Left Atrial Wall Stress and the Long-Term Outcome of Catheter Ablation of Atrial Fibrillation: An Artificial Intelligence-Based Prediction of Atrial Wall Stress

Beyond Clinical Factors: Harnessing Artificial Intelligence and Multimodal Cardiac Imaging to Predict Atrial Fibrillation Recurrence Post-Catheter Ablation

Atrial fibrillation (AF) is the most common type of cardiac arrhythmia, with catheter ablation being a key alternative to medical treatment for restoring normal sinus rhythm. Despite advances in understanding AF pathogenesis, approximately 35% of patients experience AF recurrence at 12 months after catheter ablation. Therefore, accurate prediction of AF recurrence occurring after catheter ablation is important for patient selection and management. Conventional methods for predicting post-catheter ablation AF recurrence, which involve the use of univariate predictors and scoring systems, have played a supportive role in clinical decision-making. In an ever-changing landscape where technology is becoming ubiquitous within medicine, cardiac imaging and artificial intelligence (AI) could prove pivotal in enhancing AF recurrence predictions by providing data with independent predictive power and identifying key relationships in the data. This review comprehensively explores the existing methods for predicting the recurrence of AF following catheter ablation from different perspectives, including conventional predictors and scoring systems, cardiac imaging-based methods, and AI-based methods developed using a combination of demographic and imaging variables. By summarising state-of-the-art technologies, this review serves as a roadmap for developing future prediction models with enhanced accuracy, generalisability, and explainability, potentially contributing to improved care for patients with AF.

Application of artificial intelligence in the diagnosis and treatment of cardiac arrhythmia

The rapid growth in computational power, sensor technology, and wearable devices has provided a solid foundation for all aspects of cardiac arrhythmia care. Artificial intelligence (AI) has been instrumental in bringing about significant changes in the prevention, risk assessment, diagnosis, and treatment of arrhythmia. This review examines the current state of AI in the diagnosis and treatment of atrial fibrillation, supraventricular arrhythmia, ventricular arrhythmia, hereditary channelopathies, and cardiac pacing. Furthermore, ChatGPT, which has gained attention recently, is addressed in this paper along with its potential applications in the field of arrhythmia. Additionally, the accuracy of arrhythmia diagnosis can be improved by identifying electrode misplacement or erroneous swapping of electrode position using AI. Remote monitoring has expanded greatly due to the emergence of contactless monitoring technology as wearable devices continue to develop and flourish. Parallel advances in AI computing power, ChatGPT, availability of large data sets, and more have greatly expanded applications in arrhythmia diagnosis, risk assessment, and treatment. More precise algorithms based on big data, personalized risk assessment, telemedicine and mobile health, smart hardware and wearables, and the exploration of rare or complex types of arrhythmia are the future direction.

Using computed tomogram atrial myocardial thickness maps in high-power short-duration radiofrequency pulmonary vein isolation: UTMOST AF

Background

High-power short-duration (HPSD) ablation creates wide, shallow lesions using radiofrequency (RF) heating. It is uncertain if adjusting RF energy based on atrial wall thickness provides extra benefits. We studied the safety and effectiveness of tailored HPSD energy based on left atrial (LA) wall thickness (LAWT) for circumferential pulmonary vein isolation (CPVI) in patients with paroxysmal atrial fibrillation (PAF).

Methods

We enrolled 212 patients (68.4% male, mean age: 59.5 ± 11.0 years) and randomly assigned them to two groups: LAWT-guided CPVI (WT, n = 108) and conventional CPVI (control, n = 104). Both groups used an open irrigated-tip deflectable catheter to apply 50 W for 10 s to the posterior LA, while controls used 60 W for 15 s on other LA regions. RF delivery time in WT was titrated (15 s at LAWT > 2.1 mm, 13 s at 1.4-2.1 mm, and 11 s at <1.4 mm) according to the computed tomogram-myocardial thickness color map.

Results

After a mean follow-up of 13.4 ± 7.0 months, the WT and control groups showed no significant difference regarding clinical recurrence rate (13.9% vs. 5.8%, respectively; p = .061) and major complication rate (4.6% vs. 3.8%, respectively; p > .999). The total procedure time, cardioversion rate, and post-procedural AAD prescription rates did not significantly differ between the groups.

Conclusions

The LAWT-guided energy titration strategy did not result in improved procedural safety and efficacy compared to the conventional 50-60 W-HPSD CPVI in patients with PAF.

Clinical Characteristics and Rhythm Outcomes in Patients With Atrial Myopathy After Successful Catheter Ablation of Atrial Fibrillation

BACKGROUND

Although successful atrial fibrillation (AF) ablation can maintain sinus rhythm and reduce the left atrial (LA) dimension, blunted LA reverse remodeling can be observed in patients with atrial myopathy. We explored the potential mechanisms and long-term outcomes in patients with blunted LA reverse remodeling after successful AF catheter ablation.

METHODS AND RESULTS

We included 1685 patients who underwent baseline and 1-year follow-up echocardiograms, had a baseline LA dimension ≥40 mm, and did not have a recurrence of AF within a year. The patients were divided into tertile groups according to the delta value of the change in LA dimension on the preprocedure and 1-year postprocedure echocardiography. After propensity score matching for age, sex, AF type, and LA dimension, 1272 patients were finally included in the analyses (424 in each group; the least/blunted, moderate, and the most reverse remodeling group). The patients in the T1 group (blunted LA reverse remodeling) were independently associated with higher left ventricular mass index (odds ratio [OR], 1.014 [95% CI, 1.005-1.022], P=0.001), change in ΔH2FPEF score (heavy, hypertensive, atrial fibrillation, pulmonary hypertension, elder, filling pressure) score (OR, 1.445 [95% CI, 1.121-1.861], P=0.004), ventricular epicardial adipose tissue volume (OR, 1.010 [95% CI, 1.003-1.017], P=0.003), thinner LA wall thickness (OR, 0.461 [95% CI, 0.271-0.785], P=0.004), lower LA voltage (OR, 0.670 [95% CI, 0.499-0.899], P=0.008), and showed higher long-term AF recurrence (log-rank P<0.001) than other groups.

CONCLUSIONS

Blunted LA reverse remodeling after AF catheter ablation, which is suggestive of atrial myopathy, was independently associated with a larger ventricular epicardial adipose tissue volume and worsening of H2FPEF score. Blunted LA reverse remodeling after AF catheter ablation was also an independent predictor for higher recurrences of AF post-1-year AF catheter ablation.

Clinical significance of substrate characteristics and ablation outcomes in patients with atrial fibrillation and significant functional mitral regurgitation

Background

Atrial fibrillation (AF) and mitral regurgitation (MR) have a complex interplay. Catheter ablation (CA) of AF may be a potential method to improve the severity of MR in AF patients.

Methods

Patients with symptomatic AF and moderate to severe MR who underwent catheter ablation from 2011 to 2021 were retrospectively included in the study. Patients' baseline characteristics and electrophysiological features were examined. These patients were classified as group 1 with improved MR and group 2 with refractory MR after CA.

Results

Fifty patients (age 60.2 ± 11.6 years, 29 males) were included in the study (32 in group 1 and 18 in group 2). Group 1 patients had a lower CHA2DS2-VASc score (1.7 ± 1.5 vs. 2.7 ± 1.5, P = 0.005) and had a lower incidence of hypertension (28.1% vs. 66.7%, P = 0.007) and diabetes mellitus (3.1% vs. 22.2%, P = 0.031) as compared to group 2 patients. Electroanatomic three-dimensional (3D) mapping showed that group 1 patients demonstrated less scars on the posterior bottom of the left atrium compared to group 2 patients (12.5% vs. 66.7%, P < 0.001). AF recurrence was not different between the two groups. After multivariate logistic regression analysis, a posterior bottom scar in the left atrium independently predicted refractory MR despite successful AF ablation.

Conclusion

Most patients with AF and MR showed improvement of MR after AF ablation. A scar involving the posterior bottom of the left atrium is associated with poor recovery of MR.

Inflammatory Markers as Predictors of Atrial Fibrillation Recurrence: Exploring the C-Reactive Protein to Albumin Ratio in Cryoablation Patients

BACKGROUND

Atrial fibrillation (AF) is a common cardiac rhythm disorder associated with hemodynamic disruptions and thromboembolic events. While antiarrhythmic drugs are often recommended as the initial treatment, catheter ablation has emerged as a viable alternative. However, the recurrence of AF following ablation remains a challenge, and there is growing interest in exploring inflammatory markers as predictors of recurrence.

METHODS

This retrospective, cross-sectional analysis included 249 patients who underwent cryoablation for paroxysmal AF. The relationship between the 'C-reactive protein (CRP) to albumin ratio (CAR)' and AF recurrence was examined.

RESULTS

Two hundred and forty-nine patients with paroxysmal non-valvular atrial fibrillation were included. They were divided into two groups: those without recurrence (Group 1) and those with recurrence (Group 2). Significant differences were observed in age (57.2 ± 9.9 vs. 62.5 ± 8.4, p = 0.001) and left atrial size (4.0 ± 0.5 vs. 4.2 ± 0.7, p = 0.001) between the two groups. In blood parameters, significant differences were found in CRP (5.2 ± 1.3 vs. 9.4 ± 2.8, p < 0.001) and neutrophil counts (5.1 ± 2.2 vs. 6.7 ± 3.6, p = 0.001). In univariate regression analysis, age (OR: 1.058, CI: 1.024-1.093, p = 0.001), WBC count (OR: 1.201, CI: 1.092-1.322, p < 0.001), neutrophil count (OR: 1.239, CI: 1.114-1.378, p = 0.001), CAR (OR: 1.409, CI: 1.183-1.678, p < 0.001), and left atrial diameter (OR: 0.968, CI: 0.948-0.989, p = 0.002) showed significant associations with AF recurrence.

CONCLUSIONS

Inflammation plays a crucial role in the initiation and progression of AF. This study demonstrated that along with age, the CAR can serve as an independent predictor of AF recurrence following cryoablation.

State of the art paper: Cardiac computed tomography of the left atrium in atrial fibrillation

The clinical spectrum of atrial fibrillation means that a patient-individualized approach is required to ensure optimal treatment. Cardiac computed tomography can accurately delineate atrial structure and function and could contribute to a personalized care pathway for atrial fibrillation patients. The imaging modality offers excellent spatial resolution and has been utilised in pre-, peri- and post-procedural care for patients with atrial fibrillation. Advances in temporal resolution, acquisition times and analysis techniques suggest potential expanding roles for cardiac computed tomography in the future management of patients with atrial fibrillation. The aim of the current review is to discuss the use of cardiac computed tomography in atrial fibrillation in pre-, peri- and post-procedural settings. Potential future applications of cardiac computed tomography including atrial wall thickness assessment and epicardial fat volume quantification are discussed together with emerging analysis techniques including computational modelling and machine learning with attention paid to how these developments may contribute to a personalized approach to atrial fibrillation management.

Sex difference in atrial fibrillation recurrence after catheter ablation and antiarrhythmic drugs

OBJECTIVE

The risk of recurrence after atrial fibrillation (AF) catheter ablation (AFCA) is higher in women than in men. However, it is unknown whether a sex difference exists in antiarrhythmic drug (AAD) responsiveness among patients with recurrence.

METHODS

Among 2999 consecutive patients (26.5% women, 58.3±10.9 years old, 68.1% paroxysmal AF) who underwent de novo AFCA, we compared and evaluated the sex differences in rhythm outcome in 1094 patients with recurrence and in 788 patients who subsequently underwent rhythm control with AAD.

RESULTS

During a follow-up of 48.2±34.9 months, 1094 patients (36.5%) had AF recurrence after AFCA, and 508 of 788 patients (64.5%) had AF recurrence under AAD. Although the rhythm outcome of a de novo AFCA was worse (log-rank p=0.041, HR 1.28, 95% CI 1.02 to 1.59), p=0.031) in women, AAD response after postprocedural recurrences was better in women than in men (log-rank p=0.003, HR 0.75, 95% CI 0.59 to 0.95, p=0.022), especially in women older than 60 years old (log-rank p=0.003). In 249 patients who underwent repeat procedure after AAD use, the pulmonary vein (PV) reconnection rate (62.7% vs 76.8%, p=0.048) was lower in women than in men but not the existence of extra-PV trigger (37.8% vs 25.4%, p=0.169).

CONCLUSIONS

Although women showed worse rhythm outcomes than men after AFCA, the post-AFCA AAD response was better in elderly women than in men.

TRIAL REGISTRATION NUMBER

NCT02138695.

Reduction in atrial and pulmonary vein stretch as a therapeutic target for prevention of atrial fibrillation

Atrial fibrillation (AF) is a common cardiac arrhythmia that is associated with increased mortality. Heart failure, hypertension, valvular disease, and obstructive sleep apnea are risk factors for incident AF. A common characteristic of these diseases is that they increase atrial wall stretch. Multiple experimental studies confirm a proarrhythmic effect of atrial stretch. Conversely, a reduction in stretch is antiarrhythmic. A therapeutic target for AF, therefore, lies in local reduction of atrial stretch. This review focuses on atrial stretch and its clinical associations in patients with AF and its downstream effects on electrophysiology. We discuss the possible application of targeted atrial stretch reduction in AF prevention. We conclude that a reduction in local atrial stretch should be considered an essential element in rhythm control.

Emerging role of artificial intelligence in cardiac electrophysiology

Artificial intelligence (AI) and machine learning (ML) have significantly impacted the field of cardiovascular medicine, especially cardiac electrophysiology (EP), on multiple fronts. The goal of this review is to familiarize readers with the field of AI and ML and their emerging role in EP. The current review is divided into 3 sections. In the first section, we discuss the definitions and basics of AI, ML, and big data. In the second section, we discuss their application to EP in the context of detection, prediction, and management of arrhythmias. Finally, we discuss the regulatory issues, challenges, and future directions of AI in EP.

Lower pulmonary vein-to-left atrium volume ratio predicts poor rhythm outcome after atrial fibrillation catheter ablation

Although left atrial (LA) dimension (LAD) is one of the predictors of atrial fibrillation (AF) recurrence after catheter ablation, repetitive recurrences occur in patients without enlarged LAD. We explored the predictive value of pulmonary vein (PV) to LA volume percent ratio (PV/LA%vol) for rhythm outcomes after AF catheter ablation (AFCA). We included 2913 patients (73.5% male, 60.0 [52.0–67.0] years old, 60.6% paroxysmal AF) who underwent AFCA. We evaluated the association between PV/LA%vol and AF recurrence after AFCA and compared the predictive value for AF recurrences according to the LA size with LAD. We additionally investigated the association between PV/LA%vol and PITX2 gene using a genome-wide association study. LAD affected 1-year recurrence only in the highest tertile group (T3, p = 0.046), but PV/LA%vol determined 1-year recurrence in all LAD groups (T1, p = 0.044; T2, p = 0.021; and T3, p = 0.045). During 20.0 (8.0–45.0) months of follow-up, AF recurrence rate was significantly higher in patients with lower PV/LA%vol (Log-rank p = 0.004, HR 0.91 [0.84–1.00], p = 0.044). In the T1 and T2 LAD groups, predicting AF recurrences was better with PV/LA%vol than with LAD (AUC 0.63 vs. 0.51, p < 0.001 at T1; AUC 0.61 vs. 0.50, p = 0.007 at T2). We replicated PITX2-related rs12646447, which was independently associated with PV/LA%vol (β = 0.15 [0–0.30], p = 0.047). In conclusion, smaller PV volumes after LA volume adjustments have genetic background of PITX2 gene and predictive value for poorer rhythm outcomes after AFCA, especially in patients without LA enlargement.

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.