Intra-Atrial Dyssynchrony Using Cardiac Magnetic Resonance to Quantify Tissue Remodeling in Patients with Atrial Fibrillation

Abstract Background: Recent studies suggest that left atrial (LA) late gadolinium enhancement (LGE) can quantify the underlying tissue remodeling that harbors atrial fibrillation (AF). However, quantification of LA-LGE requires labor-intensive magnetic resonance imaging acquisition and postprocessing at experienced centers. LA intra-atrial dyssynchrony assessment is an emerging imaging technique that predicts AF recurrence after catheter ablation. We hypothesized that 1) LA intra-atrial dyssynchrony is associated with LA-LGE in patients with AF and 2) LA intra-atrial dyssynchrony is greater in patients with persistent AF than in those with paroxysmal AF. Method: We conducted a cross-sectional study comparing LA intra-atrial dyssynchrony and LA-LGE in 146 patients with a history of AF (60.0 ± 10.0 years, 30.1% nonparoxysmal AF) who underwent pre-AF ablation cardiac magnetic resonance (CMR) in sinus rhythm. Using tissue-tracking CMR, we measured the LA longitudinal strain in two- and four-chamber views. We defined intra-atrial dyssynchrony as the standard deviation (SD) of the time to peak longitudinal strain (SD-TPS, in %) and the SD of the time to the peak pre-atrial contraction strain corrected by the cycle length (SD-TPSpreA, in %). We used the image intensity ratio (IIR) to quantify LA-LGE. Results: Intra-atrial dyssynchrony analysis took 5 ± 9 minutes per case. Multivariable analysis showed that LA intra-atrial dyssynchrony was independently associated with LA-LGE. In addition, LA intra-atrial dyssynchrony was significantly greater in patients with persistent AF than those with paroxysmal AF. In contrast, there was no significant difference in LA-LGE between patients with persistent and paroxysmal AF. LA intra-atrial dyssynchrony showed excellent reproducibility and its analysis was less time-consuming (5 ± 9 minutes) than the LA-LGE (60 ± 20 minutes). Conclusion: LA Intra-atrial dyssynchrony is a quick and reproducible index that is independently associated with LA-LGE to reflect the underlying tissue remodeling.

研究背景：近期研究表明，左心房（left atrial, LA）晚期钆增强（late gadolinium enhancement, LGE）可量化心房颤动（atrial fibrillation, AF）患者潜在的心房组织重构。然而，LA-LGE的量化分析需要在经验丰富的医学中心开展耗时费力的磁共振成像采集与后处理工作。心房内同步性评估是一项新兴影像学技术，可预测导管消融术后AF的复发风险。本研究提出两项假设：其一，心房颤动患者的LA心房内同步性与LA-LGE存在相关性；其二，持续性AF患者的LA心房内同步性较阵发性AF患者更高。
研究方法：本研究为横断面研究，纳入146例有AF病史且在窦性心律下接受AF消融术前心脏磁共振（cardiac magnetic resonance, CMR）检查的患者（年龄60.0±10.0岁，30.1%为非阵发性AF），对比分析其LA心房内同步性与LA-LGE水平。采用组织追踪CMR技术，在两腔心与四腔心切面测量LA纵向应变。我们将心房内同步性定义为两类指标：峰值纵向应变达峰时间的标准差（standard deviation of the time to peak longitudinal strain, SD-TPS，单位：%），以及经心动周期长度校正的心房收缩前峰值应变达峰时间的标准差（standard deviation of the time to peak pre-atrial contraction strain corrected by the cycle length, SD-TPSpreA，单位：%）。通过图像强度比（image intensity ratio, IIR）量化LA-LGE水平。
研究结果：单例患者的心房内同步性分析耗时仅5±9分钟。多变量分析显示，LA心房内同步性与LA-LGE存在独立相关性。此外，持续性AF患者的LA心房内同步性显著高于阵发性AF患者。与之相反，持续性AF与阵发性AF患者的LA-LGE水平无显著差异。LA心房内同步性分析具有极佳的可重复性，且分析耗时（5±9分钟）远少于LA-LGE量化分析（60±20分钟）。
研究结论：LA心房内同步性是一项快速且可重复的指标，其与LA-LGE存在独立相关性，可反映心房颤动患者潜在的心房组织重构。