Predicting the presence of left atrial appendage thrombus with clinical features and transthoracic measurements using machine learning

Background

Atrial fibrillation and flutter (AF/AFl) increase the risk of thromboembolic events by promoting clot formation in the left atrium (LA), which can be visualised using transoesophageal echocardiography (TEE). Current guidelines recommend initiation of oral anticoagulation (OAC) in patients with AF/AFl based solely on CHA2DS2VASc score (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, history of stroke or thromboembolism, vascular disease, age 65 to 74 years, female sex). Yet, some patients develop left LA thrombus (LAT) and experience thromboembolic events despite OAC.

Purpose

We sought to develop and externally validate a machine learning model for prediction of presence of LAT based on clinical, laboratory and transthoracic echocardiography (TTE) features.

Methods

We analyzed data from the multicenter, prospective LATTEE registry (Left Atrial Thrombus on Transesophageal Echocardiography) that included patients from 13 sites who underwent TEE before cardioversion or ablation between November 2018 and March 2021. We used XgBoost model to predict presence of LAT in TEE based on 29 clinical features, 10 biomarkers and 5 TTE measurements. We trained and tested the model internally using 10-fold hold-out cross validation and data from 12 sites (N=2489). We then tested the final model externally using data from the 13th site (that had recruited most patients, N=400). We compared the predictive performance with that of CHA2DS2VASc score using areas under receiver operating curve (AUC) and DeLong test.

Results

In the training and internal testing cohort the median age was 67 (Inter Quartile Range [IQR] 59, 74), 63% were male, 85% received OAC and LAT was found in 8.4%. Ablation was the indication for TEE in 43%, cardioversion in 57%. In internal, 10-fold hold-out cross validation, the model achieved AUC of 0.755 (95% confidence interval [CI]: 0.722, 0.788) while CHA2DS2VASc performed significantly worse with AUC of 0.638 (95% CI: 0.604, 0.673), P<0.0001 (Figure 1). Left ventricular ejection fraction, rhythm at the time of study (AF/AFl or sinus rhythm) and age received the highest feature importance ranking (Figure 2).

In the external testing cohort the median age was 67 (IQR 59, 74), 66% were male, 88% received OAC, ablation was the indication for TEE in 49% of cases and LAT was found in 6.8%. In this external cohort, our model achieved AUC of 0.815 (95% CI: 0.741, 0.889) while CHA2DS2VASc performed significantly worse with AUC of 0.684 (95% CI: 0.583, 0.785), P=0.028.

Conclusion

Machine learning based on readily available clinical data allows accurate prediction of the presence of LAT in patients with AF/AFl irrespective of OAC treatment. Such score could be used to identify patients who should undergo TEE before ablation or cardioversion. Subsequent studies to clinically evaluate such application of our model as well as how the model can predict future thromboembolic events are warranted.

Funding Acknowledgement

Type of funding sources: None.

Atrial functional mitral regurgitation in patients qualified for pulmonary vein isolation: a negative prognostic factor for catheter ablation efficacy

Background

Atrial functional mitral regurgitation (AF-MR) related to atrial fibrillation (AF) could affect the effectiveness of the sinus rhythm restoring procedures.

Purpose

The aim of the study was to evaluate the impact of AF-MR on pulmonary vein isolation (PVI) efficacy.

Methods

One hundred thirty-six patients (65.4% males; mean age 56±11 years) with symptomatic paroxysmal or persistent AF qualified for PVI were enrolled into the study. AF-MR assessment was performed in transthoracic (TTE) and transesophageal (TEE) echocardiography before PVI procedure. PVI efficacy was evaluated in 3-month and long-term follow-up.

Results

AF-MR was diagnosed in 74.3% patient in transthoracic echocardiography (TTE) (trace: 26.5%, mild: 43.4%, moderate: 3.7%, severe 0.7%) and 94.9% in transesophageal echocardiography (TEE) (trace: 17.6%, mild: 59.6%, moderate: 16.2%, severe: 1.5%). PVI 3-month efficacy was 75.7% in 3-month and 64% in the long-term observation.

Severe AF-MR in TEE at baseline was associated with lower 3-month PVI efficacy (P=0.012) while moderate to severe AF MR in TEE was related to inefficient PVI assessed in long-term follow-up (P=0.041). In Kaplan- Meier analysis only moderate to severe AF-MR diagnosed in TEE had an impact on long-term procedure outcome (P=0.048).

Conclusions

Significant AF-MR confirmed by TEE predicts 3-month as well as long-term PVI efficacy.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The institutional budget of the First Department of Cardiology, Medical University of Silesia, Katowice, Poland

P1816 Cerebral microembolism in low-risk patients with paroxysmal atrial fibrillation before and after pulmonary vein isolationCerebral microembolism in low-risk patients with paroxysmal atrial fibrillation

BACKGROUND

Invasive treatment of atrial fibrillation (AF) becomes more suitable and effective therapy. There are no consistent data describing the occurrence of potential neurological complications in low-risk patients with paroxysmal AF.

AIM

to determine the occurrence, consequences and risk factors for brain white matter hiperintensities (WMH) assessed in magnetic resonance imaging (MRI) in low-risk patients before and after pulmonary vein isolation (PVI) treatment.

METHODS

Eighty patients with symptomatic paroxysmal AF (median age: 58 years (IQR 50-63), K/M: 30/50), CHA2DS2-Vasc ≤ 3 (CHA2DS2-Vasc: 2 (IQR 1-2.5)) were included in the study. Before and after a minimum of 6-month period after PVI-RF treatment (med. 9,9 months, IQR 7.6-11.8 months) a clinical evaluation with brain MRI and Mini Mental State Examination (MMSE) test were determined. Severity of brain WMH in MRI was assessed in the Fazekas scale (pic 1). The efficacy of PVI-RF treatment analyzed in a 7-day Holter monitoring was confirmed in 43 (53.8%) patients.

RESULTS

Baseline WMH lesions were found in 55 (68.8%) patients. Patients with baseline WMH lesion obtained similar results in the MMSE test, compared to patients with a normal brain image in the MRI study. There was a statistically significant more frequent occurrence of cerebral WMH lesions among older patients, with a higher CHA2DS2-Vasc score, with left atrial (LA) dilatation and dysfunction. Factors affecting the severity of the WMH were: the co-occurrence of the patent foramen ovale (PFO) and coronary artery disease (CAD).

After PVI-RF treatment there were no significant changes in the presence and severity of WMH lesions. Similarly, there were no significant changes in the cognitive abilities assessed with MMSE test compared to the pre-procedural evaluation. There were also similar factors predisposing to brain WMH changes: older age, higher CHA2DS2-Vasc score and higher BMI. In turn, the degree of the brain WMH severity after observation period was dependent on age, higher CHA2DS2-Vasc score, presence of PFO and CAD and the initial LA function.

CONCLUSIONS Cerebral microembolism assessed in MRI is often found in low-risk patients with paroxysmal AF, and its presence and severity are associated with LA dilatation and dysfunction, age and higher CHA2DS2-Vasc score. Additional factors affecting the severity of WMH lesions are: the co-occurrence of PFO and CAD. PVI-RF procedure and its efficacy does not influence on MRI lesions. In the population of relatively young AF patients with no significant cardiovascular disease burden, cerebral microembolism is not related to cognitive impairment.

Abstract P1816 Figure. pic 1

The mechanism of action of DNA photolyases

Structural analysis, biochemistry and model studies have provided new insights into the mechanism of action of photolyases. The light-driven electron and energy transfer events that lead to the photolyase-catalyzed repair of lethal, mutagenic and carcinogenic UV-light-induced DNA lesions have all been examined in the past few years.