Under the new definition, heart attacks classified into 3 clinical settings:
Primary myocardial infarction
Primary myocardial infarction occurs spontaneously because of a problem involving a coronary artery, which is the artery that supplies blood to the heart.
Typically, this can occur due to a blood clot, but other causes may include:
- spontaneous coronary artery dissection, or SCAD
- coronary artery spasm
- coronary embolism
- certain problems involving previously placed stents or bypass grafts.
This broader definition aims to reduce the risk of overlooking less common causes of myocardial infarction, such as SCAD, which predominantly affects females and can be underdiagnosed.
Secondary myocardial infarction
Secondary myocardial infarction occurs when another medical problem causes an imbalance between the heart’s oxygen demand and the oxygen supply.
For example, a very rapid heartbeat or extremely high or low blood pressure can place the heart under considerable stress and contribute to myocardial ischemia.
The important distinction is that the infarction is triggered by another condition rather than by a primary coronary artery problem.
Procedure-related myocardial infarction
The third category covers heart attacks occurring as a complication of a cardiac procedure.
This includes infarctions occurring after procedures such as coronary stenting or heart surgery, with the new definition specifically addressing events occurring within 30 days of a cardiac procedure.