Your doctor will diagnose a heart attack based on your signs and symptoms, your medical and family histories, and test results.

Diagnostic tests:

•           ECG (Electrocardiogram)

An ECG is a simple, painless test that detects and records the heart's electrical activity. The test shows how fast the heart is beating and its rhythm (steady or irregular). An ECG also records the strength and timing of electrical signals as they pass through each part of the heart.

An ECG can show signs of heart damage due to ischemic heart disease and signs of a previous or current heart attack.

It should be done within 10 minutes of being admitted to the hospital.

An ECG measures the electrical activity of your heart. Every time your heart beats, it produces tiny electrical impulses. An ECG machine records these signals onto paper, allowing your doctor to see how well your heart is functioning.

An ECG is painless and takes about 5 minutes to do. During the test, flat metal discs (electrodes) are attached to your arms, legs, and chest. Wires from the electrodes are connected to the ECG machine, which records the electrical impulses.

An ECG is important because:

•           it confirms the diagnosis of a heart attack;

•           it helps determine what type of heart attack you have had, which will help determine the most effective treatment.

Heart attacks can be classified by measurement from an ECG known as the ST segment. This corresponds to the area of damage inflicted on the heart.

Acute coronary syndrome:

A heart attack is a form of an acute coronary syndrome (ACS), where there is a significant blockage in the coronary arteries.

The 3 main types of ACS include:

•           ST-segment elevation myocardial infarction (STEMI);

•           non-ST segment elevation myocardial infarction (NSTEMI);

•           unstable angina.

1.         ST-segment elevation myocardial infarction (STEMI)

A STEMI is the most serious type of heart attack where there is a long interruption to the blood supply. This is caused by a total blockage of the coronary artery, which can cause extensive damage to a large area of the heart. A STEMI is what most people think of when they hear the term "heart attack".

2.         Non-ST segment elevation myocardial infarction (NSTEMI)

An NSTEMI can be less serious than a STEMI because the supply of blood to the heart may be only partial, rather than completely, blocked. As a result, a smaller section of the heart may be damaged. However, an NSTEMI is still regarded as a serious medical emergency. Without treatment, it can progress to serious heart damage or STEMI.

3.         Unstable angina

Unstable angina is the least serious type of ACS. However, like NSTEMI, it is still a medical emergency as it can also progress to serious heart damage or STEMI. In unstable angina, the blood supply to the heart is still seriously restricted, but there is no permanent damage, so the heart muscle is preserved.

•           Blood Tests:

Damage to your heart from a heart attack causes certain proteins to slowly leak into your blood. Enzymes are special proteins that help regulate chemical reactions that happen in your body.

If you have had a suspected heart attack, a sample of your blood will be taken, so it can be tested for these heart proteins (known as cardiac markers).

The most common protein measurement is called cardiac troponin. Your troponin level will be measured through a series of blood tests done over the course of a few days.

This will allow damage to your heart to be assessed, and also help determine how well you are responding to treatment.

Commonly used blood tests include troponin tests, CK or CK–MB tests, and serum myoglobin tests. Blood tests are often repeated to check for changes over time.

•           Chest X-ray:

A chest X-ray can be useful if the diagnosis of a heart attack is uncertain and there are other possible causes of your symptoms, such as a pocket of air trapped between the layers of your lungs (pneumothorax).

A chest X-ray can also be used to check whether complications have happened because of the heart attack, such as a build-up of fluid inside your lungs (pulmonary oedema).

•           Coronary Angiography:

Coronary angiography is a test that uses dye and special x-rays to show the insides of your coronary arteries. This test is done during a heart attack to help find blockages in the coronary arteries.

To get the dye into your coronary arteries, your doctor will use a procedure called cardiac catheterization.

A thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck. The tube is threaded into your coronary arteries, and the dye is released into your bloodstream.

Special x-rays are taken while the dye is flowing through the coronary arteries. The dye lets your doctor study the flow of blood through the heart and blood vessels.

If your doctor finds a blockage, he or she may recommend a procedure called percutaneous coronary intervention (PCI), sometimes referred to as coronary angioplasty. This procedure can help restore blood flow through a blocked artery. Sometimes a small mesh tube called a stent is placed in the artery to help prevent blockages after the procedure.

•           Echocardiogram:

An echocardiogram is a type of scan that uses sound waves to build a picture of the inside of your heart.

This can be useful to identify exactly which areas of the heart have been damaged and how this damage has affected your heart's function.