324 Troponin in Emergency Department: an overused test for patient screening without clinical suspicion of acute coronary syndrome?

Abstract

Cardiac troponin is the preferred biomarker of acute coronary syndrom (ACS) and a reliable indicator of mortality in many other clinical settings. It is routinely used for the assessment of patients admitted in Emergency Departments (ED) even in the absence of clinical suspicion of acute coronary syndrome (ACS). The clinical interest of such practice remains to be determined. 295 consecutive patients admitted for various medical conditions in our ED from January to June 2009 have been enrolled on the basis of high troponin I level in their first blood sample (>0.08 μg/l) and followed up for survival until April 2010. Population was divided into two groups according to the etiology of troponin elevation: group 1 when ACS; group 2 when no criteria of ACS with or without alternative diagnosis for high troponin level. Final diagnosis for troponin elevation was ACS in 62 patients (21%) and non ACS in 233 (79%). Forty six % had neither chest pain nor ECG ischemic changes. Mean age was 69 +/-13 years in group 1 and 78+/− 13 in group 2. In group 2, high troponin level was related to congestive heart failure or arythmia in 41% of cases, sepsis 22%, acute respiratory failure 7%, stroke 5%, miscellaneous 10% (myopericarditis n = 3, Takotsubo n = 5, rhabdomyolysis n = 4, pulmonary embolism n = 5, haemorrhage n = 6) and undetermined 15%. Hospital mortality was 12.5% in group 1 and 37% in group 2. Overall survival at 12 months was 59% in group 2 compared to 85% for patients with ACS. After multivariate analysis age, creatinine and BNP level were predictors of survival. The variable ACS versus non ACS was not an independent factor. In ED, troponin is currently used in patients with of a low probability of ACS. Troponin elevation is mainly due to medical conditions other than ACS. When compared with the ACS group, the worse prognosis of the non ACS patients appears to be strongly correlated to clinical variables such as age, renal function and severe associated diseases. In conclusion risk stratification of patients without ACS should first be based on clinical data because troponin elevation elicits diagnosis confusion.