The impact of obesity on the prognosis of atrial fibrillation (AF) remains controversial. We conducted an exposure‐effect meta‐analysis of prospective studies to clarify the relationship between body mass index (BMI) and outcomes in patients with AF. The Cochrane Library, PubMed, and Embase databases were searched through May 1, 2019. Summary relative risks (RRs) were calculated using random‐effects models. Nonlinear associations were explored using restricted cubic spline models. Twenty publications involving 161,922 individuals were included. Categorical variable analysis showed that underweight was associated with an increased risk of all‐cause mortality (RR: 2.6), cardiovascular death (RR: 2.91), major bleeding (RR: 1.57), stroke or systemic embolism (RR: 1.62), and a composite endpoint (RR: 2.23). In exposure‐effect analysis, the risk per 5 BMI increase was reduced for adverse outcomes (RR=0.86, 95% CI: 0.80‐0.92 for all‐cause death; RR=0.82, 95% CI: 0.71‐0.95 for cardiovascular death; RR=0.89, 95% CI: 0.84‐0.95 for stroke or systemic embolism; and RR=0.78, 95% CI: 0.67‐0.92 for a composite endpoint). There was a significant “U”‐shaped exposure‐effect relationship with all‐cause death, and the nadir of the curve was observed at a BMI of approximately 28. Our results showed that underweight is associated with a worse prognosis, but that overweight and obesity are associated with improved adverse outcomes in patients with AF.

中文翻译：

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房颤预后的肥胖悖论：前瞻性研究的暴露效应分析得出的证据。

肥胖对房颤（AF）预后的影响仍存在争议。我们进行了一项前瞻性研究的暴露效应荟萃分析，以阐明房颤患者的体重指数（BMI）与预后之间的关系。检索截至2019年5月1日的Cochrane图书馆，PubMed和Embase数据库。使用随机效应模型计算摘要相对风险（RRs）。使用限制三次样条模型探索非线性关联。收录了20种出版物，涉及161,922个人。分类变量分析显示，体重过轻与全因死亡率（RR：2.6），心血管死亡（RR：2.91），大出血（RR：1.57），中风或全身性栓塞（RR：1.62）的风险增加相关；复合端点（RR：2.23）。在暴露效应分析中，不良结局导致每5 BMI升高的风险降低（全因死亡的RR = 0.86，95％CI：0.80-0.92;心血管死亡的RR = 0.82，95％CI：0.71-0.95; RR = 0.89，95％ CI：中风或全身性栓塞的0.84-0.95; RR = 0.78，95％CI：复合终点的0.67-0.92）。全因死亡具有显着的“ U”形暴露效应关系，在BMI约为28时观察到曲线的最低点。我们的结果表明，体重过轻与预后较差有关，但体重超重与预后较差有关。肥胖与房颤患者不良后果的改善有关。92（复合端点）。全因死亡具有显着的“ U”形暴露效应关系，在BMI约为28时观察到曲线的最低点。我们的结果表明，体重过轻与预后较差有关，但体重超重与预后较差有关。肥胖与房颤患者不良后果的改善有关。92（复合端点）。全因死亡具有显着的“ U”形暴露效应关系，在BMI约为28时观察到曲线的最低点。我们的结果表明，体重过轻与预后较差有关，但体重超重与预后较差有关。肥胖与房颤患者不良后果的改善有关。