Monday, May 15, 2017

Interpreting Elevated Troponins and Types of Myocardial Infarction

Elevations of cardiac biomarkers in the blood reflect injury leading to necrosis of myocardial cells but biomarkers do not indicate the underlying mechanism of this injury. Myocardial injury can be due to ischemic and non-ischemic causes. Therefore, small amounts of myocardial injury with necrosis may be detected, which are associated with CCF, renal failure, myocarditis, arrhythmias, pulmonary embolism and percutaneous or surgical coronary procedures. Troponin elevation in these contexts should not be called as Myocardial Infarction but Myocardial Injury.




Onset of myocardial ischaemia is the initial step resulting from an imbalance between oxygen supply and demand. This can be identified from history and ECG. Possible ischaemic symptoms include various combinations of chest, upper extremity, mandibular or epigastric discomfort or an ischaemic equivalent such as dyspnoea or fatigue (in women). Pain associated with vomiting, worse on exertion, sweating is definitely worrisome. The discomfort with acute MI usually lasts 20 min. In an ideal world, the sequence should be history, physical exam, ECG and troponins. Whenever symptoms recur, it is important to repeat the ECG. If you are ordering trop troponins, you must order serial ECGs as well. remember, ECG is more of a rule in test not a rule out test for ACS.

MI is classified into various types, based on pathological, clinical and prognostic differences, along with different treatment strategies 


References:

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     Lakshay Chanana
     
     Speciality Doctor
     Northwick Park Hospital
     Department of Emergency Medicine
     England

     @EMDidactic





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