Fourth Universal Definition of Myocardial Infarction 2018

Fourth Universal Definition of Myocardial Infarction 2018

The ESC/ACC/AHA/WHF Expert Consensus Document

The current consensus document, endorsed by the ESC (European Society of Cardiology), the ACC (American College of Cardiology), the American Heart Association (AHA), the World Heart Federation (WHF), and adopted by the WHO describes the universal definitions of myocardial injury and myocardial infarction in the light of new evidence and researches that have occurred since the last definition of MI structured in 2012. The document has been published in the Journal of the American College of Cardiology.

Although myocardial injury is a prerequisite for the diagnosis of MI, it is also an entity in itself. To establish a diagnosis of MI, criteria in addition to abnormal biomarkers are required. Non-ischaemic myocardial injury may arise secondary to many cardiac conditions such as myocarditis, or may be associated with non-cardiac conditions such as renal failure. 

Therefore, for patients with increased cTn (cardiac troponin) values, clinicians must distinguish whether patients have suffered a non-ischaemic myocardial injury or one of the MI subtypes. If there is no evidence to support the presence of myocardial ischaemia, a diagnosis of myocardial injury should be made. This diagnosis can be changed if subsequent evaluation indicates criteria for MI.

Clinical criteria for MI 
The clinical definition of MI denotes the presence of acute myocardial injury detected by abnormal cardiac biomarkers in the setting of evidence of acute myocardial ischaemia.

What’s new in the universal definition of myocardial infarction? 

New concepts
• Differentiation of myocardial infarction from myocardial injury
• Highlighting peri-procedural myocardial injury after cardiac and noncardiac procedures as discrete from myocardial infarction
• Consideration of electrical remodelling (cardiac memory) in assessing repolarization abnormalities with tachyarrhythmia, pacing, and rate related conduction disturbances
• Use of cardiovascular magnetic resonance to define aetiology of myocardial injury
• Use of computed tomographic coronary angiography in suspected myocardial infarction

Universal definitions of myocardial injury and myocardial infarction

Criteria for myocardial injury

The term 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 (URL). The myocardial injury is considered acute if there is a rise and/or fall of cTn values.

Criteria for acute myocardial infarction (types 1, 2 and 3 MI)

The term acute myocardial infarction should be used when there is acute myocardial injury with clinical evidence of acute myocardial ischaemia and with detection of a rise and/or fall of cTn values with at least one value above the 99th percentile URL 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 (not for type 2 or 3 MIs)


*Post-mortem demonstration of acute athero-thrombosis in the artery supplying the infarcted myocardium meets criteria for type 1 MI. 

**Evidence of an imbalance between myocardial oxygen supply and demand unrelated to acute athero-thrombosis meets criteria for type 2 MI. 

***Cardiac death in patients with symptoms suggestive of myocardial ischaemia and presumed new ischaemic ECG changes before cTn values become available or abnormal meets criteria for type 3 MI.

Criteria for coronary procedure-related myocardial infarction (types 4 and 5 MI)

Percutaneous coronary intervention (PCI) related MI is termed type 4a MI. Coronary artery bypass grafting (CABG) related MI is termed type 5 MI. 
Coronary procedure-related MI ≤ 48 hours after the index procedure is arbitrarily defined by an elevation of cTn values >5 times for type 4a MI and >10 times for type 5 MI of the 99th percentile URL in patients with normal baseline values. 

Patients with elevated pre-procedural cTn values, in whom the preprocedural cTn level are stable (≤20% variation) or falling, must meet the criteria for a >5 or >10 fold increase and manifest a change from the baseline value of >20%. In addition with at least one of the following:

•  New ischaemic ECG changes (this criterion is related to type 4a MI only)
•  Development of new pathological Q waves
•  Imaging evidence of loss of viable myocardium that is presumed to be new and in a pattern consistent with an ischaemic aetiology
•  Angiographic findings consistent with a procedural flow-limiting complication such as coronary dissection, occlusion of a major epicardial artery or graft, side-branch occlusion-thrombus, disruption of collateral flow or distal embolization.

Isolated development of new pathological Q waves meets the type 4a MI or type 5 MI criteria with either revascularization procedure if cTn values are elevated and rising but less than the pre-specified thresholds for PCI and CABG. Other types of 4 MI include type 4b MI stent thrombosis and type 4c MI restenosis that both meet type 1 MI criteria. Post-mortem demonstration of a procedure-related thrombus meets the type 4a MI criteria or type 4b MI criteria if associated with a stent.

Criteria for prior or silent/unrecognized myocardial infarction

Any one of the following criteria meets the diagnosis for prior or silent/ unrecognized MI: 
• Abnormal Q waves with or without symptoms in the absence of nonischaemic causes
• Imaging evidence of loss of viable myocardium in a pattern consistent with ischaemic aetiology
• Patho-anatomical findings of a prior MI

Read the consensus document in detail here:

About Author
Dr. Prachi Chhimwal
Dr. Prachi Chhimwal is an Editor at PlexusMD and is a part of the Engagment Team. She curates the Technical Content posted daily on the news feed. She graduated from Army College of Dental Sciences (B.D.S) and went on to pursue her post-graduation (M.D.S) in Oral & Maxillofacial Pathology. After a decade in the field of dentistry she took a leap of faith and joined PlexusMD. A badminton enthusiast, when not working you can find her reading, Netflixing or enjoying stand-up comedy shows.
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Dr. J●●●r T●●●●●●●a and 14 others like this12 shares
J●y C●●●●●●u
J●y C●●●●●●u General Medicine
As a student its great to gain updated knowledge on various diseases and conditions. Thank You ma' am.
Oct 23, 2018Like
Dr. r●j k●●●r
Dr. r●j k●●●r Paediatrics
Very good authentic information
Oct 24, 2018Like
Dr. R●●●●●●a A●N
Dr. R●●●●●●a A●N Paediatrics
One can easily understand MI it' s pathophysiology with clinical correlation. A good update.
Oct 25, 2018Like