The Canadian Cardiovascular Society Classification of Acute Atherothrombotic Myocardial Infarction Based on Stages of
Andreas Kumar1, Kim Connelly2, Keyur Vora3
1Northern Ontario School of Medicine University, and Department of Cardiovascular Sciences, Health Sciences North, Sudbury, Ontario, Canada; Health Sciences North, Sudbury, Ontario, Canada.
Insights
A new classification for acute myocardial infarction (MI) categorizes tissue injury into four stages, from aborted MI to hemorrhagic MI. This system aids in risk stratification and developing targeted therapies for better patient outcomes.
Area of Science:
- Cardiology
- Pathology
- Biomedical Engineering
Background:
- Myocardial infarction (MI) is a major cause of death, with atherothrombotic MI involving coronary artery blockage and subsequent tissue damage.
- Current risk scores and classifications for MI do not fully account for the specific characteristics of myocardial tissue injury.
- Ischemia and reperfusion injury in MI presents a wide spectrum, from minimal damage to extensive necrosis with complications like microvascular obstruction and hemorrhage.
Purpose of the Study:
- To introduce the Canadian Cardiovascular Society (CCS) classification of acute MI, focusing on myocardial tissue injury.
- To provide a framework for understanding the progression of myocardial damage in MI based on expert consensus.
- To establish a basis for developing novel, stage-specific therapies for MI.
Main Methods:
- Expert consensus development based on extensive data regarding atherothrombotic MI and reperfusion therapy.
- Definition of four distinct stages of myocardial tissue injury, reflecting increasing severity of necrosis and microvascular damage.
- Review of clinical studies correlating injury stages with adverse remodeling and clinical outcomes.
Main Results:
- The CCS classification identifies four stages: aborted MI, MI with cardiomyocyte necrosis, MI with microvascular obstruction (no-reflow), and hemorrhagic MI.
- Each stage represents a progression of myocardial ischemia and reperfusion injury.
- Progressive injury stages are associated with worse cardiac remodeling and increased adverse clinical outcomes.
Conclusions:
- The proposed CCS classification offers a detailed stratification of MI patients based on tissue injury characteristics.
- Microvascular injury, particularly hemorrhagic MI, is linked to infarct expansion and mechanical complications.
- This classification can guide the development of tailored therapies addressing specific stages of MI pathology.
Abstract:
Myocardial infarction (MI) remains a leading cause of morbidity and mortality. In atherothrombotic MI (ST-elevation MI and type 1 non-ST-elevation MI), coronary artery occlusion leads to ischemia. Subsequent cardiomyocyte necrosis evolves over time as a wavefront within the territory at risk. The spectrum of ischemia and reperfusion injury is wide: it can be minimal in aborted MI or myocardial necrosis can be large and complicated by microvascular obstruction and reperfusion hemorrhage. Established risk scores and infarct classifications help with patient management but do not consider tissue injury characteristics. This document outlines the Canadian Cardiovascular Society classification of acute MI. It is an expert consensus formed on the basis of decades of data on atherothrombotic MI with reperfusion therapy. Four stages of progressively worsening myocardial tissue injury are identified: (1) aborted MI (no/minimal myocardial necrosis); (2) MI with significant cardiomyocyte necrosis, but without microvascular injury; (3) cardiomyocyte necrosis and microvascular dysfunction leading to microvascular obstruction (ie, "no-reflow"); and (4) cardiomyocyte and microvascular necrosis leading to reperfusion hemorrhage. Each stage reflects progression of tissue pathology of myocardial ischemia and reperfusion injury from the previous stage. Clinical studies have shown worse remodeling and increase in adverse clinical outcomes with progressive injury. Notably, microvascular injury is of particular importance, with the most severe form (hemorrhagic MI) leading to infarct expansion and risk of mechanical complications. This classification has the potential to stratify risk in MI patients and lay the groundwork for development of new, injury stage-specific and tissue pathology-based therapies for MI.
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