Elevated Cardiac Troponin Concentration in the Absence of an Acute Coronary Syndrome

Abstract

SUMMARY B iological markers, or biomarkers, are tools used to identify high-risk individuals, quickly and accurately diagnose disease states, and determine treatment plans and prognoses. Cardiac troponins have a high sensitivity and specificity for myocardial damage and are considered the biomarker of choice for detection of cardiac cellular injury. Abnormal levels of serum cTn are occasionally found in patients who are not suffering a myocardial infarction. This may be observed in several well-known situations including cardiac and non cardiac causes. Cardiac causes include pericarditis, myocarditis, coronary vasospasm, congestive heart failure, supraventricular tachycardia, aortic dissection, cardiac contusion and cardiomyopathy. Non cardiac causes include pulmonary embolism, sepsis, renal insufficiency, acute neurological disease, acute respiratory failure, burn and prolonged strenuous endurance exercise. Blood from healthy individuals with no evidence of cardiac disease contains very low amounts of cardiac troponin. Cardioversion and defibrillation can lead to mild but significant rise in cardiac troponin levels. Troponin assays are widely used for their diagnostic and prognostic utility in several clinical settings, including detection or exclusion of myocardial infarction, heart failure, and pulmonary embolism, and as supportive tests in sepsis and stroke. Troponin elevation in the absence of an ACS still retains significant prognostic value, and screening may be justified on this basis. Troponin elevations in a variety of settings predict worse short- and long-term survival. The reasons for this increase in mortality are currently poorly understood, but may be related to several factors, including myocardial necrosis with myocyte loss, or underlying quiescent coronary artery disease. Alternatively, increased troponin levels may reflect a more fulminant disease process. Regardless of the reason for poorer prognosis, patients with troponin elevation require appropriate diagnostic evaluation and therapy aimed at the underlying disorder. Determining whether a troponin elevation is due to an ACS can be difficult. Factors that suggest coronary heart disease and an ACS include ischemic electrocardiographic changes, chest pain, wall-motion abnormalities on echocardiography, and the presence of atherosclerotic risk factors. If present, these should guide the use of further cardiovascular evaluation, including early risk stratification. Patients with a low pretest probability of coronary heart disease are unlikely to derive benefit from a treatment strategy aimed at coronary thrombosis (eg, aggressive antiplatelet therapy, coronary angiography, and revascularization). In such patients, the main goal is to identify the underlying cause of the troponin elevation. This frequently becomes evident after a thorough history and physical examination, which can identify conditions.