Atypical Atrial Flutter

Introduction Mapping and ablation of atypical atrial flutter (AFL) continue to be a challenge for clinical electrophysiologists. The advent of high-density (HD) mapping has allowed the generation of electro-anatomic maps with a very high resolution level. Purpose In this single center retrospective analysis, we evaluated the clinical impact of the ultra HD activation sequence mapping compared with the standard low density (LD) ablation catheter mapping technique in the treatment of AFLs. Methods We performed a 7 years-single center retrospective analysis of patients undergoing radiofrequency ablations (RFA) for right and left atypical AFL. We evaluated procedural and clinical outcomes of patients approached with a Low Density (LD) electro-anatomical (EAM) strategy compared with patients mapped with new automatic multipolar HD Mapping (HD Group). Results Seventy-five patients were included. Patients were almost male (60%), relatively old (65±8 years), with a moderate CHA2DS2Vasc score (2.3±1.3), a preserved ejection fraction (58±6) and moderate atrial dilatation (44±7 mm). Baseline clinical characteristics were comparable between groups (p=NS). Among 88 AFLs, 10 (11%) were located in the right and 78 (89%) in the left atrium, including 22 (28%) roof dependent and 37 (47%) mitral dependent (p=NS). Regarding procedural outcomes, Sinus rhythm restoration during ablation was more frequently observed in the HD Group (79% vs 56%, p=0.037), even if no differences in mapping time, procedural time and radiological dose were observed (p=NS). Freedom from AFL/atrial fibrillation (AF) at 1-year was lower in the HD Group (83% vs 45%, p=0.009) with an increased trend for AF recurrences during long term follow-up (17% vs 23% at 1 and 3-years respectively, p=0.059). At the multivariate analysis, HD map (OR 0,17; 95% CI 0,04–0,66) and younger age (OR 1,09; 95% CI 1,01–1,19) were identified as independent predictors of ablation success at 1 year. Conclusions Acute procedural success of ablation of atypical atrial flutter is higher in case of HD mapping strategy. Patient age and HD strategy resulted independent predictors of overall atrial arrhythmias recurrences. During follow-up, AFL recurrences are rare beyond 12 months, differently from AF which continues to show increasing trends. Funding Acknowledgement Type of funding sources: None. Procedural outcomesAtypical atrial flutter HD map

Background Although entrainment mapping is an established approach to atypical atrial flutter ablation, postpacing intervals shorter than tachycardia cycle length (difference between postpacing interval and tachycardia cycle length [dPPI] <0 ms) remain of unknown significance. We sought to compare anatomic and electrophysiological properties of sites with dPPI <0, dPPI=0-30, and dPPI >30 ms. Methods We studied 24 noncavotricuspid isthmus-dependent macroreentrant atypical atrial flutter in 19 consecutive patients. Ultra high-density electroanatomic activation maps were acquired with a 64-electrode basket catheter. Entrainment mapping was performed at multiple candidate sites. Ablation was performed at the narrowest accessible slow-conducting critical isthmuses. Results Of 102 entrainment mapping sites, dPPI <30 was observed at 72 sites on complete maps of 24 atypical atrial flutter. Compared with dPPI=0-30 sites (N=45), dPPI<0 sites (N=27) were more commonly located within isthmuses <15 mm wide (67% versus 6.7%, P<0.00001; odds ratio, 28.0; 95% CI, 6.8-115.7), more frequently located within 5 mm of the leading wavefront (93% versus 64%, P=0.008), exhibited slower local conduction velocity (0.49±0.43 versus 0.93±0.57 m/s, P=0.0005), lower voltages (0.48±0.79 versus 0.92±0.97 mV, P=0.04), and more frequently fractionated electrograms (67% versus 24%, P=0.0004). High rates of arrhythmia termination or cycle length increase >15 ms by ablation were observed in both dPPI groups (94% versus 86%, P=0.53). Compared with all dPPI <30, dPPI >30 sites (N=30) were less commonly observed within isthmuses (3.3%, P<0.001) or within 5 mm of the leading wavefront (30%, P<0.0001); conduction velocity (1.0±0.7 m/s, P=0.002) and voltage (1.1±1.4 mV, P=0.049) were higher compared with dPPI<0 but similar to dPPI=0-30 sites. Conclusions In atypical atrial flutter, sites with dPPI <0 are markers of limited width critical isthmuses with slower conduction velocity, whereas sites with dPPI=0-30 ms are often not in close proximity to the reentry circuit. Virtual electrode simultaneous down and upstream (antidromic) capture of a confined isthmus of slow conduction can explain a dPPI <0. Identifying these sites may improve selective and efficient ablation strategies compared with the standard 30-ms threshold.

Im Gegensatz zum typischen Vorhofflattern handelt es sich beim atypischen Vorhofflattern um eine heterogene Gruppe von rechts- und linksatrialen Makro- bzw. Localized-Reentry-Tachykardien, deren kritischer Bestandteil zur Aufrechterhaltung der Tachykardie nicht der cavotrikuspidale Isthmus ist. Atypisches Vorhofflattern tritt gehäuft nach vorangegangener Katheterablation sowie nach herzchirurgischen Eingriffen auf. Die intraprozedurale Erfolgsrate während der Ablation ist hoch, wobei die Rezidivrate von strukturellen Veränderungen der Vorhöfe sowie des zugrundeliegenden Mechanismus abhängig ist. Dieser Artikel bietet einen Überblick über die Mechanismen sowie über Mapping- und Ablationsstrategien der häufigsten Formen von rechts- und linksatrialem atypischem Vorhofflattern. Dieser Beitrag ist Teil der Serie „EP-Basics“ zur gezielten Fortbildung im Bereich Invasive Elektrophysiologie. Grundlagen, Klinik und Therapie des atypischen Vorhofflatterns werden mit Fokus auf klinisch relevante Aspekte dargelegt. Vorgehensweise und Befunde der invasiven elektrophysiologischen Diagnostik und die Ablationsbehandlung bilden den Schwerpunkt dieses Artikels.

The aim of this study was to assess the efficacy of high-frequency (HF) pacing from the right atrial appendage (RAA) or coronary sinus ostium (CS-Os) for the termination of acute atrial fibrillation (AF) and atypical atrial flutter (AAFL) during an electrophysiological (EP) study. 128 episodes of acute fast atrial arrhythmias (FAAs; 93 AF and 35 AAFL) were analyzed in 110 patients. Patients were initially observed for 60s leading to spontaneous termination of 28 FAAs. The remaining 100 FAAs (70 AF) episodes were randomized to the following strategies: (A) pacing at RAA using up to 10 consecutive 20-Hz trains followed by the same stimulation protocol at CS-Os if RAA pacing failed, (B) pacing at CS-Os using the same stimulation protocol followed by HF pacing at RAA, or (C) observation up to 6 minutes ("no pacing"). The 20-Hz pacing at both RAA and CS-Os was associated with higher conversion of AAFL, as compared to strategy C (60% and 77% vs 11%; P < 0.05). Only HF pacing at CS-Os was superior to observation strategy for the conversion of AF (21% vs 4%; P < 0.05). The 20-Hz pacing protocol is superior to observation strategy for interruption of either acute AF or acute AAFL episodes; however, its efficacy is higher in AAFLs. These results can be helpful for the termination of acute atrial tachyarrhythmias during EPstudy and should be further evaluated in patients with implantable devices capable of antitachycardia pacing.

Typical and atypical atrial flutters (AFLs) and atrial tachycardias (ATs) have been reported in patients with prior surgical atrial fibrillation ablation. The underlying mechanisms for this group of atrial tachyarrhythmias have not been well characterized and the efficacy of catheter ablation in their treatment is unknown. Twenty patients (6 females) with a surface ECG diagnosis of AFL or AT following surgical atrial fibrillation ablation underwent 26 electrophysiology studies. Patients manifesting sustained, organized, and beat-by-beat reproducible atrial electrical activity underwent complete right and left atrial catheter mapping and catheter ablation. One patient had no inducible tachyarrhythmia, while 5 patients had nonmappable arrhythmias. Nineteen of the 31 potentially mappable atrial tachyarrhythmias were completely characterized in 14 patients. The underlying mechanisms were macro-reentrant left AFL (n = 9), focal left AT (n = 3), typical right AFL (n = 6), and atypical right AFL (n = 1). Of the 19 completely characterized atrial arrhythmias, catheter ablation was performed for 18, and the procedure was successful for 13 of these. After a mean follow-up of 15 +/- 10 months, 15 of 20 patients (75%) were in sinus rhythm including 10 of 13 patients (77%) with AT/flutter ablation. Ten patients, including 6 following ablation, were maintaining sinus rhythm without antiarrhythmic medications. Patients with an ECG diagnosis of AFL or AT following surgical atrial fibrillation ablation may have multiple tachycardia mechanisms with the right or left atrium as the site of origin. Many of these rhythms may resolve with further maturation of surgical atrial fibrillation ablation (SAFA) lesions or be treatable with antiarrhythmic medication. However, persistent tachyarrhythmias can often be treated successfully with catheter mapping and ablation.

Identification of atypical atrial flutter (AFL) (non-cavo-tricuspid isthmus-dependent) prior to the electrophysiology laboratory is potentially useful because it allows appropriate procedural planning and enables discussion of the likely success rates and risks of the procedure with the patient. Typical counterclockwise AFL has a stereotypic appearance, the electrocardiogram (ECG) is predictive of the diagnosis in the majority of cases, and ablation procedures are associated with a high degree of safety and success. Atypical right atrial and left AFLs have a highly variable flutter wave morphology and may appear atypical, resemble typical flutter or appear to be focal in origin. Targeting these complex and often multiple re-entrant circuits is aided by expertise and use of electroanatomic mapping systems. This review will address whether there are clues from the 12-lead ECG which assist in the localization of AFL circuits.

BackgroundThe efficacy of radiofrequency (RF) ablation of an uncommon coronary sinus (CS)-dependent atrial flutter (AFL) was evaluated using conventional electrophysiological criteria in a highly selected subset of patients with typical and atypical AFL.MethodsFourteen patients with atrial flutter (11 males, mean age 69 ± 9 years) without previous right or left atrial RF ablation were included. Heart disease was present in eight patients. Baseline ECG suggested typical AFL in 12 patients and atypical AFL in two. Mean AFL cycle length was 324 ± 64 ms at the time of RF ablation in the CS. Lateral right atrium activation was counterclockwise (CCW) in 13 patients and clockwise in one. CS activation was CCW in all. Criteria for CS ablation included the presence of CS mid-diastolic fractionated atrial potentials (APs) associated with concealed entrainment with a postpacing interval within 20 ms. Success was defined as termination of AFL and subsequent noninducibility.ResultsThe initial target for ablation was the cavotricuspid isthmus (CTI) in 11 patients and the CS with further CTI ablation in three. AP duration at the CS target site was 122 ± 33 ms, spanning 40 ± 12% of the AFL cycle length. CS ablation site was located 1–4 cm from the CS ostium. Ablation was successful in all patients. Mean time to AFL termination during CS ablation was 39 ± 52 s (<20 s in eight patients). No recurrence of ablated arrhythmia occurred during a follow-up of 18 ± 8 months.ConclusionsThe CS musculature is a critical part of some AFL circuits in patients with typical and atypical AFL. AFL can be terminated in patients with CS or CTI/CS AFL reentrant circuits by targeting CS mid-diastolic fragmented APs.

Atypical atrial flutter has become amenable to catheter ablation with remarkable improvement in the acute and long-term efficacy of this therapy for this macro reentrant atrial arrhythmia. Here it was described a case of atypical atrial flutter which arises from left atrium and demonstrates the importance of a systematic approach to mapping and ablating atypical atrial flutter to prevent a recurrence of symptomatic arrhythmia. We also highlighted importance of 3D mapping which is a key tool for analysis and successful ablation. Bangladesh Heart Journal 2022; 37(2): 139-142

Previous reports have shown that radiofrequency ablation can terminate atrial flutter and prevent recurrences. However, different methods have been used, and the current experience remains limited. The objective of the present study was to determine the efficacy of radiofrequency ablation of atrial tissue in patients with atrial flutter using an anatomically guided approach. We treated 22 patients aged 30 to 73 years. Atrial flutter was recurrent for a mean of 5 years despite the administration of multiple antiarrhythmic drugs. Radiofrequency current was directed to the atrial isthmus between the inferior vena cava and the tricuspid ring, regardless of the morphology of local electrograms. Radiofrequency energy was applied during typical atrial flutter in 12 patients, atypical atrial flutter in 2 patients, and successively both forms in 8 patients. In 19 patients, atrial flutter abruptly terminated. In 3 patients, atrial flutter persisted despite 37, 48, and 25 applications, respectively. Atrial recordings demonstrated that atrial flutter termination occurred as a consequence of conduction block at the site of radiofrequency energy application, regardless of the type of atrial flutter. The number of applications before termination ranged from 1 to 82 (mean, 32). Atrial flutter could no longer be induced in every case. There were no complications. During a 13-month mean follow-up, atrial flutter recurred in only 2 of the 19 patients who had a successful ablation. Four patients experienced chronic atrial fibrillation, and 2 of them returned to sinus rhythm with antiarrhythmic therapy. Radiofrequency ablation of atrial flutter using anatomic guidance is feasible and effective. Further experience is needed to delineate its role as an alternative approach to the management of refractory atrial flutter.

Stepwise linear approach to catheter ablation of atrial fibrillation

Curative treatment of chronic atrial fibrillation (AF) remains a challenging task for electrophysiologists. Eliminating the initiating triggers by focal radiofrequency ablation in a subset of patients with paroxysmal AF and modifying the maintaining substrate by performing linear lesions within the left atrium in patients with prolonged episodes of AF are among the alternative approaches for management of these patients. Recently, a new intraoperative treatment procedure aimed at eliminating left atrial anatomic "anchor" reentrant circuits by induction of contiguous lesions using radiofrequency energy under direct vision was introduced. However, atypical left atrial flutter may occur during follow-up after intraoperative ablation of AF. These arrhythmias most likely are due to discontinuities in linear lesions; therefore, they can be successfully mapped and ablated in a subsequent percutaneous catheter ablation procedure. We report and discuss the case of a patient who underwent successful intraoperative ablation of chronic AF, but who developed atypical left atrial flutter postoperatively. Three-dimensional nonfluoroscopic electroanatomic mapping revealed a gap in the linear lesion line connecting the left upper and right upper pulmonary vein orifices. Ablation at the exit site of the breakthrough was successful.

Introduction Iatrogenic atrial tachyarrhythmias have increased with the widespread application of left atrial ablative procedures to treat atrial fibrillation. Methods and results Entrainment and activation mapping were utilized to study the mechanisms of atrial flutter in two patients who presented with atypical atrial flutter after high intensity focused ultrasound (HIFU) atrial ablation for persistent atrial fibrillation during the course of concomitant cardiac surgery. Case 1: Atrial flutter with CL of 340 ms was demonstrated to be mediated by entry into and exit from the partially isolated posterior left atrium (LA) with conduction delay across at least one of the connections. The exit site was near the left superior pulmonary vein (LSPV) and the entrance site was near the right inferior pulmonary vein (RIPV) as demonstrated by activation and entrainment mapping. Case 2: Entrainment mapping was highly suggestive of inferior exit from the HIFU ablation line between the two inferior pulmonary veins. Flutter terminated during trans-septal procedure and could not be re-induced. Activation mapping of the LA during pacing revealed the inferior exit and left superior entrance site, both of which were successfully ablated, isolating the posterior LA. Conclusions Re-entrant atrial flutter post-HIFU epicor Maze is caused by slow conduction at entry and exit sites from the otherwise isolated posterior LA wall. In both cases, gaps were found close to the LSPV and RIPV which may reflect difficulty in achieving proper contact between the HIFU device and the left atrial wall at these sites. These gaps are amenable to catheter ablation.

Atrial fibrillation is a common cardiac arrhythmia, and has been a significant financial burden. Class III antiarrhythmics such as dofetilide, ibutilide, and amiodarone are indicated for rhythm control. Magnesium may possess intrinsic antiarrhythmic properties, and may potentially increase the efficacy of class III antiarrhythmics when used concomitantly. The purpose of this article is to review the literature on the efficacy of magnesium in addition to Class III antiarrhythmics, specifically amidarone, ibutilide, and dofetilide for the cardioversion of atrial fibrillation. Databases Pubmed and CINAHL are utilized along with the search terms amiodarone, dofetilide, ibutlide, magnesium, atrial fibrillation, conversion, rhythm control, and cardioversion. One study on dofetilide and 5 studies on ibutilide were identified. No studies were found on amiodarone. Patients with atrial fibrillation who received dofetilide and magnesium had higher rates of successful cardioversion as compared to those who only received dofetilide. Conversion rates were similar between the 2 treatment groups for patients with atrial flutter. As for ibutilide, 4 studies have shown that the addition of magnesium significantly increases conversion rates for patients with atrial fibrillation or typical atrial flutter. Conversion rates were similar for patients with atypical atrial flutter. One study showed that addition of magnesium did not improve efficacy of ibutilide. Higher doses of magnesium (4 g) were associated with improved outcomes. Adverse effects of magnesium were mild and included flushing, tingling, and dizziness. Patients who received magnesium had shorter corrected QT intervals and smaller increase in corrected QT interval from baseline. Compare to previous studies, studies included in this review had higher conversion rates for dofetilide and ibutilide as well as dofetilide and magnesium or ibutilide and magnesium combination therapies. However, only 2 ibutilide studies and 1 dofetilide study reported baseline characteristics such as left atrial size, history of heart failure, and duration of atrial fibrillation, which are significant predictors of successful cardioversion. Therefore, differences in baseline demographics may have influenced the results. Magnesium may be used as adjunct for dofetilide and ibutilide due to potential improved efficacy and minimal toxicity. Dose ranging studies should be conducted in the future to establish the optimal dose and duration of therapy as well as the optimal serum magnesium concentration in order for the clinician to manage and monitor patients appropriately.

Comparative Efficacy of Dofetilide Versus Amiodarone in Patients With Atrial Fibrillation.

It has not been previously investigated whether the recurrence mechanism after cryoballoon ablation (CBA) of paroxysmal atrial fibrillation (AF) is similar to that of radiofrequency catheter ablation (RFCA). We aimed to evaluate the differences of recurrence characteristics between RFCA and CBA after the index procedure. A total of 210 patients were enrolled in the study, and 69 patients underwent pulmonary vein (PV) isolation using a 28-mm second-generation CBA. The control group comprising 140 patients underwent PV isolation using an open-irrigated radiofrequency ablation catheter. A total of 69 patients in the CBA group and 69 patients in the RFCA group were investigated after propensity score matching. Recurrence patterns of AF were studied in the repeated procedure. During the index procedure, there was no difference in PV or non-PV triggers between the two groups. Nineteen (27.5%) patients in the CBA group and 19 (27.5%) patients in the RFCA group had recurrence after a follow-up of 11.3 ± 7 months. The Kaplan-Meier curve did not reveal significant difference in recurrence (log-rank, P = 0.364) between the two groups. In the second procedure, the CBA group had more non-PV triggers (63.6%, P = 0.009) and left atrial (LA) flutters (54.5%, P = 0.027) compared with the RFCA group (12.5% and 12.5%, respectively). The PV reconnection rates were similar between both groups. There was no difference in AF recurrence after catheter ablation between CBA and RFCA, but significant increases of non-PV triggers and LA flutter during the second procedure suggest the importance of the atrial substrate in maintaining AF during the second procedure after previous CBA.