A randomized clinical trial to evaluate the efficacy and safety of rivaroxaban in patients with bioprosthetic mitral valve and atrial fibrillation or flutter: Rationale and design of the RIVER trial.

The efficacy and safety of rivaroxaban in patients with bioprosthetic mitral valves and atrial fibrillation or flutter remain uncertain. DESIGN: RIVER was an academic-led, multicenter, open-label, randomized, non-inferiority trial with blinded outcome adjudication that enrolled 1005 patients from 49 sites in Brazil. Patients with a bioprosthetic mitral valve and atrial fibrillation or flutter were randomly assigned (1:1) to rivaroxaban 20 mg once daily (15 mg in those with creatinine clearance <50 mL/min) or dose-adjusted warfarin (target international normalized ratio 2.0-30.); the follow-up period was 12 months. The primary outcome was a composite of all-cause mortality, stroke, transient ischemic attack, major bleeding, valve thrombosis, systemic embolism, or hospitalization for heart failure. Secondary outcomes included individual components of the primary composite outcome, bleeding events, and venous thromboembolism. SUMMARY: RIVER represents the largest trial specifically designed to assess the efficacy and safety of a direct oral anticoagulant in patients with bioprosthetic mitral valves and atrial fibrillation or flutter. The results of this trial can inform clinical practice and international guidelines.

Catheter ablation of supraventricular tachycardia in patients with dextrocardia and situs inversus.

BACKGROUND: Dextrocardia with situs inversus is a rare cardiac positional anomaly. Catheter ablation procedures performed in this set of patients have not been sufficiently reported. METHODS: A total of 10 patients with dextrocardia and situs inversus who received catheter ablation for supraventricular tachycardia (SVT) were included from a cohort of over 20 000 cases of catheter ablation for SVT in three centers from 2005 to 2016. All patients underwent electrophysiologic study and catheter ablation of SVT. Ablation targets were selected based on different tachycardia mechanisms with the primary endpoint of noninduction of tachycardia. RESULTS: The average age was 32.4 ± 5.6 years. Congenitally corrected transposition of great arteries (TGA) with situs inversus and D-looping of the ventricles and aorta (congenitally corrected TGA {I,D,D}) was found in four patients, while the other six patients exhibited mirror-image dextrocardia {I,L,L}. The mechanisms of SVT were atrioventricular nodal reentrant tachycardia in four patients, atrioventricular reentrant tachycardia in three, typical atrial flutter in one, intra-atrial reentrant tachycardia in one, and focal atrial tachycardia in one. Immediate procedural success was achieved in 9 out of 10 patients with no procedural complications. During a follow-up period of 6.3 ± 3.5 years on average, all patients remained free from recurrent tachycardia. CONCLUSIONS: For patients with dextrocardia and situs inversus, catheter ablation of SVT is safe and feasible. Differences in catheter maneuver and fluroscopy projection, along with difficulties in distorted anatomy are major obstacles for successful ablation.

Predictors of Acute Failure Ablation of Intra-atrial Re-entrant Tachycardia in Patients With Congenital Heart Disease: Cardiac Disease, Atypical Flutter, and Previous Atrial Fibrillation.

BACKGROUND: Intra-atrial re-entrant tachycardia (IART) in patients with congenital heart disease (CHD) increases morbidity and mortality. Radiofrequency catheter ablation has evolved as the first-line treatment. The aim of this study was to analyze the acute success and to identify predictors of failed IART radiofrequency catheter ablation in CHD. METHODS AND RESULTS: The observational study included all consecutive patients with CHD who underwent a first ablation procedure for IART at a single center from January 2009 to December 2015 (94 patients, 39.4% female, age: 36.55±14.9 years). In the first procedure, 114 IART were ablated (acute success: 74.6%; 1.21±0.41 IART per patient) with an acute success of 74.5%. Cavotricuspid isthmus-related IART was the only arrhythmia in 51%; non-cavotricuspid isthmus-related IART was the only mechanism in 27.7% and 21.3% of the patients had both types of IART. Predictors of acute radiofrequency catheter ablation failure were as follows: nonrelated cavotricuspid isthmus IART (odds ratio 7.3; confidence interval [CI], 1.9-17.9; P=0.04), previous atrial fibrillation (odds ratio 6.1; CI, 1.3-18.4; P=0.02), transposition of great arteries (odds ratio, 4.9; CI, 1.4-17.2; P=0.01) and systemic ventricle dilation (odds ratio 4.8; CI, 1.1-21.7; P=0.04) with an area under the receiver operating characteristic curve of 0.83±0.056 (CI, 0.74-0.93, P=0.001). After a mean follow-up longer than 3.5 years, 78.3% of the patients were in sinus rhythm (33.1% of the patients required more than 1 radiofrequency catheter ablation procedure). CONCLUSIONS: Although ablation in CHD is a challenging procedure, acute success of 75% can be achieved in moderate-highly complex CHD patients in a referral center. Predictors of failed ablation are IART different from cavotricuspid isthmus, previous atrial fibrillation, and markers of complex CHD (transposition of great arteries, systemic ventricle dilation).

Left atrial thrombus resolution in atrial fibrillation or flutter: Results of a prospective study with rivaroxaban (X-TRA) and a retrospective observational registry providing baseline data (CLOT-AF).

BACKGROUND: Data on left atrial/left atrial appendage (LA/LAA) thrombus resolution after non-vitamin K antagonist (VKA) oral anticoagulant treatment are scarce. The primary objective of X-TRA was to explore the use of rivaroxaban for the resolution of LA/LAA thrombi in patients with nonvalvular atrial fibrillation (AF) or atrial flutter, with the CLOT-AF registry providing retrospective data after standard-of-care therapy in this setting. METHODS: X-TRA was a prospective, single-arm, open-label, multicenter study that investigated rivaroxaban treatment for 6 weeks for LA/LAA thrombus resolution in patients with nonvalvular AF or atrial flutter and LA/LAA thrombus confirmed at baseline on a transesophageal echocardiogram (TEE). CLOT-AF retrospectively collected thrombus-related patient outcome data after standard-of-care anticoagulant treatment for 3 to 12 weeks in patients with nonvalvular AF or atrial flutter who had LA/LAA thrombi on TEE recorded in their medical file. RESULTS: In X-TRA, patients were predominantly (95.0%) from Eastern European countries. The adjudicated thrombus resolution rate was 41.5% (22/53 modified intention-to-treat [mITT] patients, 95% CI 28.1%-55.9%) based on central TEE assessments. Resolved or reduced thrombus was evident in 60.4% (32/53 mITT patients, 95% CI 46.0%-73.6%) of patients. In CLOT-AF, the reported thrombus resolution rate was 62.5% (60/96 mITT patients, 95% CI 52.0%-72.2%) and appeared better in Western European countries (34/50; 68.0%) than in Eastern European countries (26/46; 56.5%). CONCLUSION: X-TRA is the first prospective, multicenter study examining LA/LAA thrombus resolution with a non-VKA oral anticoagulant in VKA-naïve patients or in patients with suboptimal VKA therapy. Rivaroxaban could be a potential option for the treatment of LA/LAA thrombi.

A Stunning Left Atrial Appendage Thrombus.

BACKGROUND: Left atrial appendage thrombus formation is a known major complication of atrial fibrillation and atrial flutter which increases the risk of embolism and stroke. This risk of thrombosis is greatly increased with a lack of anticoagulation. After conversion to a normal sinus rhythm in these arrhythmias, the risk of thrombus formation in the left atrium persists through a phenomenon termed atrial myocardial stunning. CASE: We present the case of a patient who previously underwent successful pulmonary vein isolation and was found to be in typical isthmus-dependent atrial flutter with a questionable recurrence of atrial fibrillation. The decision was made to return for atrial flutter ablation and for evaluation of prior pulmonary vein isolation. Initially, a transesophageal echocardiogram showed a normal ejection fraction, biatrial enlargement and no left atrial appendage thrombus. Ablation of the cavotricuspid isthmus was successfully accomplished with documented bidirectional block. A transesophageal echocardiogram probe was still in place prior to planned transseptal puncture for the evaluation of pulmonary veins. A large thrombus was now observed filling the left atrial appendage. Conclusion and Objective: Atrial stunning is a transient atrial contractile dysfunction that occurs whether sinus rhythm is restored spontaneously, electrically, pharmacologically or by ablation. We know after conversion that there is higher propensity to increased spontaneous echogenic contrast and decreased velocities; however, we do not have documented knowledge of exactly how soon after the conversion to a sinus rhythm a thrombus may be seen. We demonstrate a case of acute left atrial appendage thrombus formation immediately following the successful ablation of isthmus-dependent atrial flutter. Our report validates the belief that strategies of not interrupting anticoagulation prior to the conversion of these arrhythmias should be implemented.

Adoption of direct oral anticoagulants for stroke prevention in atrial fibrillation.

BACKGROUND: Direct oral anticoagulants (DOAC) are being increasingly utilised for stroke prevention in atrial fibrillation (AF) and atrial flutter. AIMS: To analyse the adoption and application of these drugs in a regional hospital inpatient cohort and compare with national prescribing data. METHODS: Digital medical records identified prescribed anticoagulants for patients admitted with AF and atrial flutter during 2013-2014. Analysis of patient demographics and stroke risk identified trends in prescribing DOAC versus warfarin. For broader comparison, data from the Pharmaceuticals Benefits Scheme were sourced to determine the nation-wide adoption of DOAC. RESULT: Of the 615 patients identified, 505 (255 in 2013, 250 in 2014) had sufficient records to include in the study. From 2013 to 2014, DOAC prescriptions increased from 9 to 28% (P < 0.001), warfarin and aspirin remained comparatively stable (38-34%, 22-20%), and those prescribed no medication declined (17-8%, P < 0.001). DOAC were prescribed to patients with lower CHA2 DS2 VASc scores than warfarin (3.6 vs 4.4; P = 0.005), lower HAS-BLED scores (1.7 vs 2.3; P < 0.01), higher glomerular filtration rates; 70 vs 63 ml/min; P = 0.002) and younger age (74 vs 77 years; P = 0.006). Nationally, warfarin prescriptions are higher in total numbers but increasing at a slower rate than DOAC, which increased 10-fold (101 158 in 2013, 1 095 985 in 2014). CONCLUSION: DOAC prescribing grew rapidly from 2013 to 2014, regionally and nationally. Warfarin prescriptions have remained stable, indicating that more patients are being appropriately anticoagulated for AF who previously were not. DOAC were found to be prescribed to patients with lower CHA2 DS2 VASc and HAS-BLED scores, younger age and higher glomerular filtration rates. Aspirin therapy remains over utilised in AF.

[Prophylaxis of thromboembolism in atrial fibrillation: new oral anticoagulants and left atrial appendage closure]. / Embolieprophylaxe bei Vorhofflimmern: Neue orale Antikoagulanzien und Vorhofohrverschluss.

Thrombo-embolic prophylaxis is a key element within the therapy of atrial fibrillation/atrial flutter. Besides new oral anticoagulants the concept of left atrial appendage occlusion has approved to be a good alternative option, especially in patients with increased risk of bleeding.

Radiofrequency-assisted transseptal perforation for electrophysiology procedures in children and adults with repaired congenital heart disease.

BACKGROUND: Patients with congenital heart disease carry a high burden of arrhythmias and may pose special challenges when these arrhythmias are addressed invasively. We sought to describe our early experience with radiofrequency (RF) needle transseptal perforation to facilitate ablation procedures in this population. METHODS: Retrospective chart review to identify all cases of attempted transseptal access with a commercial RF needle at Children's Hospital Boston between February 2007 and January 2010. RESULTS: A total of 10 patients had attempted RF transseptal perforation. Median age was 27 years. Five patients had undergone atrial switch procedures (Mustard/Senning), four had undergone Fontan operations, and one had atrial septal defect repair. The indication for left atrial access was mapping/ablation of atrial flutter in nine cases, and left-sided accessory pathway in one case. The RF needle was chosen primarily in eight of 10 cases, whereas in the remaining two cases RF was used only after failed attempts with a conventional Brockenbrough needle. Septal material was atrial muscle in five cases, pericardium in three, and synthetic fabric in two. In nine of 10 patients, RF transseptal perforation was successful, including both patients in whom a conventional needle had failed. There were no clinically significant complications. CONCLUSIONS: RF transseptal perforation can be an effective method of obtaining left atrial access for electrophysiologic procedures in patients with complex congenital heart disease, including cases where a conventional Brockenbrough needle has failed.

Catheter ablation of typical atrial flutter in severe pulmonary hypertension.

BACKGROUND: Radiofrequency ablation is first-line therapy for atrial flutter (AFL). There are no studies of ablation in patients with severe pulmonary arterial hypertension (PAH). METHODS: Consecutive patients with severe PAH (systolic pulmonary artery pressure >60 mmHg) and AFL referred for ablation were evaluated. Patients with complex congenital heart disease were excluded. RESULTS: A total of 14 AFL ablation procedures were undertaken in 12 patients. A total of 75% of patients were female; mean age 49 ± 12 years. SPAP prior to ablation was 99 ± 35 mmHg. Baseline 6-minute walk distance was 295 ± 118 m. ECG demonstrated a typical AFL pattern in only 42% of cases. Baseline AFL cycle length was longer in PAH patients compared to controls (295 ± 53 ms vs 252 ± 35 ms, P = 0.006). Cavotricuspid isthmus dependence was verified in 86% of cases. Acute success was obtained in 86% of procedures. SPAP decreased from 114 ± 44 mmHg to 82 ± 38 mmHg after ablation (P = 0.004). BNP levels were lower postablation (787 ± 832 pg/mL vs 522 ± 745 pg/mL, P = 0.02). Complications were seen in 14%. A total of 80% (8/10) of patients were free of AFL at 3 months; 75% (6/8) at 1 year. CONCLUSION: Ablation of AFL in severe PAH patients is feasible, with good short- and intermediate-term success rates. The ECG pattern is not a reliable marker of isthmus dependence. The SPAP and BNP levels may decrease postablation. AFL may be a marker of poor outcomes in patients with PAH with a 1-year mortality rate of 42% in this study. This rate is higher than expected in the general PAH population.

Antithrombotic therapy for atrial fibrillation: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.

BACKGROUND: The risk of stroke varies considerably across different groups of patients with atrial fibrillation (AF). Antithrombotic prophylaxis for stroke is associated with an increased risk of bleeding. We provide recommendations for antithrombotic treatment based on net clinical benefit for patients with AF at varying levels of stroke risk and in a number of common clinical scenarios. METHODS: We used the methods described in the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines article of this supplement. RESULTS: For patients with nonrheumatic AF, including those with paroxysmal AF, who are (1) at low risk of stroke (eg, CHADS(2) [congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, prior stroke or transient ischemic attack] score of 0), we suggest no therapy rather than antithrombotic therapy, and for patients choosing antithrombotic therapy, we suggest aspirin rather than oral anticoagulation or combination therapy with aspirin and clopidogrel; (2) at intermediate risk of stroke (eg, CHADS(2) score of 1), we recommend oral anticoagulation rather than no therapy, and we suggest oral anticoagulation rather than aspirin or combination therapy with aspirin and clopidogrel; and (3) at high risk of stroke (eg, CHADS(2) score of ≥ 2), we recommend oral anticoagulation rather than no therapy, aspirin, or combination therapy with aspirin and clopidogrel. Where we recommend or suggest in favor of oral anticoagulation, we suggest dabigatran 150 mg bid rather than adjusted-dose vitamin K antagonist therapy. CONCLUSIONS: Oral anticoagulation is the optimal choice of antithrombotic therapy for patients with AF at high risk of stroke (CHADS(2) score of ≥ 2). At lower levels of stroke risk, antithrombotic treatment decisions will require a more individualized approach.

Focal atrial tachycardia arising from the cavotricuspid isthmus with saw-tooth morphology on the surface ECG: electrocardiographic and electrophysiologic characteristics.

BACKGROUND: Limited information is available about focal atrial tachycardia (AT) arising from cavotricuspid isthmus (CTI). OBJECTIVE: The purpose of this study is to evaluate the electrocardiographic and electrophysiologic characteristics of a focal AT arising from the CTI. METHODS: From a consecutive series of 92 patients undergoing radiofrequency catheter ablation (RFCA) for focal AT, three (4.4%) patients (three men) with a focal AT arising from the CTI were studied. RESULTS: The median age was 71 years (range, 50 to 81 years). None of the patients had a history of CTI-dependent atrial flutter. The electrocardiogram (ECG) of a focal AT showed a significant negative F-wave in the inferior leads. Focal AT could be reproducibly initiated and terminated with programmed stimulation. The focus of the tachycardia was localized to the central isthmus in two and the paraseptal isthmus in one patient. The median tachycardia cycle length was 275 ms (range, 260 to 310 ms). In two patients, the focal AT was adenosine insensitive. In all of the patients, tachycardia was entrained from multiple right atrial sites, including the earliest activation site. RFCA was acutely successful in all patients. Long-term success was achieved in all patients over the median follow-up of 18 months (range, 6 to 33 months). CONCLUSIONS: Cavotricuspid isthmus is an uncommon site of origin for focal AT. This focal AT has unique electrocardiographic characteristics such as saw-tooth morphology on ECG and is suggested to be caused by a focal reentrant circuit located at the CTI. Long-term success is achieved with focal ablation.

Percutaneous transhepatic venous access for catheter ablation procedures in patients with interruption of the inferior vena cava.

BACKGROUND: Catheter ablation of left-sided atrial arrhythmias generally is performed using a transfemoral venous approach through the inferior vena cava (IVC). In this report, we assessed the feasibility of a percutaneous transhepatic approach to ablation of left-sided atrial arrhythmias in 2 patients with interruption of the IVC. METHODS AND RESULTS: Patient 1 had atrial flutter in the setting of complex congenital heart disease and prior Fontan for univentricular physiology and a single atrium. Patient 2 had atrial fibrillation. Percutaneous hepatic vein access was obtained with ultrasound and fluoroscopic guidance. Transseptal catheterization was performed in patient 2. After the procedure, the hepatic tract in patient 1 was cauterized using a bipolar radiofrequency catheter, and an Amplatzer vascular plug was used in patient 2 to obtain hemostasis. Percutaneous hepatic vein access was achieved without complications. After electroanatomical mapping, a linear lesion was placed between the single atrioventricular valve and the confluence of the hepatic veins in patient 1; this terminated the flutter, and bidirectional block was achieved. In patient 2, the pulmonary veins were electrically isolated using an extraostial approach, isolating the ipsilateral veins in pairs. Additionally, ablation of right-side atrial flutter was achieved by obtaining bidirectional block across a linear lesion between the tricuspid valve and confluence of the hepatic veins. Hemostasis of the transhepatic tract was attained in both patients. CONCLUSIONS: In patients with interrupted IVCs, a percutaneous transhepatic approach is a feasible alternative for performing catheter ablation of complex left-sided arrhythmias.

[Next cardioversion or RF ablation in professional driver with recurrent typical atrial flutter and MAS syndromes]. / Nastepna elektrowersja czy ablacja RF podloza typowego trzepotania przedsionków u zawodowego kierowcy z napadami MAS.

We describe a 42-year-old professional driver with hypertension, obesity and recurrent episodes of highly symptomatic typical atrial flutter. Despite chronic sotalol treatment, 1:1 AV conduction with RBBB-morphology was observed. After excluding of thrombus in the heart chambers, the 'urgent' and successful RF ablation was performed.

Inter-relationships between atrial flutter and atrial fibrillation.

It has been appreciated for a long time that atrial flutter and atrial fibrillation have a clinical relationship. Now, with the technological advances that permit more sophisticated electrophysiological studies, especially mapping studies, we have significantly advanced our understanding of this interrelationship. Regarding the relationship at atrial fibrillation to atrial flutter: Atrial fibrillation of variable duration (very brief to prolonged episodes) precedes the onset of atrial flutter in most instances. It seems that during the period of atrial fibrillation, the functional components of the atrial flutter reentrant circuit are formed. This is principally a line of block between the venae cavae. If this line of block does not form, classical atrial flutter does not form. And if this line of block shortens or disappears, classical atrial flutter disappear as well. In fact, it might be said that the major difference in whether classical atrial flutter or atrial fibrillation develops is whether a line of block forms between the venae cavae. Regarding the relationship of atrial flutter to atrial fibrillation: Studies have demonstrated that a driver (a single focus or reentrant circuit of very short cycle length) can be responsible for causing atrial fibrillation by producing fibrillatory conduction to the rest of the atria. In experimental models and now beginning to be demonstrated in patients, this driver may be a stable reentrant circuit of very short cycle length, i.e., a fast form of atrial flutter, if you will. In fact, there is probably a spectrum of these short cycle lengths that depend, in part, on where the reentrant circuit (i.e., "atrial flutter") exists. When the stable reentrant circuit is of sufficiently short cycle length, it will only activate small portions of the atria in a 1 : 1 manner. The rest of the atria will be activated irregularly, resulting in atrial fibrillation. Unstable reentrant circuits can also do the same thing. In short, it appears that there are several mechanisms of atrial fibrillation, one of which is due to a form of very rapid atrial flutter.

Antiarrhythmic effects of JTV-519, a novel cardioprotective drug, on atrial fibrillation/flutter in a canine sterile pericarditis model.

UNLABELLED: Effect of JTV-519 on AF. INTRODUCTION: A new cardioprotective drug, JTV-519, blocks Na+ current and inwardly rectifying K+ current and inhibits Ca2+ current. However, its role in atrial electrophysiology is unknown. We investigated the antiarrhythmic effects of JTV-519 on atrial fibrillation/flutter in the canine sterile pericarditis model. METHODS AND RESULTS: In nine dogs with sterile pericarditis, 38 episodes of sustained (>30 sec) atrial fibrillation (8 dogs) and 24 episodes of sustained atrial flutter (7 dogs) were induced by rapid atrial pacing. When atrial fibrillation or atrial flutter was sustained >15 minutes, it was cardioverted and reinduced. The inducibility of atrial fibrillation/flutter, the atrial effective refractory period, and the intra-atrial conduction time were compared before and after the continuous infusion of JTV-519 (0.03 mg/kg/min). JTV-519 significantly decreased the mean number of sustained atrial fibrillation episodes (from 4.2 +/- 2.9 to 0 +/- 0, P < 0.01). In contrast, atrial flutter was still inducible in 4 dogs after JTV-519 (from 2.7 +/- 2.5 to 1.6 +/- 2.1, P = NS). JTV-519 significantly prolonged effective refractory period (from 123 +/- 18 to 143 +/- 14 msec, from 127 +/- 18 to 151 +/- 12 msec, and from 132 +/- 13 to 159 +/- 9 msec at basic cycle lengths of 200, 300, and 400 msec, respectively, P < 0.01), but it did not affect the intra-atrial conduction time (from 47 +/- 11 msec to 48 +/- 11 msec, P = NS). CONCLUSION: JTV-519 had significant protective effects on atrial fibrillation in the canine sterile pericarditis model, mainly by increasing effective refractory period, suggesting that it may have potential as a novel antiarrhythmic agent for atrial fibrillation.

Prospective randomized comparison of closed cooled-tip versus 8-mm-tip catheters for radiofrequency ablation of typical atrial flutter.

INTRODUCTION: Cooled-tip and 8-mm-tip catheters have been found to be more effective than conventional 4-mm-tip catheters for radiofrequency (RF) ablation of common atrial flutter. The aim of this study was to compare the efficacy and safety of cooled-tip and 8-mm-tip catheters for flutter ablation in a randomized, prospective study. METHODS AND RESULTS: In 100 consecutive patients referred for ablation of common atrial flutter, cavotricuspid ablation was performed with a closed cooled-tip catheter (n = 50) or an 8-mm-tip ablation catheter (n = 50). RF current was applied for 60 to 120 seconds at powers of 40 to 50 W with the closed cooled-tip catheter and in a temperature-controlled mode (65 degrees C/70 W) with the 8-mm-tip catheter. The endpoint was achievement of a bidirectional isthmus conduction block. Cross-over was performed after 15 unsuccessful RF applications for each of the catheters. Complete bidirectional isthmus block was achieved in 99% of patients. Cross-over was performed in 11 patients after primary use of the cooled-tip catheter and in 9 patients after primary ablation with the 8-mm-tip catheter. No significant differences were found in the procedure parameters, such as overall RF applications (12.4 +/- 11.3 vs 12.9 +/- 8.6), ablation duration (42 +/- 43 min vs 39 +/- 27 min), and fluoroscopy time (17.0 +/- 18.7 min vs 15.7 +/- 10.7 min). In a mean follow-up of 8.3 months, 1 patient in the cooled-tip group and 3 patients in the 8-mm-tip group had recurrence of common atrial flutter. CONCLUSION: Use of the closed cooled-tip ablation catheter and the 8-mm-tip catheter have equal and high efficacy for RF ablation of common atrial flutter.

Identification of extremely slow conduction in the cavotricuspid isthmus during common atrial flutter ablation.

INTRODUCTION: Complete isthmus block has been used as an endpoint for radiofrequency ablation for common atrial flutter (AF). We sought to systematically evaluate extremely slow conduction (ESC), which is easily misinterpreted as complete block. METHODS AND RESULTS: We studied 107 consecutive patients (92 men, 15 women, 58 +/- 11 years) who had undergone a successful AF ablation procedure. A 24-pole catheter was positioned along the tricuspid annulus spanning the isthmus. Complete isthmus block was defined as the presence of a complete corridor of double potentials along the ablation line. Activation delay time (AT), activation difference (deltaA) between two adjacent dipoles, maximum activation difference (deltaA(max)), change in polarity (CP) and change in amplitude (CA) of the bipolar atrial electrogram were recorded and P-wave morphology in the surface electrocardiogram was analyzed. ESC was observed in 16 patients. Between ESC and complete block, differences were found on the two lateral dipoles adjacent to the ablation line (AT: 148 +/- 17 vs. 183 +/- 27 ms and 155 +/- 18 vs. 170 +/- 28 ms, P < 0.01; deltaA: -91 +/- 22 vs. -126 +/- 28 ms and -7 +/- 13 vs. 13 +/- 6 ms, P < 0.01). Statistically significant differences in CP were detected on the relevant dipoles (7/16 vs. 14/16 and 6/16 vs.13/16, P < 0.05). No significant difference was found either in CA or in terminal P wave positivity. Mean deltaA(max) were 13.8 +/- 5.0 and 27.8 +/- 9.5 ms (P < 0.001) respectively in ESC and complete block. Two types of ESC, regular and irregular, were demonstrated during the ablation procedure. CONCLUSIONS: (1) ESC was observed in 15% of the patients during the AF ablation procedure. (2) The parameters of AT, deltaA, and CP may help to differentiate ESC from complete block. DeltaA(max) might be the most powerful indicator. (3) To verify complete block, it is essential to position the mapping catheter across the CTI in order to demonstrate the activation sequence up to the ablation line.