Center for Arrhythmia Prevention, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; Department of Medicine, University Hospital, Basel, Switzerland, United States.
Int J Cardiol. 2013 Oct 3;168(3):1894-9. doi: 10.1016/j.ijcard.2012.12.060. Epub 2013 Jan 17.
Left atrial (LA) enlargement facilitates induction and/or maintenance of atrial fibrillation (AF). However, little is known about risk factors for AF with normal LA size.
We prospectively followed 34713 initially healthy women for incident AF. Information on echocardiographic LA size at first AF diagnosis was abstracted from medical charts during AF confirmation. LA enlargement was defined as LA diameter >40 mm. Using a competing risk approach, we constructed Cox proportional-hazards models to calculate hazard ratios (HR) and 95% confidence intervals (CI) of risk factors for incident AF with and without LA enlargement, respectively.
Among 796 women with incident AF and available LA size, 328 (41%) had LA enlargement. In multivariable competing risk models, the relationship between age and incident AF was stronger in those with (HR 1.12, 95% CI 1.10-1.14) versus without (HR 1.08, 95% CI 1.06-1.09) LA enlargement (p for difference <0.0001). Body weight was associated with AF only in the presence of LA enlargement (HR per 10 kg 1.34, 95% CI 1.26-1.43; versus 1.07, 95% CI 0.998-1.14, p for difference<0.0001). Hypertension and height were significantly associated with AF both in the presence (HR 1.99, 95% CI 1.49-2.65; and HR per 10 cm 1.36, 95% CI 1.13-1.63) and absence (1.55, 1.25-1.92 and 1.29, 1.10-1.50) of LA enlargement (p for difference 0.17 and 0.66, respectively).
These data suggest that LA enlargement explains much of the increased AF risk associated with obesity and age. In contrast, height and hypertension appear to also influence AF risk through other mechanisms besides LA enlargement.
左心房（LA）增大有助于心房颤动（AF）的诱导和/或维持。然而，对于 LA 大小正常的 AF 的危险因素知之甚少。
我们前瞻性地随访了 34713 名最初健康的女性，以观察 AF 的发生情况。在 AF 确诊期间，从病历中提取首次 AF 诊断时的超声心动图 LA 大小信息。LA 增大定义为 LA 直径>40mm。使用竞争风险方法，我们构建 Cox 比例风险模型，分别计算有和无 LA 增大的 AF 发生的风险因素的危险比（HR）和 95%置信区间（CI）。
在 796 名发生 AF 且有可用 LA 大小的女性中，有 328 名（41%）有 LA 增大。在多变量竞争风险模型中，年龄与 AF 发生的关系在有（HR 1.12，95%CI 1.10-1.14）和无（HR 1.08，95%CI 1.06-1.09）LA 增大的患者中更强（p<0.0001）。体重仅与 LA 增大的 AF 相关（每增加 10kg 的 HR 为 1.34，95%CI 1.26-1.43；与 1.07，95%CI 0.998-1.14，p<0.0001）。高血压和身高与 AF 均显著相关，无论是否存在 LA 增大（HR 1.99，95%CI 1.49-2.65；每增加 10cm 的 HR 为 1.36，95%CI 1.13-1.63）和无 LA 增大（HR 1.55，1.25-1.92 和 1.29，1.10-1.50）（p<0.0001）。
这些数据表明，LA 增大解释了肥胖和年龄与 AF 风险增加相关的大部分原因。相比之下，身高和高血压似乎通过除 LA 增大之外的其他机制也会影响 AF 风险。
