Bye-bye type 1 MI, hello primary MI: New universal definition of myocardial infarction proposes revamped classification system

The new universal definition of myocardial infarction (MI) gives a more clinically meaningful understanding of its presentation, progression and prognosis. It jettisons the numerical classification of MI for a classification system based on pathophysiology. The previous classification (e.g., type 1, type 2, etc.) had some factors that were difficult to apply in clinical practice. For example, the numerical classification failed to fully capture when MI is caused by another acute illness or a coronary process other than atherothrombosis.The newly proposed classification of MI is as follows:Primary: spontaneous presentation due to atherothrombosis or other acute coronary pathologySecondary: secondary to an acute condition, the result of a myocardial oxygen supply-demand imbalance due to obstructive coronary artery disease or another acute condition Procedure-related: a complication of a percutaneous or surgical cardiac procedure causes coronary or graft occlusion and new ventricular impairment or subsequent stent or graft failure within 30 daysThe new universal definition also introduces sex-specific reference limits for 99th percentile cardiac troponin levels used to define myocardial injury. The 99th percentile for cardiac troponin is lower in females than in males, so including high-sensitivity assays with sex-specific reference limits may improve recognition and diagnosis of cardiovascular conditions in female patients.The universal definition incorporates four sequential stages of increasing tissue injury resulting from an MI, as seen on cardiac imaging. Canadian experts, members of the Canadian Cardiology Society (CCS), proposed the framework of this staging of tissue injury following a primary MI.“Our CCS-acute MI classification showed that not all heart attacks are the same. By describing the underlying severity of heart muscle injury, it gives clinicians and researchers a clearer way to understand risk, guide future research, and identify opportunities for more individualized care,” explained cardiologist Dr. Andreas Kumar in a CCS press release. Dr. Kumar is from Northern Ontario School of Medicine University and is lead author of the CCS acute myocardial infarction classification. The CCS classification for the four stages of heart muscle damage are:Stage 1: no or minimal damage to the heart muscle Stage 2: damage to the heart muscle without injury to small blood vessels Stage 3: damage to the heart muscle with blockage of small blood vessels Stage 4: hemorrhagic myocardial infarction–damage to the heart muscle with blockage and rupture of small blood vessels, resulting in bleeding into the heart muscle Researchers, including Dr. Kumar, have already started using these stages in research studies. The fifth universal definition is a joint statement from the European Society of Cardiology (ESC), the American College of Cardiology (ACC), the American Heart Association (AHA), and the World Heart Federation (WHF). The CCS issued a press release stating it welcomes the new definition of myocardial infarction. It was presented at the European Society of Cardiology Congress in Munich in late August and published in the European Journal of Cardiology.

Bye-bye type 1 MI, hello primary MI: New universal definition of myocardial infarction proposes revamped classification system

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