Catheter Ablation Of Atrial Flutter Research Articles

To the Editor—Adenosine challenge following catheter ablation of atrial flutter

Comment in : Reply to the Editor--Adenosine challenge following catheter ablation of atrial flutter. [Heart Rhythm. 2012] Comment on : Adenosine facilitates dormant conduction across cavotricuspid isthmus following catheter ablation. [Heart Rhythm. 2012]

Atrioventricular block during radiofrequency catheter ablation of atrial flutter: incidence, mechanism, and clinical implications

To evaluate the incidence, mechanism, and clinical implications of atrioventricular (AV) block during catheter radiofrequency (RF) ablation of the cavotricuspid isthmus (CTI). Although RF ablation of atrial flutter is the most frequently performed ablation procedure, data on the incidence and significance of an AV block occurring during the procedure are scarce. Consecutive patients (n=845, 73.5% male) undergoing CTI ablation (913 procedures) between 1998 and 2010 were studied. Data on the occurrence of complete AV block (lasting≥3 s) during the procedure were prospectively collected. Sixteen (1.9%) patients experienced AV block, 12 during delivery of RF pulses (Group 1) and 4 (Group 2) during manipulation of catheters in the cardiac chambers. The AV block was short lived (<1 min), located in the AV node, and associated with septal isthmus RF lines in 11 Group 1 patients. It was long-lasting and led to pacemaker implantation in one Group 1 patient. Atrioventricular blocks had an infranodal location in four Group 2 patients, all of whom had a pre-existing complete left bundle branch block (LBBB). One Group 2 patient had an AV block during his two ablation procedures. Permanent pacemakers were implanted in five (0.6%) patients (one from Group 1 and four from Group 2). Atrioventricular blocks requiring pacemaker implantation following administration of RF pulses at the CTI are rare (0.12%). The occurrence rate of AV block related to the procedure and requiring pacemaker implantation is, however, not negligible (0.6%) and mostly affects patients with a pre-existing complete LBBB.

Cavotricuspid Isthmus Ablation Guided by Electroanatomic Mapping in a Patient with a Mechanical Tricuspid Valve Replacement After a Total Correction of Tetralogy of Fallot

Atrial arrhythmias are a common sequel after surgery for congenital heart disease, and often eventually cause late morbidity and mortality. Nowadays, percutaneous catheter ablation of atrial flutter (AFL) is widely practised, and is highly successful and safe. Patients with a tricuspid valve replacement (TVR) represent a distinct group for whom the appropriate nonpharmacologic therapy for AFL has not yet been established. We report a case of a 55-year-old woman with a history of a total correction of tetralogy of Fallot (ToF) who developed AFL before and after receiving a tricuspid valve prosthesis. Based on the results of the activation mapping, counterclockwise and clockwise AFL were identified. Completion of a cavotricuspid isthmus (CTI) line on the atrial side successfully terminated the AFL, with resumption of sinus rhythm. Guided by a 3D mapping system, CTI ablation is feasible and safe in patients with a prosthetic tricuspid valve.

Catheter Ablation for Peri-Mitral Atrial Flutter Post Mitral Valve Replacement

Peri-mitral atrial flutter (PMFL) may occur in patients with prior mitral valve replacement (MVR). Catheter ablation (CA) may be challenging owing to prosthetic valve and the surrounding scar. A 61 year-old man underwent MVR and LA maze procedure in 2005. He was admitted to our hospital in 2011 because of atrial flutter (AFL). CA for AFL was performed. In EPS findings, PV-LA connections were isolated by prior maze procedure. CARTO mapping during tachycardia (CL=290 msec), and revealed PMFL. Radiofrequency application with an irrigated-tip catheter using Agilis sheath at the mitral isthmus successfully eliminated this tachycardia. We confirmed the MI block line by the sequence of CS activation while pacing from the LAA, but the MI block line was incomplete. The activation map on the CARTO system during LAA pacing revealed early activation site with a fractionated potential near the MI (LAA pacing site to ABL distal pole interval was 80 ms). The bidirectional conduction block line was created in the MI by additional RF current application at this conduction gap. The interval from the LAA pacing site to CS distal pole prolonged from 130 msec to 230 msec. This case report highlights the rare case of successful CA for PMFL in a patient with prior MVR.

Canadian Cardiovascular Society Atrial Fibrillation Guidelines 2010: Catheter Ablation for Atrial Fibrillation/Atrial Flutter

Catheter ablation of atrial fibrillation (AF) offers a promising treatment for the maintenance of sinus rhythm in patients for whom a rhythm control strategy is desired. While the precise mechanisms of AF are incompletely understood, there is substantial evidence that in many cases (particularly for paroxysmal AF), ectopic activity most commonly located in and around the pulmonary veins of the left atrium plays a central role in triggering and/or maintaining arrhythmic episodes. Catheter ablation involves electrically disconnecting the pulmonary veins from the rest of the left atrium to prevent AF from being triggered. Further substrate modification may be required in patients with more persistent AF. Successful ablation of AF has never been shown to alter mortality or obviate the need for oral anticoagulation; thus, the primary indication for this procedure should be improvement of symptoms caused by AF. The success rate of catheter ablation for AF is superior to the efficacy of antiarrhythmic drugs, but success is still in the range of 75%-90% after 2 procedures. Ablation is also associated with a complication rate of 2%-3%. Thus, ablation should primarily be used as a second-line therapy after failure of antiarrhythmic drugs. In contrast to AF, catheter ablation of atrial flutter has a higher success rate with a smaller incidence of complications. Thus, catheter ablation for atrial flutter may be considered a first-line alternative to antiarrhythmic drugs.

Catheter Ablation of Atrial Flutter

Catheter Ablation of Atrial Flutter

Outcome of Invasive Electrophysiological Procedures and Gender: Are Males and Females the Same?

The aim of this review is to summarize the available evidence on gender-related differences in outcome of invasive electrophysiological procedures. Gender exerts significant influences on the epidemiology, pathophysiology, and clinical presentation of many cardiac rhythm disorders. Women with supraventricular arrhythmias have a higher incidence of atrioventricular nodal reentrant tachycardia, a lower prevalence of atrioventricular accessory pathways, and increased arrhythmia inducibility during luteal phases of the menstrual cycle. Catheter ablation of supraventricular arrhythmias appears equally effective in the 2 genders, although women present to catheter ablation later, with more symptoms, and after having failed more antiarrhythmic drugs. The outcome of catheter ablation of atrial fibrillation in women has been reported worse than in men, which may be explained by a later referral. Accordingly, women present to catheter ablation with a higher incidence of long-standing persistent atrial fibrillation. Of note, the outcome of catheter ablation of atrial flutter does not seem to differ between genders. To date, with regard to ventricular arrhythmias, no gender-related differences in outcome of catheter ablation procedures have been reported. However, pathophysiology and risk factors underlying ventricular arrhythmias appear different in the two genders. Severe left ventricular dysfunction does not perform equally as a predictor for sudden cardiac death in women as compared to men, and the survival benefit of prophylactic implantable cardioverter-defibrillator (ICD) implantation in women is inconclusive. On the other hand, the clinical outcome after cardiac resynchronization therapy seems to be more favorable in women, who experience a greater degree of reverse left ventricular remodeling.

Spontaneous Deceleration of Persistent Atrial Flutter Due to Atrial Remodeling

A 66-year-old man was admitted to our hospital for catheter ablation of atrial flutter (AFL). On 12-lead electrocardiogram (ECG), the flutter waves were negative in leads II, III, aVF and V3-V6, and positive in V1 and V2, consistent with typical counterclockwise AFL (Fig. 1A). When AFL was diagnosed, 2 years earlier (Fig. 1B), the patient was placed on a regimen of oral digoxin for ventricular rate control during persistent AFL. In the last 6 months, he experienced frequent episodes of presyncope with tran-

MRI of Right Atrial Function after Catheter Ablation of Atrial Flutter

Catheter ablation of the cavotricuspid isthmus (CTI) is an effective treatment of right atrial flutter. The objective of this study was to evaluate the changes in CTI length and right atrial (RA) function after radiofrequency ablation of isthmus-dependent atrial flutter (isthmus ablation). Magnetic resonance imaging was obtained in 14 patients (2 female, mean age 59 +/- 9) before and after isthmus ablation (mean delay 80 +/- 175 days) using steady-state free precession cine magnetic resonance imaging in right anterior oblique view orientation. Right atrial function (maximum/minimum right atrial volumes, stroke volume, ejection fraction) and maximum/minimum length of the CTI were measured. After isthmus ablation, maximum RA volume decreased by 13% (P = .02) and minimum RA volume by 22% (P = .01), whereas stroke volume and ejection fraction did not increase significantly (P = .4 and .2, respectively). After ablation, the maximum length of the CTI showed a significant decrease of 19% (P < .001) and the minimum length a decrease of 24% (P < .001). A linear correlation between change in CTI length and number of energy applications during ablation could not be observed (r = .605, P = .22 for minimum length; r = .384, P = .18 for maximum length). After eliminating the outliers in the number of energy applications, a significant correlation between energy applications and change in CTI systolic length was found (r = .808, P = .008). Magnetic resonance imaging to visualize right atrial size and function in right anterior oblique orientation was successfully performed and easy to evaluate for volumetric analysis and determination of CTI length. Scarring of the CTI with the use of catheter ablation leads to a significant and linear decrease in its length and to a subsequent reduction of right atrial volumes, whereas functional parameters such as stroke volume/ejection fraction did not change significantly.

Atrial flutter catheter ablation in adult patients with repaired tetralogy of Fallot: mechanisms and outcomes of percutaneous catheter ablation in a consecutive series

Prior investigators note successful ablation of both typical cavotricuspid isthmus-dependent and scar-related macroreentrant right atrial flutters (AFL) in adult patients with repaired tetralogy of Fallot (TOF). However, an analysis of the mechanisms (including a description of a uniform approach to diagnose such mechanisms), and clinical outcomes of catheter ablation in a consecutive series of adult patients with AFL late after surgical TOF repair has not been previously reported. Background clinical data and follow-up were evaluated in a consecutive series of TOF patients evaluated from September 2001 to June 2008. We report a prevalence of sustained, symptomatic AFL in patients with repaired TOF equal to 20% (28/140 patients), and of recurrent, drug-refractory and/or severely symptomatic AFL to be 11% (16/140 patients). The AFLs manifested variable cycle lengths ranging from 215 to 525 ms. Underlying mechanisms were: (1) cavotricuspid (CTI)-dependent, counterclockwise atrial flutter (n=8 patients); (2) non-CTI-dependent macroreentrant scar-related AFL (n=6 patients); and (3) both CTI- and non-CTI-dependent macroreentrant AFL (n=2 patients). Recurrent arrhythmias occurred in six patients, five of whom were successfully treated with repeat ablation. After a mean follow-up of 23 months, 15 of 16 patients were alive and free of sustained AFL. AFL late after surgical TOF repair occurs in 20% of such patients. In more than half of these patients, the AFLs are drug-refractory and/or severely symptomatic. Despite the presence of congenital heart disease treated with prior cardiac surgery and AFLs with variable atrial cycle lengths, the CTI-dependent mechanism underlies approximately half of the sustained, symptomatic AFLs.

Uninterrupted Warfarin for Periprocedural Anticoagulation in Catheter Ablation of Typical Atrial Flutter: A Safe and Cost‐Effective Strategy

Many patients undergoing catheter ablation of atrial flutter (AFL) require periprocedural anticoagulation. We compared a strategy of conversion to low molecular weight heparin (LMWH) periprocedure to uninterrupted warfarinization in a nonrandomized, case-controlled study. One hundred and one consecutive patients requiring periprocedural anticoagulation for catheter ablation of typical AFL were studied. The first 51 patients underwent conversion to LMWH (enoxaparin 1 mg/kg bd) with a warfarin pause (LMWH group), the subsequent 50 continued with uninterrupted oral anticoagulation (Warfarin group). Primary endpoint was a composite of major and minor bleeding complications and groin symptoms. Fewer patients in the Warfarin group reached the primary endpoint (36.0% vs 56.8%, P = 0.013). Four patients in the LMWH group but no patient in the Warfarin group required hospital admission for bleeding-related complications. Cost analysis showed mean cost per patient of anticoagulation with LMWH to be pounds sterling 100.9 (95% CI 94.46-107.30) compared to pounds sterling 10.23 (4.49-15.97) in the Warfarin group (P < 0.0001). Transesophageal echocardiography (TEE) was performed prior to ablation in 11 patients in the Warfarin group and in 3 patients in the LMWH (P = 0.019). When TEE costs were included, costs were pounds sterling 125.00 ($188.25) (96.80-153.60) for the LMWH strategy and pounds sterling 108.5 ($163.40) (54.92-162.1) for the Warfarin group (P < 0.0001). Catheter ablation of typical AFL without interruption of warfarin appears safer and more cost-effective than periprocedural conversion to LMWH. It could be used as a routine anticoagulation strategy for the ablation of right-sided arrhythmias.

Myotonic Dystrophy Initially Presenting as Tachycardiomyopathy Successful Catheter Ablation of Atrial Flutter

Myotonic dystrophy is a genetic muscular disease that is frequently associated with cardiac arrhythmias. Bradyarrhythmias, such as sinus bradycardia and atrioventricular block, are more common than tachyarrhythmias. Rarely, previously undiagnosed patients with myotonic dystrophy initially present with a tachyarrhythmia. We describe the case of a 14-year-old boy, who was admitted to the hospital with clinical signs and symptoms of decompensated heart failure and severely reduced left ventricular function. Electrocardiography showed common-type atrial flutter with 2 : 1 conduction resulting in a heart rate of 160 bpm. Initiation of medical therapy for heart failure as well as electrical cardioversion led to a marked clinical improvement. Catheter ablation of atrial flutter was performed to prevent future cardiac decompensations and to prevent development of tachymyopathy. Left ventricular function normalized during followup. Genetic analysis confirmed the clinical suspicion of myotonic dystrophy as known in other family members in this case.

A Randomized Invasive Cardiac Electrophysiology Study of the Combined Ion Channel Blocker AZD1305 in Patients After Catheter Ablation of Atrial Flutter

This study assessed the cardiac electrophysiological and hemodynamic effects of an intravenous infusion of the combined ion channel blocker AZD1305. After successful ablation of atrial flutter, patients were randomized to receive placebo (n = 12) or AZD1305 (n = 38) in 4 ascending dose groups. Electrophysiological and hemodynamic measurements were performed before and commencing 20 minutes after start of infusion. Left atrial effective refractory period increased dose and the primary outcome measure increased dose and plasma concentration dependently, with a mean increase of 55 milliseconds in dose group 3. There was a corresponding increase in right atrial effective refractory period of 84 milliseconds. The right ventricular effective refractory period and the paced QT interval also increased dose and concentration dependently, by 59 and 70 milliseconds, respectively, in dose group 3. There were indications of moderate increases of atrial, atrioventricular nodal, and ventricular conduction times. No consistent changes in intracardiac pressures were observed, but there was a small transient decrease in systolic blood pressure. Adverse events were consistent with the study population and procedure, and there were no signs of proarrhythmia despite marked delay in ventricular repolarization in some individuals. AZD1305 shows electrophysiological characteristics indicative of potential antiarrhythmic efficacy in atrial fibrillation.

Simplified Demonstration of Cavotricuspid Isthmus Block After Catheter Ablation in Patients After Mustard's Operation

The Mustard operation is a complex atrial rerouting performed in patients with transposition of the great arteries (TGA). Cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) is an important problem in these patients. While catheter ablation (CA) is successful, three-dimensional (3D) mapping is necessary to prove block at the CTI. 3D mapping, however, requires baffle puncture. We tested a simplified concept to prove isthmus block after CA for AFL in Mustard patients. During electrophysiology study, catheters were placed in the high and low systemic venous atrium (HSVA and LSVA) and in the low pulmonary venous atrium (LPVA). LPVA and then LSVA were paced while recording in the HSVA and the alternate site. While pacing from one low site, the time taken to activate the other low site and the HSVA was compared before and after successful ablation. Three patients with Mustard operation and AFL underwent successful CA. Involvement of the CTI in AFL was proved by entrainment mapping. AFL was terminated during ablation and no longer inducible after ablation in all. LSVA pacing showed LPVA activation preceded HSVA activation preablation and activation pattern reversal after ablation. Likewise, LPVA pacing showed LSVA activation preceding HSVA preablation with reversal after ablation. This study provides a simple method to demonstrate bidirectional block at the CTI in patients with CTI-based AFL after Mustard operation for TGA.

Radiofrequency Catheter Ablation of Atrial Flutter Induces the Release of Platelet and Leukocyte‐Derived Procoagulant Microparticles and a Prothrombotic State

To assess the extent of endothelium, platelet, and leukocyte damage and coagulation activation induced by radiofrequency catheter ablation (RF) of atrial flutter. In the vasculature, procoagulant microparticles (MPs) are reliable markers of vascular damage. They provide an additional phospholipidic surface, enabling the assembly of the enzyme complexes of blood coagulation and consequent thrombin generation. MPs were measured in the venous blood of 33 patients with isthmus-dependent atrial flutter undergoing RF before (RF(0)), immediately after (RF(1)), and at day 1 (RF(2)) thereafter. Concentrations of PAI-1, vWF, and D-dimers were simultaneously determined. MPs procoagulant activities were determined using a functional prothrombinase assay. RF induces an early rise of platelet-derived MPs (platelet), vWF Ag, and D-dimers levels, which is concomitant with the decrease of PAI-1 concentrations. Conversely, no significant changes in endothelial-derived MPs could be evidenced. At RF(2), sustained elevation of leukocytes-derived MPs, vWF, and D-dimers testified to an ongoing prothrombotic status. RF ablation of common flutter induces a prothrombotic state and the release of platelet and leukocyte-derived procoagulant microparticles. Whereas this activation of blood coagulation could be viewed as clinically marginal in right-sided procedures, its relevance in left-sided procedures should be established.

Diastolic isthmus length and 'vertical' isthmus angulation identify patients with difficult catheter ablation of typical atrial flutter: a pre-procedural MRI study

Catheter ablation of isthmus-dependent atrial flutter is technically demanding in some patients and extremely simple in others. The intervention targets a defined anatomical structure, the so-called cavotricuspid isthmus (CTI). We sought to characterize CTI anatomy in vivo in patients with difficult and simple catheter ablation of atrial flutter. Twenty-six patients were studied. Seven patients with difficult (n = 6) or extremely simple (n = 1) CTI ablation procedures were retrospectively selected from our catheter ablation database. Thereafter, we prospectively studied 19 patients undergoing CTI ablation in our department. We visualized CTI anatomy by ECG- and respiration-gated free precession 1.5 T cardiac magnetic resonance imaging (MRI). Magnetic resonance imaging was analysed for systolic and diastolic CTI length, the angle between the vena cava inferior and CTI, and pouch-like recesses. These parameters were compared between patients with difficult and simple procedures, split by the median number of energy applications. Patients with difficult procedures had a longer diastolic CTI length (diastolic isthmus length 20.3 +/- 1.8 mm) than those with simple procedures (diastolic isthmus length 16.6 +/- 1.7 mm, all data as mean +/- SEM, P < 0.05). Cavotricuspid isthmus angulation with respect to inferior vena cava was closer to 90 degrees in patients with difficult procedures (deviation from 90 degrees: 15 +/- 2 degrees) than those with simple procedures (deviation 23 +/- 4 degrees, P < 0.05). Systolic CTI length was not different between groups (32 +/- 2 mm in both groups, P > 0.2). Longer diastolic, but not systolic, CTI length and a rectangular angle between CTI and inferior vena cava render CTI catheter ablation difficult. Visualization of isthmus anatomy may help to guide difficult CTI ablation procedures.

A prospective randomised comparison of large-tip cryoablation and 8-mm-tip radiofrequency catheter ablation of atrial flutter

Although radiofrequency (RF) energy is routinely used for tricuspid isthmus (TI) ablation, it is often associated with discomfort. The paucity of studies comparing the feasibility and efficacy of cryo- versus RF energy for TI-ablation urged us to conduct a prospective, randomised trial. Forty patients with atrial flutter (AFl) were randomised to RF- or cryoenergy for TI-ablation. Perceived pain was scored from 1 to 10 on a Visual Analogue Scale. Significantly lower pain scores were recorded for cryoablation versus RF ablation (0.96 +/- 0.73 versus 4.2 +/- 2.4, p = 0.00004). Cryoablation was associated with significantly longer procedure duration and ablation time (137 +/- 35 versus 111 +/- 29 min, p = 0.016 and 81 +/- 40 versus 48 +/- 30 min, p = 0.007) and lower acute success rate (56% versus 100%, p = 0.001) than RF ablation. The recurrence of AFl was 20% (cryo) versus 15% (RF; p = 0.45) after a mean of 15.1 months follow-up. Cryoablation results in significantly less pain and discomfort compared to RF ablation of AFl, which is offset by the significantly lower acute success rate.

Abstract 5684: Long-Term Outcomes after Catheter Ablation of Atrial Flutter: A Meta-Analysis

Clinical outcomes after catheter ablation of atrial flutter (AFL) vary widely in reported literature. The puropose of this study was to analyze long-term outcomes after cathteter ablation of AFL using meta-analys. Meta-analysis was performed of articles published from 1988 – 2007 with outcomes after catheter ablation of cavotricuspid isthmus (CTI) dependent AFL. The analysis included 110 studies comprising 7946 patients (79% male, 59.8±0.5 years, 43% left atrial enlargement, 49% heart disease, 16±12 months follow up). The acute success rate was 97% (95% CI 95–98%) with cooled (8 –10mm tip or irrigated) radiofrequency catheters and 95% (94 –96%) when bidirectional CTI block was the endpoint. Recurrence rate of AFL was 4% (3– 6%) with cooled catheters. Use of bidirectional CTI block as ablation endpoint decreased AFL reccurrence to 8% (^−10%) versus 18% (14 –22%) without CTI as endpoint. AFL recurrence rate did not increase over time. Mortality was 3% (2– 4%) during follow up. The overall occurrence rate of atrial fibrillation (AF) after AFL ablation was 25% (21–29%). In patients with AF prior to ablation, AF occurred in 46% (41–51%) compared to 16% (11–22%) without AF prior to ablation. Five years after ablation, the AF rates were similar in those with and without AF prior to ablation (Figure ). Antiarrhythmic drug use post ablation was 28% (22–36%). The long term use of coumadin was not described. AF is common after AFL ablation and may limit the clinical utility of this procedure. 28% of patients require antiarrhythmic drugs after AFL ablation. AF before ablation may indicate a more advanced electrical disease.

Catheter Ablation for Atrial Fibrillation

▪ Abstract Atrial fibrillation is frequently disabling and resistant to antiarrhythmic drugs. Curative treatment by catheter-based ablation has been shown to be feasible either by achieving long linear lesions, mainly in the left atrium, or by targeting the initiating focus, most frequently in the pulmonary veins. This paper reviews the different ablation approaches, their results, potential complications, and relative merits.

Difference in Humoral Biomarkers for Myocardial Injury and Inflammation in Radiofrequency Ablation versus Cryoablation

Markers of myocardial injury and inflammation have been shown to be elevated following radiofrequency (RF) ablation. This study aimed to compare RF ablation and cryoablation for their impact on markers for myocardial injury and inflammation. Nineteen patients received catheter ablation for atrial flutter by either cryoablation (10 patients) or open-irrigated RF ablation (nine patients). Venous blood samples for troponin T (TnT), creatinkinase (CK), and the cardiac isoenzyme MB (CKMB) were obtained before, at six hours after the end of ablation, and the following day. C-reactive protein (CRP) levels were measured before ablation and the following day. Bidirectional isthmus block was achieved in all patients. Cryoablation showed significantly higher TnT following ablation (0.85 microg/l +/- 0.39 microg/l) compared to RF ablation (0.36 microg/l +/- 0.24 microg/l; p= 0.01) with declining levels the following day (cryoablation: 0.58 microg/l +/- 0.20 microg/l; RF ablation 0.34 microg/l +/- 0.21 microg/l; p= 0.03). We observed equal findings for CK and CKMB, both significantly higher in cryoablation. RF ablation led to a nonsignificant rise in CK and CKMB. CRP was elevated significantly higher following RF ablation (12.3 mg/dl +/- 4.1 mg/dl) compared to cryoablation (6.9 mg/dl +/- 4.0 mg/dl; p= 0.01). We show reduced inflammation despite higher markers for myocardial injury in cryoablation. The difference in biomarkers reflects different lesion formation in cryoablation and RF ablation. Cryoablation shows less systemic inflammatory reaction. This might be due to less endothelial damage and surface thrombosis in cryoablation.