients with underlying channelopathies or history of aborted sudden cardiac death (SCD) have a reduced capacity to maintain uniform activation following exercise. Electrocardiographical imaging (ECGI) reconstructs >1200 electrograms (EGMs) over the ventricles from a single beat, providing epicardial whole heart activation maps. Thirty-one individuals [11 SCD survivors; 10 Brugada syndrome (BrS) without SCD; and 10 controls] with structurally normal hearts underwent ECGI vest recordings following exercise treadmill. For each patient, we calculated the relative change in EGM local activation times (LATs) between a baseline and post-exertion phase using custom written software. A ventricular conduction stability (V-CoS) score calculated to indicate the percentage of ventricle that showed no significant change in relative LAT (<10 ms). A lower score reflected greater conduction heterogeneity. Mean variability (standard deviation) of V-CoS score over 10 consecutive beats was small (0.9 ± 0.5%), with good inter-operator reproducibility of V-CoS scores. Sudden cardiac death survivors, compared to BrS and controls, had the lowest V-CoS scores post-exertion (P = 0.011) but were no different at baseline (P = 0.50). We present a method to rapidly quantify changes in global activation which provides a measure of conduction heterogeneity and proof of concept by demonstrating SCD survivors have a reduced capacity to maintain uniform activation following exercise.

Decompensated Heart Failure With Ventricular Arrhythmia: How Useful Is VT Ablation?

Ventricular arrhythmias are common in patients with heart failure. Their management especially in the context of decompensated heart failure poses a clinical challenge to modern cardiologists. In this review article, we aim to summarise the current evidence on the epidemiology, pathophysiology, and management of ventricular tachycardia in heart failure, focusing primarily on the use of catheter ablation. The evolution of electro-anatomical mapping techniques and ablation catheter technology in the recent years has paved the path for the successful application of catheter ablation in the treatment of ventricular arrhythmias. The efficacy of catheter ablation in the management of ventricular tachycardia in patients with chronic heart failure has recently been the epicentre of a number of randomised controlled trials, demonstrating promising results with regard to arrhythmia suppression and all-cause mortality. The usefulness of catheter ablation in decompensated heart failure has been explored to a lesser degree, primarily in the setting of an electrical storm. Implantable cardiac defibrillators play the most important role in improving prognosis and preventing sudden cardiac death in patients with heart failure. Catheter ablation for the treatment of recurrent VT in patients with chronic heart failure is an efficacious strategy that can be applied adjunctively to or in instead of antiarrhythmic therapy, and it is highly successful at preventing recurrent ventricular tachycardia, ICD shocks. Its efficacy in the context of decompensated heart failure requires further research, with current evidence rendering its use promising.

Arrhythmia Mechanisms Revealed by Ripple Mapping.

Ripple mapping is a novel method of 3D intracardiac electrogram visualisation that allows activation of the myocardium to be tracked visually without prior assignment of local activation times and without interpolation into unmapped regions. It assists in the identification of tachycardia mechanism and optimal ablation site, without the need for an experienced computer-operating assistant. This expert opinion presents evidence demonstrating the benefit of Ripple Mapping, compared with traditional electroanatomic mapping techniques, for the diagnosis and management of atrial and ventricular tachyarrhythmias during electrophysiological procedures.

Contemporary Diagnosis and Management of Atrial Flutter: A Continuum of Atrial Fibrillation and Vice Versa?

Atrial flutter (AFlu) is usually a fast (>240 bpm) and regular right atrial macroreentrant tachycardia, with a constrained critical region of the reentry circuit located at the cavotricuspid isthmus (CTI; typical CTI-dependent AFlu). However, a variety of right and left atrial tachycardias, resulting from different mechanisms, can also present as AFlu (atypical non-CTI-dependent AFlu). The electrocardiogram can provide clues to its origin and location; however, additional entrainment and more sophisticated electroanatomical mapping techniques may be required to identify its mechanism, location, and target area for a successful ablation. Although atrial fibrillation and AFlu are 2 separate arrhythmias, they often coexist before and after drug and/or ablation therapies. Indeed, there appears to be a close interrelationship between these 2 arrhythmias, and one may "transform" into the other. These issues are discussed in this overview, and practical algorithms are proposed to guide AFlu localization and illustrate the AFlu and atrial fibrillation continuum.

Function and dysfunction of human sinoatrial node.

Sinoatrial node (SAN) automaticity is jointly regulated by a voltage (cyclic activation and deactivation of membrane ion channels) and Ca2+ clocks (rhythmic spontaneous sarcoplasmic reticulum Ca2+ release). Using optical mapping in Langendorff-perfused canine right atrium, we previously demonstrated that the β-adrenergic stimulation pushes the leading pacemaker to the superior SAN, which has the fastest activation rate and the most robust late diastolic intracellular calcium (Cai) elevation. Dysfunction of the superior SAN is commonly observed in animal models of heart failure and atrial fibrillation (AF), which are known to be associated with abnormal SAN automaticity. Using the 3D electroanatomic mapping techniques, we demonstrated that superior SAN served as the earliest atrial activation site (EAS) during sympathetic stimulation in healthy humans. In contrast, unresponsiveness of superior SAN to sympathetic stimulation was a characteristic finding in patients with AF and SAN dysfunction, and the 3D electroanatomic mapping technique had better diagnostic sensitivity than corrected SAN recovery time testing. However, both tests have significant limitations in detecting patients with symptomatic sick sinus syndrome. Recently, we reported that the location of the EAS can be predicted by the amplitudes of P-wave in the inferior leads. The inferior P-wave amplitudes can also be used to assess the superior SAN responsiveness to sympathetic stimulation. Inverted or isoelectric P-waves at baseline that fail to normalize during isoproterenol infusion suggest SAN dysfunction. P-wave morphology analyses may be helpful in determining the SAN function in patients at risk of symptomatic sick sinus syndrome.

Current management of focal atrial tachycardia in children: a multicenter experience.

Focal atrial tachycardia (FAT) is an uncommon cause of supraventricular tachycardia in children. Incessant FAT can lead to tachycardia-induced cardiomyopathy. There is limited information regarding the clinical course and management of FAT. This study characterizes current management strategies for FAT in children including the prevalence of spontaneous resolution and the role of catheter ablation. This is a retrospective chart review of pediatric patients with FAT managed between January 2000 and November 2010 at 10 pediatric centers. There were 249 patients with a median age at diagnosis of 7.2 (95% confidence interval, 5.8-10.4) years. Cardiomyopathy was observed in 28%. Resolution of FAT occurred in 89%, including spontaneous resolution without catheter ablation in 34%. Antiarrhythmic medications were used for initial therapy in 154 patients with control of FAT in 72%. Among first-line medications, β-blockers were the most common (53%) and effective (42%). Catheter ablation was successful in 80% of patients. FAT recurrence was less common with electroanatomic mapping compared with conventional mapping techniques (16% versus 35%; P=0.02). Patients were followed for a median of 2.1 (95% confidence interval, 1.8-2.6) years. FAT is managed successfully in most children. Current approaches are variable. Many patients have control of FAT with medications; however, catheter ablation is used for most patients. Spontaneous resolution is common for young children, emphasizing the role for delayed ablation in this group. Ablation is successful for all ages. Lower recurrence occurs when electroanatomic mapping techniques are used.

Imaging techniques in electrophysiology and implantable device procedures: results of the European Heart Rhythm Association survey

The purpose of this European Heart Rhythm Association (EHRA) survey is to assess the implementation and use of imaging techniques in cardiac electrophysiology (EP) and device procedures across European cardiovascular centres. Forty European centres, all members of the EHRA EP research network, responded to this survey. Thirty-one centres (88%) use transthoracic echocardiography (TTE) to evaluate left atrial size and/or volume before atrial fibrillation (AF) ablation. Sixteen centres (46%) perform delayed-enhancement cardiac magnetic resonance imaging (MRI) to guide ventricular tachycardia ablation. Electroanatomical mapping (EAM) systems are available in >65% of responding centres and the use of robotic catheter and remote magnetic navigation systems is limited to <10%. Fusion of EAM data with cardiac computed tomography (CT) and/or MRI is performed in up to 43% of AF ablation procedures. Seventeen out of 35 (49%) responding centres also perform TTE to predict a favourable response to cardiac resynchronization therapy (CRT). Imaging of the cardiac venous system with CT and identification of myocardial scar using CT or MRI, is not routinely performed in the majority of centres [32 (91%) and 26 (75%) centres, respectively) prior to CRT. This EHRA survey shows that several imaging techniques are used to guide catheter ablation and CRT procedures in European centres. Echocardiographic imaging, EAM techniques, and cardiac CT/MRI are commonly used.

Ultraschall im elektrophysiologischen Herzkatheterlabor

During recent years the need for intraprocedural imaging has increased. Fluoroscopy and angiography are frequently supplemented by pre-procedural magnetic resonance or computed tomography imaging as well as electroanatomic mapping techniques. However, poor real-time imaging quality of soft tissue, radiation exposure, and contrast media consumption are disadvantageous. Ultrasound techniques are characterized by high-quality imaging of soft tissue that can be obtained in real time. All relevant anatomical structures and their relationships to catheters can be evaluated at any time during the procedure. Moreover, functional analysis, e.g., flow measurements and monitoring for complications, is possible. Transesophageal and especially intracardiac echocardiography (ICE) contribute enormously to effectiveness and safety of complex procedures. ICE has been shown to be useful in transseptal procedures like atrial fibrillation ablation but also in ablation procedures for ventricular tachycardias.

Modern Electrophysiology Mapping Techniques

Three-dimensional electroanatomical mapping (EAM) techniques have been developed to assist with the treatment of complex arrhythmias in the electrophysiology laboratory. The most common techniques are contact and non-contact EAM, which have been demonstrated to reduce fluoroscopic exposure and procedural duration. Accuracy has been further enhanced by the integration of these techniques with imaging modalities such as magnetic resonance imaging, computed tomography and real-time ultrasound. In addition, EAM utilising high-density surface electrocardiograms in conjunction with cardiac imaging is being explored as a non-invasive technique for mapping complex arrhythmias. This review will summarise the most recent developments in three-dimensional arrhythmia mapping.

Catheter ablation of three macroreentrant atrial tachycardias after surgical repair of Double-Outlet Right Ventricle

A 54-year-old man with a surgically repaired double-outlet right ventricle (DORV) presented with palpitations and worsening right heart failure. His 12-lead ECG showed atrial tachycardia (AT) with an atrial cycle length (CL) of 300ms and an inverted saw-tooth F-wave pattern in the inferior leads II, III, and aVF typical of atrial flutter. Electrophysiological study and radiofrequency catheter ablation were performed. A total of 3 sustained ATs (AT1–AT3) were induced. Using the electroanatomical mapping system, CARTO3, and conventional mapping techniques, the ATs were identified as macroreentrant tachycardias circling around an incisional line on the free wall of the right atrium (AT1), the tricuspid annulus (AT2), and low voltage area in the lateral wall including the right septum (AT3). Accuracy of CARTO3 in three-dimensional reconstruction was sufficient to elucidate anatomical features (including catheter sites, incision, and low voltage areas) and macroreentrant circuits. However, conventional mapping techniques were also necessary to identify the mechanism of the tachycardias, and therefore to eliminate all of them successfully. This case demonstrates that the use of combined conventional and electroanatomical mapping techniques, such as CARTO3, can be helpful in identifying the critical isthmus for catheter ablation of macroreentrant AT in patients with surgically corrected congenital heart disease (CHD).

Multifunctional catheters combining intracardiac ultrasound imaging and electrophysiology sensing

A family of 3 multifunctional intracardiac imaging and electrophysiology (EP) mapping catheters has been in development to help guide diagnostic and therapeutic intracardiac EP procedures. The catheter tip on the first device includes a 7.5 MHz, 64-element, side-looking phased array for high resolution sector scanning. The second device is a forward-looking catheter with a 24-element 14 MHz phased array. Both of these catheters operate on a commercial imaging system with standard software. Multiple EP mapping sensors were mounted as ring electrodes near the arrays for electrocardiographic synchronization of ultrasound images and used for unique integration with EP mapping technologies. To help establish the catheters' ability for integration with EP interventional procedures, tests were performed in vivo in a porcine animal model to demonstrate both useful intracardiac echocardiographic (ICE) visualization and simultaneous 3-D positional information using integrated electroanatomical mapping techniques. The catheters also performed well in high frame rate imaging, color flow imaging, and strain rate imaging of atrial and ventricular structures. The companion paper of this work discusses the catheter design of the side-looking catheter with special attention to acoustic lens design. The third device in development is a 10 MHz forward-looking ring array that is to be mounted at the distal tip of a 9F catheter to permit use of the available catheter lumen for adjunctive therapy tools.

Characterization of Left Atrial Tachyarrhythmias in Patients Following Atrial Fibrillation Ablation:Correlation of surface ECG with Intracardiac Mapping.

With expected success rates in excess of 80% for achieving long term arrhythmia control, catheter based ablation has become a popular treatment strategy in the management of patients with atrial fibrillation (AF). However, the success of AF ablation has been tempered by the occurrence of post procedure left atrial tachycardias and / or flutters, which can be seen in up to 30% of the patients. These arrhythmias are perpetuated either due to abnormalities of impulse formation (abnormal automaticity / triggered activity), or abnormalities of impulse conduction (micro / macroreentry). Regardless of the underlying mechanism, these tachycardias manifest distinct "P" or flutter waves on the surface ECG, recognition of which may facilitate their characterization / localization. However, because of the frequent overlap in the morphology of P waves, intracardiac mapping is often the only way to distinguish them apart. This is accomplished using a combination of activation, entrainment and electroanatomic mapping techniques. Tachycardias resulting from abnormalities of impulse formation and / or microreentry are characteristically focal and usually confined in and around pulmonary vein (PV) segments which have reconnected (septal aspect of right PVs and anterior aspect of left PVs). In contrast, macroreentrant tachycardias manifest a large circuit dimension involving zone(s) of slow conduction. These are most commonly seen to occur around the mitral valve but can develop in any part of the left atrium where "gaps" across prior ablation lesion sets create altered conduction. Successful ablation of focal tachycardias is usually accomplished by isolating the reconnected PV segment(s). In case of macroreentrant arrhythmias however, a more extensive ablation approach is typically required in order to achieve conduction block across isthmus of the circuit. Using these strategies, the majority of left atrial tachycardias occurring post AF ablation can be successfully cured with excellent long term results.

The acoustic lens design and in vivo use of a multifunctional catheter combining intracardiac ultrasound imaging and electrophysiology sensing

A multifunctional 9F intracardiac imaging and electrophysiology mapping catheter was developed and tested to help guide diagnostic and therapeutic intracardiac electrophysiology (EP) procedures. The catheter tip includes a 7.25-MHz, 64-element, side-looking phased array for high resolution sector scanning. Multiple electrophysiology mapping sensors were mounted as ring electrodes near the array for electrocardiographic synchronization of ultrasound images. The catheter array elevation beam performance in particular was investigated. An acoustic lens for the distal tip array designed with a round cross section can produce an acceptable elevation beam shape; however, the velocity of sound in the lens material should be approximately 155 m/s slower than in tissue for the best beam shape and wide bandwidth performance. To help establish the catheter's unique ability for integration with electrophysiology interventional procedures, it was used in vivo in a porcine animal model, and demonstrated both useful intracardiac echocardiographic visualization and simultaneous 3-D positional information using integrated electroanatomical mapping techniques. The catheter also performed well in high frame rate imaging, color flow imaging, and strain rate imaging of atrial and ventricular structures.

Surface electrocardiogram characteristics of atrial tachycardias occurring after pulmonary vein isolation

The purpose of this study was to describe the surface electrocardiogram (ECG) morphology of common atrial tachycardias (ATs) that occur after pulmonary vein (PV) isolation. Focal ATs from reconnected PVs and macroreentrant mitral annular (MA) flutter are the most common form of ATs occurring after PV isolation. Patients with persistent AT after PV isolation underwent mapping and ablation. Tachycardia origin and mechanism were determined using electroanatomic mapping and entrainment techniques. Patients with typical right atrial flutter occurring after PV isolation were also included for comparison. Thirty-nine tachycardias were identified in 36 patients, either focal left AT (n = 24) or MA flutter (n = 15). Focal ATs originated from reconnected segments of the right PVs (n = 14) and left PVs (n = 10). MA flutters were counterclockwise (CCL; n = 9) or clockwise (CL; n = 6). Patients with MA flutter had a shorter tachycardia cycle length (239 +/- 7 vs. 259 +/- 34 s; P <.05) than those with focal ATs. CCL MA flutter was positive in the inferior and precordial leads and had a significant negative component in leads I and aVL. CL MA flutter demonstrated the converse limb lead morphology with a significant negative F wave in the inferior leads and positive F wave in leads I and aVL. A negative component in lead I, when present, was best at differentiating CCL MA flutter from left PV ATs, while a positive F wave in lead I was best at differentiating CL MA flutter from CCL right atrial flutter. There are unique surface ECG characteristics for CL and CCL MA flutter and AT due to reconnected PVs; knowledge of these characteristics may help when planning an ablation strategy.

Electrophysiological Findings During Ablation of Persistent Atrial Fibrillation With Electroanatomic Mapping and Double Lasso Catheter Technique

Pulmonary veins (PVs) can be completely isolated with continuous circular lesions (CCLs) around the ipsilateral PVs. However, electrophysiological findings have not been described in detail during ablation of persistent atrial fibrillation (AF). Forty patients with symptomatic persistent AF underwent complete isolation of the right-sided and left-sided ipsilateral PVs guided by 3D mapping and double Lasso technique during AF. Irrigated ablation was initially performed in the right-sided CCLs and subsequently in the left-sided CCLs. After complete isolation of both lateral PVs, stable sinus rhythm was achieved after AF termination in 12 patients; AF persisted and required cardioversion in 18 patients. In the remaining 10 patients, AF changed to left macroreentrant atrial tachycardia in 6 and common-type atrial flutter in 4 patients. All atrial tachycardias were successfully terminated during the procedure. Atrial tachyarrhythmias recurred in 15 of 40 patients at a median of 4 days after the initial ablation. A repeat ablation was performed at a median of 35 days after the initial procedure in 14 patients. During the repeat study, recovered PV conduction was found in 13 patients and successfully abolished by focal ablation of the conduction gap of the previous CCLs. After a mean of 8+/-2 months of follow-up, 38 (95%) of the 40 patients were free of AF. In patients with persistent AF, CCLs can result in either AF termination or conversion to macroreentrant atrial tachycardia in 55% of the patients. In addition, recovered PV conduction after the initial procedure is a dominant finding in recurrent atrial tachyarrhythmias and can be successfully abolished.