Troponins: current status in coronary artery disease

The acute coronary syndromes (ACS) represent a pathological, diagnostic and risk continuum from unstable angina (UA) through myocardial infarction (MI) with or without ST segment elevation. The past 12 years have seen extensive investigations into the use of various cardiac markers to establish the diagnosis and prognosis in ACS and to evaluate perfusion after thrombolysis. The Troponins comprise a group of three proteins (C, I and T) which interact with tropomyosin to form a troponin-tropomyosin complex. Troponin-T is a structural component of the troponin complex and is known to exist in three isoforms. Troponins have both diagnostic, post-event risk stratification and prognostic significance. Apart from myocardial infarction however they are raised in several conditions like Myocarditis, dilated Cardiomyopathy, Severe congestive cardiac failure, severe pulmonary embolism with right ventricular strain and Preterm infants with respiratory distress. False positives have been reported with Angioplasty, cardiac surgery, RF ablation, Allograft rejection following cardiac transplant and seropositive rheumatoid arthritis. False negatives have been reported with early sampling, early reading, use of wrong anticoagulant, clotted blood, careless storage of kits. Significantly, lower troponin values have been reported in heparinised plasma than in serum.