Predictor Of Atrial Fibrillation Recurrence Research Articles

Incidence, types, and predictors of AF recurrence after AF ablation with pulsed field ablation. A single-centre experience

Abstract Background Pulsed field ablation (PFA) is an emerging method for the ablation of atrial fibrillation (AF). As there are few data on incidence, types, and predictors of AF recurrence after PFA for AF ablation, we are continuously analysing our cohort. Methods We report our outcome data after PVI with PFA. Each procedure was performed under deep sedation with propofol and fentanyl. Before transeptal puncture, unfractionated heparin was administered to maintain an ACT level >300sec throughout the procedure. Isolation of pulmonary veins was started after administration of 1mg of atropine with 8 applications per vein (4 in basket, 4 in flower configuration). In recent months we have routinely performed 2 additional ablations in flower configuration with an anterior twist at both right pulmonary veins. All veins were checked for entrance- and exitblock to confirm isolation in sinus rhythm. An additional ablation was performed if necessary. Results In total, 231 patients were analysed. Mean age was 62±10 years, 38% were female. Mean CHADS-VASc score was 2±1. 61% had paroxysmal AF (PAF), 36% persistent AF, and 3% patients had long-standing persistent AF. In 85% (n=197) first-pass isolation of all veins was possible. Primary PV isolation was achieved in all patients at the end of the procedure. In addition to PVI, the cavo-tricuspid isthmus (CTI) was blocked in 6% (using radiofrequency ablation in case of previously or during the procedure documented typical flutter) and the posterior wall was isolated in another 6% during the first procedure. Mean procedure time was 60±20 minutes (24-175 minutes), mean X-ray time 19±9 minutes. In 231 procedures, only two catheter-associated complications were documented. 38 patients (16%) had arrhythmia recurrence after a blanking period of 3 months and a mean follow-up of 273±177 days. Mean time to recurrence was 171±84 days. Women were more likely to have recurrences [OR 2.042 (CI 95% 1.012-4.121), p<0,05]. Patients who had undergone any type of cardiac surgery prior to ablation were also significantly more likely to have recurrence [OR 0.517 (CI 95% 0.116-0.212); p<0.001]. Patients with no other comorbidities were more likely to remain free from arrhythmias [OR 0.792 (95% CI 0.736-0.853); p<0,01]. The type of AF did not make a significant difference according to the risk of recurrence in this cohort. To date, we have performed 18 re-do procedures in patients after PVI with PFA. The recurrent arrhythmia was AF in 39% (n=7), atypical AT in 50% (roof-dependent: 28%, n=5; mitral isthmus dependent: 22%, n=4), and CTI-dependent flutter in 39% (n=7). All but one patient had PV reconnections, and all were successfully reablated. Conclusion PFA success rate is similar to that of thermal techniques. Procedure time is shorter in experienced operators and the complication rate is low in our cohort. Results from RCTs are needed to further evaluate this new method compared to other ablation techniques.

Characterisation of ablation strategies at redo catheter ablation for atrial fibrillation and predictors of arrhythmia recurrence: results from the AFREDO registry

Abstract Background Patients who have undergone prior pulmonary vein isolation (PVI) for atrial fibrillation (AF) often require a repeat ablation for AF recurrence. The optimal ablative strategy for the redo procedure and predictors of AF recurrence thereafter remain largely unknown. Purpose We aimed to characterise the ablation strategies applied at re-PVI and identify possible predictors of AF recurrence. Methods Our single-centre, retrospective study included all consecutive patients who underwent first redo PVI at our centre from 2017 to 2022. Inclusion criteria required at least one available follow-up visit within the first 12 months after the redo procedure. Ablation strategies of the initial and redo procedure were captured. Kaplan-Meier curves were used to illustrate time of AF recurrence, as classified by predictors of outcome determined by multivariable regression analyses. Results We included 215 patients (39.1% female) with a median age of 66.6 years (IQR 58.6-73.2) at the time of redo procedure. The initial PVI was cryoablation in 39.9%, RFA in 57.7% and surgical ablation in 2.4%. After the initial procedure, 55.8% had paroxysmal AF and 44.2% had persistent AF. At the redo procedure, 25.1% of patients were found to have no PV reconnection, whereas 20.5% had a single reconnected PV, and 54.4% had two or more reconnected PVs. A left-sided flutter ablation was performed in 18.8%, a left atrial (LA) roof line in 16.9%, a posterior mitral isthmus line in 5.2%, an anterior mitral isthmus line in 27.9%, and a posterior box lesion in 8.4%. Overall, 34.4% of patients showed areas of low-voltages in the redo procedure. Patients with areas of low voltages were less likely to have any reconnected PVs in the redo-procedure (p<0.001). After the second ablation procedure, 54.0% experienced AF recurrence. Univariable regression analysis revealed moderate (p=0.006) or severe (p= 0.015) LA dilatation, persistent AF (p=0.005), and posterior LA low voltage areas (p=0.011) as significant predictors of AF recurrence after the redo procedure. The number of reconnected PVs at the re-PVI did not predict AF recurrence (p=0.1090). As illustrated in Fig. 1 and 2, patients with paroxysmal AF experienced less AF recurrence compared to those with persistent AF (log-rank p=0.0025). Moreover, moderate or severe LA dilatation at baseline was associated with more frequent AF recurrences (log-rank p=0.0279). Conclusion A significant proportion of patients undergoing re-PVI experienced AF recurrence. We found that persistent AF and moderate or severe LA enlargement emerged as significant predictors of AF recurrence after the redo procedure. Although PV reconnection was observed in more than two thirds of patients at the re-PVI, it did not predict AF recurrence thereafter. However, patients without PV reconnection had significantly more low-voltage areas, which may be indicative of a different AF recurrence mechanism in this subgroup.Figure 1:Type of AFFigure 2:LA dilatation

Electrophysiological findings, incidence, and predictors for AF recurrence after pulsed field versus radiofrequency pulmonary vein isolation. A retrospective analysis

Abstract Background Pulsed field ablation (PFA) is an emerging method for catheter ablation of atrial fibrillation (AF). Data comparing efficacy and safety of PFA compared to thermal ablation is still scarce. In this study, we compared a cohort of patients who underwent PFA with those who received very high power short duration (vHPSD) radiofrequency catheter ablation at the University Hospital Graz. Methods We analysed baseline data from both cohorts (PFA: n=231; RF: n=243). Both procedures were performed under deep sedation, using propofol and fentanyl. The PFA procedure involved 2x2x2 pulses, with additional pulses as required. RF procedures were performed using the QDOT Micro catheter to deliver 90 watts of energy over 4 seconds. Statistical analysis was performed using IBM SPSS Statistics for Windows, version 29. The Kruskal-Wallis test was used for quantitative non-parametric data in the baseline analysis, and the Man-Whitney-U test was used for quantitative non-parametric procedural data. For qualitative variables the Chi-squared test was used. A p-value of less than 0,05 was considered significant. Results Both groups were similar, apart from chronic heart failure, which was more prevalent in the RF group (p=0.003). Mean age for both groups was 62±10 years and mean body mass index did not differ as well. CHADS-VASc score was 2±2 in the RF and 2±1 in the PFA group (p=0.7). The types of AF were distributed as follows: (RF vs.PFA): PAF: 64%/61%; persAF: 34/36%; long standing persAF: 2%/3%. As to this date performing a CTI line with PFA is off-label, a significantly higher number of patients with additional flutter were ablated in the RF group. In the RF-group, 91 patients underwent additional cavotricuspid isthmus ablation, compared to only 14 patients in the PFA group (p<0.001). Procedural time (RF:PFA 122±min:57±26min; p<0.001), fluoroscopy time (RF:PFA 15±9min:19±9min; p<0.001) and fluoroscopy dose (RF:PFA 17±40Gycm2:15±15Gycm2, p=0.026) showed significant differences, with procedural time and fluoroscopy dose presenting lower values in the PFA group. First pass isolation was achieved more frequently in the PFA group (85% vs. 57%; p<0,001). There was significant difference in recurrence rates between the vHPSD and PFA groups (RF: 56/242 (28%), PFA: 38/231 (17%); p=0.005). Additionally, time to recurrence in the RF group was 138±117 days, compared to 166±84min in the PFA group. We exclude operator dependence as the same operators performed both procedures. Conclusion Based on our findings, PFA could potentially become the standard procedure for many patients. However, randomized trials are needed to confirm these findings.

Different predictors of AF recurrence after pulmonary vein isolation with cryoballoon and radiofrequency ablation: insights from clinical and electroanatomical mapping data of the NO-PERSAF study

Abstract Background Pulmonary vein isolation (PVI) with cryobaloon ablation (CBA) and radiofrequency ablation (RFA) lead to a similar outcome of freedom from atrial tachyarrhythmia (ATA) during follow-up as showed by the NO-PERSAF study. Analyses of ATA recurrence for these two techniques based on data of electroanatomical mapping (EAM) are scarce from randomized clinical trials. Purpose This study aimed to evaluate and compare clinical outcomes and EAM data recorded in the left atrium (LA) during CBA and RFA procedures in patients with persistent atrial fibrillation (AF). Methods For the NO-PERSAF study, 101 patients (mean 63.2±8.6 years, 80 male, 21 female) with persistent AF (77 persistent AF, 24 long-standing persistent AF) referred to PVI were randomized (1:1) to CBA or RFA and followed for 12 months. A prolonged 3-year follow-up was carried out. EAM was performed by a circular mapping catheter with a 3-dimensional mapping system in all patients. EAM data were recorded and analyzed off-line. The areas of the LA, posterior wall, low-voltage (<0.5mV) and complex fractionated electrogram (cycle length <120 ms) were measured and corrected by body surface area (BSA). EAM data from 90 patients were qualified for further analysis and the others (5 in CBA and 6 in RFA) excluded because of disqualification or technical failure of recording. Correlation between clinical results of 3-year follow-up and the EAM data were analyzed using univariate cox regression. Results After 3-year follow-up, freedom from ATA was achieved in 51 (50.5%) of the 101 patients, 28 (54.9%) out of 51 patients in the CBA group and 23 (46.0%) out of 50 patients in the RFA group and no difference was found (p=0.327). RFA compared with CBA resulted in larger ablation lesions in the LA (23.9% vs. 21.3%; p=0.037) and particularly in the posterior wall (44.2% vs 31.8%; p<0.001). Compared between the patients with and without recurrence, there was no difference with respect to age, gender, AF history, body mass index, heart disease and CHA2DS2-vasc score. For EAM data, the area of the LA and low voltage were significantly higher in ATA recurrent patients in CBA group, but not in RFA group (Table 1). Univariate cox regression analyses suggested that 3-year follow-up outcomes were associated with the size of the LA and the amount of low voltage corrected by BSA. The criteria of the LA area >55 cm2/m2 or low voltage area <19 cm2/m2 could predict ATA recurrence after CBA, but not after RFA procedure (Figure 1). Conclusions The size of the LA and the amount of low voltage corrected by BSA was associated with the outcomes of PVI during follow-up and could be employed as predictors of ATA recurrence for CBA, but not for RFA procedure.Table 1Figure 1K-M curves after CBA and RFA

Machine learning for outcome prediction of atrial fibrillation recurrence after catheter ablation

Abstract Background Outcome prediction after catheter ablation for atrial fibrillation (AF) based on electronic health records (EHR) using machine learning (ML) is not yet established. Purpose The aim of the study was to assess the value of ML methods to predict the risk of AF recurrence after catheter ablation based on easily accessible EHR. Methods We analyzed 1362 patients from our prospective registry. Only patients undergoing a first AF ablation were studied. Follow-up was performed at 3, 6 and 12 months after the ablation including 24-hour and 7-day Holter electrocardiogram (ECG). Four different analyses with increasing complexity out of a set of overall 22 features using seven simple and three ensemble method ML algorithms were performed: model 1 (including age, sex, height, weight, and established anamnestic risk factors: AF-type, coronary artery disease, myocardial infarction, stroke, heart failure, hypertension, current smoker, diabetes, renal insufficiency), model 2: model 1 plus additional AF-history features (duration of AF in months, previous typical atrial flutter, number of previous electrical cardioversions, number of failed antiarrhythmic drugs), model 3: model 2 plus simple echocardiographic parameters (left ventricular ejection fraction, LA diameter), model 4: model 3 plus biomarkers (CRP, creatinine, NTproBNP). To evaluate the performance of the prediction, we report C-statistics, accuracy, and recall (sensitivity). The C-statistics of five risk scores for AF recurrence (APPLE, DR-FLASH, BASE-AF2, ATLAS, CHA2DS2-Vasc) and a logistic regression with a forward selection were calculated for comparison. Results Of the 1362 patients, 996 (73%) were male, mean age was 62±10 years and 60% presented with paroxysmal AF. Recurrence of AF during 1-year follow-up was observed in 458 patients (34%). The results for the four models using the eleven different ML algorithms are summarized in the Figure. In detail, the C-statistics were modest with a maximal value of 0.602 for the random forest (RF) classifier for the most complex model 4. The performance for the risk scores was maximal for the APPLE score (C-statistics 0.572) and comparable for the forward-selection logistic regression including five features with a C-statistics of 0.607 (95% CI 0.573-0.641). Conclusion In conclusion, outcome prediction of AF recurrence after catheter ablation with easily accessible EHR data remains challenging and cannot be improved simply by applying machine learning methods. Whether a more comprehensive feature selection, such as more complex ECG parameters instead of the selection of easily available features from the EHR, a combination with deep neural network-based feature extraction, or unsupervised ML might improve the result in a clinically relevant way needs further investigation.Results of the eleven ML algorithms

Adherence to CLOSE protocol, high-power and low baseline generator impedance predicts durable pulmonary vein isolation

Abstract Background Atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) is predominantly attributed to pulmonary vein reconnection (PVR). Predictors of AF recurrence were widely studied. However, data are scarce on the procedural parameters that predict chronic PVR. Aims to study the PVR rates and the predictors of PVR after initial PVI procedure. Methods We included 100 consecutive patients who underwent repeated ablation due to AF recurrence after initial PVI with the CARTO system, both procedures performed between 2018 and 2023. Results The mean age of the patients was 60 ± 12 years, 36% were female, and 44% had persistent AF. Thirty-eight patients underwent initial CLOSE-guided, and sixty-two underwent initial non-CLOSE PVI. Repeat procedure was performed 21 ± 14 months after the initial procedure. In total, PVR was found in 192 of 373 PVs (51.5%) and all PVs were isolated in 17/100 (17%) patients. Factors associated with all PVs being isolated were adherence to the CLOSE protocol (39.5% vs. 3.5%, p < 0.0001), higher delivered mean power (37.5W vs 30W, p = 0.027), presence of first-pass isolation (88.2% vs 40.4%, p = 0.0007), and lower baseline generator impedance (127.6 vs 136.6 Ω, p = 0.0027; respectively). Baseline generator impedance >130 Ω (AUC = 0.7403, sensitivity: 77.1%, specificity: 68.8%, p = 0.0032) was associated with significantly higher probability of PVR (OR = 6.757; p < 0.0001). Conclusions Our findings indicate that adherence to the CLOSE protocol, higher power setting, first-pass isolation, and baseline generator impedance <130 Ω during AF ablation improves the durability of PVI and reduces the incidence of PVR.

Post-ablation atrial arrhythmogenic channels predict atrial fibrillation recurrence - iatrogenic substrate revisited

Abstract Background Fibrosis is a hallmark of atrial fibrillation (AF) arrhythmogenic substrate, and the extent of atrial fibrosis, as determined by late gadolinium enhancement (LGE)-MRI, predicts AF recurrence after ablation. However, ablation fundamentally alters the individual composition of fibrotic tissue, and inhomogeneous ablation lesions may constitute an arrhythmogenic substrate themselves. From ventricular arrhythmias (VA) we know that it is not the extent of scar tissue that determines arrhythmogenicity, but rather the scar-pervading channels of surviving tissue with residual conduction. Purpose To investigate post-ablation arrhythmogenic substrate in terms of atrial scar channels using LGE-MRI. Methods Patients with PVI-only AF ablation were included. All patients received a systematic 12-months follow-up and an LGE-MRI 3 months post-ablation. Scar channels were defined as corridors of borderzone tissue (residual conduction), protected by dense scar. Channels were automatically identified using a software algorithm that has been extensively validated in the ventricle and was now adapted for the atrium. To differentiate healthy tissue, borderzone and dense scar, LGE was quantified based on the signal intensity ratios of each voxel relative to the blood pool. Signal intensity ratio thresholds defining dense scar and borderzone, were then empirically tested to enhance the predictive value of the identified channels. The algorithm was then applied to an independent validation cohort using the empirically determined thresholds. Results 150 patients were included. 10 different combinations of signal intensity ratio thresholds defining borderzone tissue and dense scar were empirically tested regarding the prediction of potentially arrhythmogenic channels in 50 patients (derivation cohort). For each of the threshold combinations, the number of predicted channels was linked to 12-months arrhythmia-free survival using logistic regression. The computed channels best predicted 12-months arrhythmia recurrence, when based on signal intensity ratios of 1.1-1.32 (borderzone) and >1.32 (dense scar). This threshold combination was then validated in an independent cohort of 100 patients. Patients with scar channels had significantly lower arrhythmia-free survival than those without (55% vs. 88%, p=0.016, Fig. 1). The number of detected scar channels was predictive of 12-months arrythmia recurrence (OR 4.9; p=0.012) – independent of other factors like LA diameter, AF type or the extent of native atrial fibrosis (pre-ablation LGE-MRI). Of note, the number of gaps in the PV-encircling lesions was not predictive of AF recurrence. Conclusions LGE-MRI-detected post-ablation scar channels predict recurrent AF after PVI and may be a surrogate of iatrogenic substrate. In light of large-area ablations with PFA and other single-shot devices fueling a trend towards more and more extensive lesions, the concept of iatrogenic arrhythmogenic substrate may have to be reconsidered.

Preprocedural atrial fibrillation burden is associated with recurrence in patients undergoing atrial fibrillation ablation: findings from the ISOLATION AF Ablation Cohort Study

Abstract Background Non-invasive quantification of electrophysiological properties of the atria is increasingly used for outcome prediction in atrial fibrillation (AF) patients. Data on the benefit of the current classification of AF compared to AF burden based on single lead ECG measurements to predict AF recurrences are scarce. Objective This study sought to assess the predictive performance of low versus high AF burden compared to the conventional AF classification for predicting recurrences after AF catheter ablation. Methods A cross-sectional analysis was conducted in AF patients scheduled for catheter ablation included in the prospective multicenter ISOLATION cohort study between July 2020 and November 2022. Clinical characteristics, routine tests, blood tests and rhythm monitoring through single lead ECGs were collected prior to ablation. ECGs were recorded three times daily for four weeks, with additional measurements in case of the onset or relief of symptoms. The primary endpoint was "ablation success" defined as freedom from documented arrhythmia after the blanking period. Of 650 included patients, pre-procedural rhythm monitoring was available in 580. 261 patients had at least 14 days of ECG measurements and completed 12 months of follow-up. In these patients, we compared the recurrences after 12 months between paroxysmal and persistent AF and high versus low AF burden through survival analysis. Maximally selected rank statistics were used to determine the best cut-off value for AF burden. Results In 261 patients, the mean age was 64 ± 9 years, and 33.7% were female. Physicians classified 170 patients (65.1%) as paroxysmal AF and 91 (34.9%) as persistent AF based on medical history. The AF burden is shown in Figure 1. The optimal calculated cut-off value for AF burden was 42%. Out of 170 patients with paroxysmal AF, 17 (10%) had a burden of > 42%. Of the 91 patients with persistent AF, 35 (38%) had a burden of < 42%. After 12 months, a significant difference in recurrences was observed between patients with paroxysmal AF versus persistent AF (p= 0.015). Patients with high AF burden, had more recurrences after 12 months, than patients with a low AF burden (p= 0.006) (Figure 2). Conclusion Our preliminary results suggest that the addition of a new classification of AF based on burden might provide additional benefit in predicting AF recurrences after catheter ablation compared to the current existing classification and may improve prognostication. Completion of patient follow-up is necessary to determine the predictive value of AF burden derived from single lead ECGs for the prediction of AF recurrence.Figure 2.

Impact of pulmonary vein variant anatomy during cryo-ablation in paroxysmal and persistent AF patients: 1-year outcome from a nationwide multicenter clinical setting

Abstract Background Complete electrical pulmonary vein isolation (PVI) by cryo-balloon approach is a well-established ablation strategy of atrial fibrillation (AF). While contrast findings exist regarding the influence of variant pulmonary vein (PV) anatomy on predicting AF recurrence, limited data are currently available specifically for cases involving the POLARx cryoablation system during PVI. Purpose We report the real-world experience of POLARx in the context of de novo AF ablation in a multicenter Italian registry. Methods Consecutive patients undergoing AF ablation from the CHARISMA registry at 10 Italian centres were included. Protocol-directed cryoablation was delivered for 180 sec or 240 sec according to operator’s preference for isolation achieved in ≤60 sec, or 240 sec if isolation occurred >60 sec or when time to isolation was not available. The ablation endpoint was PVI as assessed by entrance and exit block. All patients were followed-up for at least 12 months after the procedure. Results Four-hundred twenty-nine patients were included (n=358, 83.4% paroxysmal AF, n=71, 16.6% persistent AF, mean age 60.7±10 years, 28.3% female, mean LVEF 58±8%). PVI was achieved in all pts using only cryoablation. Twenty-eight (6.6%) patients exhibited an anatomical variant: 17 (4.0%) a common ostium and 11 (2.6%) an adjunctive PV. The mean number of freeze applications per patient was 5.1 (1.2 for LSPV, 1.3 for LIPV, 1.2 for RSPV and 1.3 for RIPV). Over a median of 398[370-461] days of follow-up, 14 (3.2%) patients experienced an early recurrence of AF during the 90-day blanking period. Overall, 63 patients (14.7%) suffered an AF recurrence after the 90-day blanking period (median time to recurrence 342[171-381] days). The proportion of patients exhibiting AF/AT recurrences was higher in the persistent AF group (17 out 71, 23.9%) than in the paroxysmal AF group (46 out 358, 12.8%, p=0.026), with a hazard ratio of 2.02 (95%CI: 1.2 to 3.5, p=0.0137) whereas patients with anatomy variant showed a similar AF/AT recurrence rate (5 out 28, 17.9%) than in the standard anatomy group (58 out of 401, 14.5%) with a hazard ratio of 1.43 (0.6 to 3.6, p=0.441). Four (0.9%) transient phrenic nerve palsy were observed, both with full recovery in the 48-h post procedure; no major procedure-related adverse events were reported. Conclusion In this multicenter study, the cryo-balloon system demonstrated safety and efficacy in treating both paroxysmal and persistent AF patients, yielding a low incidence of AF/AT recurrence during follow-up, regardless of the presence of variant PV anatomy.

Predicting atrial fibrillation recurrence after catheter ablation using an artificial intelligence-enabled electrocardiogram algorithm

Abstract Introduction Predicting atrial fibrillation (AF) recurrence post catheter ablation may help to assess procedural eligibility and determine AF management. While several predictors of AF recurrence post ablation have been established and numerous clinical risk scores have been proposed, their performance remained underwhelming and clinical utility was limited. Hence, new predictors are needed. Artificial intelligence (AI) algorithms using deep neural networks (DNN) to analyze biometrical data might generate such predictors. DNN algorithms have been developed to identify patients with AF based on a 12-lead electrocardiogram (ECG) in sinus rhythm. Whether these algorithms can function as a predictor of AF recurrence after AF ablation remains unknown. Purpose To evaluate the prediction of AF recurrence after ablation using an AI-enabled ECG algorithm trained to predict AF on an ECG in sinus rhythm. Methods This study retrospectively analyzed observational data from the DIGITOTAL study, that monitored AF recurrence with a PPG-based smartphone application in 96 subjects after AF ablation. Patients with a 12-lead ECG in SR available within a timeframe of 3 months before the ablation procedure were included in the analysis. Although all patients had a history of AF, an AF-risk score was calculated by the DNN described elsewhere.1 Results An ECG in sinus rhythm was available in 53 patients (14 women [26.4%]; mean [SD] age, 62.0 [9.7] years) out of the 96 patients followed-up in the DIGITOTAL study. Testing the DNN on the last ECG before the ablation procedure resulted in an area under the receiver operating curve (AUC) of 0.65 (95% CI, 0.49 - 0.80), and an area under the precision recall curve (AUPRC) of 0.56 (95% CI, 0.34 - 0.78). The optimal cutoff score resulted in a sensitivity of 60.0% (95% CI, 36.1% - 80.9%), specificity of 66.7% 66.7% (95% CI, 48.2% - 82.0%), accuracy of 0.64 (95% CI, 0.50 - 0.77), F1-score of 55.8% (95% CI, 38.5% - 74.4%), positive predictive value 52.2% (95% CI, 30.6% - 73.2%) and negative predictive value 73.3% (95% CI, 54.1% - 87.7%). Patients classified in the high-risk group versus low-risk group were more likely to exhibit AF recurrence up to one year after AF ablation (hazard ratio, 2.6; 95% CI, 1.1 - 6.5; P-value = 0.037). Conclusions The AI-enabled ECG algorithm, trained to predict AF on a sinus rhythm ECG, was able to predict AF recurrence after ablation with an accuracy comparable to the existing clinical risk scores. Further studies are needed to determine whether the DNN score can be used as an independent predictor and improve existing risk scores.

Left atrial wall thickness measured by a machine learning method predicts AF recurrence after pulmonary vein isolation

Abstract Background Left atrial (LA) remodeling plays a significant role in the progression of atrial fibrillation (AF). Although LA wall thickness (LAWT) has emerged as an indicator of structural remodeling, its impact on AF outcomes remains unclear. We aimed to determine the association between LAWT and AF recurrence after pulmonary vein isolation (PVI). Methods Single-center registry of patients enrolled for radiofrequency PVI from 2016 to 2018. In all cases, a pre-ablation CT scan was performed within less than 48 hours. Mean LAWT was retrospectively determined by a semi-automated machine learning method with minimal human intervention (ADAS 3D®). Additionally, regional tissue thickness was assessed in four locations: roof and inferior, posterior, and anterior walls. In a subgroup of patients, a pre-ablation cardiac magnetic resonance (CMR) was also performed within the same week. LA functional parameters and fibrosis, using 3D delayed gadolinium enhancement, were analyzed. The primary endpoint was AF recurrence after a 3-month blanking period. Results A total of 439 patients (mean age 61±12years, 62% male, 78% with paroxysmal AF) were included. The mean LAWT was 1.4±0.2mm (ranging from 0.9 to 1.9mm). Software processing duration was 8.2±0.4 min, and the mean human input time was 1.3±0.1 min. There was no correlation between LAWT and CT-derived LA-indexed volume (Spearman –0.01, p=0.845). During a median follow-up of 5.8 (IQR 4.9–6.6) years, 238 patients (54%) had an AF relapse. LAWT was an independent predictor of recurrence, after adjusting for known confounders including age, non-paroxysmal AF, LA-indexed volume, and chronic kidney disease (adjusted HR 6.49 [95% CI 2.70-15.49], p<0.001). AF recurrence rates were 11%, 15%, and 21%/year across terciles of increasing LAWT (log-rank p<0.001) – Figure. The posterior LAWT revealed the strongest association with the study endpoint (HR 1.93 [95% CI 1.24-3.02], p=0.004). In the cohort of 62 patients with both CT and CMR, LAWT showed weak correlations with LA ejection fraction and LA coupling index (Spearman <0.25; p=0.054 and p=0.093, respectively), and a moderate correlation with LA fibrosis (Spearman 0.468; p<0.001). Conclusions Mean LAWT, easily assessed by commercially available machine learning software, is an independent predictor of AF recurrence after PVI in the long-term follow-up. This association is mainly driven by the posterior LAWT. Whether patients with increased LAWT should receive tailored therapy deserves further investigation.Figure

Peak frequency can be effectively used to characterize atrial remodelling in atrial fibrillation

Abstract Introduction Characterizing atrial fibrillation (AF) substrate can guide ablation strategies, particularly as current efficacy leaves room for substantial improvement. Low voltage zones (LVZs) correlate with atrial fibrosis and scar and can independently predict AF recurrence. Ablation of these zones improves freedom from arrhythmia, but the chaotic nature of atrial excitation frequently results in overestimation of LVZs limiting accurate substrate identification. Purpose While omnipolar voltage (OV) mapping has emerged to address this issue by closely correlating with sinus rhythm (SR) voltage maps, our study builds upon this by investigating a novel parameter, peak frequency (PF), to further refine AF substrate characterization. Methods Patients undergoing catheter ablation for persistent AF were enrolled. OV maps and PF maps were created during AF while bipolar voltage (BV) maps were created in SR with atrial pacing at pacing intervals (PIs) of 600ms and 250ms. Areas were classified as fixed scar (consistent LVZs across all maps), functional remodelling (LVZs in AF OV and SR BV 250ms maps) and non-LVZs (normal voltage across all maps). PF was assessed in these areas and defined as the highest frequency detected in the electrogram. Results Among 20 patients, the average voltage in AF OV maps differed significantly from SR BV 600ms (0.49±0.76mV in AF OV vs. 1.12±0.97mV SR BV 600ms, p<0.001) but not SR BV 250ms maps (0.49±0.76mV in AF OV vs. 0.52±0.84mV SR BV 250ms, p=0.10). Comparing co-registered points, there was a significant difference between AF OV and SR BV 600ms maps (0.21±0.09mV, p<0.001) but not between AF OV and SR BV 250ms maps (0.06±0.04mV, p=0.10). These findings were also consistent with regards to the proportion of LA area occupied by LVZs (42.4±8.2% AF OV, 24.3±7.4% SR BV 600ms and 39.4±6.7% SR BV 250ms; p=0.001). AF OV maps thereby correlated better with SR BV 250ms maps hence representing both fixed scar and functional remodelling. PF values ≥244Hz were predictive of non-LVZs (OR 3.91, 95% CI 3.77-4.07,) with an AUC of 0.71. A PF of ≤214Hz was predictive of fixed scar (OR 17.67, 95% CI 16.82-18.56, p<0.001) with an AUC of 0.90. A PF between 215-236Hz was predictive of functional remodelling (OR 2.83, 95% CI 2.71-2.95, p<0.001) with an AUC of 0.60. The majority of LVZs identified exclusively in AF OV maps exhibited PFs akin to those in non-LVZs highlighting the ability of PF to pinpoint potential overestimations in LVZs. Conclusions PF mapping can effectively discern between areas of fixed scar, functional remodelling, and potential overestimation of LVZs. PF may enhance substrate characterization in AF utilising data solely from electrograms.Trial Design and Zone AssignmentPeak Frequency and Voltage Zones

Predictive Value of Serum microRNA-29b-3p in Recurrence of Atrial Fibrillation After Radiofrequency Catheter Ablation.

Atrial fibrillation (AF) is a common arrhythmia. This study explored serum miR-29b-3p expression in AF patients and its value in predicting AF recurrence after radiofrequency catheter ablation (RFCA). Totally 100 AF patients who underwent RFCA were enrolled, with 100 individuals without AF as controls. Serum miR-29b-3p expression in participants was determined using RT-qPCR. The correlation between miR-29b-3p and atrial fibrosis markers (FGF-21/FGF-23) was assessed by Pearson analysis. The diagnostic efficacy of serum miR-29b-3p and FGF-21/FGF-23 in predicting AF recurrence after RFCA was analyzed by the receiver operating characteristic (ROC) curves. The Kaplan-Meier method was adopted to evaluate the effect of miR-29b-3p expression on the incidence of AF recurrence after RFCA. The independent risk factors for AF recurrence after RFCA were analyzed by logistic regression analysis. Serum miR-29b-3p was poorly expressed in AF patients. After RFCA, AF patients showed elevated serum miR-29b-3p expression. Serum miR-29b-3p expression in AF patients negatively correlated with serum FGF-21 and FGF-23 concentrations. The cut-off values of serum miR-29b-3p, FGF-21, and FGF-23 in identifying AF recurrence were 0.860 (sensitivity: 100.00%, specificity: 39.71%), 222.2 pg/mL (sensitivity: 96.88%, specificity: 32.35%) and 216.3 ng/mL (sensitivity: 53.13%, specificity: 70.59%), respectively. Patients with low miR-29b-3p expression had a significantly higher incidence of AF recurrence than patients with high miR-29b-3p expression. Serum miR-29b-3p expression was one of the independent risk factors for AF recurrence after RFCA. Low miR-29b-3p expression in AF patients has certain predictive values and is one of the independent risk factors for AF recurrence after RFCA.

Epicardial adipose tissue volume assessed by cardiac CT as a predictor of atrial fibrillation recurrence following catheter ablation

IntroductionIn patients with atrial fibrillation (AF), up to one third have recurrence after a first catheter ablation (CA). Epicardial adipose tissue (EAT) has been considered to be closely related to AF, with a potential role in its recurrence. We aimed to evaluate the association between the volume of EAT measured by cardiac computed tomography (CT) and AF recurrence after CA. MethodsConsecutive AF patients underwent a standardized cardiac CT protocol for quantification of EAT, thoracic adipose volume (TAV) and left atrium (LA) volume before CA. An appropriate cut-off of EAT was determined and risk recurrence was estimated. Results305 patients (63.6 % male, mean age 57.5 years, 28.2 % persistent AF) were followed for 24 months; 23 % had AF recurrence at 2-year mark, which was associated with higher EAT (p = 0.037) and LAV (p < 0.001). Persistent AF was associated with higher EAT volumes (p = 0.010), TAV (p = 0.003) and LA volumes (p < 0.001). EAT was predictive of AF recurrence (p = 0.044). After determining a cut-off of 92 cm3, survival analysis revealed that EAT volumes > 92 cm3 showed higher recurrence rates at earlier time points after the index ablation procedure (p = 0.006), with a HR of 1.95 (p = 0.008) of AF recurrence at 2-year. After multivariate adjustment, EAT > 92 cm3 remained predictive of AF recurrence (p = 0.028). ConclusionThe volume of EAT measured by cardiac CT can predict recurrence of AF after ablation, with a volume above 92 cm3 yielding almost twice the risk of arrhythmia recurrence in the first two years following CA. Higher EAT and TAV are also associated with persistent AF.

Epicardial Atrial Fat at Cardiac Magnetic Resonance Imaging and AF Recurrence after Transcatheter Ablation.

The relationship between epicardial adipose tissue (EAT) and atrial fibrillation (AF) has gained interest in recent years. The previous literature on the topic presents great heterogeneity, focusing especially on computed tomography imaging. The aim of the present study is to determine whether an increased volume of left atrial (LA) EAT evaluated at routine pre-procedural cardiac magnetic resonance imaging (MRI) relates to AF recurrences after catheter ablation. A total of 50 patients undergoing AF cryoballoon ablation and pre-procedural cardiac MRI allowing quantification of LA EAT were enrolled. In one patient, the segmentation of LA EAT could not be achieved. After a median follow-up of 16.0 months, AF recurrences occurred in 17 patients (34%). The absolute volume of EAT was not different in patients with and without AF recurrences (10.35 mL vs. 10.29 mL; p-value = 0.963), whereas the volume of EAT indexed on the LA volume (EATi) was lower, albeit non-statistically significant, in patients free from arrhythmias (12.77% vs. 14.06%; p-value = 0.467). The receiver operating characteristic curve testing the ability of LA EATi to predict AF recurrence after catheter ablation showed sub-optimal performance (AUC: 0.588). The finest identified cut-off of LA EATi was 10.65%, achieving a sensitivity of 0.5, a specificity of 0.82, a positive predictive value of 0.59 and a negative predictive value of 0.76. Patients with values of LA EATi lower than 10.65% showed greater survival, free from arrhythmias, than patients with values above this cut-off (84% vs. 48%; p-value = 0.04). In conclusion, EAT volume indexed on the LA volume evaluated at cardiac MRI emerges as a possible independent predictor of arrhythmia recurrence after AF cryoballoon ablation. Nevertheless, prospective studies are needed to confirm this finding and eventually sustain routine EAT evaluation in the management of patients undergoing AF catheter ablation.

Does radiofrequency ablation procedural data improve the accuracy of identifying atrial fibrillation recurrence?

Radiofrequency ablation (RFA) using the CARTO 3D mapping system is a common approach for pulmonary vein isolation to treat atrial fibrillation (AF). Linkage between CARTO procedural data and patients' electronical health records (EHR) provides an opportunity to identify the ablation-related parameters that would predict AF recurrence. The objective of this study is to assess the incremental accuracy of RFA procedural data to predict post-ablation AF recurrence using machine learning model. Procedural data generated during RFA procedure were downloaded from CARTONET and linked to deidentified Mercy Health EHR data. Data were divided into train (70%) and test (30%) data for model development and validation. Automate machine learning (AutoML) was used to predict 1 year AF recurrence, defined as a composite of repeat ablation, electrical cardioversion, and AF hospitalization. At first, AutoML model only included Patients' demographic and clinical characteristics. Second, an AutoML model with procedural variables and demographical/clinical variables was developed. Area under receiver operating characteristic curve (AUROC) and net reclassification improvement (NRI) were used to compare model performances using test data. Among 306 patients, 67 (21.9%) patients experienced 1-year AF recurrence. AUROC increased from 0.66 to 0.78 after adding procedural data in the AutoML model based on test data. For patients with AF recurrence, NRI was 32% for model with procedural data. Nine of 10 important predictive features were CARTO procedural data. From CARTO procedural data, patients with lower contact force in right inferior site, long ablation duration, and low number of left inferior and right roof lesions had a higher risk of AF recurrence. Patients with persistent AF were more likely to have AF recurrence. The machine learning model with procedural data better predicted 1-year AF recurrence than the model without procedural data. The model could be used for identification of patients with high risk of AF recurrence post ablation.

Left atrial remodeling and voltage-guided ablation outcome in obese patients with persistent atrial fibrillation.

Obesity is a risk factor for atrial fibrillation (AF). Data regarding left atrial (LA) remodeling in obese patients are scarce. Whether obesity favors AF recurrence after catheter ablation (CA) is still controversial. We assessed the distribution of epicardial atrial fat on computed tomography (CT), LA bipolar voltage, low-voltage zone (LVZ) extent, and the outcome of voltage-guided ablation of persistent AF in obese and non-obese patients. A total of 139 patients with persistent AF undergoing a first voltage-guided ablation were enrolled and divided into two groups: 74 were non-obese and 65 were obese. Epicardial adipose tissue (EAT) was assessed on a CT scanner. LA endocardial voltage maps were obtained using a 3D mapping system in sinus rhythm. LVZ was defined as a bipolar peak-to-peak voltage amplitude <0.5 mV. LA volume, voltage, and EAT amount were similar in the two groups. LVZ was less frequent in obese patients [12 (18.8%) vs. 26 (35.1%), p = 0.05], particularly on the anterior wall. The posterior and lateral EATs were correlated with posterior and lateral LVZ extent, respectively, in obese patients. After 36 months of follow-up, the AF-free survival rate was similar. Lateral EAT [odds ratio (OR) 1.21, 95% confidence interval (CI) 1-1.4, p = 0.04] and P-wave duration (OR 1.03, 95% CI 1-1.05, p = 0.03), but not body mass index (BMI), were predictors of AF recurrence after CA. In obese patients, LVZ was less marked than in non-obese patients with similar LA volumes, voltage, and EAT amounts. In obese patients, posterior and lateral EATs were correlated with posterior and lateral LVZ extents. Obese patients had a similar and favorable 36-month outcome after AF ablation. BMI was not predictive of AF recurrence.

Adherence to the CLOSE Protocol and Low Baseline Generator Impedance Are Independent Predictors of Durable Pulmonary Vein Isolation.

Background: Atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) is predominantly attributed to pulmonary vein reconnection (PVR). Predictors of AF recurrence have been widely studied; however, data are scarce on procedural parameters that predict chronic PVR. We aimed to study PVR rates and predictors of PVR. Methods: We retrospectively included 100 patients who underwent repeated ablation due to AF recurrence after initial PVI with the CARTO system. PVR was determined during the repeated procedure by electrophysiological evaluation, and initial procedural characteristics predicting PVR were studied, including adherence to the CLOSE protocol, use of high power, first-pass isolation (FPI), and baseline generator impedance (BGI). Results: Thirty-eight patients underwent initial CLOSE-guided PVI, and sixty-two underwent initial non-CLOSE PVI. A repeat procedure was performed 23 ± 16 months after the initial procedure. In total, PVR was found in 192 of 373 PVs (51.5%), and all PVs were isolated in 17/100 (17%) patients. Factors associated with all PVs being isolated were adherence to the CLOSE protocol, a higher power setting, the presence of bilateral FPI, and lower BGI (88% vs. 28%, p < 0.0001; 37.5 W vs. 30 W, p = 0.0276; 88.2% vs. 40.4%, p = 0.0007; and 127.6 Ω vs. 136.6 Ω, p = 0.0027, respectively). In initial procedures with adherence to the CLOSE protocol, the FPI rate was significantly higher (73.7% vs. 25%, p < 0.0001), while there were no significant differences in terms of procedure time and left atrial dwell time (81 vs. 85 min, p = 0.83; and 60 vs. 58 min, p = 0.08, respectively). BGI ≥ 130 Ω (AUC = 0.7403, sensitivity: 77.1%, specificity: 68.8%, p = 0.0032) was associated with a significantly higher probability of PVR (OR = 6.757; p < 0.0001). In multivariable analysis, independent predictors for PVR were non-adherence to the CLOSE protocol and BGI ≥ 130 Ω. Conclusions: Our findings indicate that adherence to the CLOSE protocol and baseline generator impedance < 130 Ω during AF ablation are independent predictors of PVI durability.

Left Atrium Volume Measured with Multislice Computed Tomography as a Prognostic Predictor for Atrial Fibrillation Catheter Ablation Outcomes.

Background: Current guidelines consider atrial fibrillation (AF) type as the prognostic factor for a recommendation of catheter ablation. We aimed to determine whether LA and LA appendage (LAA) volumes measured using multislice computed tomography (MSCT) were related to long-term outcomes in AF following radiofrequency catheter ablation (RFCA). Methods: We evaluated 152 consecutive patients with drug-refractory AF (median age, 55.8 ± 9.6 years), including 110 male patients, who underwent RFCA in a single center. All patients underwent MSCT imaging for anatomical assessment. The endpoint of this study was documented AF recurrence after RFCA. Results: The overall procedure success rate was 77.6% (n = 118) during a mean follow-up period of 12.6 months. The LA volume was significantly larger for those who experienced AF recurrence after RFCA than for the patients without recurrent AF after the procedure (153.8 ± 29.9 mL vs. 139.2 ± 34.1 mL, p = 0.025). However, LAA volumes were nearly equivalent between the patients with and without AF recurrence after RFCA (16.2 ± 6.3 mL and 14.7 ± 6.5 mL, respectively; p = 0.235). LA volume ≥ 153.2 mL was the optimal cutoff value for estimating AF recurrence after RFCA, with 94% sensitivity and 66% specificity. LA volume remained an independent predictor of both AF recurrence and permanent AF. Conclusions: LA volume as assessed by MSCT might be helpful for identifying patients likely to achieve successful AF ablation. LA volume ≥ 153.2 mL, but not LAA volume, showed good accuracy in predicting AF recurrence after RFCA.

Atrial Functional Substrates for the Prediction of Atrial Fibrillation Recurrence After Pulmonary Vein Isolation

Low-voltage areas have been used as atrial structural substrates in estimating fibrotic degeneration in patients with atrial fibrillation (AF). The high-resolution maps obtained by recently developed mapping catheters allow the visualization of several functional abnormalities. We investigated the association between left atrial (LA) functional abnormal findings on a high-resolution substrate map and AF recurrence in patients who underwent pulmonary vein isolation without any additional LA substrate ablation. This observational study included 100 consecutive patients who underwent second ablation for AF (paroxysmal, 48%; persistent, 52%). Patients with extra-pulmonary-vein LA substrate ablation during the initial and second ablation were excluded. LA mapping was performed using a 64-pole mini-basket catheter on the Rhythmia mapping system. Patients were followed for 2 years. AF recurrence developed in 39 (39%) patients. On the high-resolution substrate map, AF recurrence was associated with the presence of the following findings: low-voltage areas (<1.0 mV, >5cm2; hazard ratio [HR]=2.53; 95% confidence interval [CI]=1.30-4.93; p<0.006), fractionated-electrogram areas (≥5 peaks, >5cm2; HR=2.15, 95%CI=1.10-4.19; p=0.025), LA conduction time of >130 msec (HR=3.11, 95%CI=1.65-5.88, p<0.0001), deceleration zone (≥5 isochrones/cm2; HR=1.97, 95%CI=1.04-3.37, p=0.039), and multiple septal breakout points (HR=3.27, 95%CI=1.50-7.16, p=0.003). Accumulation of these risk factors increased AF recurrence in a stepwise manner, with an HR=1.90, 95%CI=1.44-2.52, p<0.00001 for each additional risk factor. In conclusion, high-resolution map revealed new LA functional substrates associated with AF recurrence. Implementation of functional substrates may improve the prediction of AF recurrence after ablation, and possibly aid the development of tailored AF ablation strategies.