An updated universal definition of myocardial infarction (MI) incorporating new developments related to cardiac biomarkers, more sensitive imaging techniques, and improvements in the management of patients with MI was released on Aug. 25 as part of the ESC Congress 2012 in Munich. The definition also distinguishes the various settings in which MI occurs, such as "spontaneous" and "procedure-related" MI.

 

"This is a truly global document that will be used worldwide. It will help doctors diagnose their patients so that they can provide the most appropriate treatment, and help researchers design clinical trials with standardized endpoints," said Kristian Thygesen, MD, co-chair of the document task force. One of the biggest changes to the definition involves levels of troponin required for a diagnosis of procedure-related MI after percutaneous coronary intervention (PCI), coronary bypass (CABG), other cardiac procedures, and non-cardiac procedures. In addition, post PCI, evidence of symptoms, reduced flow, or complication is needed to meet the new universal definition, not just a biomarker elevation. The new document contains a brand new section describing these situations to help clinicians and scientists understand how they differ from MI and make correct diagnoses, said Thygesen.

Additional Resources Full Definition  Ten Points to Remember  ACC Practice Guidelines and Quality Standards

Anthony DeMaria, MD, MACC, from the University of California in San Diego and editor-in-chief of the Journal of the American College of Cardiology, told MedPage Today that the new troponin section is one of the most controversial areas in the definition of MI. "There are a large number of people undergoing PCI in the setting of an acute MI. It's almost impossible to know whether a subsequent increase in troponin was part and parcel of the acute MI or related to the procedure itself," he said. He went on to note that "some people speculate that troponin may be too sensitive in this situation and what is needed is evidence that an elevation of some degree of troponin following a procedure actually results in some alteration of the natural history of the patient. In other words, the definition of acute MI after a procedure really is of significance if it increases the risk of subsequent events such as death."

The new universal definition, which was jointly developed by the ESC, the ACC, the American Heart Association and the World Heart Federation, will have important and immediate therapeutic implications. In the U.S., it is anticipated that the definition could be used as the basis for clinical trial protocols designed according to Food and Drug Administration (FDA) regulations. "This is significant because it will help to standardize the way myocardial infarction is defined in clinical trials, making comparisons between trials more meaningful," said Thygesen. "Steering committees that write protocols for clinical trials do follow FDA requirements."

On a global level, the new universal definition is intended to help doctors diagnose their patients so that they can provide the most appropriate treatment, and help researchers design clinical trials with standardized endpoints, said Thygeson. However, the study authors note that the definition may need to be more flexible in countries with limited economic resources, where cardiac biomarkers and imaging techniques may not be available and where even the option of ECG recordings may be lacking. "Cultural, financial, structural and organizational problems in the different countries of the world in the diagnosis and therapy of acute MI will require ongoing investigation," the study authors said. "It is essential that the gap between therapeutic and diagnostic advances be addressed in this expanding area of cardiovascular disease."

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