Department of General Medicine, St John's Medical College Hospital, Koramangala, Bengaluru 560034, Karnataka, India.
Natl Med J India. 2023 Sep-Oct;36(5):305-309. doi: 10.25259/NMJI_801_2021.
Background Various clinical conditions can cause troponin elevation in the absence of myocardial ischaemia. Elevated troponin represents the likely occurrence of myocardial necrosis and does not itself provide any indication of the aetiology. Identifying the cause for troponin elevation and its sensitivity and specificity in predicting acute coronary syndrome (ACS) and cardiac mortality is an important step in determining the optimal management for these patients. Methods We retrospectively collected data of inpatients who had troponin I (TnI) testing as part of their clinical assessment, either in the emergency department, medical wards, coronary care unit (CCU) or intensive care unit (ICU) with their final diagnosis. TnI was used as the index test of sensitivity to diagnose ACS and either echocardiography or coronary angiogram in those available as the reference gold standard. They were classified into two groups of normal and elevated TnI, and further divided into those with ACS and no ACS. Data on clinical parameters and aetiology of elevated TnI in patients without ACS were analysed. Results Of the 254 patients studied, 114 patients (45%) had normal TnI and 140 (55%) had elevated TnI. Seventy-eight patients had ACS, 66 (84.6%) of whom had elevated TnI and 12 (15.38%) had normal TnI. Seventy-four (52.85%) of 140 patients with elevated TnI had alternate causes of TnI elevation; the most common being sepsis, acute kidney injury (AKI) and heart failure without ACS. All-cause mortality was significantly higher in patients with elevated TnI with or without ACS. There was no cardiac mortality among patients with ACS with normal TnI. Sensitivity and specificity of TnI for predicting ACS was 84.6% (95% CI 74.7%-91.8%) and 58% (95% CI 50.3%-65.3%), respectively. Conclusion A variety of conditions apart from myocardial infarction can lead to elevated TnI. Hence, caution should be exercised while diagnosing a patient with ACS based on TnI value in the absence of other supporting evidence given its low specificity. Elevated TnI portends a worse prognosis regardless of the aetiology and has a role in predicting all-cause and cardiac mortality.
背景
各种临床情况都可能导致肌钙蛋白升高而无心肌缺血。肌钙蛋白升高代表可能发生心肌坏死，本身并不能提供病因的任何迹象。确定肌钙蛋白升高的原因及其在预测急性冠状动脉综合征 (ACS) 和心脏死亡率方面的灵敏度和特异性是确定这些患者最佳治疗方案的重要步骤。
方法
我们回顾性收集了在急诊科、内科病房、冠心病监护病房 (CCU) 或重症监护病房 (ICU) 进行肌钙蛋白 I (TnI) 检测的住院患者数据，这些患者的临床评估均包括 TnI 检测，最终诊断如下。TnI 用作诊断 ACS 的灵敏度的指标测试，对于那些可获得的患者，超声心动图或冠状动脉造影用作参考金标准。他们被分为正常和升高的 TnI 两组，并进一步分为 ACS 组和非 ACS 组。分析了无 ACS 患者的临床参数和升高的 TnI 的病因。
结果
在研究的 254 名患者中，114 名患者 (45%) 的 TnI 正常，140 名患者 (55%) 的 TnI 升高。78 名患者患有 ACS，其中 66 名 (84.6%) TnI 升高，12 名 (15.38%) TnI 正常。140 名 TnI 升高的患者中有 74 名 (52.85%) 有其他原因导致 TnI 升高；最常见的是脓毒症、急性肾损伤 (AKI) 和心力衰竭而无 ACS。无论是否有 ACS，TnI 升高的患者的全因死亡率均明显更高。ACS 患者中 TnI 正常者无心脏死亡率。TnI 预测 ACS 的灵敏度和特异性分别为 84.6% (95%CI 74.7%-91.8%) 和 58% (95%CI 50.3%-65.3%)。
结论
除心肌梗死外，多种情况都可能导致肌钙蛋白升高。因此，在缺乏其他支持证据的情况下，根据 TnI 值诊断 ACS 时应谨慎，因为其特异性较低。无论病因如何，升高的 TnI 预示着预后更差，并且在预测全因和心脏死亡率方面有一定作用。
