Heart Attack and Acute Coronary Syndrome

Symptoms of the acute coronary syndrome (ACS) may include:

• A pressing or squeezing pain in the centre of the chest, sometimes spreading to the jaw, arm, back or abdomen
• shortness of breath, sometimes coughing or wheezing
• feeling sick and light headed
• a great feeling of anxiety

Signs may include a rapid pulse, low blood pressure, pallor of the skin and sweating.

In some cases the pain is minor and can be mistaken for indigestion. Symptoms may occur without any chest pain, particularly in older individuals and in those with diabetes. In women symptoms are often less dramatic and more likely to be misinterpreted as due to another cause than in men.

If you experience these symptoms, dial 999 immediately for an ambulance. Do not worry if you are uncertain whether you are having a heart attack. Between 60% and 80% of patients taken to hospital with chest pain are found not to have had a heart attack. Paramedics would rather be called out to a false alarm than arrive too late to save a life.

If someone who complains of severe chest pain becomes unconscious and no pulse can be felt, it could be due to a cardiac arrest caused by a heart attack. Their life could be saved if cardiopulmonary resuscitation is commenced and performed until the paramedics arrive. Find out how here.

When a person with the acute coronary syndrome (ACS) arrives as an emergency at hospital, a number of tests are done urgently to help decide whether the cause is a heart attack, unstable angina or a problem outside the heart.

An electrocardiogram (ECG) is performed within the first few minutes. Those who have a major clot completely blocking a coronary artery and damaging a large area of heart muscle tissue show the most severe changes in the ECG tracing, with a part of the line called the ST segment elevated above the baseline. This is called an ST segment elevation myocardial infarction or STEMI. More commonly the block is only partial, less muscle is damaged and the ST segment is not elevated. This is called a non-STEMI or NSTEMI. Unstable angina is a less serious form of ACS. The blood supply to the heart muscle is severely restricted but there is usually no permanent damage.

Patients with ACS who have no ST segment elevation need blood tests to find out whether they have a non-STEMI, unstable angina or a non-cardiac condition. When heart muscle cells die they release proteins (cardiac biomarkers) into the blood. Raised levels can detect a heart attack, provide an indication of how much muscle has been damaged and also give an indication of response to treatment. The most specific blood tests for heart muscle damage are cardiac troponins T and I (TnT and TnI). High sensitivity troponin tests can rapidly rule in and rule out heart damage.

Other tests that may be done include a chest X-ray to exclude air between the lung and the lining of the chest wall (pneumothorax) and to look for fluid accumulation in the lungs (pulmonary oedema). Echocardiography can help identify the area of heart damage and its effect on heart function.

The two principal treatments for a myocardial infarction are thrombolysis and angioplasty. In thrombolysis a ‘clot-busting’ drug is injected that attacks and dissolves fibrin that forms the protein meshwork of the clot. Other blood-thinning drugs such as low dose aspirin or heparin may also be given to prevent the clot reforming. In angioplasty, a thin catheter is passed through an artery in the groin or arm to the narrowed coronary artery under X-ray guidance using a radio-opaque dye and a balloon at its tip inflated. Often a flexible wire mesh tube called a stent is implanted to hold the widened artery open.

Patients with a STEMI usually have urgent angioplasty. However, if the patient cannot be taken to a UK Heart Attack Centre within two and a half hours, thrombolysis is used instead. Patients with a non-STEMI are usually treated with ‘clot-busting’ drugs initially, although angioplasty may be needed later. Patients with ACS due to angina often have angioplasty after further investigations. When angioplasty may be a problem because of extensive arterial narrowing, a coronary artery bypass graft (CABG) may be considered. A blood vessel from another part of the body is used as a graft to replace narrowed arteries in the heart.

Recovery from a heart attack may take several months. Drugs may be prescribed to help heart function, control blood pressure and lower cholesterol. Advice will be provided about exercise during rehabilitation, and life style changes including adopting a prudent diet, maintaining a healthy weight and not smoking are recommended.