Predictors of arrhythmia recurrence after balloon cryoablation of atrial fibrillation: the value of CAAP-AF risk scoring system

Multidisciplinary management strategies for atrial fibrillation

There has been a significant increase in the prevalence of atrial fibrillation (AF) over the past 30 years. Pulmonary vein isolation (PVI) is an effective treatment for AF, but research investigations have shown that AF recurrence still occurs in a significant number of patients after ablation. Heart rhythm outcomes following catheter ablation are correlated with numerous clinical factors, and researchers developed predictive models by integrating risk factors to predict the risk of recurrence of atrial fibrillation. The purpose of this article is to outline the risk scores for predicting cardiac rhythm outcomes after PVI and to discuss the modifiable factors that increase the risk of recurrence of AF, with the hope of further improving catheter ablation efficacy through preoperative identification of high-risk populations and postoperative management of modifiable risk factors.

Evaluation of the effectiveness and safety of a novel substrate-based radiofrequency ablation for persistent atrial fibrillation: a prospective, randomised, parallel-controlled, single-blinded study protocol

INTRODUCTION

Pulmonary vein isolation (PVI) is the cornerstone of radiofrequency (RF) ablation for atrial fibrillation (AF). However, a single ablation strategy does not always achieve the desired therapeutic effect in all patients with persistent AF, and individualised strategies are required for different clinical characteristics.

METHODS AND ANALYSIS

This study aimed to determine the optimal catheter ablation strategy for persistent AF by comparing the efficacy of PVI and BCXL (BC: big circles encircling pulmonary vein isolation; XL: unfixed number of lines based on the left atrial substrate). The BCXL-AF study (clinical trial no. ChiCTR2200067081) was designed as a prospective, randomised, parallel-controlled, single-blinded clinical trial. Overall, 400 patients with persistent AF were randomised in a 1:1 ratio into PVI-only and BCXL-individualised ablation groups. Patients randomised to the individualised ablation group will be further categorised into risk strata according to their clinical condition using the actual ablation method determined by the strata. Seven postoperative visits were conducted from discharge to 24 months of age. The primary observation endpoint will be the incidence of atrial tachyarrhythmia (including AF, atrial flutter and atrial tachycardia with a duration of ≥30 s) without using antiarrhythmic drugs after a blank period of 3 months following a single ablation procedure. The BCXL-AF study will assess an optimal approach for persistent AF RF ablation and evaluate the effectiveness of individualised RF ablation strategies in reducing the recurrence rate of AF.

ETHICS AND DISSEMINATION

The study protocol was reviewed, and ethical approval was obtained from the Army Medical University Human Ethics Committee (approval number: 2022-484-01). All the participants provided written informed consent. This study was conducted according to the principles of the Declaration of Helsinki and its amendments. The results of this study will be disseminated through manuscript publication and conference presentations.

TRIAL REGISTRATION NUMBER

ChiCTR2200067081.

CHA2DS2VASc score as a predictor of ablation success defined by continuous long-term monitoring

BACKGROUND

There are few reliable risk stratification tools for successful atrial fibrillation catheter ablation (AFCA) and most prior studies have used short-term external monitors to define success. CHA₂DS₂VASc score may be useful in predicting AF recurrence. We investigated whether CHA₂DS₂VASc score correlates with AFCA success as measured by continuous monitoring via cardiac implantable electronic devices (CIEDs).

METHODS

Using the Optum® de-identified Electronic Health Record dataset (01/2007 to 06/2019) linked with the Medtronic CareLink™ database, we identified patients who underwent a 1st AFCA procedure following CIED implantation. Success was defined as absence of ≥ 1 h of AF following a 3-month blanking period.

RESULTS

A total of 632 patients (age 67 ± 9.1 years, 73.3% male, CHA₂DS₂VASc 3.6 ± 1.8, 36.9% paroxysmal AF) were analyzed and included 35.1% insertable cardiac monitor, 28.8% PPM, 21.4% ICD, 13.6% CRT-D, and 1.1% CRT-P. Success at 24 months post blanking period was 40.3% (95% CI 32.6-49.7%), 36.2% (95% CI 26.9-45.4%), and 21.8% (95% CI 14.6-32.5%) for CHA₂DS₂VASc subgroups of 0-2, 3-4, and ≥ 5, respectively. Median daily burden of AF was reduced to zero regardless of CHA₂DS₂VASc score, but there were significant differences in survival free from any AF ≥ 1 h between the three CHA₂DS₂VASc subgroups (p = 0.013). Patients with a score ≥ 5 had a HR of 1.29 (95% CI 1.00-1.67) for AF recurrence compared to patients with a score of 0-2, with similar results after controlling for AF type.

CONCLUSIONS

In real-world patients with continuous monitoring undergoing AFCA, only CHA₂DS₂VASc scores ≥ 5 predicted higher AF recurrence.

New Radiomic Markers of Pulmonary Vein Morphology Associated With Post-Ablation Recurrence of Atrial Fibrillation

Objective: To identify radiomic and clinical features associated with post-ablation recurrence of AF, given that cardiac morphologic changes are associated with persistent atrial fibrillation (AF), and initiating triggers of AF often arise from the pulmonary veins which are targeted in ablation. Methods: Subjects with pre-ablation contrast CT scans prior to first-time catheter ablation for AF between 2014-2016 were retrospectively identified. A training dataset (D1) was constructed from left atrial and pulmonary vein morphometric features extracted from equal numbers of consecutively included subjects with and without AF recurrence determined at 1 year. The top-performing combination of feature selection and classifier methods based on C-statistic was evaluated on a validation dataset (D2), composed of subjects retrospectively identified between 2005-2010. Clinical models ([Formula: see text]) were similarly evaluated and compared to radiomic ([Formula: see text]) and radiomic-clinical models ([Formula: see text]), each independently validated on D2. Results: Of 150 subjects in D1, 108 received radiofrequency ablation and 42 received cryoballoon. Radiomic features of recurrence included greater right carina angle, reduced anterior-posterior atrial diameter, greater atrial volume normalized to height, and steeper right inferior pulmonary vein angle. Clinical features predicting recurrence included older age, greater BMI, hypertension, and warfarin use; apixaban use was associated with reduced recurrence. AF recurrence was predicted with radio-frequency ablation models on D2 subjects with C-statistics of 0.68, 0.63, and 0.70 for radiomic, clinical, and combined feature models, though these were not prognostic in patients treated with cryoballoon. Conclusions: Pulmonary vein morphology associated with increased likelihood of AF recurrence within 1 year of catheter ablation was identified on cardiac CT. Significance: Radiomic and clinical features-based predictive models may assist in identifying atrial fibrillation ablation candidates with greatest likelihood of successful outcome.

A deep learning model to predict recurrence of atrial fibrillation after pulmonary vein isolation

Background and Objectives

The efficacy of radiofrequency catheter ablation (RFCA) in atrial fibrillation (AF) is well established. The standard approach to RFCA in AF is pulmonary vein isolation (PVI). However, a large proportion of patients experiences recurrence of atrial tachyarrhythmia. The purpose of this study is to find out whether the AI model can assess AF recurrence in patients who underwent PVI.

Materials and methods

This study was a retrospective cohort study that enrolled consecutive patients who underwent catheter ablation for symptomatic, drug-refractory AF and PVI. We developed an AI algorithm to predict recurrence of AF after PVI using patient demographics and three-dimensional (3D) reconstructed left atrium (LA) images.

Results

We included 527 consecutive patients in the study. The overall mean LA diameter was 42.0 ± 6.8 mm, and the mean LA volume calculated using 3D reconstructed images was 151.1 ± 46.7 ml. During the follow-up period, atrial tachyarrhythmia recurred in 158 patients. The area under the curve (AUC) of the AI model based on a convolutional neural network (including 3D reconstruction images) was 0.61 (95% confidence interval [CI] 0.53–0.74) using the test dataset. The total test accuracy was 66.3% (57.0–75.6), and the sensitivity was 53.3% (34.8–71.9). The specificity was 73.2% (51.8–75.0), and the F1 score was 52.5% 34.5–66.7).

Conclusion

In this study, we developed an AI algorithm to predict recurrence of AF after catheter ablation of PVI using individual reconstructed LA images. This AI model was unable to predict recurrence of AF overwhelmingly; therefore, further large-scale study is needed.

Evaluation of predictive scores for late and very late recurrence after cryoballoon-based ablation of atrial fibrillation

Purpose

Studies on predictive scores for very late recurrence (VLR) (recurrence later than 12 months) after second-generation cryoballoon-based pulmonary vein isolation (CB2-PVI) are sparse. We aimed to evaluate the frequency of late recurrence (LR) (later than 3 months) and VLR, and to validate predictive scores for LR and VLR after initial CB2-PVI.

Methods

A total of 288 patients undergoing initial CB2-PVI (66 ± 11 years, 46% paroxysmal) were retrospectively enrolled in the LR cohort. In the VLR cohort, 83 patients with recurrence within 3–12 months or with < 12-month follow-up were excluded. The predictive scores of arrhythmia recurrence were assessed, including the APPLE, DR-FLASH, PLAAF, BASE-AF₂, ATLAS, SCALE-CryoAF, and MB-LATER scores.

Results

During a mean follow-up of 15.3 ± 7.1 months, 188 of 288 (65.2%) patients remained in sinus rhythm without any recurrences. Thirty-two of 205 (15.6%) patients experienced VLR after a mean of 16.6 ± 5.6 months. Comparing the predictive values of these specific scores, the MB-LATER score showed a reliable trend toward greater risk of both LR and VLR (area under the curve in LR; 0.632, 0.637, 0.632, 0.637, 0.604, 0.725, and 0.691 (p = ns), VLR; 0.612, 0.636, 0.644, 0.586, 0.541, 0.633, and 0.680 (p = 0.038, vs. BASE-AF₂, respectively)). Kaplan-Meier analysis estimated patients with higher MB-LATER scores which had favorable outcomes (24-month freedom from LR; 26.0% vs. 56.7%, p < 0.0001, VLR; 53.4% vs. 82.1%, p = 0.013).

Conclusion

The MB-LATER score provided more reliable predictive value for both LR and VLR. Patients with higher MB-LATER scores may benefit from more intensive long-term follow-up.

Predicting recurrent atrial fibrillation after catheter ablation: a systematic review of prognostic models

AIMS

We assessed the performance of modelsf (risk scores) for predicting recurrence of atrial fibrillation (AF) in patients who have undergone catheter ablation.

METHODS AND RESULTS

Systematic searches of bibliographic databases were conducted (November 2018). Studies were eligible for inclusion if they reported the development, validation, or impact assessment of a model for predicting AF recurrence after ablation. Model performance (discrimination and calibration) measures were extracted. The Prediction Study Risk of Bias Assessment Tool (PROBAST) was used to assess risk of bias. Meta-analysis was not feasible due to clinical and methodological differences between studies, but c-statistics were presented in forest plots. Thirty-three studies developing or validating 13 models were included; eight studies compared two or more models. Common model variables were left atrial parameters, type of AF, and age. Model discriminatory ability was highly variable and no model had consistently poor or good performance. Most studies did not assess model calibration. The main risk of bias concern was the lack of internal validation which may have resulted in overly optimistic and/or biased model performance estimates. No model impact studies were identified.

CONCLUSION

Our systematic review suggests that clinical risk prediction of AF after ablation has potential, but there remains a need for robust evaluation of risk factors and development of risk scores.

Predicting long-term freedom from atrial fibrillation after catheter ablation by a machine learning algorithm: Validation of the CAAP-AF score

BACKGROUND

Preprocedural clinical predictors of the successful maintenance of sinus rhythm may contribute to optimal treatment strategies for atrial fibrillation (AF). The CAAP-AF score, a novel simple tool scored as 0-13 points (including six independent variables) has been proposed to predict long-term freedom from AF after catheter ablation. To clarify its reproducibility, we examined the CAAP-AF score's predictive performance and then created subgroups to best predict AF recurrence by using a machine learning algorithm.

METHODS

We studied 583 consecutive patients who underwent initial AF catheter ablation at our institute (median CAAP-AF score, 5; age, 66 ± 10 years old; female, 28.3%; coronary artery disease, 10.8%; left atrial diameter, 39.9 ± 6.6 mm; number of antiarrhythmic drugs failed, 0.4 ± 0.6; nonparoxysmal AF, 45.3%). All were systematically followed up with an endpoint of atrial tachyarrhythmia recurrence after the last ablation procedure.

RESULTS

During the 1.8 ± 1.2-year follow-up, 157 patients had atrial tachyarrhythmia recurrence. Repeated procedures were performed (n = 115). Arrhythmia recurrence after the last session occurred in 69 patients. We created Kaplan-Meier curves for freedom from AF after final AF ablation for ranges of CAAP-AF scores; these confirmed the original study results. The machine learning using Classification and Regression Trees divided the patients into three categories by the risk score: low (score ≤5), intermediate (score 6-8), and high (score ≥9).

CONCLUSIONS

The CAAP-AF score was useful to stratify the atrial tachyarrhythmia recurrence risk in AF patients undergoing catheter ablation into three categories. The score should be considered when deciding whether to perform AF ablation in clinical practice.

Predicting atrial fibrillation recurrence after ablation in patients with heart failure: Validity of the APPLE and CAAP-AF risk scoring systems

BACKGROUND

Compared with medical therapy, catheter ablation of atrial fibrillation (AF) in patients with heart failure (HF) improves cardiovascular outcomes. Risk scores (CAAP-AF and APPLE) have been developed to predict the likelihood of AF recurrence after ablation, have not been validated specifically in patients with AF and HF.

METHODS

We analyzed baseline characteristics, risk scores, and rates of AF recurrence 12 months postablation in a cohort of 230 consecutive patients with AF and HF undergoing PVI in the Duke Center for Atrial Fibrillation registry from 2009-2013.

RESULTS

During a follow-up period of 12 months, 76 of 230 (33%) patients with HF experienced recurrent AF after ablation. The median APPLE and CAAP-AF scores were 1.5 ([Q1, Q3]: [1.0, 2.0]) and 4.0 ([Q1, Q3]: [3.0, 5.0]), respectively and were not different from those patients with and without recurrent AF. Freedom from AF was not different according to APPLE and CAAP-AF scores. Discrimination for recurrent AF with the CAAP-AF score was modest with a C-statistic of 0.60 (95% CI 0.52-0.67). Discrimination with the APPLE score was similarly modest, with a C-statistic of 0.54 (95% CI: 0.47-0.62).

CONCLUSIONS

Validated predictive risk scores for recurrent AF after catheter ablation exhibit limited predictive ability in cohorts of AF and HF. Additional tools are needed to facilitate risk stratification and patient selection for AF ablation in patients with concomitant HF.

PLAAF score as a novel predictor of long-term outcome after second-generation cryoballoon pulmonary vein isolation

Aims

Predictors of atrial arrhythmia recurrence have not been described in a long-term follow-up study of patients undergoing pulmonary vein isolation (PVI) using the cryoballoon technique. We aimed to evaluate the efficacy of a second-generation cryoballoon and identify pre-procedural predictors of 3-year outcome after PVI.

Methods and results

For this observational cohort study, we enrolled 440 patients ablated at our institution with a second-generation cryoballoon. The endpoint was the first documented recurrence (>30 s) of atrial fibrillation (AF), atrial flutter, or atrial tachycardia after a 3-month blanking period. The impact of several pre-existing variables on clinical outcome was evaluated by univariate and multivariate analyses using the Cox proportional hazards regression model. The PLAAF (persistent AF, left atrial area, abnormal PV anatomy, AF history, female gender) score was defined to predict outcome. After a median follow-up of 36 months (interquartile range 25/75-27/42), the endpoint was achieved in 95 of 440 (21.6%) patients. Cox regression analysis showed that persistent AF, left atrial (LA) area, abnormal PV anatomy, AF history, and female gender independently predicted recurrence. The calculated optimal cut-offs for LA area and AF history were 21 cm2 and 3 years, respectively. Patients with a PLAAF score of 0 showed the best outcome, with an arrhythmia-free survival of 86.7%.

Conclusion

PVI using the cryoballoon technique shows acceptable long-term results depending on predictors described by the new PLAAF score, which may facilitate patient selection for PVI.

Stratifying risk of recurrence of atrial fibrillation following balloon cryoablation using the CAAP-AF risk scoring system

OBJECTIVE

To determine if the CAAP-AF tool could be applied to a cohort of patients in the United States undergoing cryoablation or AF utilizing second-generation cryoballoons.

BACKGROUND

Atrial fibrillation (AF) is a major source of morbidity and expense, with over 33 million individuals affected worldwide and over 450 000 hospitalizations annually in the United States. Catheter ablation for AF is a class I indication for patients with symptomatic AF. The ability to predict postablation recurrence would have an enormous impact on both patient outcomes and cost to the health care system.

METHODS

Our study was an observational, single-center retrospective study to evaluate the utility of the CAAP-AF risk scoring system in predicting recurrence of AF following second-generation balloon cryoablation for AF.

RESULTS

There were a total of 235 patients. From the initial cohort, 30.2% (71) had a recurrence of AF within 1 year of the cryoablation procedure. There was a statistically significant increase in mean age, left atrial diameter, left atrial volume index, CHADS₂ , CHADS₂ -VASc, and number of antiarrhythmics failed in the group that had recurrence of AF. There was also a statistically significant increase in the CAAP-AF score in patients who had recurrence of AF.

CONCLUSIONS

The CAAP-AF score predicted the freedom from AF 1 year following cryoablation for AF. The CAAP-AF score can aid in selecting patients most likely to benefit from cryoablation, which includes patients with a low CAAP-AF score, as they are most likely to remain AF free at 1 year.

Validation of the MB-LATER score for prediction of late recurrence after catheter-ablation of atrial fibrillation

BACKGROUND

Reliable identification of atrial fibrillation (AF) patients more likely to be AF-free long-term post-single catheter ablation (CA) would facilitate appropriate risk communication to patients. We validated the recently proposed MB-LATER score for prediction of late recurrences of AF (LRAF) post-CA.

METHODS

Patients who underwent CA for symptomatic AF refractory to ≥1 antiarrhythmic drugs at the Johns Hopkins Hospital, Baltimore, between March 2003 and December 2015, for whom ≥1-year post-CA follow-up data were available, were enrolled.

RESULTS

Of 226 patients (median age 58.5 years [IQR: 52.0-65.0], 163 males [72.1%], 142 [62.8%] with paroxysmal AF), LRAF occurred in 133 patients (58.8%) during a median 2-year follow-up (IQR: 1.1-4.1). The mean MB-LATER score was significantly higher in patients with versus those without LRAF (2.4 ± 1.2 vs. 1.9 ± 1.3, p = 0.002) and showed modest but significant predictive ability for LRAF (AUC: 0.62 [95% CI: 0.54-0.69], p = 0.003). A score cut-off value of >2 showed the best predictive ability for LRAF (70.4% [61.5-77.9]), with modest sensitivity (42.9% [34.3-51.7]) and specificity (74.2% [64.1-82.7]). Kaplan-Meyer survival free from AF was significantly better for patients with a MB-LATER score of ≤2 than for those with a score of >2 (log-rank p = 0.005).

CONCLUSION

In our study, the MB-LATER score showed a significant but modest predictive ability for LRAF post-AF ablation. Further prospective validation is needed to better define the potential role of the MB-LATER score in patient selection and treatment decision-making post-AF ablation.