目的 确定胸痛症状发作后不同时间间隔内，床边心肌肌钙蛋白T（point of care troponin-T testing， POCT-cTnT）对急性心肌梗死（acute myocardial infarction， AMI）的诊断性能，了解其在快速排除AMI方面的意义。 方法 这项回顾性研究包括了2019年1月至2022年12月期间出现胸痛症状的6 024例患者。在入院时测量了POCT-cTnT和中心实验室cTnI水平。通过按时间窗口划分的受试者工作特征（receiver operating characteristics， ROC）分析，评估POCT-cTnT在诊断AMI时的准确性。 结果 总体而言，POCT-cTnT诊断AMI的AUC为0.826（95%CI：0.816 ~ 0.836），灵敏度和特异度分别为72.81%和86.26%。根据胸痛发作的时间进行区间分组（< 3 h、3 ~ 6 h、6 ~ 12 h、12 ~ 24 h、24 ~ 72 h和≥ 72 h），6~12 h以后的分组AUC值分别为0.918、0.928、0.920和0.908，差异无统计学意义（P > 0.05），均要高于6 h时以内的组（P < 0.001）；根据胸痛发作时间点进行分组，≥ 8 h组的AUC为0.921，阴性预测值（negative predictive value，NPV）98.1%和阴性似然比（negative likelihood ratio，-LR）0.11，其AUC高于≥3 h、≥2 h、≥1 h和overall组（P < 0.05），而与≥ 4 h以后的各时间组相比，差异无统计学意义（P > 0.05）。 结论 胸痛发作时间对单次检测POCT-cTnT诊断AMI的性能存在一定的影响，结合胸痛发作至就诊时间，可能提高其诊断或排除AMI的可靠性。在胸痛发作4 h后，单次POCT-cTnT检测能可靠地诊断或排除AMI；当胸痛发作8 h后，其诊断或排除AMI方面具有更高的可靠性。

The sensitivity of cardiac troponin testing for diagnosing acute myocardial infarction （AMI） varies over time from chest pain onset. This study aimed to determine the diagnostic performance of point?of?care testing cardiac troponin T （POCT?cTnT） at different time intervals post?symptom onset to refine rapid rule?out approaches for AMI. Methods This retrospective study included 6，024 patients presenting with chest pain from January 2018 to December 2022. POCT?cTnT and central lab cTnI levels were measured on admission. Receiver operating characteristics analysis stratified by time windows assessed the accuracy of POCT?cTnT for diagnosing AMI. Results The overall AUC of POCT?cTnT for diagnosing AMI was 0.826 （95% CI：0.816 ~ 0.836）， with a sensitivity of 72.81% and a specificity of 86.26%. According to the time intervals of chest pain onset （< 3 hours， 3 ~ 6 hours， 6 ~ 12 hours， 12 ~ 24 hours， 24 ~ 72 hours， and ≥ 72 hours）， the AUC values for groups after 6 ~ 12 hours were 0.918， 0.928， 0.920 and 0.908， respectively， with no statistically significant difference （P > 0.05）， but all were higher than the groups within 6 hours （P < 0.001）. According to the time of chest pain onset， the AUC for the ≥8h group was 0.921， with a negative predictive value （NPV） of 98.1% and a negative likelihood ratio （?LR） of 0.11. Its AUC was higher than those of the ≥ 3 h， ≥ 2 h， ≥ 1 h， and overall groups （P < 0.05）， but there was no statistically significant difference compared with the groups after ≥ 4 h （P > 0.05）. Conclusions Chest pain onset time has a certain impact on the performance of a single POCT?cTnT test for diagnosing AMI. The duration from chest pain onset to hospital admission combined with POCT?cTnT test may improve the reliability in diagnosing AMI. Specifically， a single POCT?cTnT test at four hours after chest pain onset， especially eight hours after chest pain onset， can diagnose or exclude AMI.