How doctors diagnose a heart attack?

How doctors diagnose a heart attack?
February 28, 2014 7:07 PM

Heart attack is the most prevalent of all disease. The morbidity and mortality rate due to heart attack is getting high day by day. Those ages have past now when heart attack was just the disease of old aged people. Now even the middle aged people are at a very high risk of heart diseases. Our lifestyle changes, lack of healthy physical activities and eating habits are the real culprits behind the high incidence of heart attack.

A number of patients present in hospitals emergencies everyday with the complaint and clinical symptoms of heart attack. The commonest complaint with which the patients usually present in hospital is chest pain and shortness of breath. But there are many other diseases with symptoms quite similar to heart attack.

So, the proper treatment of patient cannot be initiated until and unless a confirmed diagnosis is made.

To confirm the diagnosis of heart attack or to differentiate it from the other diseases, a doctor may do certain tests of a patient or take the following steps:

History and physical examination

When a patient with heart attack presents in medical emergency, the first thing to be done by doctor is to take the medical history of the patient. The doctor will ask various questions about the signs and symptoms of patient that will help him establish a diagnosis.

No doctor can proceed without taking the complete medical history. After recording the medical history, the doctor will move on to the general physical examination of the patient. The blood pressure, pulse rate, temperature, heart and chest sounds of patient will be monitored carefully to note any abnormalities.

A proper medical history and general physical examination of patient is a necessary step in reaching a certain diagnosis. The patients of heart attack usually present with following symptoms to the hospital emergency:

  • Chest pain that spreads to left arm
  • Feeling of chest tightness and heaviness
  • Difficulty in breathing or shortness of breath
  • Light headedness or dizziness
  • Sweating
  • Feeling of fatigue and weakness
  • Nausea
  • Palpitations
  • Anxiety

If you find any of the above sign and symptoms, immediately go to the nearby hospital to get a proper treatment and care. If the symptoms are not diagnosed within time there may be the chances for the worsening of heart attack.

Electrocardiogram (ECG)

Although medical history or symptoms of the patient help a lot in establishing a diagnosis of heart attack but they are not reliable because the symptoms of heart attack may be confused with the symptoms of other heart diseases. ECG or electrocardiogram is the first non invasive test that is done immediately, when patient arrives in hospital, to confirm the diagnosis of heart attack.

Electrocardiogram is done to monitor the electrical activity and rhythm of heart. In this method, several electrodes are placed on the chest of the patient and those electrodes are connected to a monitor, which displays the electrical rhythm of heart. When the heart beats, electrical impulses are generated in tissues that are picked up by electrodes and are transmitted to the display monitor. The ECG waves show the rhythm of heart beat. Various heart diseases can be diagnosed through the abnormal patterns of ECG waves.

In heart attack, the pathological Q eaves and ST elevation or depression of ECG waves are the diagnostic features.

Blood tests

Like electrocardiogram, blood tests are another reliable indicator of heart attack. Why blood tests are done? How can they help in assessing the heart function? To understand the importance of blood tests in supporting the diagnosis, one must know about the sequences of heart attack. Heart attack occurs when the blood supply to heart tissue is reduced due to the blockage of blood vessels.

Reduced blood supply results in damage to the heart tissues. These damaged heart tissues release certain proteins or enzymes slowly in the blood stream. These enzymes are known by the name of “cardiac markers”.

The levels of these cardiac markers are assessed to confirm the diagnosis of heart attack.

For this, a blood sample is drawn and a number of tests are performed on it to detect the level of these enzymes in blood.

The following cardiac markers are helpful in diagnosing heart attack:

  • Troponin is a protein present within normal heart cells. Troponin test is highly sensitive and specific for diagnosing heart attack. A high level of troponin in blood is an indication of damage to heart tissues. Troponin levels begin to increase in blood 3-4 hours after heart attack. The peak level reaches within 12-16 hours. Troponin remains in blood for 2 weeks, following a heart attack.
  • Creatinine phosphokinase (CPK) is an enzyme released into blood after heart attack. The levels of CPK begin to rise within 3-6 hours with the peak level attained within 12-24 hours.
  • Myoglobin is a protein present within heart muscles which are released after heart attack. It appears 2 hours after heart attack and reaches the peak level at 8-12 hours.

Coronary angiography

Coronary angiography is an invasive technique used to locate the blockage in coronary vessels that supply the heart. This test is done to find out that the blockage of which artery is causing heart attack. In coronary angiography, a thin flexible catheter is passed through groin region and is guided towards the coronary vessels with the help of special x ray techniques.

After passing the catheter, a radioactive or contrast dye is injected into the catheter. As the contrast dye passes along the blood circulation it will help in detecting the point of occlusion of artery.


In electrocardiography, high frequency sound waves are used to form a three-dimensional image of heart. The sound waves are directed on to the chest of patient through a transducer.

These waves are reflected back and are processed by electrocardiography machine to form the image of heart. Any abnormality in the motion, shape and size of heart might be a diagnostic feature of heart attack. Other tests: The above mentioned tests are done on routine basis for the diagnosis of heart attack but some other tests like CT scan and MRI (magnetic resonance imaging) can also be done to produce a detailed image of heart.

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Written by: Michal Vilímovský (EN)
Education: Medical student, 3rd Faculty of Medicine, Charles University, Prague, Czech Republic
Published: February 28, 2014 7:07 PM
Next scheduled update: February 28, 2016 7:07 PM
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