A heart attack is a common and important cause of chest pain. In a heart attack (also called a myocardial infarction) the blood supply to part of the heart muscle becomes suddenly interrupted by the formation of a clot or thrombus within one of the arteries that supply blood to the heart (the coronary arteries). This occurs because the arteries that supply blood to the heart have become diseased as a result of cholesterol being deposited in their walls (plaque formation, see picture). In contrast to angina where these deposits build up over time leading to a gradual narrowing of the heart arteries in a heart attack the wall of the artery fissures (or splits) causing a small tear on which a thrombus or clot then forms. This clot then blocks or occludes the blood flow down the heart arteries. This then leads to chest pain, usually at rest as the heart muscle cannot survive without a continuous blood supply and part of the heart muscle starts to die (infarct).
There are several treatment options for a heart attack which depend on the type of heart attack (see below). These can include treatment with specific medication, treating the blocked or diseased arteries by stretching the narrowed part of the artery with a balloon and then inserting a stent (percutaneous coronary intervention or PCI) or an operation to bypass the blocked or narrowed arteries (coronary artery bypass surgery or a CABG). The longer that the blocked heart arteries remain blocked the greater the amount of permanent damage to the heart muscle that will occur and therefore a heart attack is a medical emergency.
In some cases the heart attack can lead to disturbances in the rhythm of the heart such as ventricular fibrillation (where the heart will stop beating) which require resuscitation or the inability of the heart to pump properly to maintain adequate blood supply to the other organs in the body (heart failure). These require additional treatment.
Symptoms of a Heart Attack
Severe prolonged chest pain at rest is the most common symptom of a heart attack. The chest pain is very similar to that during an attack of angina but tends to be more severe and is not relieved with simple medication or with resting. The pain you feel in your chest may spread down your arms or into your neck, jaw or back. Other symptoms can include:
Breathlessness, which is sometimes the only symptom and may occur without a pain in your chest
Risk Factors for a Heart Attack
The risk factors for a heart attack are the same as those for angina, namely:
A family history of circulatory disease, particularly of a first degree relative
High blood pressure
High cholesterol, in particular a high level of LDL cholesterol which promotes narrowing of your arteries
Smoking, as the chemicals in cigarette smoke harm your blood vessels
Although some people already have angina but often a heart attack is the first presentation or indication that you have coronary artery disease.
Diagnosing a Heart Attack
As well as assessing your symptoms and identifying risk factors for coronary artery disease, you will need investigations to confirm the diagnosis of a heart attack. As this is a medical emergency these will be performed quickly to ensure the correct diagnosis and then rapid, appropriate treatment. The exact treatment differs according to the type of heart attack. To determine this requires a combination of blood tests and an ECG. In some cases a test called a coronary angiogram is required immediately and in other cases medication to stabilise the heart is given first and then a coronary angiogram is performed.
Treating a Heart Attack
A coronary angiogram is an invasive test where a small tube (known as a catheter) will be inserted through the artery either at the top of your leg or your wrist around into the heart arteries and pictures of the heart arteries are then taken using dye and x-rays. This test will identify the artery that has become blocked with clot. This will then be treated by opening this artery with a balloon to remove the clot and then inserting a stent (PCI) to keep the artery open. It is also needed if you then need coronary artery bypass surgery so that the surgeon knows where the narrowings and blockages in your heart arteries are located.
Secondary Prevention of a Heart Attack
After the immediate treatment of a heart attack there is further treatment and management. There are several medications that are used after a heart attack to reduce the chances of another heart attack and also to minimise the amount of damage that occurs to the heart. Aspirin is nearly always prescribed along with another blood thinning drug (eg Clopidogrel, Prasugrel or Ticlopidine). These reduce the chances of a heart attack in the future and are also needed to reduce the chances of problems developing with the stent that has been inserted to repair the heart artery. Beta blockers (eg Atenolol or Bisoprolol) and angiotensin converting enzyme inhibitors (eg Ramipril or Lisinopril) are also given. They help the heart to pump more effectively after a heart attack and reduce the chances of heart rhythm problems developing after a heart attack. Cholesterol lowering agents such as statins (eg Atorvastatin or Rosuvastatin) are also given after a heart attack. Any other risk factors for coronary artery disease, such as high blood pressure, will also be appropriately treated. Other tests which may be performed include an echocardiogram to assess the function of the heart and the amount of damage that has occurred. Dietary and lifestyle advice will be given and a programme of graded exercise will be offered over a period of weeks to help with returning to normal activities after the heart attack (rehabilitation).