Background:Brugada syndrome (BrS) is considered a purely electrical disease with variable electrical substrates. Variable rates of mechanical abnormalities have been also reported. Whether exists a link between electrical and mechanical abnormalities has never been previously explored. This investigational physiopathological study aimed to determine the relationship between the substrate size/location, as exposed by ajmaline provocation, and the severity of mechanical abnormalities, as assessed by cardiac magnetic resonance in patients with BrS.Methods:Twenty-four consecutive high-risk patients with BrS (mean age, 38±11 years, 17 males), presenting with malignant syncope and documented polymorphic ventricular tachycardia/ventricular fibrillation, and candidate to implantable cardioverter defibrillator implantation, underwent cardiac magnetic resonance and electroanatomic maps. During each examination, ajmaline test (1 mg/kg over 5 minutes) was performed. Cardiac magnetic resonance findings were compared with 24 age, sex, and body surface area-matched controls. In patients with BrS, the correlation between the electrical substrate extent and right ventricular regional mechanical abnormalities before/after ajmaline challenge was analyzed.Results:After ajmaline, patients with BrS showed a reduction of right ventricular (RV) ejection fraction (P<0.001), associated with decreased transversal displacement (U, P<0.001) and longitudinal strain (ε, P<0.001) localized at RV outflow tract. In patients with BrS significant preajmaline/postajmaline changes of transversal displacement (ΔU, P<0.001) and longitudinal strain (Δε, P<0.001) were found. In the control group, no mechanical changes were observed after ajmaline. The electrical substrate consistently increased after ajmaline from 1.7±2.8 cm² to 14.2±7.3 cm² (P<0.001), extending from the RV outflow tract to the neighboring segments of the RV anterior wall. Postajmaline RV ejection fraction inversely correlated with postajmaline substrate extent (r=−0.830, P<0.001). In patients with BrS and normal controls, cardiac magnetic resonance detected neither myocardial fibrosis nor RV outflow tract morphological abnormalities.Conclusions:BrS is a dynamic RV electromechanical disease, where functional abnormalities correlate with the maximal extent of the substrate size. These findings open new lights on the physiopathology of the disease.Registration:URL: https://clinicaltrial.gov; Unique identifier: NCT03524079.

中文翻译：

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Brugada 综合征：心脏磁共振和电解剖成像的新见解

背景：Brugada 综合征 (BrS) 被认为是一种具有可变电底物的纯电病。还报告了不同比例的机械异常。以前从未探索过电气和机械异常之间是否存在联系。这项研究性病理生理学研究旨在确定由 ajmaline 激发暴露的基质大小/位置与机械异常严重程度之间的关系，如通过心脏磁共振对 BrS 患者进行评估。方法：24 名连续的高危患者患有 BrS（平均年龄，38±11 岁，17 名男性），表现为恶性晕厥和记录的多形性室性心动过速/心室颤动，并且是植入式心律转复除颤器植入的候选者，接受了心脏磁共振和电解剖图。在每次检查期间，都进行了 ajmaline 测试（5 分钟内 1 毫克/公斤）。将心脏磁共振结果与 24 名年龄、性别和体表面积匹配的对照进行比较。分析了 BrS 患者在 ajmaline 激发前后电底物范围与右心室局部机械异常之间的相关性。P <0.001），与位于 RV 流出道的横向位移（U，P <0.001）和纵向应变（ε，P <0.001）减少相关。在 BrS 患者中，发现了显着的 preajmaline/postajmaline 变化（ΔU，P <0.001）和纵向应变（Δε，P <0.001）。在对照组中，ajmaline 后没有观察到机械变化。ajmaline 后电基板从 1.7±2.8 cm ²持续增加到14.2±7.3 cm ² ( P<0.001)，从 RV 流出道延伸到 RV 前壁的相邻部分。Postajmaline RV 射血分数与 postajmaline 底物范围呈负相关（r =-0.830，P <0.001）。在 BrS 患者和正常对照组中，心脏磁共振未检测到心肌纤维化和 RV 流出道形态异常。结论：BrS 是一种动态的 RV 机电疾病，其功能异常与基质尺寸的最大程度相关。这些发现为该疾病的病理生理学开辟了新的思路。Registration:URL: https://clinicaltrial.gov; 唯一标识符：NCT03524079。