Tricuspid Isthmus Research Articles

Pulmonary vein isolation with additional substrate ablation for atrial fibrillation results in an increased risk for the development of atypical atrial flutter

Abstract Introduction Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) catheter ablation. Several extra pulmonary vein (PV) ablation strategies for substrate modification (PVI plus) have been employed to AF patients. It has not been proven that this approach decreases the recurrence of AF, and it could contribute to increase the risk of developing atypical atrial flutter. Methods Patients submitted to AF catheter ablation at our centre between 2005 and 2020 were included. Using logistic regression, we did a retrospective analysis of the association between the application of PVI plus strategies (such as ablation of the cavo tricuspid isthmus (CTI), ganglion plexus, isolation of the superior vena cava (SVC), mitral isthmus ablation and atrial roof line ablation) and the development of atypical flutter later submitted to ablation. Results Five hundred and seventy-five patients were included (64% males, age 57±12 years [between 14 and 81], 68.2% with paroxysmal AF) with > 1-year follow-up. Five hundred and five (87.8%) had PVI alone. From the 575 patients, 11 (1.9%) developed an atypical flutter during the follow-up, which was later submitted to ablation. The crude ODDS of a patient submitted to a PVI plus strategy developing atypical atrial flutter are 13.92 times higher than the one of those submitted to a stand-alone PVI technique, with a p value <0.001 (95% CI 3.96 – 48.87). When adjusted for age and history of heart failure, the ODDS of a patient submitted to a PVI plus strategy developing atypical atrial flutter are 16.29 times higher than the one of those submitted to a stand-alone PVI technique, with a p value <0.001 (95% CI 3.92 – 67.65). Conclusions Additional substrate ablation for AF significantly increases the risk of developing atypical auricular flutter.Characteristics of the study populationCharacterization of PIV plus strategies

"UNUSUAL" ATRIAL FLUTTER: A CASE REPORT

Abstract A 64–years old male patient was admitted in the Emergency Department with signs of heart failure in a setting of dilated hypokinetic cardiomyopathy with severe depression of left ventricular ejection fraction and no severe coronary artery disease. In the previous medical history: systemic arterial hypertension, obesity, dysthyroidism due to amiodarone, history of atrial fibrillation treated by transcatheter ablation in the left atrium with pulmonary veins isolation (PVI) and the creation of an anterior line in 2010. The ECG documented an atrial flutter rhythm 2:1 probably typical (Fig. 1). An indication was therefore made for hospitalization in Cardiology. After the restoration of a good hemodynamic state, given the persistence of the atrial tachyarrhythmia, an indication for transcatheter ablation was formulated. The electrophysiological study highlighted an activation sequence suggestive of typical common flutter (cranial–caudal right atrial activation; proximal–distal left atrial activation). We then proceeded to ablate the cavo–tricuspid isthmus without interrupting the arrhythmia. Therefore, left and right atrial electroanatomical mapping was performed which confirmed the right isthmic block and documented the left origin of the flutter, showing conduction gaps in the ostia of the pulmonary veins and in the previous anterior ablation line between the mitral annulus and the right superior pulmonary vein (RSPV) (Fig 2,3). Ablation of these gaps effectively stopped the arrhythmia. At the end of the procedure, after stimulation via atrial bursts of up to 200 msec there was no induction of arrhythmias. One month after the procedure, there was an improvement in the contractile function of the left ventricle. Discussion: This clinical case offers us an example of how the analysis of the surface ECG alone is not sufficient to adequately describe the complexity of the arrhythmic substrate characterizing an arrhythmia such as atrial flutter or atrial fibrillation. The electrophysiological study through electroanatomical reconstruction of endocavitary activation proves indispensable for the correct identification and consequent treatment of these complex arrhythmias, with clear clinical benefits for the patient.

Different electrophysiological characteristics of cavo-tricuspid isthmus dependent atrial flutter guided by robotic magnetic navigation in patients with and without prior cardiac surgery.

Cavo- tricuspid isthmus dependent atrial flutter (CTI- AFL) is a common atrial arrhythmia in patients with prior cardiac surgery (postsurgical AFL) and without prior cardiac surgery (nonsurgical AFL). However, there is only limited data regarding the eletrophysiological differences between the CTI- AFL in the postsurgical patients and the nonsurgical patients. We aimed to investigate the differences in clinical and electrophysiological characteristics between the postsurgical group and nonsurgical group and to evaluate the acute and long-term outcomes after ablation guided by robotic magnetic navigation (RMN) in both the groups. Methods Fourty-two consecutive patients with nonsurgical AFL and 21 with postsurgical AFL were retrospectively analyzed in our center. Electrocardiographic (ECG) analysis and three-dimensional electrophysiological study were performed in all the patients. The results revealed that only 55.6% of postsurgical patients with proven counterclockwise (CCW) AFL presented with a typical ECG suggesting this mechanism. In contrast, 86.1% of nonsurgical patients demonstrated a typical ECG pattern for CCW AFL. In addition, we employed a reverse "U-curve" to facilitate radiofrequency delivery when ablating near the inferior vena cava ostium in the present study. Compared with the nonsurgical group, electroanatomical mapping showed the mean AFL cycle length was significantly longer (253.3 ± 40.4 vs. 234.1 ± 24.2 ms, p = 0.03) and the right atrium volume was larger (114.8 ± 26.0 vs. 97.5 ± 19.1 mL, p = 0.004) in the postsurgical group. Additionally, the procedural time (75.9 ± 21.3 vs. 61.6 ± 26.6 minutes, p = 0.03) and ablation time (53.0 ± 21.4 vs. 36.7 ± 25.6 minutes, p = 0.02) are much longer in the postsurgical group. However, the navigation index in the postsurgical group was significantly smaller (0.35 ± 0.08 vs. 0.43 ± 0.13, p = 0.01). Moreover, the acute and long-term success rates were comparable between the two groups. Catheter ablation of CTI-AFL with and without prior cardiac surgery guided by RMN are associated with high acute and long-term success rates, despite the procedural and ablation times are much longer in the postsurgical patients. However, ECG characteristics of the tachycardia may be misleading as they are more often atypical in patients after cardiac surgery.

C46 ELECTROPHYSIOLOGICAL ASSESSMENT OF ATRIAL TACHYCARDIA SUBSTRATES IN PATIENTS WITH REPAIRED TETRALOGY OF FALLOT

Abstract Introduction Adults with repaired tetralogy of Fallot (rToF) experience episodes of atrial tachycardia (AT) and radiofrequency catheter ablation (RFCA) is often required but systematic evaluation of the mechanisms and recurrences is lacking. Methods Between January 2013 and October 2021, 20 rToF patients with AT referred for catheter ablation were enrolled. Electrophysiologic study with 3D electroanatomic mapping with multi–electrode mapping catheters was done, with right atrial bipolar voltage and activation mapping of the AT. Three mechanisms were searched: intra–atrial re–entrant tachycardias (IART), focal (FAT), other. Critical isthmus (CI) for IART was identified with activation mapping. FATs were localized according to the earliest uni/bipolar signal. All induced AT were treated. RFCA was aimed at the earliest activation point for FAT and at the critical isthmus for IART, anchoring lesion to fixed obstacles (valve annuli or scar). Written informed consent was provided. Results Among 20 adult (age 46±14 years) and mainly females (n=11, 55%) enrolled pts, 36 AT were documented: 25 (70%) IART, 10 (27%) FAT and only 1 (3%) had a typical atrioventricular nodal reentrant tachycardia. Mean tachycardia cycle length was 307±95 ms. Two ATs were induced in 11 pts, 3 in 4 pts and 4 in 2 during index EPS. Among IART, cavo–tricuspid isthmus (CTI) was the prevalent CI (n=14, 60%), while incisional IART (IARTinc, atriotomy and superior and inferior vena cava orifices, SVC and IVC, respectively) was the second mechanism (n=9, 39%). In two pts, due to non–inducibility, a pre–emptive lesion set comprising in one case CTI and in the second case CTI+SVC–atriotomy–IVC line was performed. Among FAT, in 3 cases the AT was mapped in the coronary sinus, in two at the tricuspid annulus, other at the crista terminalis, right appendage base, posterolateral scar or between atriotomy and SVC. During a median follow–up of 23 months (interquartile range, 6–37) recurrence occurred in 8 pts (25% of pts, 22% of tachycardias). Pts with recurrences were younger (43±7 vs. 48±17 y, p=0.04); no differences were found according to critical isthmus location (4 CTI and 4 IARTinc, 50%, p=ns). Conclusions Among rToF pts with AT, IART is the prevalent mechanism and CTI is the prevalent CI; atriotomy scar, however, is involved in a substantial portion of the critical isthmuses of the IART; FAT location is much more variable. Long–term freedom from AT in this clinical setting is encouraging.

Comparison of Intra Cardiac Echo (ICE) Guided Verses Non- Intra Cardiac Echo Radiofrequency Catheter Ablation of Cavotricuspid Isthmus Dependent Atrial Flutter

The isthmus-dependent atrial flutter can be effectively treated with Radiofrequency (RF) catheter ablation. Objectives: To compare the ICE guided versus non-ICE radiofrequency catheter ablation of Cavo tricuspid isthmus dependent atrial flutter. Methods: A cross-sectional study was carried out on 40 patient’s atrial flutter data in the Cardiac Electrophysiology Department, Hayatabad medical Complex Peshawar, Pakistan from August 2017 to August 2022. Patients were categorized into two groups: Group-I (ICE-guided RF catheter ablation) and Group-II (non-ICE RF catheter ablation). The standard protocol of ablation was followed using 40-50 watts power at temperature 60oC. In the case of an irrigated cooled tip catheter, the flow was limited to 30 mL/hour and the power was limited to 30 watts. Results: The overall mean ablation and flouro time was 9.44 ± 6.93 minutes and 20.64 ± 9.77 minutes respectively. The frequency of patients in Group-I and Group-II was 29 (72.5%) and 11 (27.5%) respectively. Out of the total patients, about 8 (20%) patients had shown failed status in terms of procedure success, out of which 5 (62.5%) were from Group-II. Compared to non-ICE guided procedure, the ICE guided procedure had lesser flouro and ablation time with higher rate of success and lower complications and recurrence. Conclusions: The present study observed that intracardiac echocardiography (ICE) can effectively disclose the Cavo tricuspid isthmus and guide ablation anatomy. Additionally, ICE guided radiofrequency catheter ablation had higher success rate, less flouro and ablation time, and lower complications than non-ICE guided radiofrequency catheter ablation.

Carbon footprint of atrial fibrillation catheter ablation.

Climate change represents the biggest global health threat of the 21st century. Health care system is itself a large contributor to greenhouse gas (GHG) emissions. In cardiology, atrial fibrillation (AF) catheter ablation is an increasing activity using numerous non-reusable materials that could contribute to GHG emission. Determining a detailed carbon footprint analysis of an AF catheter ablation procedure allows the identification of the main polluting sources that give opportunities for reduction of environmental impact. To assess the carbon footprint of AF catheter ablation procedure. To determine priority actions to decrease pollution. An eco-audit method used to predict the GHG emission of an AF catheter ablation procedure was investigated. Two workstations were considered including surgery and anaesthesia. In the operating room, every waste produced by single-use medical devices, pharmaceutical drugs, and energy consumption during intervention were evaluated. All analyses were limited to the operating room. Thirty procedures were analysed over a period of 8 weeks: 18 pulmonary veins isolation RF ablations, 7 complex RF procedures including PVI, roof and mitral isthmus lines, ethanol infusion of the Marshall vein and cavo tricuspid isthmus line, and 5 pulmonary vein isolation with cryoballoon. The mean emission during AF catheter ablation procedures was 76.9 kg of carbon dioxide equivalent (CO2-e). The operating field accounted for 75.4% of the carbon footprint, while only 24.6% for the anaesthesia workstation. On one hand, material production and manufacturing were the most polluting phases of product life cycle which, respectively, represented 71.3% (54.8 kg of CO2-e) and 17.0% (13.1 kg of CO2-e) of total pollution. On the other hand, transport contributed in 10.6% (8.1 kg of CO2-e), while product use resulted in 1.1% (0.9 kg of CO2-e) of GHG production. Electrophysiology catheters were demonstrated to be the main contributors of environmental impact with 29.9 kg of CO2-e (i.e. 38.8%). Three dimensional mapping system and electrocardiogram patches were accounting for 6.8 kg of CO2-e (i.e. 8.8% of total). AF catheter ablation involves a mean of 76.9 kg of CO2-e. With an estimated 600 000 annual worldwide procedures, the environmental impact of AF catheter ablation activity is estimated equal to 125 tons of CO2 emission each day. It represents an equivalent of 700 000 km of car ride every day. Electrophysiology catheters and patches are the main contributors of the carbon footprint. The focus must be on reducing, reusing, and recycling these items to limit the impact of AF ablation on the environment. A road map of steps to implement in different time frames is proposed.

Persistent Atrial Fibrillation Ablation Using Circular Irrigated Ablation Catheter

Introduction: Persistent atrial fibrillation (PsAF) ablation remains time consuming, even when guided by non-invasive mapping. We investigated the role of a multielectrode irrigated circular radiofrequency (RF) catheter for PsAF ablation. Methods: A circular catheter (nMARQ®, Biosense Webster, Inc) with 10 irrigated simultaneous mapping and ablation electrodes was used in 50 patients with PsAF (age 60 ± 11 years, left atrial (LA) size 21.8 ± 9.7 cm2 and atrial fibrillation (AF) maximum duration 10.6 ± 9.3 months). Ablation was guided by non-invasive mapping (ECUVETM, Cardioinsight Inc.) in 32 (64%) patients. Pulmonary vein isolation (PVI) was systematically performed. Results: After targeting additional non-PV regions including 3 ± 2 indicated by ECVUETM (1-6), AF terminated in 37 (74%) patients, into atrial tachycardia (AT) in 22 and directly into sinus rhythm (SR) in 15 patients. Thirteen patients were in SR during the procedure. PVI required 8.01 ± 5.27 minutes of RF. Eleven patients required direct current (DC) shock to terminate AF. Linear lesions were performed for AT: 14 LA roof lines, 13 mitral isthmus lines and 27 cavo tricuspid isthmus (CTI). Using total of 20.24 ± 17.25 minutes of RF. Interestingly, 5/8 roof line block, 4/5 mitral isthmus line block and 19/24 CTI line block, were blocked with circular catheter only with 5.08 ± 4.58, 3.30 ± 2.56 and 3.26 ± 2.12 minutes of RF duration, respectively. A single tip conventional ablation catheter was required to complete linear lesions and obtain the block in 3 roof lines, 1 mitral isthmus line and 5 CTI. Mean procedure duration was 3.18 ± 1.03 hours. Complications included 1 pericardia effusion managed conservatively and 1 transient ischemic attack (TIA) resolved without any neurological sequelae. One year follow up data was available in 27 (54%) patients, 18 (67%) patients were in SR and 9 (33%) patients had AF recurrence in whom 1 (3%) patient had AT recurrence. Conclusion: Circular radiofrequency ablation catheter demonstrated encouraging results for rapid, safe and effective PsAF ablation when guided by non-invasive phase mapping. The catheter can be used for linear ablations and CTI in addition to PVI, thus obviating the need for an additional ablation catheter in the majority of patients.

P2845Recurrent atrial flutter and incidence of atrial fibrillation ablation after first-time ablation for typical atrial flutter: a nation-wide Danish cohort study

Abstract Introduction Cavo tricuspid isthmus ablation (CTIA) is an effective first-line treatment for typical atrial flutter (AFL). However, many patients develop atrial fibrillation (AF) after successful CTIA. Knowledge about recurrent arrhythmia after CTIA mainly comes from small cohort studies with limited follow-up. Purpose To describe incidences of AFL re-ablation and AF-ablation after first-time CTIA in a nation-wide cohort. Method In the Danish National Ablation Registry we identified patients undergoing first-time CTIA during 2010–2016. Subsequent CTIA and AF-ablation procedures were identified until March 1st, 2018. We gathered information on patient comorbidities in the Danish National Patient Registry. Results We identified 2409 patients undergoing first-time CTIA. Median age was 66 (IQR 58–72) years, and 1952 (81%) were men. 78 (3%) had a history of AF. Acute procedural succes was achieved in 2288 (95%) patients. During mean follow-up of 4±1.7 years, 242 (10%) patients underwent CTI re-ablation and 326 (13.5%) ablation for AF. Baseline characteristics associated with CTI re-ablation included prolonged procedural time, unsuccessful first CTIA, age<75 years and CHA2DS2-VASc score<2. Hypertension, history of AF, age<65 years and CHA2DS2-VASc score<2 were associated with later AF-ablation (Table). Predictive characteristics Characteristics associated with CTI re-ablation HR 95% CI p-value Procedural time 1.003 (1.001–1.006) 0.01 Unsuccesful first CTIA procedure 3.42 (2.10–5.55) <0.0001 Age <75 years 1.52 (1.03–2.26) 0.04 CHA2DS-VAS2c score <2 1.45 (1.11–1.90) 0.01 Characteristics associated with later AF-ablation Hypertension 1.31 (1.02–1.69) 0.04 History of AF 1.70 (1.07–2.71) 0.03 Age <65 years 2.38 (1.89–3.01) <0.0001 CHA2DS-VAS2c score <2 1.77 (1.40–2.45) <0.0001 AF: Atrial fibrillation; HR: Hazard ratio. All HR's are adjusted for age, gender, hypertension, diabetes, heart failure, iscemic heart disease, valvular heart disease, chronic obstructive lung disease, chronic kidney disease and history of AF using Cox regression analysis. Conclusion In a nation-wide cohort undergoing CTIA for AFL, 10% of patients underwent CTI re-ablation and 13.5% were ablated for AF during mean follow-up of 4±1.7 years. Probability of undergoing a second ablation procedure was higher in younger patients with less comorbidity.

Recurrent atrial flutter ablation and incidence of atrial fibrillation ablation after first-time ablation for typical atrial flutter: A nation-wide Danish cohort study

BackgroundCavo tricuspid isthmus ablation (CTIA) is considered an effective first-line treatment for typical atrial flutter (AFL). However, many patients develop atrial fibrillation (AF) after successful CTIA. Knowledge about recurrent arrhythmia after CTIA mainly comes from small cohort studies with limited follow-up. ObjectiveTo describe incidences of re-ablation for AFL and ablation for AF after first-time CTIA in a nation-wide cohort. MethodsIn the Danish National Ablation Registry we identified patients undergoing first-time CTIA during 2010–2016. Subsequent CTIA and AF-ablation procedures were identified until March 1st, 2018. We collected information on patient comorbidities in the Danish National Patient Registry. ResultsWe identified 2409 patients undergoing first-time CTIA. Median age was 66 (IQR 58–72) years, 1952 (81%) were men, and 78 (3%) patients had a history of previous ablation for AF. Acute procedural success was achieved in 2288 (95%) patients. During mean follow-up of 4.0 ± 1.7 years, 242 (10%) patients underwent CTI re-ablation and 326 (13.5%) underwent ablation for AF. Baseline characteristics associated with CTI re-ablation included prolonged procedural time, unsuccessful index CTIA, age <75 years and CHA2DS2-VASc score <2. Hypertension, history of AF-ablation, age <65 years use of a contact force sensing catheter and CHA2DS2-VASc score <2 were associated with later ablation for AF. ConclusionIn a nation-wide cohort undergoing first-time CTIA for AFL, 10% of patients underwent CTI re-ablation and 13.5% ablation for AF during mean follow-up of 4.0 ± 1.7 years. Probability of a second procedure was higher in younger patients with less comorbidities.

ANTICOAGULATION THERAPY DURING RADIOFREQUENCY ABLATION

Purpose. The study assess the effectiveness and safety of pulmonary veins atriums isolation (PVI) and radiofrequency ablation of the cavo - tricuspid isthmus with different modes of anticoagulation in patients with atrial fibrillation (AFb) and atrial flutter (AFl). Materials and methods. The study included 83 patients - 52 with AFb, 18 - with AFl and 13 - with both types of arrhythmia. Of all the included patients 12 used warfarin for antioagulation (15%), 17 - dabigataran (21%), 39 - rivaroxaban (46%) and 15 - apixaban (18%). For patients using warfarin a “bridge therapy” tactic was used. For patients using POAC the drug was cancelled at 2 half - life periods before the procedure. Intraoperational thromboembollic and haemorrhagic complications were calculated, arrhythmia relapses and delayed complications were controlled in 3 and 6 months after the procedure. Results. 18 arrhytmia relapses were reported during the study, among them 79% happened after PVI, 89% - after cavotricuspid isthmus, 62% - after treatment of both types of arrhythmia. 4 major haemorrhagic complications were reported during the study (intraoperational haemopericardium), 3 major thromboembolic complications (a stroke through 6 months after the procedure). The frequency of minor hemorrhagic events amounted to 8 cases. Both modes of anticoagulation are effective and safe for prevention of thromboembolic events in atrial fibrillation and flutter correction surgery, however, a large, although statistically insignificant number of minor haemorrhagic events occurred in the early post - procedure period with dabigataran. The results of the study show the effectiveness of arrhythmia surgery to be 79% in patients with AFb and 89% in patients with AFl.

Catheter ablation for failed surgical maze: comparison of cut and sew vs. non-cut and sew maze

PurposeTo compare findings in patients undergoing atrial fibrillation(AF) and/or atrial flutter(AFl) ablation after failed cut and sew (CS) vs. non-cut and sew (NCS) surgical maze.MethodsWe compared 10 patients with prior CS to 25 with prior NCS maze undergoing catheter ablation after failed maze.ResultsPatient demographics: Age 68.3 ± 8.7 CS vs. 68.2 ± 9.2 NCS(P = 0.977), male 70% CS vs. 72% NCS(P = 1.000), LA size 5.11 ± 0.60 cm CS vs. 4.54 ± 0.92 cm NCS(P = 0.096), sternotomy 100% CS vs. 64% of NCS(P = 0.036). Concomitant heart surgery in 100% CS and 68% NCS(P = 0.073). NCS used radiofrequency 84%, cryoablation 8%, microwave 4%, and ultrasound 4%. All maze operations targeted pulmonary vein (PV) isolation. The maze also targeted the mitral isthmus 100% CS vs. 36% NCS(P = 0.001) and the tricuspid isthmus 90% CS vs. 40% NCS (P = 0.018). Maze failure arrhythmia mechanism was AF 0% CS and 56% NCS (P = 0.0006). Nine CS pts failed for AFl and 1 for RA tachycardia. For NCS pts, 11 failed for AFl. CS isolated 94% of PVs and NCS isolated only 26% of PVs (P < 0.0005). At EPS, clinical and induced arrhythmias were ablated and non-isolated PVs were isolated. After final ablation, arrhythmia-free rates were 60% for CS and 52% for NCS (P = 0.723) after 2.99 ± 2.35 years.ConclusionsAfter failed surgical maze, CS isolated nearly all PVs and NCS never isolated all PVs and the clinical rhythm was more frequently AF for NCS and AFl for CS. CS remains the surgical gold standard for durable PV isolation.

Initial Experience Using AutoMark in Atrial Fibrillation Ablation

Background: EnSite Precision AutoMark Module (Abbott) refers to automated lesion creating tool. Only lesions meeting user-defined requirements are placed on the map. The amount of ablation is represented by the size and color of marking spheres. The aim of this study is to present our initial experience with AutoMark Module in AF ablation. Methods: Nine patients with AF underwent electroanatomic mapping and radiofrequency ablation (RF) using AutoMark Module for marking RF lesions. Pulmonary vein isolation was performed in all patients. Cavo tricuspid isthmus ablation was done in 3 patients with atrial flutter. Lesions were marked in different colors depending on force-time integral, absolute impedance drop and RF duration as follows: white (10 Ω; >30 s). An auto-mark was created when catheter remained in a stable location for more than 3 s, with a minimum distance between spheres (center-to-center) of 3 mm. Auto-marks were compared with manually placed spheres. 24-hour Holter ECG monitoring was performed regularly until the end of the follow-up. Results: Nine patients (mean age of 53 ± 10 years, 3 male) were included in the study with EHRA class 2b (44%) and class 3 (56%). Auto-marks were placed only when user-defined criteria were reached whereas manual points were marked subjectively. The auto-marks numbered 299 ± 82 per procedure and 5.39 ± 1.42 per RF application. Auto-marks provided good visualization of the ablation lines using the predefined criteria. AutoMark Module visualized probable gaps in the ablation line, which appeared as an area without spheres or with white spheres. That was not possible with manual marking because of its subjective nature. Conclusion: AutoMark is better than manual marking in providing real-time visual feedback on lesion creation. Our preselected lesion parameters ensure a tool to visualize possible gaps in the ablation line.

Further Evidence of Tricuspid Isthmus "Muscle Bundles" Using Rhythmia Mapping Technology.

Radiofrequency ablation of the cavotricuspid isthmus (CTI) is recognized as a highly successful technique in the treatment of typical atrial flutter. Transmural CTI ablation with the achievement of bidirectional conduction block is a recognized marker for success. The “muscle bundle hypotheses”

Right atrial diameter and outcome of catheter ablation of atrial fibrillation.

While AF is considered more like a left atrial (LA) disease, to what extent the right atrium contributes to the pathogenesis and ablation outcome of AF remains unclear. This study aimed to identify if right atrial diameter (RAD) could predict arrhythmia recurrence after catheter ablation of atrial fibrillation (AF). Four hundred and seventy patients with drug-resistant AF [paroxysmal AF (PAF) 196; non-PAF 274] who underwent primary catheter ablation were enrolled. Ablation strategy included complete bilateral pulmonary vein isolation (PVI) in all patients and additional linear ablation across mitral isthmus, LA roof, and tricuspid isthmus in non-PAF cases. Risk factors associated with recurrence were determined by a Cox regression model, and the predictive power was evaluated by using receiver operating characteristic curve. After 24.3±18.0months, 284 patients (60.6%) experienced atrial tachyarrhythmia recurrence (111 in PAF, 173 in non-PAF). RAD was moderately associated with LA diameter (r=0.371, P<0.001), left ventricular ejection fraction (r=-0.205, P<0.001), and left ventricular end-diastolic diameter (r=0.319, P<0.001). Multivariate Cox regression analysis demonstrated that RAD was an independent predictor for recurrence only in PAF patients with LAD ≥35mm (HR 1.044, 95% CI 1.007-1.082, P=0.021). The RAD cutoff value of 35.5mm predicts atrial tachyarrhythmia recurrence with 85.4% sensitivity and 29.2% specificity. Kaplan-Meier analysis indicated that RAD over 35.5mm is associated with more recurrence after PAF ablation (log-rank P=0.034), comparing to those with RAD <35.5mm. RAD predicts outcome of ablation only in patients with PAF and concurrent LA enlargement. Under this condition, RAD <35.5mm is associated with a more favorable recurrence-free survival at over 2-year follow-up.

Atrial Flutter, Typical and Atypical: A Review

Clinical electrophysiology has made the traditional classification of rapid atrial rhythms into flutter and tachycardia of little clinical use. Electrophysiological studies have defined multiple mechanisms of tachycardia, both re-entrant and focal, with varying ECG morphologies and rates, authenticated by the results of catheter ablation of the focal triggers or critical isthmuses of re-entry circuits. In patients without a history of heart disease, cardiac surgery or catheter ablation, typical flutter ECG remains predictive of a right atrial re-entry circuit dependent on the inferior vena cava–tricuspid isthmus that can be very effectively treated by ablation, although late incidence of atrial fibrillation remains a problem. Secondary prevention, based on the treatment of associated atrial fibrillation risk factors, is emerging as a therapeutic option. In patients subjected to cardiac surgery or catheter ablation for the treatment of atrial fibrillation or showing atypical ECG patterns, macro-re-entrant and focal tachycardia mechanisms can be very complex and electrophysiological studies are necessary to guide ablation treatment in poorly tolerated cases.

Atrial Flutter, Typical and Atypical: A Review.

Clinical electrophysiology has made the traditional classification of rapid atrial rhythms into flutter and tachycardia of little clinical use. Electrophysiological studies have defined multiple mechanisms of tachycardia, both re-entrant and focal, with varying ECG morphologies and rates, authenticated by the results of catheter ablation of the focal triggers or critical isthmuses of re-entry circuits. In patients without a history of heart disease, cardiac surgery or catheter ablation, typical flutter ECG remains predictive of a right atrial re-entry circuit dependent on the inferior vena cava-tricuspid isthmus that can be very effectively treated by ablation, although late incidence of atrial fibrillation remains a problem. Secondary prevention, based on the treatment of associated atrial fibrillation risk factors, is emerging as a therapeutic option. In patients subjected to cardiac surgery or catheter ablation for the treatment of atrial fibrillation or showing atypical ECG patterns, macro-re-entrant and focal tachycardia mechanisms can be very complex and electrophysiological studies are necessary to guide ablation treatment in poorly tolerated cases.

Flúter auricular en paciente con isomerismo izquierdo y vena cava inferior izquierda interrumpida

Se comunica la ablación de un flúter auricular con una longitud de ciclo de 260 ms en un paciente de 28 años con isomerismo izquierdo y vena cava inferior izquierda interrumpida. Mediante encarrilamiento, demostramos la participación del istmo suprahepáticotricuspídeo en el circuito de macroreentrada. Realizamos líneas de ablación con radiofrecuencia que detuvieron la arritmia primaria y culminó en ritmo de escape nodal.

Mechanisms of postoperative atrial tachycardia following biatrial surgical ablation of atrial fibrillation in relation to the surgical lesion sets

Atrial tachycardia (AT) may develop after biatrial surgical ablation of atrial fibrillation. However, the mechanism has not been determined in detail. We aimed to determine the mechanism and treatment of postoperative AT following biatrial surgical ablation in relation to the design and durability of the surgical lesion sets. An electrophysiologic study and radiofrequency ablation were performed in 34 consecutive patients (23 male, mean age of 63 ± 9.4 years) who were referred for AT that developed late after biatrial surgical ablation. The mechanism of a total of 53 ATs was macroreentry in 30, a focal mechanism in 20, and localized reentry in 1, and could not be determined in 2. The cause of the macroreentrant AT was residual conduction across a surgical lesion, most of which was located at the annular end of the mitral (n = 18) or tricuspid isthmus incision (n = 7), where cryoablation was applied during the surgery. We did not find any gaps across the cut-and-sew lesions. Radiofrequency (RF) applications to the gap, or an alternative site to transect the circuit, or the earliest activation site of the focus was effective for 48 ATs (91%). After a total of 1.3 ± 0.6 RF sessions, 27 patients (79%) were free of AT (n = 2) or AF (n = 5) during a follow-up period of 50 ± 49 months. Macroreentry due to a gap in a surgical lesion and focal AT were the major mechanisms of AT in patients after biatrial surgical ablation. Radiofrequency ablation of those ATs is feasible.

Biatrial linear ablation in sustained nonpermanent AF: Results of the substrate modification with ablation and antiarrhythmic drugs in nonpermanent atrial fibrillation (SMAN-PAF) trial

More advanced atrial fibrillation (AF) is associated with lower success rates after pulmonary vein isolation (PVI), and the optimal ablation strategy is uncertain. To assess the impact of additional linear ablation (lines) compared to PVI alone. In this multicenter randomized controlled trial, 122 patients (mean age 61.9 ± 10.5 years; left atrial diameter 43 ± 6 mm) with persistent AF (PeAF) or sustained (>12 hours) paroxysmal AF (SusPAF) with risk factors for atrial substrate were included and followed up for 12 months. Patients were randomized to PVI-only or PVI + lines (left atrial roof line, mitral isthmus line, and tricuspid isthmus line) group. Holter monitoring was performed at 3, 6, and 12 months and according to symptoms. The primary outcome was atrial tachyarrhythmia recurrence lasting ≥30 seconds. Baseline characteristics were comparable between groups; 61% had PeAF and 39% SusPAF. Successful PVI was achieved for 98% of pulmonary veins, and bidirectional block was obtained in 90% of lines. The primary end point occurred in 38% of the PVI + lines group and 32% of the PVI-only group (P = .50), which was consistent in both PeAF (36% vs 28%; P = .45) and SusPAF (42% vs 39%; P = .86). Compared with the PVI-only group, the PVI + lines group had higher procedure duration (209 ± 52 minutes vs 172 ± 44 minutes; P < .001), ablation time (4352 ± 1084 seconds vs 2503 ± 1061 seconds; P < .001), and radiation exposure (Dose-area product 3992 ± 6496 Gy·cm(2) vs 2106 ± 1679 Gy·cm(2); P = .03). Quality of life (disease-specific Atrial Fibrillation Effect on Quality of Life questionnaire and mental component scale of the Short Form 36 Health Survey) improved significantly during the study but did not differ between groups. Adding lines to wide antral PVI in substrate-based AF requires significantly more ablation, increases procedure duration and radiation dose, but provides no additional clinical benefit.

ORAL PRESENTATION

ORAL PRESENTATION