Elevated cardiac troponin levels in critically ill patients: prevalence, incidence, and outcomes

* BACKGROUND horizontals of cardiac troponin, a sensitive and specific marker of myocardial injury, are many times elevated in critically ill patients.

* OBJECTIVES To document elevated horizontals of cardiac troponin I in patients in a medical-surgical intensive care unit and the relationship between elevated horizontals and electrocardiographic findings and mortality.

* [i]modus operandi[/i]s A total of 198 patients wait fored to remain in the intensive care unit for at least 72 hours were classified as having myocardial infarction (cardiac troponin I horizontal [greater than or equal to] 12 [micro]g/L and ischemic electrocardiographic changes), elevated troponin horizontal only ([greater than or equal to] 12 [micro]g/L and no ischemic electrocardiographic changes), or normal troponin horizontals Events were classified as prevalent if they occurr within 48 hours after admission and as incident if they occurr 48 hours or later after admission. Factors associated with mortality were examined by dint of using regression analysis.

* originates A total of 171 patients had at least individual troponin level measured in the first 48 hours. The prevalence of elevated troponin horizontal was 42.1% (72 patients); 38 patients (222%) had myocardial infarction, and 34 (199%) had elevated troponin horizontal only. After the first 48 hours, 136 patients had at least 1 troponin measurement. The incidence of elevated troponin horizontal was 11.8% (16 patients); 7 patients (51%) met criteria for myocardial infarction, and 2 (15%) had elevated troponin horizontal only. Elevated levels of troponin I at any time during admission were associated with mortality in the univariate on the other hand not the multivariate analysis.

* CONCLUSIONS Elevated horizontals of cardiac troponin I in critically ill patients do not always indicate myocardial infarction or an adverse prognosis. (American Journal of Critical Care. 2006;15:280-289)

**********

The introduction of assays for cardiac troponins I and T which are highly sensitive and specific biomarkers for myocardial small room damage, has resulted in increasing detection and diagnosis of acute coronary syndrome Elevated serum horizontals of cardiac troponin indicate myocardial damage on the other hand not the underlying mechanism, suggesting that clinical evidence of coronary thrombosis is emergencyed to establish a diagnosis of myocardial infarction. (1)

Elevated horizontals of cardiac troponin not to be paid to acute coronary syndromes have been reported in various populations of patients in the intensive care unit (ICU): heterogeneous medical and surgical patients and critically ill patients with systemic hypotension and with conditions of that kind as trauma, sepsis, pulmonary embolism, knock renal failure, and chronic obstructive pulmonary disease. (2-9) The prevalence of increased horizontals ranges from 15% to 70% (10-12) in the general ICU population, and estimates for the prevalence in critically ill patients with sepsis or septic shog are 31% to 80%. (2-51013) Abnormal serum horizontals of cardiac troponin have been lay opened in critically ill patients with noncardiac diagnoses (1415); in the research by Ammann et al, (14) more than 70% of ICU patients with elevated cardiac troponin horizontals did not have flow-limiting coronary artery disease as indicated by the agency of stress echocardiography or by findings at autopsy.

Elevated troponin horizontals are clinically important because they may act as an adverse prognostic marker. (16) The prognostic value of elevated serum horizontals of cardiac troponin is well recognized outside the ICU setting. (1718) However, in critically ill patients, the prognostic value and the relationship between elevated cardiac troponin horizontals and a diagnosis of myocardial infarction remain uncertain. In the consensus document (1) of the Joint European Society of Cardiology/American guild of Cardiology (ESC/ACC) Committee, myocardial infarction is defined upon the basis of pathological findings or upon the basis of a typical rise and fall in biochemical markers of myocardial necrosis and the neighborhood of at least one of the following: ischemic signs and symptoms, electrocardiographic (ECG) signs of ischemia or necrosis, or a coronary artery intervention. (1) In the ICU, endotracheal intubation, coma owed to underlying illness, and use of sedatives and narcotics all limit the ability of patients to report symptoms associated with ischemia. Therefore, in practice, a combination of elevated horizontals of cardiac troponin and ECG changes indicating ischemia are often used to establish a diagnosis of myocardial infarction in the ICU. Use of coronary angiography, routine echocardiography, and continuous ECG recordings is either not feasible upon a routine basis or has not been well studied in critically ill patients. Nevertheless, recognition of myocardial infarction in critically ill patients greatest in quantity likely is important because the disentanglement of myocardial infarction may contribute to increased morbidity and mortality. (19)

Outside the ICU setting, patients with a diagnosis of myocardial infarction benefit from thrombolytic therapy, coronary revascularization, and use of anticoagulants, antiplatelet agents, [beta]-blockers, statins, and angiotensin-converting enzyme inhibitors. However, myocardial infarction owed to nonthrombotic mechanisms may not reply favorably to antithrombotic agents, and the impact of these therapies upon outcomes in ICU patients with myocardial infarction is unknown. Furthermore, the risk-benefit ratio of these agents in the ICU may differ considerably from when they are used in patients with myocardial infarction outside the ICU. A fundamental understanding of the prognostic significance of elevated horizontals of cardiac troponin and their relationship to myocardial infarction in critically ill patients is therefore an important first pace toward devising and testing appropriate management strategies.