Cardiac troponin: a new biochemical marker for peri-operative myocardial injury.

Abstract

Background who have objective evidence of MI. The ECG is difficult to interpret in the post-operative setting and often Peri-operative myocardial infarction (MI) occurs in does not display the classical ST segment elevation of acute myocardial infarction. Lastly, even if there is a 5–10% of patients undergoing major vascular surgery, is fatal in 50% of these cases and in total will account significant rise in creatine kinase leaked from dying myocardial cells (CK-MB) this may be masked by for more than 50% of all post-operative deaths. An even larger proportion of operated patients will suffer large quantities of creatine kinase (CK) released from skeletal muscle as the result of direct surgical trauma cardiac complications, which may be fatal or non-fatal, that are not demonstrably related to peri-operative or ischaemia/reperfusion injury. This makes the CK/ CK-MB ratio difficult to interpret. MI. These complications may have metabolic causes, but are perhaps more likely to be due to myocardial infarction that cannot be detected by the standard diagnostic tests for peri-operative MI. This injury Micro-infarction and the acute coronary may be referred to as minor myocardial injury or syndromes micro-infarction. Defining the aetiology, incidence, and treatment of Recently it has become possible to detect micro-inperi-operative cardiac complications has been farction by measuring cardiac structural proteins, such hampered by the limitations inherent in World Health as cardiac troponin, that are released following myoOrganisation (WHO) criteria for diagnosis of acute MI. cardial cell death. It has become apparent that even The WHO criteria require that two of the following though the occurrence of micro-infarction may not lead three features are present: a history of characteristic to an acute deterioration of left ventricular function, it prolonged ischaemic chest pain; evolutionary changes is associated with a very adverse longer term progon the electrocardiogram (ECG) and elevation of serial nosis. Most studies conducted with regard to this cardiac enzymes. However, in post-operative patients, have focused on the acute coronary syndromes. This is symptoms may be masked by the use of opiate anala group of conditions characterised by the spontaneous gesia, and atypical or even absent in up 75% of patients development of myocardial ischaemia due to the erosion, fissuring or rupture of coronary atherosclerotic ∗ Please address all correspondence to: A. W. Bradbury, University plaque resulting in intra-vascular thrombosis. At one Department of Vascular Surgery, Lincoln Building (Research Inextreme, this thrombosis will result in acute MI charstitute), Birmingham Heartlands & Solihull NHS Trust, Bordesley Green East, Birmingham B9 5SS, U.K. acterised by chest pain, ST-segment elevation on the