Long-term outcome of radiofrequency catheter ablation for typical atrial flutter: risk prediction of recurrent arrhythmias

Prediction of Recurrent Atrial Tachyarrhythmia After Receiving Atrial Flutter Ablation in Patients With Prior Cardiac Surgery for Valvular Heart Disease

Background: Surgical scars cause an intra-atrial conduction delay and anatomical obstacles that facilitate the perpetuation of atrial flutter (AFL). This study aimed to investigate the outcome and predictor of recurrent atrial tachyarrhythmia after catheter ablation in patients with prior cardiac surgery for valvular heart disease (VHD) who presented with AFL.

Methods: Seventy-two patients with prior cardiac surgery for VHD who underwent AFL ablation were included. The patients were categorized into a typical AFL group (n = 45) and an atypical AFL group (n = 27). The endpoint was the recurrence of atrial tachyarrhythmia during follow-up. A multivariate analysis was performed to determine the predictor of recurrence.

Results: No significant difference was found in the recurrence rate of atrial tachyarrhythmia between the two groups. Patients with concomitant atrial fibrillation (AF) had a higher recurrence of typical AFL compared with those without AF (13 vs. 0%, P = 0.012). In subgroup analysis, typical AFL patients with concomitant AF had a higher incidence of recurrent atrial tachyarrhythmia than those without it (53 vs. 14%, P = 0.006). Regarding patients without AF, the typical AFL group had a lower recurrence rate of atrial tachyarrhythmia than the atypical AFL group (14 vs. 40%, P = 0.043). Multivariate analysis showed that chronic kidney disease (CKD) and left atrial diameter (LAD) were independent predictors of recurrence.

Conclusions: In our study cohort, concomitant AF was associated with recurrence of atrial tachyarrhythmia. CKD and LAD independently predicted recurrence after AFL ablation in patients who have undergone cardiac surgery for VHD.

Implantable loop recorder for augmenting detection of new-onset atrial fibrillation after typical atrial flutter ablation

Background

Patients with typical atrial flutter (AFL) undergoing successful cavotricuspid isthmus ablation remain at risk for future development of new-onset atrial fibrillation (AF). Conventional monitoring (CM) techniques have shown AF incidence rates of 18%–50% in these patients.

Objectives

To evaluate whether continuous monitoring using implantable loop recorders (ILRs) would enhance AF detection in this patient population.

Methods

Veteran patients undergoing AFL ablation between 2002 and 2019 who completed at least 6 months of follow-up after the ablation procedure were included. We compared new-onset AF detection between those who underwent CM and those who received ILRs immediately following AFL ablation.

Results

A total of 217 patients (age: 66 ± 9 years; all male) participated. CM was used in 172 (79%) and ILR in 45 (21%) patients. Median follow-up duration after ablation was 4.1 years. Seventy-nine patients (36%) developed new-onset AF, which was detected by CM in 51 and ILR in 28 (30% vs 62%, respectively, P < .001). AF detection occurred at 7.7 months (IQR: 4.7–17.5) after AFL ablation in the ILR group vs 41 months (IQR: 23–72) in the CM group (P < .001). Eleven patients (5%) experienced cerebrovascular events (all in the CM group) and only 4 of these patients (36%) were on long-term anticoagulation.

Conclusion

Patients undergoing AFL ablation remain at an increased risk of developing new-onset AF, which is detected sooner and more frequently by ILR than by CM. Improving AF detection may allow optimization of rhythm management strategies and anticoagulation in this patient population.

Prevalence and Predictors of Additional Ablation Beyond Pulmonary Vein Isolation in Patients With Paroxysmal Atrial Fibrillation

Background: Pulmonary vein isolation (PVI) is an effective strategy in the treatment of paroxysmal atrial fibrillation (PAF). Yet, there are limited data on additional ablation beyond PVI. In this study, we sought to assess the prevalence, predictors, and outcomes of additional ablation in PAF patients.

Methods: A total of 537 consecutive patients with PAF were retrospectively evaluated for the index procedure. PVI was successfully conducted in all patients, after which electrophysiological study and drug provocation were performed, and additional ablations were delivered for concomitant arrhythmias, non-PV triggers, and low voltage zone (LVZ). The prevalence, predictors, and outcomes of additional ablation were analyzed.

Results: Among 537 consecutive patients, 372 addition ablations were performed in 241 (44.88%) patients, including 252 (67.74%) concomitant arrhythmias in 198 (36.87%) patients, 56 (15.05%) non-PV triggers in 52 (9.68%) patients and 64 (17.20%) LVZ modification in 47 (8.75%) patients. Lower LVEF (OR = 0.937, p = 0.015), AF episode before procedure (OR = 2.990, p = 0.001), AF episode during procedure (OR = 1.998, p = 0.002) and AF episode induced after PVI (OR = 15.958, p < 0.001) were independent predictors of additional ablation. Single-procedure free from atrial arrhythmias at 58.36 ± 7.12 months post-ablation was 70.48%.

Conclusions: Additional ablations were common in patients with PAF for index procedure. Lower LVEF and AF episodes before, during the procedure, and induced after PVI predicts additional ablation.

Supraventricular Arrhythmias: Clinical Framework and Common Scenarios for the Internist

Supraventricular arrhythmias can cause uncomfortable symptoms for patients. Often, the first point of contact is in the primary care setting, and thus, it is imperative for the general internist to have a clinical framework in place to recognize this cluster of cardiac arrhythmias, be familiar with immediate and long-term management of supraventricular tachycardias, and understand when cardiac electrophysiologic consultation is necessary. The electrocardiographic characteristics can have subtle but important clues to the diagnosis and initial management. An understanding of the mechanisms of these arrhythmias is essential to provide proper therapy to the patient. In addition, there are common practice strategies that should be emphasized to avoid common misperceptions that could pose risk to the patient. In this review, we provide a framework to more easily recognize and classify these arrhythmias. We also illustrate the mechanism for these arrhythmias to provide an understanding of the interventions generally used.

Incidence of new-onset atrial fibrillation after cavotricuspid isthmus ablation for atrial flutter

Aims

In patients with cavotricuspid isthmus (CTI) ablation for atrial flutter (AFL), the decision to hold oral anticoagulation (OAC) often becomes an issue. The purpose of this study was to describe the incidence of the development of atrial fibrillation (AF) after CTI ablation in patients with documented AFL with and without a previous history of AF and to identify risk predictors for the occurrence of AF after CTI.

Methods and results

We included 364 consecutive patients undergoing successful CTI ablation. Thereof, 230 patients (170 male; age 66 ± 11 years) had AFL only (AFL group) and 134 patients (94 male; age 65 ± 11 years) had AFL and previously documented AF (AFL and AF group). Over a mean follow-up of 22 ± 20 months, 163 (71%) patients in the AFL group and 67 (50%) patients in the AFL and AF groups had no documentation of a recurrent atrial arrhythmia (P < 0.001). AF developed in 51 patients (22%) in the AFL group and in 57 (43%) patients in the AFL and AF groups (P < 0.001). In patients without history of AF, left atrial diameter was the only predictor of development of AF (HR 1.058 [95%CI 1.011-1.108], P = 0.016). Multivariate analysis of the total population identified history of AF (HR 1.918 [95%CI 1.301-2.830], P = 0.001) and BMI as predictors for AF development (HR 1.052 [95%CI 1.012-1.093], P = 0.011).

Conclusion

Our results indicate that new-onset AF develops in a significant proportion of patients undergoing CTI for AFL. One should therefore be careful to withhold OAC. Furthermore, pulmonary vein isolation should be considered in conjunction with CTI, particularly in patients with previously documented AF.

CHA₂DS₂-VASc Score in the Prediction of Ischemic Stroke in Patients after Radiofrequency Catheter Ablation of Typical Atrial Flutter

PURPOSE

Despite undergoing successful catheter ablation of typical atrial flutter (AFL), patients remain at increased risk for ischemic stroke. However, data on risk prediction tools for the development of stroke after AFL ablation are lacking. This study investigates whether CHA₂DS₂-VASc score is useful for predicting ischemic stroke after successful ablation of typical AFL.

MATERIALS AND METHODS

A total of 293 patients (236 men, mean age 56.1±13.5 years) who underwent successful radiofrequency catheter ablation for typical AFL were included in this study. The clinical end point was occurrence of ischemic stroke during follow-up after AFL ablation.

RESULTS

During the follow-up period (60.8±45.9 months), ischemic stroke occurred in 18 (6%) patients at a median of 34 months (interquartile range, 13-65 months). CHA₂DS₂-VASc score [hazard ratio 2.104; 95% confidence interval (CI), 1.624-2.726; p<0.001] was an independent predictor for the occurrence of stroke after AFL ablation. The area under the receiver operating characteristic curve for CHA₂DS₂-VASc score was 0.798 (95% CI, 0.691-0.904). The CHA₂DS₂-VASc score could be used to stratify patients into two groups with different incidences of ischemic stroke (1.6% vs. 14.4%, p<0.001) at a cutoff value of 2.

CONCLUSION

CHA₂DS₂-VASc score is useful in a prediction model for the risk of stroke after catheter ablation of typical AFL.

Interest of waiting time for spontaneous early reconnection after cavotricuspid isthmus ablation: A monocentric randomized trial

INTRODUCTION

The aim of this study was to determine the rate of recurrent atrial flutter (AFl) after isolated cavotricuspid isthmus (CTI) ablation and to evaluate the impact of a waiting period with the search for early resumption of the CTI block on the long-term outcome.

METHOD

Three hundred and nineteen consecutive patients referred for typical AFl ablation were randomly assigned to CTI ablation with continuous reevaluation of the CTI block during 30 minutes and early reablation if needed (waiting time [WT] + group, n  =  155) or to CTI ablation with no waiting period after proven bidirectional CTI block (WT - group, n  =  164). All patients were regularly followed-up.

RESULT

In the WT+ group, 10 patients (6%) presented a recovery across the CTI (time to recovery: 17 ± 7') and were reablated at the end of the waiting period. After a median follow-up of 21 months, the rate of recurrent AFl was significantly higher in the WT - group as compared to the WT+ group (11.6% [19/164] vs 2.5% [4/155], respectively; P  =  0.007). However, no significant differences in the subsequent rate of AF were observed between the two groups (29% [WT -] vs 32% [WT+], P  =  0.66). During the follow-up, 28 patients from the WT - group underwent a second ablation procedure (16 AFl redo and 12 AF ablation) versus 10 patients form the WT+ group (three AFl redo and seven AF ablation).

CONCLUSION

Waiting 30 minutes after CTI ablation to check for early resumption and early reablation allows for decreasing significantly the rate of recurrent atrial flutter.

Crucial role of pulmonary vein firing as an initiator of typical atrial flutter: Evidence of a close relationship between atrial fibrillation and typical atrial flutter

Background

Several studies reported that cavotricuspid isthmus-dependent atrial flutter (typical AFL) frequently coexists with atrial fibrillation (AF); however, the underlying mechanisms have not been fully investigated. This study aimed to reveal the mechanisms of the initiation of typical AFL and the association between typical AFL and AF.

Methods

Among 154 consecutive patients undergoing a first catheter ablation of AF, we investigated the appearance and mechanism of spontaneous initiation of typical AFL during catheter ablation. Then, we retrospectively investigated 67 consecutive patients without a previous AF episode who underwent typical AFL ablation. The occurrence and predictors of AF after catheter ablation were evaluated.

Results

During AF ablation, spontaneous initiation of typical AFL occurred during sinus rhythm in eight (5.2%) patients. The initiations of typical AFL were pulmonary vein (PV) firings except in one patient, in whom paroxysmal AF following superior vena cava firing initiated reverse typical AFL after PV isolation. After typical AFL ablation, AF occurred in 23 (34.3%) patients (mean follow up, 28.2±20.3 months). Kaplan-Meier analysis showed the occurrence of AF after typical AFL ablation to be significantly higher in the patients with a larger left atrial diameter over 40 mm (log-rank test, P=0.046).

Conclusions

PV firing through AF played an important role in initiating typical AFL. The occurrence of AF after typical AFL ablation was high, and a dilated left atrium was associated with increased occurrence of AF. These findings disclosed the close relationship between typical AFL and AF, especially PV firing.

Rapid Mapping of Right Atrial Tachycardia Using a New Multielectrode Basket Catheter

INTRODUCTION

The mapping of atrial tachycardia (AT) can often be challenging and time-consuming, especially in patients with ATs that develop following cardiac surgery or are concomitant with atrial fibrillation. Recently, a new multielectrode basket catheter (MBC) has become available; we hypothesized that the MBC could be utilized to diagnose AT circuits.

METHODS AND RESULTS

This study included 51 consecutive patients undergoing catheter ablation of clinically documented right-sided ATs (including 17 cases following cardiac surgery). Using a NavX system, 2 activation maps of the ATs were created, one using the new MBC (32 mm, 31 poles) and the other using a circular catheter. The time needed to complete the activation maps and the points acquired with both mapping catheters were compared. In all 64 ATs, including 34 non-cavotricuspid isthmus-dependent ATs, the AT activation maps created by both catheters were essentially identical. The number of points acquired to complete the activation maps did not differ significantly between the MBC and the circular catheter (387 [285-511] vs. 374 [269-533], P = 0.19), but the mapping time was significantly shorter using the MBC (4.0 [3.0-6.0] minutes vs. 8.0 [6.5-10.0] minutes, P < 0.0001). Inadvertent mechanical AT termination (n = 6) was observed only during mapping with the circular catheter.

CONCLUSION

In patients with right-sided ATs, the use of an MBC could save mapping time.

Impact of a 4q25 genetic variant in atrial flutter and on the risk of atrial fibrillation after cavotricuspid isthmus ablation

BACKGROUND

The prediction of atrial fibrillation (AF) following catheter ablation of atrial flutter (Afl) would be helpful to facilitate targeted arrhythmia monitoring and anti-coagulation strategies. A single nucleotide polymorphism, rs2200733, is strongly associated with AF. We sought to characterize the association between rs2200733 and prevalent Afl and to determine if the variant could predict AF after cavotricuspid isthmus ablation.

METHODS AND RESULTS

We performed a genetic association study of 295 patients with Afl and/or AF and 469 controls using multivariable logistic regression. The variant was then assessed as a predictor of incident AF after cavotricuspid isthmus ablation in 87 consecutive typical Afl patients with Cox proportional hazards models. The rs2200733 rare allele was associated with an adjusted 2.06-fold increased odds of isolated Afl (95% CI: 1.13-3.76, P = 0.019) and an adjusted 2.79-fold increased odds of a combined phenotype of AF and Afl (95% CI: 1.81-4.28, P < 0.001). Following catheter ablation for Afl, carrier status of rs2200733 failed to predict an increased risk of AF either among all subjects (adjusted HR: 0.94; 95% CI: 0.58-1.53, P = 0.806) or among those with isolated Afl (adjusted HR: 1.29; 95% CI: 0.51-3.26, P = 0.585).

CONCLUSIONS

Our study demonstrates that Afl, whether occurring in isolation or along with AF, is associated with the rs2200733 AF risk allele. Genetic carrier status of rs2200733 failed to predict an increased risk of incident or recurrent AF following catheter ablation for Afl. These findings suggest that the causal mechanism associated with rs2200733 is germane to both AF and Afl.

Two-dimensional echocardiographic features of the inferior right atrial isthmus: the role of vestibular thickness in catheter ablation of atrial flutter

OBJECTIVES

The aim of this study was to examine the feasibility of transthoracic two-dimensional (2D)-echocardiography in defining the cavo-tricuspid isthmus (CTI) anatomy and its value concerning the ease of catheter ablation of isthmic atrial flutter (AF).

METHODS

CTI analysis was accomplished in 39 cases: 16 necropsy specimens and 23 patients. Sixteen were patients with isthmus-dependent AF and seven controls with other supraventricular re-entrant tachycardias. Two-dimensional transthoracic echocardiography and a right atrium angiogram were performed before radiofrequency catheter ablation (RFCA).

RESULTS

The measurements of the CTI with angiography were compared with those taken with echocardiography and correlation was excellent (r= 0.91; P < 0.0001). In normal patients, the dimension of the vestibular thickness was successfully compared and validated with the histological examination of the necropsy specimens: histology median 6.8 mm, range 4.4-10.5 vs. echo median 6.2 mm, range 5.4-8.7; P: NS. Vestibular thickness was greater in complex than in simple RFCA (13.6 ± 1.9 mm vs. 10.0 ± 2.3 mm; P = 0.01). When vestibular thickness ≥11.5 mm, the ablation prone to be complex (sensitivity 83.3%, specificity 80%, positive predictive value 71.4%, and negative predictive value 88.9%).

CONCLUSIONS

Two-dimensional transthoracic echocardiography clearly depicts the inferior isthmus and, displaying the thickness of the tricuspid vestibule, it was related with complexity of the ablation procedure in isthmus-dependent AF.

Predictors of the atrial fibrillation following catheter ablation of typical atrial flutter

Background:

Despite technical refinements and improved long-term efficacy of the ablation procedure for treating AFL (AFL), the subsequent occurrence of AF (AF) following this procedure remains a significant clinical problem.

Objectives:

To determine long-term incidence and predictors of AF after catheter ablation of typical AFL.

Material and Methods:

Between March 2005 and February 2010, a total of 84 consecutive patients who underwent catheter ablation of documented typical AFL were enrolled.

Results:

Cavotricuspid isthmus ablation was successful in terminating and preventing the re-induction of AFL in all 84 patients (100%). The mean follow-up duration for study was 26± 22 months. During the follow-up period, early AF occurred in 5% after successful catheter ablation of AFL and late AF in 11% of the patients. The clinical variables associated with the occurrence of AF after catheter ablation of AFL were female, a history of AF before AFL ablation, body mass index (BMI), and left atrial abnormality. However, logistic multivariate analysis demonstrated that only BMI was independently associated with the late AF (OR 1.36, 95% CI 1.11-1.70, P = 0.004).

Conclusions:

Catheter ablation of flutter circuit will not prevent later manifestation of AF in 16% of the patients undergoing catheter ablation of the typical AFL. BMI was the only independent predictor of AF following catheter ablation of the typical AFL.

Catheter ablation of scar-related atypical atrial flutter

AIMS

The aim of the study was to assess the impact of isthmus location of atypical atrial flutters/atrial tachycardias (ATs) on outcomes of catheter ablation. Atrial tachycardias are clinically challenging arrhythmias that can occur in the presence of atrial scar--often due to either cardiac surgery or prior ablation for atrial fibrillation. We previously demonstrated a catheter ablation approach employing rapid multielectrode activation mapping with targeted entrainment manoeuvrs. However, the role that AT isthmus location plays in acute and long-term success of ablation remains uncertain.

METHODS AND RESULTS

Retrospective multicenter analysis of 91 consecutive AT patients undergoing ablation using a systematic four-step approach: (i) high-density activation mapping; (ii) analysis of atrial activation to identify wavefronts of electrical propagation; (iii) targeted entrainment of putative channels; and (iv) irrigated radiofrequency ablation of constrained regions of the circuit. Clinical outcomes, procedural details, and clinical profiles were determined. A total of 171 ATs (1.9 ± 1.0 per patient, 26% septal ATs) were targeted for ablation. The acute success rates were 97 and 77% for patients with either non-septal ATs or septal ATs, respectively (P = 0.0023). Similarly, the long-term success rates were 82 and 67% for patients with either no septal ATs or at least one septal AT, respectively (P = 0.1057). The long-term success rates were 75, 88, and 57% for patients with ATs associated with prior catheter ablation, cardiac surgery or MAZE, and idiopathic atrial scar, respectively.

CONCLUSION

Catheter ablation of AT can be successfully performed employing a strategy of combined high-density activation and entrainment mapping. Septal ATs are associated with higher rates of acute and long-term recurrences.

Importance of tachycardia cycle length for differentiating typical atrial flutter from scar-related in adult congenital heart disease

BACKGROUND

 Radiofrequency catheter ablation (RFCA) for intraatrial reentrant tachycardia (IART) in congenital heart disease (CHD) remains difficult.

METHODS

 Thirty-four consecutive adult patients (age, 37.6 ± 12.8 years; male, 21) with previously repaired CHD and IART underwent an electrophysiological study and RFCA. CHD included atrial septal defect (ASD, n = 14), tetralogy of Fallot (n = 11), ventricular septal defect (n = 4), pulmonary atresia (n = 2), atrioventricular septal defect (n = 1), transposition of the great arteries (n = 1), and double-outlet right ventricle (n = 1).

RESULTS

 Duration of CHD repair to IART onset was 19.1 ± 8.5 years. Thirty and four patients had single- and double-loop reentrant tachycardia, respectively. Among the total of 38 IARTs, which were mapped, 22 (57.9%) and 13 (34.2%) IARTs were cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) and scar-related AFL, respectively. Typical AFL electrocardiography findings including definite sawtooth appearance in inferior leads and positive F wave in lead V1 were observed in only 12 of 21 patients (57.1%) with CTI-dependent AFL. CTI-dependent AFL had a significantly longer tachycardia cycle length (TCL) than scar-related AFL (267.6 ± 34.4 ms and 235.9 ± 37.0 ms, respectively; P = 0.031). TCL > 250 ms had 79% sensitivity as the cutoff value for differentiating CTI-dependent from scar-related AFL. The acute success rates of RFCA in CTI-dependent and scar-related AFLs were 85.7% and 90.0%, respectively. The recurrence rates in CTI-dependent and scar-related AFLs were 11.1% and 11.1%, respectively, during a follow-up of 21.2 ± 28.3 months.

CONCLUSIONS

 CTI-dependent AFL was the most common IART in adult patients with repaired CHD and was easily manageable by RFCA. TCL might help to differentiate CTI-dependent AFL from other IARTs.

Evaluation of the surface ECG in detecting isthmus conduction block after ablation of typical atrial flutter

OBJECTIVES

To investigate the value of changes in P wave morphology and duration detected by surface electrocardiogram (ECG) during proximal coronary sinus (PCS) and low lateral right atrial (LLRA) stimulation as a marker for complete bidirectional isthmus conduction block in the procedure of typical atrial flutter ablation.

METHODS

Morphology, duration, and ratio of a positive terminal P wave were estimated in 52 typical atrial flutter patients before and after radiofrequency catheter ablation (RFCA).

RESULTS

Atrial flutter ablation resulted in a complete bidirectional isthmus block in all 52 patients. The terminal portion of the P wave towards a positive morphology was detected in 90.7% (47/52) patients both during PCS and LLRA stimulation. These changes were predominantly observed in the inferior leads. Positive morphological changes of the terminal P wave portion and the measured P wave ratio (40% +/- 12%) in the inferior leads indicating bidirectional isthmus conduction block with a sensitivity of 87.5% and a specificity of 91.7% were observed. An increment of 20 ms or more in P wave duration during the PCS stimulation and 10 ms or more during the LLRA stimulation indicating the conduction block with a sensitivity of 90% and a specificity of 100%.

CONCLUSIONS

The variation of P wave morphology and duration in inferior leads of the surface ECG is a helpful technique to assess the complete bidirectional isthmus conduction block in the procedure of typical atrial flutter ablation.

Cardiac ripple mapping: a novel three-dimensional visualization method for use with electroanatomic mapping of cardiac arrhythmias

BACKGROUND

Mapping of regular cardiac arrhythmias is frequently performed using sequential point-by-point annotation of local activation relative to a fixed timing reference. Assigning a single activation for each electrogram is unreliable for fragmented, continuous, or double potentials. Furthermore, these informative electrogram characteristics are lost when only a single timing point is assigned to generate activation maps.

OBJECTIVE

The purpose of this study was to develop a novel method of electrogram visualization conveying both timing and morphology as well as location of each point within the chamber being studied.

METHODS

Data were used from six patients who had undergone electrophysiological study with the Carto electroanatomic mapping system. Software was written to construct a three-dimensional surface from the imported electrogram locations. Electrograms were time gated and displayed as dynamic bars that extend out from this surface, changing in length and color according to the local electrogram voltage-time relationship to create a ripple map of cardiac activation.

RESULTS

Ripple maps were successfully constructed for sinus rhythm (n = 1), atrial tachycardia (n = 3), and ventricular tachycardia (n = 2), simultaneously demonstrating voltage and timing information for all six patients. They showed low-amplitude continuous activity in four of five tachycardias at the site of successful ablation, consistent with a reentrant mechanism.

CONCLUSION

Ripple mapping allows activation of the myocardium to be tracked visually without prior assignment of local activation times and without interpolation into unmapped regions. It assists the identification of tachycardia mechanism and optimal ablation site, without the need for an experienced computer-operating assistant.

Meta-analysis of ablation of atrial flutter and supraventricular tachycardia

The purpose of this study was to perform a systematic review and meta-analysis to evaluate the safety and efficacy of radiofrequency ablation (RFA) of typical atrial flutter (AFL) and atrioventricular node-dependent supraventricular tachycardia (SVT) in adult patients. Medline and EMBASE were searched (1990 to 2007) for all study design trials of RFA. Data relating to single- and multiple-procedure success, arrhythmia recurrence, repeat ablation, adverse events, and death were extracted. For RFA in AFL, 18 primary studies with 22 treatment arms and 1,323 patients were identified. Single-procedure success for AFL was 91.7% (95% confidence interval [CI] 88.4% to 94.9%). Multiple-procedure success was 97.0% (95% CI 94.7% to 99.4%). Postablation arrhythmia was noted in 13.2% of patients (95% CI 7.5% to 18.9%), while repeat ablation was reported in 8% (95% CI 4.5% to 11.4%). For RFA of SVT, 39 primary studies with 49 treatment arms in 7,693 patients with accessory pathways and atrioventricular nodal reentrant tachycardia were identified. Single-procedure success for SVT was 93.2% (95% CI 90.8% to 95.5%). Multiple-procedure success was 94.6% (95% CI 92.4% to 96.9). Postablation arrhythmia was noted in 5.6% patients (95% CI 4.1% to 7.2%). Repeat ablation occurred in 6.5% (95% CI 4.7% to 8.3%). For AFL studies, all-cause mortality was 0.6%, and adverse events were reported in 0.5% of patients. For SVT studies, all-cause mortality was 0.1%, and adverse events were reported in 2.9% of patients. In conclusion, studies of RFA for the treatment of patients with AFL and SVT report high efficacy rates and low rates of complications.

Diagnosis and management of typical atrial flutter

Typical atrial flutter (AFL) is a common atrial arrhythmia that may cause significant symptoms and serious adverse effects including embolic stroke, myocardial ischemia and infarction, and rarely a tachycardia-induced cardiomyopathy as a result of rapid atrioventricular conduction. As a result of the well-defined anatomic and electrophysiological substrate, and the relative pharmacologic resistance of typical AFL, radiofrequency catheter ablation has emerged in the past decade as a safe and effective first-line treatment. This article reviews the electrophysiology of typical AFL and the techniques currently used for its diagnosis and management.

Cavotricuspid isthmus conduction split by pouch-like recesses during typical atrial flutter

A 58-year-old man had typical cavotricuspid-isthmus-dependent atrial flutter (AFL). Right atrial angiography and multidetector computed tomography revealed a deep pouch-like recess in the mid-isthmus region. Linear ablation from the pouch to the edge of the inferior vena cava resulted in widely split double potentials without any change in the AFL cycle length. This observation suggested that the pouch played an electrophysiological role by dividing the flutter wavefront into 2 parallel conduction wave fronts through both sides of the pouch along the isthmus during typical AFL. When a widely split potential is created on 1 side of the pouch, the other side of the pouch should be targeted.

Development and validation of diagnostic criteria for atrial flutter on the surface electrocardiogram

BACKGROUND

There are no universally accepted ECG diagnostic criteria for atrial flutter (AFL), making its differentiation from "coarse" atrial fibrillation (AF) difficult.

METHODS

To develop diagnostic criteria for AFL, we examined two sets of ECGs. Set 1 consisted of 100 ECGs (50 AF, AFL) with diagnoses confirmed by intracardiac recordings. Criteria evaluated were presence of F waves in the frontal plane leads, F waves in V(1), sawtooth F waves, rate, and regularity of ventricular response. Set 2 included 200 ECGs taken from the hospital database each of which had already been interpreted by a cardiologist as either AF (n = 100) or AFL (n = 100). Set 2 was blindly read by electrophysiologists whose consensus-diagnoses were compared to the diagnoses made by using the best criteria identified from the Set 1 data.

RESULTS

The criteria of frontal plane F waves, regular or partially regular ventricular response, and their combination had sensitivities of 92%, 98%, and 90% and specificities of 100%, 78%, and 100% in Set 1 for the diagnosis of AFL. In Set 2, concordance of electrophysiologist and cardiologist diagnoses was only 84%. The criteria of frontal plane Fwaves, regular or partially regular ventricular response, and their combination resulted in concordances with the cardiologist diagnoses of 85%, 85%, and 82% and with the electrophysiologist-consensus diagnoses of 90%, 89%, and 94% (P < 0.001).

CONCLUSIONS

The criteria of frontal plane F waves and regular or partially regular ventricular response aid in the proper diagnosis of AFL. Because management strategies may differ for AF and AFL, it is important to adopt a more rigorous diagnostic approach.

Effect of radiofrequency ablation of atrial flutter on the natural history of subsequent atrial arrhythmias

Flutter Ablation and Subsequent Arrhythmia.

INTRODUCTION

Patients with atrial flutter (AFL) treated medically are at high risk for subsequent development of atrial fibrillation (AF). Whether curative radiofrequency ablation of AFL can modify the natural history of arrhythmia progression is not clear. We aimed to determine whether ablation of AFL decreases the subsequent development of AF in patients without previous AF.

METHODS AND RESULTS

Patients with AFL as the sole atrial arrhythmia were selected from patients who underwent successful AFL ablation at Mayo Clinic between 1997 and 2003 (N = 137). The cohort was divided by presence (n = 50) or absence (n = 87) of structural heart disease. A control group comprised 59 patients with AFL and no history of paroxysmal AF, who received only medical therapy. Occurrence of AF after AFL ablation was compared among study groups and controls. Symptomatic AF occurred in 49 patients during 5 years of follow-up after AFL ablation, with similar frequency in both study groups. The cumulative probability of paroxysmal and chronic AF was similar in controls and each study group. By multivariate analysis, the AFL ablation procedure carries significant risk of AF occurrence during follow-up. Fifty patients discontinued antiarrhythmic drugs after AFL ablation, and the rate of cardioversions decreased.

CONCLUSION

Successful ablation of AFL does not improve the natural history of atrial arrhythmia progression; postablation AF is frequent. This suggests that AFL may be initiated by bursts of AF and that in the absence of AFL substrate the AF continues to progress.

Right atrial substrate properties associated with age in patients with typical atrial flutter

BACKGROUND

Data detailing the age-related difference in the atrial substrate for formation of typical atrial flutter (AFL) are sparse.

OBJECTIVE

The purpose of this study was to characterize the difference in the right atrial substrate related to aging using noncontact mapping of the right atrium.

METHODS

A total of 54 patients (23 young [<60 years; 45 +/- 12 years] and 31 old [>or=60 years; 74 +/- 6 years]) with typical AFL who underwent three-dimensional noncontact mapping of typical AFL were enrolled in the study. The atrial substrate was characterized according to (1) regional wavefront activation mapping, (2) regional conduction velocity, and (3) regional voltage distribution by dynamic substrate mapping.

RESULTS

During activation mapping of the crista terminalis, two activation patterns were observed: (1) around the upper end of the crista terminalis (67%) and (2) through a gap in the crista terminalis. The presence of a crista terminalis gap was associated with a high incidence of induced atypical AFL/atrial fibrillation (P <.001). The conduction velocities of the medial cavotricuspid isthmus were slower in the old group than in the young group. In regional activation mapping of the AFL, the location of the slowest conduction shifted from the lateral cavotricuspid isthmus (71%) in the young group to the medial cavotricuspid isthmus (40%) in the old group. More cases with a low-voltage zone (<or=30% peak negative voltage) extending to the medial side of the cavotricuspid isthmus occurred in the old group than in the young group (55% vs 17%, P = .012).

CONCLUSION

The atrial substrate responsible for formation of typical AFL differed between young and old patient groups.

Anatomic and electrophysiologic differences between chronic and paroxysmal atrial flutter: intracardiac echocardiographic analysis

BACKGROUND

It remains unknown why atrial flutter (AFL) occurs as either a chronic or paroxysmal arrhythmia.

PURPOSE

The aim of the study was to compare intracardiac echocardiographic (ICE) images of the crista terminalis (CT) and transverse conduction properties of the CT between chronic and paroxysmal forms of common AFL.

METHODS

Chronic AFL (n = 7) was defined as non-self-terminating AFL lasting >1 month, and paroxysmal AFL (n = 8) was defined as an intermittent arrhythmia with symptomatic episodes of 24 hours maximum duration. ICE images of the right atrium were recorded with a 9 F 9-MHz intracardiac ultrasound catheter during pullback at 0.5-mm intervals from the superior vena cava to the inferior vena cava triggered by electrocardiogram and respiration. The two-dimensional image of the right atrium was reconstructed into a three-dimensional (3-D) image.

RESULTS

Three-dimensional images from patients with chronic AFL showed the CT to be thick and continuous, and conduction across the CT was blocked at a pacing rate just above sinus rhythm in all seven patients. In contrast, 3D images from paroxysmal AFL showed the CT to be thin and discontinuous, and conduction across the CT during midseptal pacing was observed in five of the eight patients.

CONCLUSION

The nature of AFL is determined, at least in part, by anatomic and electrophysiologic characteristics of the CT.

Acute success and short-term follow-up of catheter ablation of isthmus-dependent atrial flutter; a comparison of 8 mm tip radiofrequency and cryothermy catheters

Objectives

To compare the acute success and short-term follow-up of ablation of atrial flutter using 8 mm tip radiofrequency (RF) and cryocatheters.

Methods

Sixty-two patients with atrial flutter were randomized to RF or cryocatheter (cryo) ablation. Right atrial angiography was performed to assess the isthmus. End point was bidirectional isthmus block on multiple criteria. A pain score was used and the analgesics were recorded. Patients were followed for at least 3 months.

Results

The acute success rate for RF was 83% vs 69% for cryo (NS). Procedure times were similar (mean 144 ± 48 min for RF, vs 158 ± 49 min for cryo). More applications were given with RF than with cryo (26 ± 17 vs. 18 ± 10, p < 0.05). Fluoroscopy time was longer with RF (29 ± 15 vs. 19 ± 12 min, p < 0.02). Peak CK, CK-MB and CK-MB mass were higher, also after 24 h in the cryo group. Troponin T did not differ. Repeated transient block during application (usually with cryoablation) seemed to predict failure. Cryothermy required significantly less analgesia (p < 0.01), and no use of long sheaths (p < 0.005).

The isthmus tended to be longer in the failed procedures (p = 0.117). This was similar for both groups, as was the distribution of anatomic variations. Recurrences and complaints in the successful patients were similar for both groups, with a very low recurrence of atrial flutter after initial success.

Conclusions

In this randomized study there was no statistical difference but a trend to less favorable outcome with 8 mm tip cryocatheters compared to RF catheters for atrial flutter ablation. Cryoablation was associated with less discomfort, fewer applications, shorter fluoroscopy times and similar procedure times. The recurrence rate was very low. Cryotherapy can be considered for atrial flutter ablation under certain circumstances especially when it has been used previously in the same patient, such as in an AF ablation.

Diagnosis and management of typical atrial flutter

Can "past decade" be rephrased to refer to more specific years? Typical atrial flutter (AFL) is a common atrial arrhythmia that may cause significant symptoms and serious adverse effects, including embolic stroke, myocardial ischemia and infarction, and, rarely, a tachycardia-induced cardiomyopathy resulting from rapid atrioventricular conduction. As a result of the well-defined anatomic and electrophysiologic substrate and the relative pharmacologic resistance of typical AFL, radiofrequency catheter ablation has emerged since its first description in 1992 as a safe and effective first-line treatment. This article reviews the electrophysiology of typical AFL and techniques currently used for its diagnosis and management.

Markers of inflammation before and after curative ablation of atrial flutter

BACKGROUND

Atrial arrhythmias are associated with inflammation. The cause and effect of the association are unknown.

OBJECTIVE

The purpose of this study was to test the hypothesis that atrial tachyarrhythmias contribute to inflammation.

METHODS

We performed a prospective observational study wherein C-reactive protein (CRP) and interleukin-6 (IL-6) levels from the femoral vein and coronary sinus (CS) were compared before curative ablation for atrial flutter (AFL; n = 59) and paroxysmal supraventricular tachycardia (SVT; n = 110). Follow-up levels were obtained at 1 and 6 months.

RESULTS

Peripheral levels of both biomarkers were significantly higher in the AFL group. After multivariate adjustment, only those in the AFL group who presented in AFL or atrial fibrillation (AF) had significantly elevated CRP levels (odds ratio 1.26; P = .033). Levels of each marker were similar in the CS and peripheral blood in the SVT group; in the AFL group, both CRP and IL-6 were significantly lower in the CS than in the periphery (P = .0076 and P = .0021, respectively). CRP was significantly lower a median of 47 days after AFL ablation (from a median of 6.28 mg/L to a median of 2.92 mg/L; P = .028) and remained reduced at second follow-up. IL-6 decreased across three time points after AFL ablation (P = .002). No reduction in inflammatory biomarkers was observed after SVT ablation.

CONCLUSIONS

CRP and IL-6 levels are elevated in patients presenting in AFL. Given the lower CS values in these patients, their origin appears to be systemic rather than cardiac. Because these levels significantly fall after ablation of AFL, the atrial tachyarrhythmia appears to be the cause (not the effect) of the inflammation.

Criteria for the electrocardiographic diagnosis of atrial flutter improve diagnostic accuracy

PURPOSE

We previously developed and validated diagnostic criteria for the differentiation of atrial flutter from atrial fibrillation. In this study we examine if the criteria (F waves in the frontal plane and a partially or completely regular ventricular response) can improve the diagnostic accuracy of internists.

METHODS

Two groups of 10 internists (1 group given the criteria and 1 not) read a set of electrocardiograms (ECGs) selected from the hospital database with cardiologist-confirmed diagnoses of atrial fibrillation, atrial flutter, or "atrial fibrillation-flutter" (100 each). The final diagnoses of all ECGs were provided by a consensus of electrophysiologists. The criteria also were used to establish the criteria-based diagnoses.

RESULTS

Of the 298 ECGs analyzed, the electrophysiologist diagnosis was atrial fibrillation in 71% and atrial flutter in 29%. The concordance of the internists' diagnoses with the electrophysiologist consensus diagnoses was 66+/-12% for those not given the criteria and 81+/-4% (P <.01) for those given the criteria. The concordance of the internists' diagnoses with the criteria based diagnoses was 66+/-12% for those not given the criteria and 83+/-4% (P <.01) for those given the criteria.

CONCLUSIONS

The simple criteria of F waves in the frontal plane and a partially or completely regular ventricular response can be used to improve the differentiation of atrial flutter from atrial fibrillation based on the ECG.

Quality of life and occurrence of atrial fibrillation in long-term follow-up of common type atrial flutter ablation: ablation with irrigated 5 mm tip and conventional 8 mm tip electrodes

OBJECTIVES

The ablation of common type atrial flutter is mainly performed by two approved techniques, whose efficacy and outcome in terms of quality of life have not been evaluated so far in a long-term follow-up study over years. A high proportion of patients suffer from coexistent atrial fibrillation, which may worsen the ablation result. The question arises whether one technique is more effective than the other when immediate ablation results, the occurrence of atrial fibrillation and the quality of life are compared. Considering these facts, it is reasonable to think about new ablation strategies for common type atrial flutter in the era of new concepts in catheter ablation of atrial fibrillation.

METHODS

In a retrospective study we evaluated a detailed questionnaire in 132 patients who underwent ablation of common type between 1999 and 2004. Radiofrequency ablation was performed irrespective of coexistent atrial fibrillation either with an irrigated tip or the 8 mm tip electrode. Acute and long-term ablation outcome, and the associated quality of life, pre-, under- and post-ablation was compared in the two different ablation groups. Recurrent tachycardia were re-evaluated by 12 lead ECG analysis and assessed for both ablation groups.

RESULTS

88 (67%) of the 132 patients contacted answered the questionnaire polling the perceived benefits of the procedure. Of the other 44 patients (33%); 4 (3%) had died, 7 (5.3%) had moved, 33 patients (25%) could not be included due to missing or incoherent answers. Independent of the ablation technique there was a high acute and long-term ablation success rate at about 95%. After a mean of 3 years of follow-up this benefit persists in spite of a high proportion of recurrent tachycardia, mainly atrial fibrillation (55/88 patients, 59.1%). Despite the occurrence of secondary tachycardia, there was a high significant long-term symptomatic benefit in the state of healthy and daily practice work, evaluated with a p-value of < 0.0005. The frequency of episodes and the symptom "tachycardia" were significantly reduced after effective ablation of common type atrial flutter, p-values of 0.003 and 0.002, respectively. Therefore the need for hospitalization was significant reduced (p = 0.001). Comparison of both approaches revealed that there was no significant difference related to the incidence and occurrence of atrial fibrillation.

CONCLUSIONS

The two mainly accepted and applied techniques for the ablation of common type atrial flutter show an excellent outcome under the aspect of ablation efficacy and quality of life in longterm follow-up. Three years after the ablation procedure the majority of patients consider the intervention beneficial. Despite the relatively high appearance of atrial fibrillation in the long-term follow-up this effect is still traceable.

Atrial fibrillation is common after ablation of isolated atrial flutter during long-term follow-up

BACKGROUND

Previous studies have shown that the incidence of atrial fibrillation after atrial flutter ablation is approximately 20% among patients presenting with typical atrial flutter and no history of fibrillation. However, studies involving this population have been small, with follow-up typically less than 2 years.

OBJECTIVE

The purpose of this study was to provide a more accurate perspective on the long-term risk of atrial fibrillation in patients presenting with isolated typical flutter.

METHODS

Clinical records of consecutive patients who had flutter ablations at Presbyterian Medical Center between 1999 and 2004 were assessed (n = 254). Patients with no apparent history of atrial fibrillation before their flutter ablation were identified. Retrospective follow-up data on these patients were obtained by review of medical records from our institution, from patients' cardiologists and primary care physicians, and by direct patient questionnaires. Postablation atrial fibrillation and other arrhythmias were identified by electrocardiography, Holter monitoring, and subsequent clinical records.

RESULTS

Postablation atrial fibrillation was identified in 40 (50%) of 80 patients, and an additional three patients presented with atypical atrial flutter, after a mean follow-up of 29.6 +/- 21.7 months. The incidence of atrial fibrillation was progressive, with 49% occurring after 2 years. There was no difference in age, left atrial size, hypertension, structural heart disease, or left ventricular dysfunction in patients who developed atrial fibrillation compared with those who did not.

CONCLUSION

Atrial fibrillation occurs in over half of patients who present with isolated typical flutter after cavotricuspid isthmus ablation. Asymptomatic patients should be screened for recurrent arrhythmias indefinitely after ablation. In certain patients, atrial fibrillation and flutter may be different expressions of the same electrical disease, and eradication of the flutter circuit will not prevent the eventual manifestation of atrial fibrillation.

Anatomical characteristics of the cavotricuspid isthmus in patients with and without typical atrial flutter: Analysis with two- and three-dimensional intracardiac echocardiography

INTRODUCTION

The cavotricuspid isthmus (CTI) is crucial in the ablation of typical atrial flutter (AFL), and consequently the CTI anatomy and/or its relation to resistant ablation cases have been widely described in human angiographic studies. Intracardiac echocardiography (ICE) has been shown to be a useful tool for determining detailed anatomical information. Thus, this technology may also allow the visualization of the anatomical characteristics of the CTI, providing an opportunity to further understand the anatomy.

AIM

We conducted a study to compare the anatomy of the CTI between the patients with and without AFL and to characterize the anatomy of the CTI in the patients with AFL resistant to ablation.

MATERIALS AND METHODS

Twelve patients with typical AFL and 20 without AFL were enrolled in the study. Two-dimensional (2D) intracardiac echocardiography (ICE) was performed. The recordings were obtained with a 9F, 9-MHz ICE catheter from the right ventricular outflow tract to the inferior vena cava by pulling the catheter back 0.3 mm at a time under guidance with echocardiographic imaging in a respiration-gated manner. Three-dimensional (3D) reconstruction of the images of the CTI were made with a 3D reconstruction system. After the acquisition of the ICE, the CTI ablation was performed in the patients with AFL.

RESULTS

The 2D and 3D images provided clear visualization of the tricuspid valve, coronary sinus ostium, fossa ovalis and Eustachian valve/ridge (EVR). The CTI was significantly longer in the patients with AFL than in those without AFL (median length 24.6 mm (range 17.0-39.1 mm) versus median length 20.6 mm (range 12.5-28.0 mm), respectively, P < 0.05). However, a deep recess due to a prominent EVR was observed in 9 of 12 (75%) patients with AFL and in 12 of 20 (60%) patients without AFL (N.S.). A deep recess and the relatively long CTI were related to aging in all the study patients, and that relationship was similar in a limited number of patients without AFL. In five patients with AFL resistant to ablation, a deep recess and prominent EVR were observed.

CONCLUSIONS

The 2D and 3D ICE were useful for visualizing the complex anatomy of the CTI and identifying the anatomical characteristics of the CTIs refractory to ablation therapy. The anatomical changes observed in the CTI region may simply be the result of aging and may partially be involved in the development of AFL.

The Electroanatomic Characteristics of the Cavotricuspid Isthmus: Implications for the Catheter Ablation of Atrial Flutter

INTRODUCTION

Radiofrequency ablation (RFA) of typical AFL is sometimes difficult because of the poor electroanatomic approach to the cavotricuspid isthmus (CTI). The aim of this study was to correlate the anatomy of the CTI between contact mapping (NavX) and right atrial angiography (RAG), and to investigate the impact of the electroanatomic characteristics of the CTI on the RFA of typical atrial flutter (AFL).

METHODS

One hundred patients with typical AFL undergoing RFA were studied. The image-guided group consisted of 50 consecutive patients with the guidance of NavX. NavX geometry and RAG were performed to investigate the morphology of the CTI. The bipolar voltages of the CTI were collected during sinus rhythm by a NavX. The control group consisted of 50 consecutive patients with the guidance of conventional fluoroscopy.

RESULTS

There was a good correlation between the angiography and NavX for the anatomy of the CTI. The pouch type had a longer length of CTI than the flat type (33.4 +/- 5.0 vs 22.6 +/- 8.4 mm, P < 0.0001) and deeper depth than the concave type (6.5 +/- 2.2 vs 3.7 +/- 0.8 mm, P < 0.0001) on the angiography. The pouch-type CTI had a longer ablation time and larger pulses of RFA than the other two types. The control group had a longer ablation time, fluoroscopy time, and larger pulses of RFA than image-guided group.

CONCLUSIONS

The 3-D mapping system provided a good reconstruction of CTI, which may help in the RFA in patients with a complex anatomy of the CTI.

High-Resolution Mapping Around the Eustachian Ridge During Typical Atrial Flutter

BACKGROUND

Although the reentrant circuit of typical atrial flutter (AFL) has been well recognized, the activation around the Eustachian ridge (ER) has not been fully characterized. The aim of this study was to delineate the activation patterns around the ER during typical AFL using high-resolution noncontact mapping.

METHODS

Fifty-three patients (M/F = 43/10, 62 +/- 14 years) with typical AFL were included. The high-resolution mapping of the right atrium using a noncontact mapping system during AFL and pacing from the coronary sinus (CS) was performed to evaluate the conduction through the ER.

RESULTS

Three types of activation patterns around the ER could be classified according to the ER conduction during AFL and CS pacing. Type I (n = 21, M/F = 16/5, 61 +/- 13 years) exhibited conduction block at the ER during AFL and CS pacing. The local unipolar electrograms at the ER exhibited long double potentials (DPs) (109 +/- 12 ms, range 77-153 ms) during AFL and CS pacing (84 +/- 18 ms, range 48-129 ms). Type II (n = 8, M/F = 7/1, 61 +/- 15 years) exhibited conduction block at the ER during AFL, but conduction through the ER during CS pacing. The unipolar electrograms exhibited long DPs (119 +/- 12 ms, range 97-141 ms) at the ER during the tachycardia and an rS pattern during CS pacing. Type III (n = 24, M/F = 20/4, 61 +/- 16 years) exhibited an activation wavefront that passed along the ER, with the sinus venosa as the posterior barrier during AFL. During CS pacing, all cases exhibited conduction through the ER with an rS pattern.

CONCLUSIONS

This study is the first to demonstrate the three patterns of activation along the ER during AFL and CS pacing. This finding suggested that the ER is an anatomic and functional barrier during typical AFL.

Simple and efficient identification of conduction gaps in post-ablation recurring atrial flutters

AIMS

Cavo-tricuspid isthmus (CTI) radiofrequency (RF) ablation is a curative therapy for common atrial flutter (AFl), but is associated with a recurrence rate of 5-26%. Although complete bidirectional conduction block is usually achieved, the recurrence of AF is due to recovered conducting isthmus tissue through which activation wavefronts pass. We evaluated a simple and efficient electrophysiological strategy, which pinpoints the ablation target.

METHODS AND RESULTS

Twenty-five patients (19 men), mean age 61 +/- 6, with recurrent AFl required a repeat ablation, 250 +/- 160 days after a successful RF CTI procedure. Transverse CTI conduction was monitored during AFl or coronary sinus (CS) pacing by a 24-pole mapping catheter positioned in the right atrium (RA), with the distal poles in the CS, proximal poles on the lateral RA, and intermediate poles on the CTI. A slow conduction area traversing the CTI (velocity, 37 +/- 22 vs. 98 +/- 26 cm/s on either side, P < 0.05) and a lower potential amplitude than at both sides (0.2 +/- 0.15 vs. 0.5 +/- 0.5 mV, P < 0.05), defined by a bayonet-shaped depolarization sequence, were considered to represent the incomplete line of block (InLOB). An ablation catheter was progressively dragged up to this InLOB, from the tricuspid annulus to the inferior vena cava, analysing the widely separated double potentials (DPs) until these coalesced. In nine patients (35%), the target conduction gap was a coalesced fractionated atrial potential within the InLOB (duration, 77 +/- 12 ms), and in 16 patients (65%), a narrow DP toward the healthy margins of this InLOB (duration, 28 +/- 15 ms). Adopting this strategy yields 100% successful re-ablation of recurring AFl leading to bidirectional block, with a mean 2.7 +/- 1.4 RF applications.

CONCLUSION

Transverse CTI mapping precisely locates the InLOB and helps find conduction gaps along the CTI in re-ablation procedures for common AFl.