Characterization of Left Atrial Substrate in Patients With Ventricular Arrhythmias

Recruiting

Brief Summary: The goal of this observational study is to analyze the characteristics of left atrial electroanatomical maps in patients without a history of atrial fibrillation but with a high clinical risk of developing it, as indicated by the presence of structural heart disease or a CHA2DS2-VASc score ≥ 2 points. The study cohort will be compared to a historical cohort of patients with diagnosed atrial fibrillation in a propensity-matched fashion.

The main questions it aims to answer are:

* Are the left atrial electroanatomical changes a consequence or a precursor to the development of atrial fibrillation?

* Are the left atrial electroanatomical findings different between patients with atrial fibrillation and those at high risk of developing it?

* What is the prognostic impact of left atrial pathologic changes in patients without diagnosed atrial fibrillation in terms of cardiovascular outcomes?

Recruitment & Eligibility

Inclusion Criteria

Absence of a prior history of atrial fibrillation or flutter.
Patients presenting for ablation of any ventricular tachycardia related to structural heart disease or any ventricular arrhythmia with a CHA2DS2-VASc score ≥ 2.

Exclusion criteria:

Exclusion Criteria

Not provided

Arm && Interventions

Group	Intervention	Description
Left atrial mapping group in patients without atrial fibrillation	Left atrial electroanatomical mapping	Inclusion criteria: * Age ≥ 18 years old. * Absence of a prior history of atrial fibrillation or flutter. * Patients presenting for ablation of any ventricular tachycardia related to structural heart disease or any ventricular arrhythmia with a CHA2DS2-VASc score ≥ 2. Exclusion criteria: * Presence of thrombus in the left atrial appendage. * Complications related to the index procedure. * Insufficient quality of the left atrial electroanatomical map.

Primary Outcome Measures

Name	Time	Method
Substrate characterization of the left atrium.	18 months	Substrate characterization will involve measuring Low Voltage (LV) and Transition Voltage (TV) Zones (LV zone voltage cut-off of \<0.5mV; TV zone voltage limits within 0.5 and 1mV). These zones will be considered if they encompass an area of at least 1cm², containing ≥3 neighboring points within ≤10mm distance. The total LVZ and TVZ surfaces will be expressed as a percentage relative to the total surface area of the left atrium (excluding the pulmonary veins and the mitral annulus). A comparative analysis of substrate characteristics will be conducted between two groups: the study group (comprising patients without atrial fibrillation but at risk of developing it) and the control group (a historical cohort of patients with known atrial fibrillation).
Functional characterization of the left atrium.	18 months	Functional analysis will rely on identifying deceleration zones characterized by isochronal crowding, defined as having ≥3 isochrones within a 1cm radius, using an 8-color scale of left atrial isochronal activation mapping. A comparative analysis of functional characteristics will be conducted between two groups: the study group (comprising patients without atrial fibrillation but at risk of developing it) and the control group (a historical cohort of patients with known atrial fibrillation).

Secondary Outcome Measures

Name	Time	Method

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