How serious is a myocardial infarction?

Average rating:

This often depends on the amount of heart muscle that is damaged. In many cases only a small part of the heart muscle is damaged (infarcts or dies) which heals as a small patch of scar tissue. The heart can usually function normally with a small patch of scar tissue. A larger MI is more likely to be life-threatening or cause complications.
Even before 'clot busting' drugs became available, many people made a full recovery as many MIs are small. With the help of modern treatment, particularly if you are given a 'clot busting' drug quickly, a higher percentage of people now make a full recovery.
Some possible complications that may occur after an MI include the following.

Heart failure. If a large area of the heart muscle is damaged, then the pumping ability of the heart may be reduced. Less blood than usual is then pumped around the body, especially when extra blood is needed when you exercise. Symptoms such as breathlessness, tiredness, and swollen ankles may develop. Mild heart failure can often be treated with medication. Severe heart failure can be serious and life-threatening.
Abnormal heart rhythms may occur if the electrical activity of the heart is affected. The main risk of this happening is within the first few hours after an MI. Sudden, chaotic, fast heart beats may occur. This is called ventricular fibrillation and is the common cause of 'cardiac arrest'. This needs immediate treatment with an electrical shock given by a defibrillator. Otherwise, collapse and sudden death is likely.
A further MI may occur sometime in the future. This is more likely if the coronary arteries are badly affected with atheroma, or further build up of atheroma continues. If the risk of this is thought to be high then surgery may be advised to bypass or widen severely narrowed coronary arteries.

The most crucial time is during the first day or so. If no complications arise, and you are well after a couple weeks, then you have a good chance of making a full recovery. A main objective then is to get back into normal life, and to minimise the risk of a further MI.