Friday, December 07, 2012


The definition of AMI ( heart attacks ), has evolved over the years. When I was in med school, it was symptoms of chest pain consistent with myocardial ischemia, ECG changes with Q waves or ST - T changes consistent with myocardial ischemia, and a rise in cardiac enzymes of at least 2x normal. Any 2 of the above 3 criteria will qualify for a diagnosis of AMI,
At the last European Society of Cardiology Congress, August 2012, at Munich, the Joint Societies ( AHA, ACC and ESC ) announced the new definition of AMI, namely,
         1. Raise cardiac troponin or CKMB ( if troponin is unavailable ),
         2. Sympotoms of chest pain consistent with myocardial ischemia,
        3.  ECG changes of new ischemia, like ST elevation, bundle branch block or Q waves.
        4. Imaging evidence of new loss of viable myocardium, or new segmental wall motion abnormalities.

The Joint Society also recognised 5 types of AMI, namely,
      Type 1. The standard AMI from atherosclerotic plaque rupture ( established CAD ), causing coronary thrombosis and loss of myocardium.
       Type 2. An ill defined group of acute myocardium loss without evidence of CAD.
       Type 3. Sudden cardiac death likely due to myocardial ischemia. and death before a rise in cardiac troponin could be established.
       Type 4. AMI from PCI, where the cardiac enzymes rise should be greater then 5x normal.
       Type 5. AMI from CABG where the cardiac enzyme rise should be greater then 10x normal.  

Since August 2012, I had always wanted to post these new definitions but for some reasons, have always delayed, and then forgotten about it. I suppose, it is not too late. The year is not out yet.
Actually, nothing great has changed with the definition except the acceptance of the role of imaging modalities, and the greater use of cardiac troponin where there are some 20 sub assays ( and this has caused a headache, as they sometimes do not agree or correlate well ). The Europeans also like the highly sensitive cardiac troponins, which the Americans still do not have FDA approval to use, as the validation is not so consistent ( according to US FDA ).
Well, at least the definition of AMI is now more overall encompassing. Lets see how practical it can be, especially as different clinical trials seem to use different criteria, some old, some new.
So we all may end up more confused.

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