Atrial tachycardia (AT) is a common rhythm disorder, especially in patients with atrial structural abnormalities. Although voltage mapping can provide a general picture of structural alterations which are mainly secondary to prior ablations, surgery or pressure/volume overload, data is scarce regarding the functional characteristics of low voltage regions in the atrium to predict critical isthmus of ATs. Recently, functional substrate mapping (FSM) emerged as a potential tool to evaluate the functionality of structurally altered regions in the atrium to predict critical sites of reentry. Current evidence suggested a clear association between deceleration zones of isochronal late activation mapping (ILAM) during sinus/paced rhythm and critical isthmus of reentry in patients with left AT. Therefore, these areas seem to be potential ablation targets even not detected during AT. Furthermore, abnormal conduction detected by ILAM may also have a role to identify the potential substrate and predict atrial fibrillation outcome after pulmonary vein isolation. Despite these promising findings, the utility of such an approach needs to be evaluated in large‐scale comparative studies. In this review, we aimed to share our experience and review the current literature regarding the use of FSM during sinus/paced rhythm in the prediction of re‐entrant ATs and discuss future implications and potential use in patients with atrial low‐voltage areas.

中文翻译：

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心房疤痕患者心房功能基质测绘：预测房性心动过速临界峡部的新方法

房性心动过速（AT）是一种常见的节律紊乱，尤其是心房结构异常的患者。尽管电压图可以提供主要继发于先前消融、手术或压力/容量超负荷的结构改变的总体情况，但关于心房低电压区域的功能特征以预测 AT 关键峡部的数据很少。最近，功能基底图（FSM）成为评估心房结构改变区域的功能以预测折返关键部位的潜在工具。目前的证据表明，窦性/起搏心律期间等时晚激活标测 (ILAM) 的减速区与左 AT 患者折返的关键峡部之间存在明显关联。因此，这些区域似乎是潜在的消融目标，即使在 AT 期间未检测到。此外，ILAM 检测到的异常传导也可能有助于识别潜在底物并预测肺静脉隔离后心房颤动的结果。尽管有这些有希望的发现，但这种方法的实用性需要在大规模比较研究中进行评估。在这篇综述中，我们的目的是分享我们的经验并回顾有关在窦性/起搏心律期间使用 FSM 预测折返性 AT 的现有文献，并讨论对心房低电压区患者的未来影响和潜在用途。