Fourth Universal Definition of MI Released

The ACC, European Society of Cardiology (ESC), American Heart Association (AHA) and World Heart Federation (WHF) have released the 2018 Fourth Universal Definition of Myocardial Infarction. The expert consensus document was released Aug. 25 during ESC Congress 2018 in Munich and published in the Journal of the American College of Cardiology.

The consensus document aims to clear up confusion over how to diagnose a myocardial infarction (MI) universally, and adheres to the clinical approach of the definition of MI — the presence of acute myocardial injury detected by abnormal cardiac biomarkers in the setting of evidence of acute myocardial ischaemia.

The document details the criteria for myocardial injury, which on its own is now considered a separate condition. Of note, myocardial injury should be used when there is evidence of elevated cardiac troponin values (cTn) with at least one value above the 99th percentile upper reference limit. The myocardial injury is considered acute if there is a rise and/or fall of cTn values. According to the authors, the first step of treatment is to address the underlying disorder.

As for MI, the documents notes that the criteria for type 1 MI is detection of a rise and/or fall of cTn values with at least one value above the 99th percentile upper reference limit and at least one of the following:

  • Symptoms of myocardial ischaemia;
  • New ischaemic ECG changes;
  • Development of pathological Q waves;
  • Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a pattern consistent with an ischaemic aetiology;
  • Identification of a coronary thrombus by angiography or autopsy.

"Many doctors have not understood that elevated troponin levels in the blood are not sufficient to diagnosis a heart attack and this has created real problems," said Kristian A. Thygesen, MD, DSC, FACC, co-chair of the writing committee.

The criteria for type 2 MI is similar to type 1 but adds the evidence of an imbalance between myocardial oxygen supply and demand unrelated to coronary thrombosis. In type 2 MI, oxygen deprivation is not caused by plaque rupture in an artery but is due to other reasons such as respiratory failure or severe hypertension. "Some doctors have incorrectly called this type 1 and given the wrong treatment, which can be harmful," said Joseph S. Alpert, MD, FACC, co-chair of the writing committee. "Treatment should be directed at the underlying condition, for example blood pressure lowering medications for patients with hypertension."

"The incorporation of type 2 into the International Classification of Diseases (ICD) codes is another step towards accurate recognition followed by appropriate treatment. A code for myocardial injury will be added to the ICD next year," adds Harvey D. White, DSC, FACC.

Keywords: ESC18, ESC Congress, Troponin, American Heart Association, Coronary Thrombosis, International Classification of Diseases, Consensus, Autopsy, Oxygen, Blood Pressure, Myocardial Infarction, Myocardial Ischemia, Myocardium, Hypertension, Arteries, Angiography, Respiratory Insufficiency, Electrocardiography, Biomarkers, Diabetes Mellitus, Type 2

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