Quantitative assessment of left atrial scar using high-density voltage mapping and a novel automated voltage analysis tool.

Purpose: Left atrial (LA) fibrosis plays an important role in the pathogenesis and perpetuation of atrial fibrillation (AF). It may be identified by bipolar voltage (BiV) mapping, but quantification of fibrosis which previously relied on visual estimation of scar has been shown to be inaccurate. Our aim was to use a novel automated voltage histogram analysis (VHA) tool to quantify LA scar burden accurately in patients with AF.

Methods: LA voltage was assessed in 100 consecutive patients undergoing first pulmonary vein isolation (PVI) for paroxysmal or persistent AF using a circular multielectrode catheter to create high-density LA BiV maps which were analysed using the VHA tool after the procedure.

Results: High-density electro-anatomic maps took 10 min to create and contained a median of 1049 points. The VHA algorithm accurately quantified the burden of Diseased LA Tissue (≤ 0.5 mV) and Dense LA Scar (≤ 0.2 mV) with a median of 17.8% and 3.5% respectively. A quartile classification was applied based on diseased LA tissue burden. Patients in class IV with the highest diseased LA burden were older (p < 0.0001), more likely female (p = 0.0095), had higher CHADS-VASc scores (p = 0.0024) and were more likely to have persistent rather than paroxysmal AF (p = 0.0179) than those in classes I-III.

Conclusions: The VHA algorithm is able to quantify percentage surface area voltage rapidly and according to preset ranges for the first time. The algorithm offers the potential for classification of patients undergoing AF ablation into different classes of diseased LA burden, which may have diagnostic, therapeutic and prognostic implications.