Empirical Ablation Research Articles

Efficacy and safety of early postoperative ablation in patients with congenital heart disease

BackgroundPostoperative arrhythmias are most often transient and medically treated, but some patients may require electrophysiology study (EPS) and ablation. ObjectiveThe purpose of this study was to describe the efficacy and safety of early postoperative ablation. MethodsThis study presents a retrospective series of patients who underwent EPS within 12 months of surgery for congenital heart disease between 2000 and 2021. The procedural outcome included complete or partial success, empirical ablation or failure, and complications. The long-term outcome included arrhythmia recurrence and burden according to a 12-point clinical arrhythmia severity score (documented arrhythmia, arrhythmia severity, cardioversion, and antiarrhythmic medication). ResultsAmong 28,902 operations during the study period, 24 patients (0.1%) underwent EPS within 3 months of surgery and 26 (0.1%) 3–12 months after surgery. Most patients had great (n = 27 [50%]) or moderate (n = 21 [42%]) congenital heart disease complexity. Mechanisms of arrhythmias included intra-atrial reentrant tachycardia (n = 23 [46%]), ectopic atrial tachycardia (n = 13 [26%]), accessory pathway (n = 6 [12%]), atrioventricular nodal reentrant tachycardia (n = 7 [14%]), twin atrioventricular node (n = 1 [2%]), atrial fibrillation (n = 1 [2%]), junctional ectopic tachycardia (n = 1 [2%]), and ventricular tachycardia (n = 2 [4%]). The procedure was acutely successful in 41 patients (82%), empirical in 5 (10%), and unsuccessful in 4 (8%). Complications occurred in 4 (8%) patients (major in 1, moderate in 1, and minor in 2). The recurrence of arrhythmia was documented in 27 patients (54%), although the burden of arrhythmia was significantly reduced. ConclusionA minority of patients require early postoperative EPS and ablation. For those, the procedure can be performed with reasonable acute success and manageable morbidity even in critically ill patients with complex surgical anatomy.

Mechanistic Insights From Trials of Atrial Fibrillation Ablation: Charting a Course for the Future.

Success rates for catheter ablation of atrial fibrillation (AF), particularly persistent AF, remain suboptimal. Pulmonary vein isolation has been the cornerstone for catheter ablation of AF for over a decade. While successful for most patients, pulmonary vein isolation alone is still insufficient for a substantial minority. Frustratingly, multiple clinical trials testing a diverse array of additional ablation approaches have led to mixed results, with no current strategy that improves AF outcomes beyond pulmonary vein isolation in all patients. Nevertheless, this large collection of data could be used to extract important insights regarding AF mechanisms and the diversity of the AF syndrome. Mechanistically, the general model for arrhythmogenesis prompts the need for tools to individually assess triggers, drivers, and substrates in individual patients. A key goal is to identify those who will not respond to pulmonary vein isolation, with novel approaches to phenotyping that may include mapping to identify alternative drivers or critical substrates. This, in turn, can allow for the implementation of phenotype-based, targeted approaches that may categorize patients into groups who would or would not be likely to respond to catheter ablation, pharmacological therapy, and risk factor modification programs. One major goal is to predict individuals in whom additional empirical ablation, while feasible, may be futile or lead to atrial scarring or proarrhythmia. This work attempts to integrate key lessons from successful and failed trials of catheter ablation, as well as models of AF, to suggest future paradigms for AF treatment.

The effect of empirical superior vena cava isolation during total thoracoscopic ablation in patients with persistent atrial fibrillation

BackgroundIn patients with non-paroxysmal AF (atrial fibrillation), various ablation strategies have been attempted to target non-pulmonary vein (PV) foci or to achieve substrate modification beyond pulmonary vein isolation. The efficacy of empirical ablation of the SVC, one of the most common non-PV foci, is unclear. The aim of this study was to investigate the efficacy and safety of additional superior vena cava (SVC) isolation in patients with non-paroxysmal AF undergoing thoracoscopic surgical ablation.Methods/resultsA total of 191 patients with persistent or long-standing persistent AF was enrolled. All patients underwent total thoracoscopic surgical ablation for AF, and half of them also received empirical SVC isolation. We compared the atrial tachyarrhythmia (ATa)-free survival rate and procedure-related complications in the two groups of patients. The 3-year ATa-free survival rate was 53% in the SVC isolation group and 52% in the no-SVC isolation group (p = 0.644). There were no differences between the two groups with respect to AF type or LA size. Procedure-related complications occurred in 12 patients (6%). Pacemakers were implanted only in three patients from the SVC isolation group. The only factor influencing recurrence of ATa was LA diameter.ConclusionsEmpirical SVC isolation during thoracoscopic ablation for persistent AF did not improve patient outcomes.

The novel left atrial anterior 'seatbelt' line reduces sustained atrial arrhythmia by 72% compared to pulmonary vein isolation alone in a cohort of 400 virtual atria models

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No.860974. Background The success-rate of pulmonary vein isolation (PVI) is modest in persistent atrial fibrillation (AF), but additional empirical ablation, such as posterior wall isolation (PWI), has not been shown to reduce the rate of AF recurrence. The "seatbelt", an anterior linear ablation lesion connecting the right superior pulmonary vein to the mitral annulus, is a novel substrate modification approach that is yet to be tested in a large-scale randomised clinical trial. Purpose To use in-silico trials with human-based modelling and simulation to compare the efficacy of (i) PVI alone, (ii) PVI and PWI (PVI+PWI), or (iii) PVI and seatbelt (PVI+SB) for the prevention of atrial arrhythmia in large populations of virtual patient models. Methods AF was simulated in a cohort of 400 virtual atrial models with anatomical and electrophysiological variability, with AF persisting for >7 seconds defined as sustained. Models which sustained AF were each independently subjected to all three ablation approaches before repeating the AF induction protocol. Results Three hundred forty-four (86%) atrial models developed sustained AF at baseline. After applying the ablation lesions, substantially fewer models sustained atrial arrhythmias in the PVI+SB group (50 [14%] vs. 134 [39%] with PVI+PWI vs. 172 [50%] with PVI). PVI+SB was more effective than PVI and PVI+PWI in preventing both AF and atrial flutter (i.e., presence of a single rotor), since PVI and PVI+PWI led to the formation of anatomical re-entries around the rings of the pulmonary veins and the posterior wall of the left atrium, respectively (Figure). Therefore, PVI+SB restricted atrial flutter mainly to the right atrium (either anatomical, around the inferior cava vein, or functional, meandering throughout the venous portion of the right atrium, Figure). Importantly, in all three ablation strategies, the likelihood of AF recurrence was directly proportional to the surface area of the right atrium (AF probability increased 0.95%/cm², 0.88%/cm² and 0.56%/cm² after PVI+SB, PVI+PWI and PVI, respectively). The role of the right atrial size was less accentuated for PVI alone, since after the ablation the entire left atrial body was still available for rotor anchoring. Moreover, an enlarged left atrium enabled the appearance of micro-re-entries in the anterior and inferior wall of the left atrium, even after applying floor and roof lines. One atrial model additionally presented a rotor in the posterior wall of the left atrium after completely isolating it from the left atrial body. Conclusion(s) In a cohort of 400 virtual atrial models, PVI+SB reduced sustained atrial arrhythmias by 72% compared to PVI alone and by 64% to PVI+PWI, but AF could still originate in an enlarged right atrium.

Comparison of the empirical linear ablation and low voltage area-guided ablation in addition to pulmonary vein isolation in patients with persistent atrial fibrillation: a propensity score-matched analysis

BackgroundThe efficacy of pulmonary vein isolation (PVI) alone is not guaranteed for persistent atrial fibrillation (PeAF), and it is unclear which type of ablation approach should be applied in addition to PVI. This study aimed to compare outcomes and prognosis between empirical linear ablation and low-voltage area (LVA) ablation after PVI for PeAF.MethodsWe enrolled 128 patients with PeAF who were assigned to the linear ablation group (n = 64) and the LVA ablation group (n = 64) using a propensity score-matched model. After PVI and cardioversion, the patients underwent either empirical linear ablation or LVA ablation during sinus rhythm. All patients in the linear ablation group underwent both roof line and mitral valve isthmus (MVI) ablations. An electrical-guided ablation targeting LVA (< 0.5 mV) was performed in the LVA group. When there was no LVA in the LVA group, only PVI was applied. We compared the procedural outcomes and recurrence after ablation between the two groups.ResultsThe baseline characteristics were well-balanced between the two groups. Fifty patients had LVA (22 and 28 patients in the linear and LVA groups). The roof and MVI lines were completed in 100% and 96.9% of the patients. During the mean follow-up of 279.5 ± 161.3 days, the LVA group had significantly lower recurrence than the linear group (15 patients [23%] vs. 29 patients [45%], p = 0.014). Thirty-five patients were prescribed antiarrhythmic drugs during the follow-up period (linear group, n = 17; LVA group, n = 18); amiodarone and bepridil were administered to most of the patients (15 and 17 patients, respectively). The difference in the prognosis was relevant among the patients with LVA, while this trend was not observed in those without LVA. The LVA ablation group demonstrated significantly lower radiofrequency energy and shorter procedural time compared to the linear ablation group. The recurrence of atrial flutter was more likely to occur in the linear group than in the LVA group (14 [22%] vs. 6 [9.4%], p = 0.052).ConclusionThe electrophysiological-guided LVA ablation is more effective than empirical linear ablation in PeAF patients with LVA. Unnecessary empirical linear ablation might have a risk of iatrogenic gap and atrial flutter recurrence.

Clinical Usefulness of Virtual Ablation Guided Catheter Ablation of Atrial Fibrillation Targeting Restitution Parameter-Guided Catheter Ablation: CUVIA-REGAB Prospective Randomized Study.

We investigated whether extra-pulmonary vein (PV) ablation targeting a high maximal slope of the action potential duration restitution curve (Smax) improves the rhythm outcome of persistent atrial fibrillation (PeAF) ablation. In this open-label, multi-center, randomized, and controlled trial, 178 PeAF patients were randomized with 1:1 ratio to computational modeling-guided virtual Smax ablation (V-Smax) or empirical ablation (E-ABL) groups. Smax maps were generated by computational modeling based on atrial substrate maps acquired during clinical procedures in sinus rhythm. Smax maps were generated during the clinical PV isolation (PVI). The V-Smax group underwent an additional extra-PV ablation after PVI targeting the virtual high Smax sites. After a mean follow-up period of 12.3±5.2 months, the clinical recurrence rates (25.6% vs. 23.9% in the V-Smax and the E-ABL group, p=0.880) or recurrence appearing as atrial tachycardia (11.1% vs. 5.7%, p=0.169) did not differ between the 2 groups. The post-ablation cardioversion rate was higher in the V-Smax group than E-ABL group (14.4% vs. 5.7%, p=0.027). Among antiarrhythmic drug-free patients (n=129), the AF freedom rate was 78.7% in the V-Smax group and 80.9% in the E-ABL group (p=0.776). The total procedure time was longer in the V-Smax group (p=0.008), but no significant difference was found in the major complication rates (p=0.497) between the groups. Unlike a dominant frequency ablation, the computational modeling-guided V-Smax ablation did not improve the rhythm outcome of the PeAF ablation and had a longer procedure time. ClinicalTrials.gov Identifier: NCT02558699.

Abstract 12187: Arrhythmia Substrate and Approaches for First-Time and Repeat Catheter Ablation in Patients With D-transposition of the Great Arteries and Atrial Baffles

Introduction: Atrial arrhythmias are common in patients with D-TGA and atrial switch. We sought to analyze the arrhythmia substrate and catheter ablation approaches and outcomes. Methods: We performed a retrospective review of all clinical and procedural data in patients with D-TGA followed at a large tertiary care center. Results: In a cohort of 152 patients (mean age 30±11 years), atrial tachycardia was present in 69(45%) patients. Ablations were performed in 39(26%) patients: macro-reentrant atrial flutter (N=37), atrial fibrillation (N=4), and focal automatic atrial tachycardia (N=3). Detailed electrophysiology study data was available for 34 patients. At first ablation (N=28), cavo-tricuspid isthmus dependent flutter (CTI, 23(82%)) was most common, followed by right atriotomy-related flutter (IART, 16(57%)) and focal atrial tachycardia (FAT, 1(3.5%)). Bidirectional CTI block often required ablation on both sides of the baffle to complete the isthmus line. Access to the pulmonary venous atrium was obtained in 82% of first-time ablations (via retrograde aortic access, 74%, baffle puncture, 6%, or baffle fenestration, 12%) and in 100% of redo procedures. The first ablation was acutely successful in 25 (89%) patients; the other 3 patients had either partial procedural success (1), failed ablation (1), or underwent an empirical ablation (1). Long-term arrhythmia recurrence occurred in 13(46%) after the first ablation and class III antiarrhythmic medications were utilized in 12 patients. At least one long-term recurrence occurred in 11(44%) patients. Importantly, clinical arrhythmia burden was significantly reduced post-ablation, with rare and short-limited episodes amenable to antiarrhythmic drugs or cardioversion. Repeat ablation was required in 3 cases. Long-term arrhythmia recurrence after a previously completed CTI line involved different arrhythmia mechanisms: scar-related reentry (80%) and automatic atrial tachycardia (40%). Conclusions: Atrial arrhythmia in patients with D-TGA often involves the CTI and atriotomy scars. Ablation of the CTI typically requires access to the pulmonary venous atrium to achieve bidirectional block. Despite late recurrence, the clinical arrhythmic burden is substantially improved.

Risk Factors for Stiff Left Atrial Physiology 1 Year After Catheter Ablation of Atrial Fibrillation.

Catheter ablation is the most effective rhythm control method for patients with atrial fibrillation (AF); however, it inevitably causes atrial tissue damage. We previously reported that AF catheter ablation (AFCA) increases left atrial (LA) pressure without changes in symptom scores. We hypothesized that extensive LA ablation increased the risk of stiff LA physiology. We included 1,720 patients (69.1% male, 60.0 [53.0–68.0] years old, 66.2% with paroxysmal AF) who underwent de novo AFCA and echocardiography before and 1-year after the procedure. Stiff LA physiology was defined, when the amount of the estimated pulmonary arterial pressure increase between the pre-procedural and the 1-year post-procedural follow-up echocardiography was >10 mmHg and when right ventricular systolic pressure (RVSP) was >35 mmHg at 1-year follow-up echocardiography. The failed rhythm control within 1 year was defined as recurrent AF despite using anti-arrhythmic drugs or cardioversion within a year of AFCA. We explored the incidence and risk factors for stiff LA physiology and the rhythm outcome of AFCA. Among the 1,720 patients, 64 (3.7%) had stiff LA physiology 1 year after AFCA. Stiff LA physiology was independently associated with diabetes (odds ratio [OR], 2.36 [95% CI, 1.14–4.87], p = 0.020), the ratio of the peak mitral flow velocity of the early rapid filling to the early diastolic velocity of the mitral annulus (E/Em; OR, 1.04 [95% CI, 1.00–1.10], p = 0.049), LA pulse pressure (Model 2: OR, 1.05 [95% CI, 1.00–1.11], p = 0.049), low LA voltage (OR, 0.36 [95% CI, 0.18–0.74], p = 0.005), empirical extra-pulmonary vein (PV) LA ablation (OR, 2.60 [95% CI, 1.17–5.74], p = 0.018), and radiofrequency (RF) ablation duration (Model 2: OR, 1.02 [95% CI, 1.01–1.03], p = 0.003). Although the incidence of post-AFCA stiff LA physiology was 3.7% and most of the cases were subclinical, the empirical extra-PV ablation was associated with this undesirable condition. In addition, patients who had low mean LA voltage before AFCA could be susceptible to stiff LA physiology.

Clinical recurrence of palpitations following slow pathway ablation in patients with suspected paroxysmal supraventricular tachycardias but non-documented, non-inducible tachycardias

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Catheter ablation is recommended as first-line treatment in patients with atrioventricular nodal reentry tachycardias (AVNRT). However, the best therapeutic modality in patients with dual AV nodal physiology but non-inducible tachycardias in electrophysiological study (EPS) remains controversial, especially when no tachycardias have been documented. Our objective was to evaluate the results of empirical slow pathway ablation in patients showing dual AV nodal physiology but non-inducible AVNRT. Methods Multicenter, retrospective, observational registry of consecutive patients undergoing EPS due to clinical suspicion of paroxysmal supraventricular tachycardias (PSVT), but with no prior ECG documentation. Clinical, EPS and ablation (when performed) data were collected and andalyzed. Results 427 patients of 12 centers were included. Mean age was 46.3 ±16.1 and 297 (69.6%) were females. AVNRT was induced in 188 patients (typical in 181 cases, atypical in 7). Dual AV nodal physiology with or without single nodal echo beats, but with no sustained tachycardia and without evidence of accessory pathway was present in 68 patients. Ablation of the slow pathway was performed in 187/188 patients with AVNRT and in 30/68 patients with dual physiology. Among subjects with non-inducible tachycardia, ablation reduced significantly recurrences (39.5% in non-ablated vs. 16.7%; p = 0.04), with a level equivalent to those with ablated AVNRT(14.4% vs. 16.7%; p = 0.75). Procedure-related complications were similar in both groups: empirical ablation n = 1; 3.3% vs. induced tachycardia n = 6; 3.2% (p = 0.98). Conclusions In patients with high clinical suspicion of PSVT but non-documented and non-inducible arrhythmias, the presence of dual AV nodal physiology makes AVNRT a likely mechanism of the clinical tachycardia. Catheter ablation of slow pathway reduces the risk of recurrence to a level equivalent to those with inducible and ablated AVNRT. AVNRT (n = 188) Dual nodal physiology (n = 68) p value Age (years) 48.6 ± 16.3 41.9 ± 14.0 &amp;lt;0.01 Female 71.8% 67.7% 0.52 Years symptomatic 9.3 ± 11.3 3.6 ± 8.1 &amp;lt;0.01 Sudden onset 83.9% 88.0% 0.54 Abrupt end 73.4% 74.6% 0.96 Previous rate-slowing drugs 30.9% 25.0% 0.36 Previous antiarrhythmic drugs 5.9% 2.9% 0.35 Isoproterenol in EPS 70.0% 89.7% &amp;lt;0.01

Clinical and electrophysiological characteristics of extra-pulmonary vein triggers in patients who underwent catheter ablation for atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Extra-pulmonary vein (PV) triggers play significant roles in atrial fibrillation (AF) recurrence after AF catheter ablation (AFCA). Purpose We explore the clinical and electrophysiological characteristics of extra-PV triggers in de novo and repeat-AFCA procedure. Methods We included 2,151 patients who had de novo AFCA and 319 repeat AFCA (female 28.0%, 59.1 ± 10.8 years old, paroxysmal AF 65.1%) those underwent post-procedural isoproterenol (ISO) provocation tests. We analysed the clinical, electrophysiological, and procedure-related factors associated with extra-PV triggers. Results Extra-PV triggers were documented in 11.9% (1.19 ± 0.42 foci) after de novo-AFCA and 27.0% (1.37 ± 0.65 foci) after repeat-AFCA (p = 0.004). LA volume index (OR 1.02 [1.01-1.03], p = 0.004), history of vascular disease (OR 0.55[0.31-0.91], p = 0.028) and Lead I amplitude of electrocardiogram (OR &amp;lt;0.01 [&amp;lt;0.01-0.62], p = 0.032) were independently associated with the existence of extra-PV triggers in de-novo procedure. Women (OR 1.84 [1.03-3.25], p = 0.037) and LA appendage volume (OR 1.04 [1.01-1.07] p = 0.027) were independently associated with extra-PV triggers during the redo-mapping procedure. Septum (28.4%), coronary sinus (24.0%), and superior vena cava (19.6%) were common extra-PV foci, and septal foci were more commonly found in repeat mapping (38.4% vs. 25.0%, p = 0.025). Among 65 patients who showed extra-PV at the repeat procedures, 19 (29.2%) matched with previous focal or empirical extra-PV ablation sites and 9 (13.8%) were multiple or unmappable sites. AF recurrence rates were significantly higher in both patients with extra-PV triggers after de novo procedures (Log-rank P &amp;lt;0.001; HR 1.93 [1.58-2.36], p= &amp;lt;0.001) and repeat procedures (Log-rank P &amp;lt;0.001, HR 1.87 [1.29-2.70], p= &amp;lt;0.001). Conclusion ISO provoked extra-PV triggers commonly found in AF patients with significant remodelling and previous empirical or focal extra-PV ablations. Existence of extra-PV triggers were independently associated with poorer rhythm outcome after both de novo and repeat AFCA. Denovo AF ablation outcome OverallExtra-PV triggers (-)Extra-PV triggers (+)p-value(n = 2151)(n = 1895)(n = 256)Age, yrs58.98 ± 10.9558.73 ± 11.0360.76 ± 10.200.006Male, (%)1550 ( 72.1)1389 ( 73.3)161 ( 62.9)0.001Follow up duration, month50.30 (37.71)51.65 (37.95)40.71 (34.58)&amp;lt;0.001Early recurrence (%)579 ( 27.8)455 ( 24.9)124 ( 48.4)&amp;lt;0.001Clinical recurrence (%)699 ( 33.6)584 ( 32.0)115 ( 44.9)&amp;lt;0.001Abstract Figure. AF free survival according to Extra PVT

Identification and Endocardial Ablation ofthe Ligament of Marshall for PulmonaryVeinIsolation.

The aims of this study were to establish criteria for identifying ligament of Marshall (LOM) connections that are responsible for pulmonary vein isolation (PVI) failure, assess their incidence, and determine if they can be targeted by focal endocardial ablation at the anterior carina of the left superior pulmonary vein (LSPV). Wide antral ablation of the left pulmonary veins (PVs) may not achieve PVI, sometimes requiring empirical ablation of the PV carina. The mechanism could be due to epicardial conduction along the LOM, which courses adjacent to the anterior carina. In patients undergoing radiofrequency ablation for atrial fibrillation, if wide ablation of the left PV did not achieve isolation, bidirectional mapping was performed. A presumptive LOM connection was diagnosed if the earliest entrance was mapped to the anterior LSPV, while the earliest exit was mapped inferior to the left inferior PV. Focal ablation at the LSPV anterior carina was performed, even if not at the site of earliest entrance activation. The primary endpoint was successful PVI immediately after ablation. The study included 455 consecutive patients who underwent 570 procedures, of which 364 were first-time ablations. Presumptive LOM connections were identified in 48 procedures (8.4%) and in 41 patients (11.2%) undergoing first-time ablation and were successfully ablated at the anterior carina of the LSPV in 47 of 48 procedures (98%). LOM connections may be a common cause of PVI failure and can be easily identified and reliablyablated with focal endocardial ablation at the anterior LSPV carina.

Risk Factors for Early Recurrence Following Ablation for Accessory Pathways: The Role of Consolidation Lesions.

Atrioventricular reentrant tachycardia is common in children. Catheter ablation is increasingly used as a first-line therapy with a high acute success rate, but recurrence during follow-up remains a concern. The aim of this study was to identify risk factors for recurrence after accessory pathway (AP) ablation. Retrospective cohort study including patients who underwent AP ablation between 2013 and 2018. Cox proportional hazards model was used to examine the association between patient and procedural characteristics and recurrence during follow-up. From 558 AP ablation procedure, 542 (97%) were acutely successful. During a median follow-up of 0.4 (interquartile range, 0.1-1.4) years, there were 42 (8%) patients with documented recurrence. On univariate analysis, early recurrence was associated with younger age, congenital heart disease, multiple AP, AP location (right sided and posteroseptal versus left sided), cryoablation (versus radiofrequency), empirical ablation, the lack of full power radiofrequency lesions (<50 W), radiofrequency consolidation time <90 seconds and the use of fluoroscopy without a 3-dimensional electroanatomic mapping system. On multivariable analysis, only multiple AP (hazard ratio, 2.78 [95% CI, 1.063-4.74]) and radiofrequency consolidation time < 90 seconds (hazard ratio, 4.38 [95% CI, 1.92-9.51]) remained significantly associated with early recurrence; this association remained true when analyzed in subgroups by pathway location for right and left free wall AP. In our institutional experience, radiofrequency consolidation time <90 seconds after ablation of AP was associated with an increased risk of early recurrence.

P1444Empirical Slow Pathway Ablation in Documented but Noninducible PSVT

Abstract Funding Acknowledgements This study was not funded Background The empirical slow pathway ablation /modification (ESPA/M) is often applied to a documented but noninducible supraventricular tachycardia (SVT) in the electrophysiology study (EPS). A clinical paroxysmal supraventricular tachycardia (PSVT) cannot be induced renders the therapeutic end point of radiofrequency catheter ablation difficult. The data supporting the ESPA/M in adult patients are limited. The aim of this study was to assess the clinical efficacy and safety of the ESPA/M in adults. Methods A retrospective study of symptomatic patients with ECG- or Holter-documented PSVTs who underwent the ESPA/M in our department between May 2011 and March 2018 was performed. A telephone questionnaire was conducted for follow-up. Recurrence was based on preprocedural symptoms and/or ECG documentation. Results 152 (5%) out of 3018 Slow pathway ablation /modification (SPA/M) procedures were identified as the ESPA/M. The mean age of the study population was 51 (range = 16–82) years, and 62% of the subjects were female. Thirty-eight (25%) patients had a atrium-His (AH) jumps only, 90 (59.2%) had AH jumps plus a single or 2 atrioventricular nodal echo beats (AVNEBs), 17 (11.2%) had a single or 2 AVNEBs without AH jumps, and 7 (4.6%) had no AH jumps or AVNEBs by programmed electrical stimulation at baseline. During a mean follow-up period of 43 months (6–81 mon), 92% of the patients benefited from the procedure (full elimination of symptoms in 80.3% and an improvement in clinical symptoms in 11.7%). The symptomatic recurrence rate, defined as preprocedural symptoms and any documented arrhythmia due to an SVT, was 8.1% (11 patients). Conclusions The ESPA/M can be performed safely and effectively in patients with documented but noninducible AVNRTs with good long-term results.

The evolution of mapping and ablation techniques in the treatment of atrial tachycardias occurring after atrial fibrillation ablation.

A possible consequence of atrial fibrillation (AF) ablation is the occurrence of organized atrial tachycardias (ATs). ATs after AF ablation (ATAAF) may be more symptomatic than AF itself, thus necessitating catheter ablation. We evaluated the prognostic significance of clinical and invasive characteristics for long-term sinus rhythm (SR) maintenance following ATAAF ablation and assessed the effect of technological developments on these results. Fifty-six consecutive patients with symptomatic ATAAF participated in the study and 114 ATAAF were revealed (2.04 ± 0.93 per patient). Sixty-eight ATAAF (60%) were macroreentrant and 33 (29%) were microreentrant circuits, while 13 (11%) were focal automatic tachycardias. The mean follow-up was 40 ± 18months with 34 (61%) patients maintaining SR. Treatment with contact force (CF) catheters and EnSite AutoMap module (n = 11) showed significantly better AT/AF free rates at 1-year follow-up (10/11, 91%) compared with treatment using CF catheters but not AutoMap module (n = 13) (8/13, 62%) and treatment with use of neither of these modalities (n = 32) (16/32, 50%). Among patients with macroreentrant circuits around the mitral annulus or left atrial roof (n = 38), the group treated with complete linear lesions in anatomical isthmuses (n = 25) showed significantly better SR maintenance (19/25, 76%) compared with patients (n = 13) treated by empirical ablation in critical functional areas (6/13, 46%). Technology advancement contributes substantially to long-term success in SR maintenance, by achieving detailed mapping and more effective ablation of ATAAF. The targeting of macroreentrant circuits by creating anatomical linear lesions appears to provide better results.

Clinical Usefulness of Computational Modeling-Guided Persistent Atrial Fibrillation Ablation: Updated Outcome of Multicenter Randomized Study.

ObjectiveCatheter ablation of persistent atrial fibrillation (AF) is still challenging, no optimal extra-pulmonary vein lesion set is known. We previously reported the clinical feasibility of computational modeling-guided AF catheter ablation.MethodsWe randomly assigned 118 patients with persistent AF (77.8% men, age 60.8 ± 9.9 years) to the computational modeling-guided ablation group (53 patients) and the empirical ablation group (55 patients) based on the operators’ experience. For virtual ablation, four virtual linear and one electrogram-guided lesion sets were tested on patient heart computed tomogram-based models, and the lesion set with the fastest termination time was reported to the operator in the modeling-guided ablation group. The primary outcome was freedom from atrial tachyarrhythmias lasting longer than 30 s after a single procedure.ResultsDuring 31.5 ± 9.4 months, virtual ablation procedures were available in 95.2% of the patients (108/118). Clinical recurrence rate was significantly lower after a modeling-guided ablation than after an empirical ablation (20.8 vs. 40.0%, log-rank p = 0.042). Modeling-guided ablation was independently associated with a better long-term rhythm outcome of persistent AF ablation (HR = 0.29 [0.12–0.69], p = 0.005). The rhythm outcome of the modeling-guided ablation showed better trends in males, non-obese patients with a less remodeled atrium (left atrial dimension < 50 mm), ejection fraction ≥ 50%, and those without hypertension or diabetes (p < 0.01). There were no significant differences between the groups for the total procedure time (p = 0.403), ablation time (p = 0.510), and major complication rate (p = 0.900).ConclusionAmong patients with persistent AF, the computational modeling-guided ablation was superior to the empirical catheter ablation regarding the rhythm outcome.Clinical Trial RegistrationThis study was registered with the ClinicalTrials.gov, number NCT02171364.

Arrhythmia Mechanisms and Outcomes of Ablation in Pediatric Patients With Congenital Heart Disease.

In contrast to the adult population with congenital heart disease (CHD), arrhythmia mechanisms and outcomes of ablation in pediatric patients with CHD in recent era have not been studied in detail. Aims of this study were to determine arrhythmia mechanisms and to evaluate procedural and long-term outcomes in pediatric patients with CHD undergoing catheter ablation. Consecutive patients <18 years of age with CHD undergoing catheter ablation over an 11-year period (2007-2018) were included. Procedural outcome included complete or partial success, failure or empirical ablation. Long-term outcome included arrhythmia recurrence and burden according to a 12-point clinical arrhythmia severity score. The study population consisted of 232 patients (11.7 years [0.01-17.8], 33.5 kg [2.2-130.1]). The most common diagnoses were Ebstein's anomaly (n=44), septal defects (n=39), and single ventricle (n=36). Arrhythmia mechanisms included atrioventricular reentry tachycardia (n=104, 90 patients), atrioventricular nodal reentry tachycardia (n=33, 29 patients), twin atrioventricular nodal tachycardia (n=3, 2 patients), macroreentrant atrial tachycardia (n=59, 56 patients), focal atrial tachycardia (n=33, 25 patients), ventricular ectopy (n=10, 8 patients), and ventricular tachycardia (n=15, 13 patients). Fifty-six arrhythmias (39 patients) were undefined. Outcomes included complete success (n=189, 81%), partial success (n=7, 3%), failure (n=16, 7%), or empirical ablation (n=20, 9%). Over 3.6 years (0.3-10.7) arrhythmia recurred in 49%. Independent of arrhythmia recurrence, arrhythmia scores decreased from 4 (0-10) at baseline to 0.5 (0-8) at 4 years follow-up (P<0.001). In 23/51 repeat procedures (45%), a different arrhythmia substrate was found. Overall adverse event rate was 9.4%, although only 1.6% (n=4) were of major severity and 0.8% (n=2) of moderate severity. Pediatric patients with CHD demonstrate a broad spectrum of arrhythmia mechanisms. Despite recurrence and emergence of novel mechanisms after a successful procedure, ablation can be performed safely and successfully resulting in decreased arrhythmia burden.

Clinical Usefulness of Simulation-Guided Catheter Ablation of Atrial Fibrillation: Updated Outcome of a Multicenter Prospective Randomized Study

Background: Catheter ablation of persistent atrial fibrillation (AF) is still challenging and is characterized by a significant AF recurrence rate; however, no optimal extra-pulmonary vein lesion set is known. We previously reported the clinical feasibility of in silico simulation-guided AF catheter ablation. Methods: We randomly assigned 118 patients with persistent AF (77.8% men, age 60.8 ± 9.9 years) to the simulation-guided ablation group (53 patients) and the empirical ablation group (55 patients) based on the operators' experience. For in silico ablation, four virtual linear and one electrogram-guided lesion sets were tested on patient heart computed tomogram-based models, and the lesion set with the fastest termination time was reported to the operator in the simulation-guided ablation group. The primary outcome was freedom from atrial tachyarrhythmias lasting longer than 30 seconds after a single procedure. The duration of the follow-up was 31.5 ± 9.4 months. Findings: Virtual in silico ablation procedures were successful in 95.2% of the patients (108/118). The clinical recurrence rate was significantly lower after a simulation-guided ablation than after an empirical ablation (20.8% vs. 40.0%, log-rank p = 0.042). Simulation-guided ablation was independently associated with a better long-term rhythm outcome of persistent AF ablation (HR = 0.29 [0.12-0.69], p = 0.005). The superiority of the rhythm outcome of the simulation-guided ablation was more significant in males, non-obese patients with a less remodeled atrium (left atrial dimension <50 mm), ejection fraction ≥ 50%, and those without hypertension or diabetes (p <0.01). There were no significant differences between the groups for the total procedure time (p = 0.403), ablation time (p = 0.510), and major complication rate (p = 0.900). Interpretation: Among patients with persistent AF, the simulation-guided ablation was superior to the empirical catheter ablation regarding the rhythm outcome. Trial Registration Number: This study was registered with the ClinicalTrials.gov number NCT02171364 Funding Statement: This work was supported by a grant [HI18C0070] from the Korea Health 21 R&D Project, Ministry of Health and Welfare and a grant [NRF-2017R1A2B4003983] from the Basic Science Research Program run by the National Research Foundation of Korea (NRF), which is funded by the Ministry of Science, ICT & Future Planning (MSIP). Declaration of Interests: The authors declare that they have no conflicts of interest. Ethics Approval Statement: The study protocol adhered to the Declaration of Helsinki and was approved by the institutional review board of each participating center. Written informed consent was obtained from all patients.

Cardiac spiral wave drifting due to spatial temperature gradients – A numerical study

Cardiac rotors are believed to be a major driver source of persistent atrial fibrillation (AF), and their spatiotemporal characterization is essential for successful ablation procedures. However, electrograms guided ablation have not been proven to have benefit over empirical ablation thus far, and there is a strong need of improving the localization of cardiac arrhythmogenic targets for ablation. A new approach for characterize rotors is proposed that is based on induced spatial temperature gradients (STGs), and investigated by theoretical study using numerical simulations. We hypothesize that such gradients will cause rotor drifting due to induced spatial heterogeneity in excitability, so that rotors could be driven towards the ablating probe. Numerical simulations were conducted in single cell and 2D atrial models using AF remodeled kinetics. STGs were applied either linearly on the entire tissue or as a small local perturbation, and the major ion channel rate constants were adjusted following Arrhenius equation. In the AF-remodeled single cell, recovery time increased exponentially with decreasing temperatures, despite the marginal effect of temperature on the action potential duration. In 2D models, spiral waves drifted with drifting velocity components affected by both temperature gradient direction and the spiral wave rotation direction. Overall, spiral waves drifted towards the colder tissue region associated with global minimum of excitability. A local perturbation with a temperature of T = 28 °C was found optimal for spiral wave attraction for the studied conditions. This work provides a preliminary proof-of-concept for a potential prospective technique for rotor attraction. We envision that the insights from this study will be utilize in the future in the design of a new methodology for AF characterization and termination during ablation procedures.

Activation Mapping With Integration of Vector and Velocity Information Improves the Ability to Identify the Mechanism and Location of Complex Scar-Related Atrial Tachycardias

Activation mapping of scar-related atrial tachycardias (ATs) can be difficult to interpret because of inaccurate time annotation of complex electrograms and passive diastolic activity. We examined whether integration of a vector map can help to describe patterns of propagation to better explain the mechanism and location of ATs. The investigational mapping algorithm calculates vectors and applies physiological constraints of electrical excitation in human atrial tissue to determine the arrhythmia source and circuit. Phase I consisted of retrospective evaluation in 35 patients with ATs. Phase II consisted of prospective validation in 20 patients with ATs. Macroreentry was defined as a continuous propagation in a circular path >30 mm; localized reentry was defined as a circular path ≤30 mm; a focal source had a centrifugal spread from a point source. In phase I, standard activation mapping identified 28 of 40 ATs (70%): 25 macroreentry and 3 focal tachycardias. In the remaining 12 ATs, the mechanism and location could not be identified by activation and required entrainment or empirical ablation for termination (radiofrequency time, 17.3±6.6 minutes). In comparison, the investigational algorithm identified 37 of 40 (92.5%) ATs, including 5 macroreentry, 3 localized reentry, and 1 focal AT not identified by standard mapping. It also predicted the successful termination site of all 37 of 40 ATs. In phase II, the investigational algorithm identified 12 macroreentry, 6 localized reentry, and 2 focal tachycardias that all terminated with limited ablation (3.2±1.7 minutes). It identified 3 macroreentry, 3 localized reentry, and 1 focal AT not well characterized by standard mapping. The diagnosis of localized reentry was supported by highly curved vectors, resetting with increasing curve and termination with limited ablation (22±6 s). Activation mapping integrating vectors can help determine the arrhythmia mechanism and identify its critical components. It has particular value for identifying complex macroreentrant circuits and for differentiating a focal source from a localized reentry.

Long-Term Clinical Comparison of Procedural End Points After Pulmonary Vein Isolation in Paroxysmal Atrial Fibrillation: Elimination of Nonpulmonary Vein Triggers Versus Noninducibility.

Pulmonary vein isolation (PVI) is effective for maintenance of sinus rhythm in 50% to 75% of patients with paroxysmal atrial fibrillation, and it is not uncommon for patients to require additional ablation after PVI. We prospectively evaluated the relative effectiveness of 2 post-PVI ablation strategies in paroxysmal atrial fibrillation. A total of 500 patients (mean age, 55.7±11.0 years; 74.6% male) were randomly assigned to undergo ablation by 2 different strategies after PVI: (1) elimination of non-PV triggers (group A, n=250) or (2) stepwise substrate modification including complex fractionated atrial electrogram or linear ablation until noninducibility of atrial tachyarrhythmia was achieved (group B, n=250). During a median follow-up of 26.0 months, 75 (32.2%) patients experienced at least 1 episode of recurrent atrial tachyarrhythmia after the single procedure in group A compared with 105 (43.8%) patients in group B (P value in log-rank test of Kaplan-Meier analysis: 0.012). Competing risk analysis showed that the cumulative incidence of atrial tachycardia was significantly higher in group B compared with group A (P=0.007). With the exception of total ablation time, there were no significant differences in fluoroscopic time or procedure-related complications between the 2 groups. Elimination of triggers as an end point of ablation in patients with paroxysmal atrial fibrillation decreased long-term recurrence of atrial tachyarrhythmia compared with a noninducibility approach achieved by additional empirical ablation. The post-PVI trigger test is thus a better end point of ablation for paroxysmal atrial fibrillation.