The Fourth Universal Definition of Myocardial Infarction (MI) is a comprehensive and updated consensus document developed by the Joint European Society of Cardiology (ESC)/American College of Cardiology (ACC)/American Heart Association (AHA)/World Heart Federation (WHF) Task Force. This document aims to standardize the definition and classification of MI, addressing both myocardial injury and MI, and providing criteria for various types of MI, including those related to coronary procedures and noncardiac procedures. Key updates and new concepts include: - Differentiation between myocardial injury and MI. - Emphasis on periprocedural myocardial injury distinct from MI. - Consideration of electrical remodeling and cardiac memory. - Use of cardiovascular magnetic resonance and computed tomographic coronary angiography. - Introduction of Takotsubo syndrome as a distinct entity. The document outlines criteria for myocardial injury and acute MI, distinguishing between Type 1 (atherothrombotic), Type 2 (ischemic), and Type 3 (fatal) MI. It also defines coronary procedure-related MI (Types 4a, 4b, and 4c) and MI associated with coronary artery bypass grafting (Type 5). The criteria for diagnosing these subtypes are detailed, emphasizing the importance of elevated cardiac troponin levels and clinical evidence of myocardial ischemia. Additionally, the document addresses recurrent and reinfarction events, myocardial injury and infarction associated with cardiac and noncardiac procedures, and the use of biochemical approaches for diagnosis. It provides guidelines for clinical practice, emphasizing the need for a multidisciplinary approach to manage these conditions effectively.The Fourth Universal Definition of Myocardial Infarction (MI) is a comprehensive and updated consensus document developed by the Joint European Society of Cardiology (ESC)/American College of Cardiology (ACC)/American Heart Association (AHA)/World Heart Federation (WHF) Task Force. This document aims to standardize the definition and classification of MI, addressing both myocardial injury and MI, and providing criteria for various types of MI, including those related to coronary procedures and noncardiac procedures. Key updates and new concepts include: - Differentiation between myocardial injury and MI. - Emphasis on periprocedural myocardial injury distinct from MI. - Consideration of electrical remodeling and cardiac memory. - Use of cardiovascular magnetic resonance and computed tomographic coronary angiography. - Introduction of Takotsubo syndrome as a distinct entity. The document outlines criteria for myocardial injury and acute MI, distinguishing between Type 1 (atherothrombotic), Type 2 (ischemic), and Type 3 (fatal) MI. It also defines coronary procedure-related MI (Types 4a, 4b, and 4c) and MI associated with coronary artery bypass grafting (Type 5). The criteria for diagnosing these subtypes are detailed, emphasizing the importance of elevated cardiac troponin levels and clinical evidence of myocardial ischemia. Additionally, the document addresses recurrent and reinfarction events, myocardial injury and infarction associated with cardiac and noncardiac procedures, and the use of biochemical approaches for diagnosis. It provides guidelines for clinical practice, emphasizing the need for a multidisciplinary approach to manage these conditions effectively.