Clinical profile of patients and sensitivity of troponin I in patients with and without acute coronary syndrome: An observational study

Abstract

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.