From the Departments of Cardiology, Kantonsspital Olten, Olten, Switzerland.
Circulation. 2011 Jul 12;124(2):136-45. doi: 10.1161/CIRCULATIONAHA.111.023937. Epub 2011 Jun 27.
Current guidelines for the diagnosis of acute myocardial infarction (AMI), among other criteria, also require a rise and/or fall in cardiac troponin (cTn) levels. It is unknown whether absolute or relative changes in cTn have higher diagnostic accuracy and should therefore be preferred.
In a prospective, observational, multicenter study, we analyzed the diagnostic accuracy of absolute (Δ) and relative (Δ%) changes in cTn in 836 patients presenting to the emergency department with symptoms suggestive of AMI. Blood samples for the determination of high-sensitive cTn T and cTn I ultra were collected at presentation and after 1 and 2 hours in a blinded fashion. The final diagnosis was adjudicated by 2 independent cardiologists. The area under the receiver operating characteristic curve for diagnosing AMI was significantly higher for 2-hour absolute (Δ) versus 2-hour relative (Δ%) cTn changes (area under the receiver operating characteristic curve [95% confidence interval], high-sensitivity cTn T: 0.95 [0.92 to 0.98] versus 0.76 [0.70 to 0.83], P<0.001; cTn I ultra: 0.95 [0.91 to 0.99] versus 0.72 [0.66 to 0.79], P<0.001). The receiver operating characteristic curve-derived cutoff value for 2-hour absolute (Δ) change was 0.007 μg/L for high-sensitivity cTn T and 0.020 μg/L for cTn I ultra (both cutoff levels are half of the 99th percentile of the respective cTn assay). Absolute changes were superior to relative changes in patients with both low and elevated baseline cTn levels.
Absolute changes of cTn levels have a significantly higher diagnostic accuracy for AMI than relative changes, and seem therefore to be the preferred criteria to distinguish AMI from other causes of cTn elevations.
URL: http://www.clinicaltrials.gov. UNIQUE IDENTIFIER: NCT00470587.
目前，急性心肌梗死（AMI）的诊断指南除了其他标准外，还需要检测心肌肌钙蛋白（cTn）水平的升高和/或降低。目前尚不清楚绝对或相对 cTn 变化的诊断准确性更高，因此应该首选哪种方法。
在一项前瞻性、观察性、多中心研究中，我们分析了 836 例因疑似 AMI 而就诊于急诊科的患者中 cTn 的绝对（Δ）和相对（Δ%）变化的诊断准确性。以盲法在就诊时以及 1 和 2 小时采集高敏 cTnT 和 cTnI ultra 的血样。最终诊断由 2 位独立的心脏病专家裁定。2 小时绝对（Δ）cTn 变化诊断 AMI 的受试者工作特征曲线下面积（AUC）显著高于 2 小时相对（Δ%）cTn 变化（AUC [95%置信区间]，高敏 cTnT：0.95 [0.92 至 0.98]比 0.76 [0.70 至 0.83]，P<0.001；cTnI ultra：0.95 [0.91 至 0.99]比 0.72 [0.66 至 0.79]，P<0.001）。2 小时绝对（Δ）变化的受试者工作特征曲线衍生截断值为高敏 cTnT 的 0.007 μg/L 和 cTnI ultra 的 0.020 μg/L（这两个截断值均为各自 cTn 检测方法第 99 百分位数的一半）。绝对变化在基线 cTn 水平低和高的患者中均优于相对变化。
与相对变化相比，cTn 水平的绝对变化对 AMI 的诊断准确性显著更高，因此似乎是区分 AMI 与其他导致 cTn 升高原因的首选标准。
