Heart Rhythm Service, Queen's University, Kingston Health Sciences, Ontario, Canada.
Abbott Medical Canada.
Heart Rhythm. 2021 May;18(5):723-731. doi: 10.1016/j.hrthm.2020.12.022. Epub 2020 Dec 27.
The conduction delay and block that compose the critical isthmus of macroreentrant ventricular tachycardia (VT) is partly "functional" in that they only occur at faster cycle lengths. Close-coupled pacing stresses the myocardium's conduction capacity and may reveal late potentials (LPs) and fractionation. Interest has emerged in targeting this functional substrate.
The purpose of this study was to assess the feasibility and efficacy of a functional substrate VT ablation strategy.
Patients with scar-related VT undergoing their first ablation were recruited. A closely coupled extrastimulus (ventricular effective refractory period + 30 ms) was delivered at the right ventricular apex while mapping with a high-density catheter. Sites of functional impaired conduction exhibited increased electrogram duration due to LPs/fractionation. The time to last deflection was annotated on an electroanatomic map, readily identifying ablation targets.
A total of 40 patients were recruited (34 [85%] ischemic). Median procedure duration was 330 minutes (interquartile range [IQR] 300-369), and ablation time was 49.4 minutes (IQR 33.8-48.3). Median functional substrate area was 41.9 cm (IQR 22.1-73.9). It was similarly distributed across bipolar voltage zones. Noninducibility was achieved in 34 of 40 patients (85%). Median follow-up was 711 days (IQR 255.5-972.8), during which 35 of 39 patients (89.7%) did not have VT recurrence, and 3 of 39 (7.5%) died. Antiarrhythmic drugs were continued in 53.8% (21/39).
Functional substrate ablation resulted in high rates of noninducibility and freedom from VT. Mapping times were increased considerably. Our findings add to the encouraging trend reported by related techniques. Randomized multicenter trials are warranted to assess this next phase of VT ablation.
构成宏观折返性室性心动过速（VT）关键峡部的传导延迟和阻滞在一定程度上是“功能性的”，因为它们仅在较快的心动周期长度下发生。紧密偶联起搏会对心肌的传导能力造成压力，并可能揭示晚期电位（LPs）和碎裂。人们对靶向这种功能性基质产生了兴趣。
本研究旨在评估功能基质 VT 消融策略的可行性和疗效。
招募接受首次消融的与瘢痕相关 VT 患者。在右心室心尖处给予紧密偶联的超刺激（心室有效不应期+30 ms），同时使用高密度导管进行映射。功能受损传导部位由于 LPs/碎裂而表现出延长的电图持续时间。最后一个偏转的时间在电解剖图上进行注释，很容易确定消融靶点。
共招募了 40 名患者（34 名[85%]为缺血性）。中位手术时间为 330 分钟（四分位间距[IQR] 300-369），消融时间为 49.4 分钟（IQR 33.8-48.3）。中位功能基质面积为 41.9 cm（IQR 22.1-73.9）。它在双极电压区域中分布相似。40 名患者中的 34 名（85%）实现了非诱发性。中位随访时间为 711 天（IQR 255.5-972.8），在此期间，39 名患者中的 35 名（89.7%）没有 VT 复发，39 名患者中的 3 名（7.5%）死亡。53.8%（21/39）的患者继续服用抗心律失常药物。
功能基质消融导致非诱发性和 VT 无复发的比例很高。映射时间大大增加。我们的发现增加了相关技术报告的令人鼓舞的趋势。需要进行随机多中心试验来评估 VT 消融的下一阶段。
