Classification of Heart Attack

There are basically two types of acute myocardial infarction or Heart Attacks including Transmural and Subendocardial.

Transmural MI – It is related to the atherosclerosis that involves major coronary artery. This MI can be further sub classified into anterior, posterior, or inferior Transmural MI depending on the location. Transmural infarcts spread across the entire thickness of the heart muscle and it results from complete blockage of the area’s blood supply.

Subendocardial – This MI involves a small area in the subendocardial wall of the ventricular septum, left ventricle, or papillary muscles. The Subendocardial infarcts results from locally decreased blood supply due to narrowing of the coronary arteries. The subendocardial area is more prone to MI as it is located the farthest from the heart’s blood supply.

In addition to the above mentioned classification, MI can be further sub classified clinically into a ST elevation MI (STEMI) and a non-ST elevation MI (non-STEMI) depending on the ECG changes.

The term “heart attack” is used to refer the sudden cardiac death sometimes that may not be result from acute myocardial infarction. A heart attack is different from cardiac arrest and the heart attack may lead to cardiac arrest. The term cardiac arrest refers to the stopping of the heartbeat, and cardiac arrhythmia. In this case, heart loses its ability to pump the blood to the body parts. In fact, the severe myocardial infarction may cause heart failure however it is not always the case.

The Myocardial Infarction can be classified into five main types:

Type 1 – This refers to the impulsive myocardial infarction that is associated to ischaemia because of primary coronary event like plaque erosion, or dissection

Type 2 – This refers to the Myocardial infarction that is secondary to ischemia. It results from to increased oxygen demand or decreased supply in events like coronary embolism, coronary artery spasm, arrhythmias, and others.

Type 3 – This refers to the sudden unexpected cardiac death comprising of cardiac arrest with symptoms that suggests myocardial ischemia. In this case, the death occurs before the appearance of cardiac biomarkers in the blood

Type 4 – This refers to Myocardial infarction associated with coronary angioplasty or stents.

Type 5 – This refers to the Myocardial infarction linked with CABG (Coronary artery bypass grafting).

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