Clinical Phenotypes and Atrial Fibrillation Recurrences after Catheter Ablation: An Unsupervised Cluster Analysis

Clinical Phenotypes and Outcomes of Patients with Left Ventricular Thrombus: An Unsupervised Cluster Analysis

BACKGROUND

Left ventricular thrombus (LVT) can develop in a diverse group of patients with various underlying causes resulting in divergent natural histories and trajectories with treatment. Our aim was to utilise cluster analysis to identify unique clinical profiles among LVT patients and then compare their clinical characteristics, treatment strategies, and outcomes.

METHODS

We conducted a retrospective study involving 472 LVT patients whose data was extracted from a tertiary center's echocardiography database, from March 2011 to January 2021. We employed the TwoStep cluster analysis method, examining 19 variables.

RESULTS

Our analysis of the 472 LVT patients revealed two distinct patient clusters. Cluster 1, comprising 247 individuals (52.3%), was characterized by younger patients with a lower incidence of traditional cardiovascular risk factors and relatively fewer comorbidities, compared to Cluster 2. Most patients had LVT attributed to an underlying ischaemic condition, with a larger proportion in Cluster 1 being due to post-acute myocardial infarction (68.8%), and Cluster 2 due to ischaemic cardiomyopathy (57.8%). Notably, patients in Cluster 2 exhibited a reduced likelihood of LVT resolution (HR 0.58, 95% CI 0.44 - 0.77, p < 0.001) and a higher risk of all-cause mortality (HR 2.27, 95% CI 1.43 - 3.60, p = 0.001). These associations persisted even after adjusting for variables like anticoagulation treatment, the presence of left ventricular aneurysms, and specific LVT characteristics such as mobility, protrusion, and size.

CONCLUSIONS

Through TwoStep cluster analysis, we identified two distinct clinical phenotypes among LVT patients, each distinguished by unique baseline clinical attributes and varying prognoses.

Unsupervised cluster analysis reveals different phenotypes in patients after transcatheter aortic valve replacement

Aims

The aim of this study was to identify phenotypes with potential prognostic significance in aortic stenosis (AS) patients after transcatheter aortic valve replacement (TAVR) through a clustering approach.

Methods and results

This multi-centre retrospective study included 1365 patients with severe AS who underwent TAVR between January 2015 and March 2019. Among demographics, laboratory, and echocardiography parameters, 20 variables were selected through dimension reduction and used for unsupervised clustering. Phenotypes and outcomes were compared between clusters. Patients were randomly divided into a derivation cohort (n = 1092: 80%) and a validation cohort (n = 273: 20%). Three clusters with markedly different features were identified. Cluster 1 was associated predominantly with elderly age, a high aortic valve gradient, and left ventricular (LV) hypertrophy; Cluster 2 consisted of preserved LV ejection fraction, larger aortic valve area, and high blood pressure; and Cluster 3 demonstrated tachycardia and low flow/low gradient AS. Adverse outcomes differed significantly among clusters during a median of 2.2 years of follow-up (P < 0.001). After adjustment for clinical and echocardiographic data in a Cox proportional hazards model, Cluster 3 (hazard ratio, 4.18; 95% confidence interval, 1.76-9.94; P = 0.001) was associated with increased risk of adverse outcomes. In sequential Cox models, a model based on clinical data and echocardiographic variables (χ2 = 18.4) was improved by Cluster 3 (χ2 = 31.5; P = 0.001) in the validation cohort.

Conclusion

Unsupervised cluster analysis of patients after TAVR revealed three different groups for assessment of prognosis. This provides a new perspective in the categorization of patients after TAVR that considers comorbidities and extravalvular cardiac dysfunction.

Platelet-to-Lymphocyte Ratio Improves the Predictive Ability of the Risk Score for Atrial Fibrillation Recurrence After Radiofrequency Ablation

Purpose

To investigate the effect and comprehensive predictive value of the platelet-to-lymphocyte ratio (PLR) for long-term recurrence in patients with atrial fibrillation (AF) post ablation.

Patients and Methods

We retrospectively analysed 638 consecutive AF patients who underwent ablation, including 302 (47.3%) with paroxysmal AF and 336 (52.7%) with nonparoxysmal AF. Patients were grouped into the recurrence and nonrecurrence groups.

Results

After a mean follow-up of 15.1±9.3 months, 175 patients (27.4%) with AF had long-term recurrence, including 114 patients (33.9%) with nonparoxysmal AF and 61 patients (20.2%) with paroxysmal AF. In the entire cohort and in patients with nonparoxysmal AF, but not in those with paroxysmal AF, the PLR was significantly higher in the recurrence group than in the nonrecurrence group (P<0.05). After adjusting for the APPLE score, the PLR as a continuous variable independently predicted AF recurrence (hazard ratio [HR], 1.003; 95% confidence interval [CI], 1.001-1.005; P<0.01). The addition of the PLR to the APPLE score improved its predictive ability for recurrence (the C-statistic value increased from 0.645 to 0.675, P=0.02; the net reclassification improvement was 0.221, 95% CI 0.049-0.394, P=0.01; and the integrated discrimination improvement was 0.029, 95% CI 0.013-0.045, P<0.01). For nonparoxysmal AF, the PLR was stratified into tertiles, the PLR independently increased the nonparoxysmal AF recurrence risk after adjusting for multiple confounding factors (HR, 1.393; 95% CI, 1.102-1.762; P<0.01), and the addition of the PLR to the left atrial diameter improved its predictive ability for arrhythmia recurrence (the C-statistic value increased from 0.601 to 0.667, P<0.01).

Conclusion

The PLR is an independent predictive factor of long-term AF recurrence post ablation after adjusting for the APPLE score and can improve the predictive ability and clinical usefulness of the APPLE score. However, the PLR is an effective predictor of recurrence in patients with nonparoxysmal AF rather than in paroxysmal AF.