Importance High-sensitivity cardiac troponin I testing is widely used to evaluate patients with suspected acute coronary syndrome. A cardiac troponin concentration of less than 5 ng/L identifies patients at presentation as low risk, but the optimal threshold is uncertain. Objective To evaluate the performance of a cardiac troponin I threshold of 5 ng/L at presentation as a risk stratification tool in patients with suspected acute coronary syndrome. Data Sources Systematic search of MEDLINE, EMBASE, Cochrane, and Web of Science databases from January 1, 2006, to March 18, 2017. Study Selection Prospective studies measuring high-sensitivity cardiac troponin I concentrations in patients with suspected acute coronary syndrome in which the diagnosis was adjudicated according to the universal definition of myocardial infarction. Data Extraction and Synthesis The systematic review identified 19 cohorts. Individual patient-level data were obtained from the corresponding authors of 17 cohorts, with aggregate data from 2 cohorts. Meta-estimates for primary and secondary outcomes were derived using a binomial-normal random-effects model. Main Outcomes and Measures The primary outcome was myocardial infarction or cardiac death at 30 days. Performance was evaluated in subgroups and across a range of troponin concentrations (2-16 ng/L) using individual patient data. Results Of 11 845 articles identified, 104 underwent full-text review, and 19 cohorts from 9 countries were included. Among 22 457 patients included in the meta-analysis (mean age, 62 [SD, 15.5] years; n = 9329 women [41.5%]), the primary outcome occurred in 2786 (12.4%). Cardiac troponin I concentrations were less than 5 ng/L at presentation in 11 012 patients (49%), in whom there were 60 missed index or 30-day events (59 index myocardial infarctions, 1 myocardial infarction at 30 days, and no cardiac deaths at 30 days). This resulted in a negative predictive value of 99.5% (95% CI, 99.3%-99.6%) for the primary outcome. There were no cardiac deaths at 30 days and 7 (0.1%) at 1 year, with a negative predictive value of 99.9% (95% CI, 99.7%-99.9%) for cardiac death. Conclusions and Relevance Among patients with suspected acute coronary syndrome, a high-sensitivity cardiac troponin I concentration of less than 5 ng/L identified those at low risk of myocardial infarction or cardiac death within 30 days. Further research is needed to understand the clinical utility and cost-effectiveness of this approach to risk stratification.

中文翻译：

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高敏心肌肌钙蛋白 I 浓度与疑似急性冠状动脉综合征患者心脏结局的关系

重要性 高灵敏度心肌肌钙蛋白 I 检测广泛用于评估疑似急性冠状动脉综合征患者。心肌肌钙蛋白浓度低于 5 ng/L 将患者视为低风险，但最佳阈值尚不确定。目的 评估 5 ng/L 的心肌肌钙蛋白 I 阈值作为疑似急性冠状动脉综合征患者的风险分层工具的性能。数据来源 系统检索 2006 年 1 月 1 日至 2017 年 3 月 18 日期间的 MEDLINE、EMBASE、Cochrane 和 Web of Science 数据库。 研究选择 测量疑似急性冠脉综合征患者高敏心肌肌钙蛋白 I 浓度的前瞻性研究，其中诊断依据心肌梗死的通用定义。数据提取和综合系统评价确定了 19 个队列。个体患者水平的数据来自 17 个队列的相应作者，以及 2 个队列的汇总数据。主要和次要结果的元估计是使用二项式正态随机效应模型得出的。主要结局和措施 主要结局是 30 天时心肌梗死或心源性死亡。使用个体患者数据对亚组和肌钙蛋白浓度范围（2-16 ng/L）的表现进行评估。结果 在确定的 11 845 篇文章中，其中 104 篇进行了全文审查，纳入了来自 9 个国家的 19 个队列。在纳入荟萃分析的 22 457 名患者中（平均年龄，62 [SD，15.5] 岁；n = 9329 名女性 [41.5%]），主要结局发生在 2786 名患者（12.4%）中。11 012 名患者 (49%) 就诊时心肌肌钙蛋白 I 浓度低于 5 ng/L，其中有 60 例漏诊指数或 30 天事件（59 例指数心肌梗死，1 例 30 天心肌梗死，无心脏事件） 30 天时死亡）。这导致主要结局的阴性预测值为 99.5%（95% CI，99.3%-99.6%）。30 天时无心源性死亡，1 年时有 7 例（0.1%）无心源性死亡，心源性死亡的阴性预测值为 99.9%（95% CI，99.7%-99.9%）。结论和相关性 在疑似急性冠脉综合征的患者中，高敏心肌肌钙蛋白 I 浓度低于 5 ng/L 即可确定患者在 30 天内心肌梗死或心源性死亡的风险较低。需要进一步的研究来了解这种风险分层方法的临床效用和成本效益。