Left atrial (LA) imaging is still not routinely used for diagnosis and risk stratification, although recent studies have emphasized its importance as an imaging biomarker. Cardiovascular magnetic resonance is able to evaluate LA structure and function, metrics that serve as early indicators of disease, and provide prognostic information, e.g. regarding diastolic dysfunction, and atrial fibrillation (AF). MR angiography defines atrial anatomy, useful for planning ablation procedures, and also for characterizing atrial shapes and sizes that might predict cardiovascular events, e.g. stroke. Long-axis cine images can be evaluated to define minimum, maximum, and pre-atrial contraction LA volumes, and ejection fractions (EFs). More modern feature tracking of these cine images provides longitudinal LA strain through the cardiac cycle, and strain rates. Strain may be a more sensitive marker than EF and can predict post-operative AF, AF recurrence after ablation, outcomes in hypertrophic cardiomyopathy, stratification of diastolic dysfunction, and strain correlates with atrial fibrosis. Using high-resolution late gadolinium enhancement (LGE), the extent of fibrosis in the LA can be estimated and post-ablation scar can be evaluated. The LA LGE method is widely available, its reproducibility is good, and validations with voltage-mapping exist, although further scan–rescan studies are needed, and consensus regarding atrial segmentation is lacking. Using LGE, scar patterns after ablation in AF subjects can be reproducibly defined. Evaluation of ‘pre-existent’ atrial fibrosis may have roles in predicting AF recurrence after ablation, predicting new-onset AF and diastolic dysfunction in patients without AF. LA imaging biomarkers are ready to enter into diagnostic clinical practice.

中文翻译：

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通过心血管磁共振评估左心房：敏感和独特的生物标志物

左心房 (LA) 成像仍未常规用于诊断和风险分层，尽管最近的研究强调了其作为成像生物标志物的重要性。心血管磁共振能够评估 LA 结构和功能、作为疾病早期指标的指标，并提供预后信息，例如关于舒张功能障碍和心房颤动 (AF)。MR 血管造影定义了心房解剖结构，可用于规划消融程序，也可用于表征可能预测心血管事件（例如中风）的心房形状和大小。可以评估长轴电影图像以定义最小、最大和心房前收缩 LA 体积和射血分数 (EF)。这些电影图像的更现代的特征跟踪提供了整个心动周期的纵向 LA 应变和应变率。应变可能是比 EF 更敏感的标志物，可以预测术后 AF、消融后 AF 复发、肥厚型心肌病的结果、舒张功能障碍的分层，以及应变与心房纤维化的相关性。使用高分辨率晚期钆增强 (LGE)，可以估计 LA 的纤维化程度，并可以评估消融后的疤痕。LA LGE 方法广泛可用，其重现性良好，并且存在电压映射验证，尽管需要进一步的扫描-重新扫描研究，并且缺乏关于心房分割的共识。使用 LGE，AF 受试者消融后的疤痕模式可以被重复定义。评估“预先存在的”心房纤维化可能有助于预测消融后的 AF 复发，预测无 AF 患者的新发 AF 和舒张功能障碍。LA 成像生物标志物已准备好进入诊断临床实践。