Department of Cardiology, Unitat de Fibril·lació Auricular (UFA), Hospital Clinic, Universitat de Barcelona, Villarroel 170, 08036 Barcelona, Catalonia, Spain.
Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.
Europace. 2017 Aug 1;19(8):1272-1279. doi: 10.1093/europace/euw219.
Identification of left atrial (LA) fibrosis through late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) remains controversial due to the heterogeneity and lack of reproducibility of proposed methods. Our aim is to describe a normalized, reproducible, standardized method to evaluate LA fibrosis through LGE-CMR.
Electrocardiogram- and respiratory-gated 3-Tesla LGE-CMR was performed in 10 healthy young volunteers and 30 patients with atrial fibrillation (AF): 10 with paroxysmal AF, 10 with persistent AF, and 10 with a previous AF ablation procedure. Local image intensity ratio (IIR) of the LA was calculated as the absolute pixel intensity to mean blood pool intensity ratio. The healthy atrial tissue threshold was defined in young healthy volunteers (upper limit of normality set at IIR tissue mean plus 2 SDs). Dense atrial scarring was characterized in patients with previous radiofrequency-induced scarring (post-AF ablation patients). Validation groups consisted of patients with paroxysmal and persistent AFs. The upper limit of normal IIR was 1.20; IIR values higher than 1.32 (60% of mean maximum pixel intensity in post-ablation patients) were considered dense scar. Image intensity ratio values between 1.2 and 1.32 identified interstitial fibrosis. Patients with paroxysmal and persistent AFs had less atrial fibrotic tissue compared with post-ablation patients. Endocardial bipolar voltage was correlated to IIR values.
An IIR of 1.2 identifies the upper limit of normality in healthy young individuals. An IIR of >1.32 defines dense atrial fibrosis in post-ablation patients. Our results provide a consistent, comparable, and normalized tool to assess atrial arrhythmogenic substrate.
由于提出的方法存在异质性和可重复性差，通过心脏磁共振钆延迟增强（LGE-CMR）来识别左心房（LA）纤维化仍然存在争议。我们的目的是描述一种标准化、可重复、规范化的方法，通过 LGE-CMR 评估 LA 纤维化。
对 10 名健康年轻志愿者和 30 名心房颤动（AF）患者（阵发性 AF 10 例、持续性 AF 10 例和既往 AF 消融术 10 例）进行了心电图和呼吸门控 3T LGE-CMR。LA 的局部图像强度比（IIR）计算为绝对像素强度与平均血池强度比。健康心房组织的阈值在年轻健康志愿者中定义（上限正常设定为组织平均加 2 个标准差的 IIR 组织）。在既往射频诱导瘢痕的患者（消融后 AF 患者）中，致密性心房瘢痕的特征。验证组包括阵发性和持续性 AF 患者。正常的 IIR 上限为 1.20；高于 1.32（消融后患者最大像素强度平均值的 60%）的 IIR 值被认为是致密瘢痕。IIR 值在 1.2 和 1.32 之间确定间质纤维化。与消融后患者相比，阵发性和持续性 AF 患者的心房纤维化组织较少。心内膜双极电压与 IIR 值相关。
1.2 的 IIR 可识别健康年轻个体的正常上限。>1.32 的 IIR 定义了消融后患者的致密性心房纤维化。我们的结果提供了一种一致、可比和标准化的工具，用于评估心房心律失常基质。
