Heart Attack (Myocardial Infarction)

The most common cause of a heart attack is the narrowing of one or more of the arteries that supply blood to the heart. This results from the build-up of cholesterol deposits (plaque) in the walls of these arteries. This process is known as atherosclerosis, which limits blood flow and reduces the supply of oxygen to the heart muscle.

This can result in a partial or complete blockage of the heart’s arteries. A sudden and severe blockage can lead to a heart attack.

Risk factors of a heart attack

The risk factors for heart attack can be divided into 2 categories, modifiable and non-modifiable. When more risk factors are present, the risk for a heart attack increases significantly.

Modifiable risk factors that contribute to a heart attack include:

• Cigarette smoking: Smoking and exposure to second-hand smoke damages the inner walls of the arteries, allowing plaque to accumulate.
• Obesity: Sedentary lifestyle or lack of physical exercise, which contributes to obesity and high cholesterol levels
• Chronic conditions such as:
  • high blood pressure, which causes the heart to work harder and the heart muscles to thicken and harden. This accelerates the process of atherosclerosis.
  • high cholesterol, which is a major component of plaque.
  • diabetes, which is linked to increased risk of heart attack and other heart problems, especially if blood sugar levels are poorly controlled.

Non-modifiable risk factors that contribute to a heart attack include:

• Age: Men aged 45 or older and women aged 55 or older are more likely to have a heart attack than younger men and women
• Family history: If one of your immediate family members, such as a parent or sibling, has had a heart attack, or was diagnosed with heart disease before the age of 60, this may indicate a family history of premature heart disease. This means that your chances of developing heart disease may be higher than normal population
• Gender: Men have a greater risk for heart attacks and at a younger age compared to women of the same age.
• Ethnicity: African Americans, Hispanics, Latinos, and Southeast Asians, are ethnic groups with an increased risk of CAD morbidity and mortality

Preventing a heart attack

You can reduce your risk for a heart attack by practising preventive measures in these areas:

• Eat a healthy, balanced diet. Consume more whole grains, fruits, vegetables and fish, and reduce or eliminate foods that are high in fat and sodium such as fried or processed foods and prepared sauces.
• Control high blood pressure, high cholesterol and diabetes which are risk factors for heart attack. This includes following any dietary restrictions and taking the medications recommended by your doctor.
• Get regular exercise. This will help to strengthen the heart and improve blood circulation. It also plays an important role in maintaining a healthy body weight to prevent obesity, another risk factor for heart attacks, and helps with managing high blood pressure, high cholesterol and diabetes.
• Stop smoking. Quitting smoking may reduce your risk of heart attack by 50%.

Common warning signs of a heart attack include:

• Chills or cold sweat
• Chest discomfort or pain that feels like pressure, squeezing or clenching, or fullness
• Feeling dizzy or light-headed
• Nausea or vomiting
• Pain or discomfort in the chest or upper body that may spread to the jaw or arms
• Prolonged and severe central chest pain (heavy and crushing sensation)
• Shortness of breath, which may occur on its own or with chest pain

While chest discomfort or pain is the most common symptom, women are more likely to experience shortness of breath, nausea, vomiting, and back or jaw pain.

A heart attack can be diagnosed using a variety of tests which can be non-invasive or invasive. Sometimes, a combination of tests may be needed.

Non-invasive tests to diagnose a heart attack include:

• Electrocardiogram

  Electrocardiogram (ECG) records the heart’s electrical activity to help determine if a heart attack has already occurred.

• Chest X-ray

  Chest X-ray helps to capture images of the heart, lungs and chest structure to reveal if the heart is enlarged or if the heart is accumulating fluid as a result of a heart attack.

• Echocardiogram

  Echocardiogram uses high frequency soundwaves or ultrasound to produce images of the heart’s size, structure and movement to identify abnormal rhythms or arrhythmia.

Invasive tests to diagnose a heart attack include:

• Blood tests

  Blood tests to check for cardiac enzymes, C-reactive protein (CRP) and other indicators to confirm if a heart attack has occurred, the extent of damage and determine the future risk for coronary artery disease.

• Cardiac catheterisation and angiogram

  A procedure in which a catheter is inserted and guided to the heart in order to inject a dye that makes the blood vessels visible on X-ray. This gives doctors a clearer view of narrowed or blocked coronary arteries. Cardiac catheterisation can also be used to perform a percutaneous coronary intervention (PCI) to open blocked segments of the coronary artery.

The aim of the treatment is to unblock the affected artery quickly to minimise the amount of damage to the heart muscle. Your doctor will evaluate the severity of your condition and perform the most effective way of unblocking the artery. This may include a combination of surgery, medication and rehabilitation.

Surgery to treat a heart attack

Surgical options, depending on the extent of the blockage and the patient’s health, include:

• Coronary angioplasty, where a small balloon or a stent (small mesh tube) is inserted into the blocked artery to help re-open it and restore blood flow
• Coronary artery bypass, in which a healthy blood vessel taken from the leg, arm or chest is used to go around a blocked artery. This provides an alternate route for blood to flow to the heart muscles.

Medication to treat a heart attack

Medications are prescribed to help relieve symptoms such as chest pain and to reduce the risk of another heart attack. Medication may also be necessary to help manage chronic conditions such as diabetes, high blood pressure and high cholesterol which increase the risk for another heart attack.

• Antiplatelet agents to prevent the formation of blood clots
• Angiotensin II receptor blocker to help control blood pressure
• Beta blockers to lower blood pressure by making the heart beat more slowly and with less force
• Calcium channel blocker to relax blood vessels
• Diuretics to eliminate excess fluids and relieve strain on the heart
• Statins to reduce blood cholesterol levels, or alternative cholesterol-lowering medication if statins are ineffective or not tolerated
• Vasodilators to relax blood vessels and increase supply of blood and oxygen to the heart

Cardiac rehabilitation

This is a programme specifically created to improve your cardiovascular health after a heart attack. A comprehensive rehabilitation programme will encompass three aspects:

• Exercise, to help reduce weight and manage modifiable risk factors such as diabetes, high cholesterol and high blood pressure
• Education on improving your diet and managing your medications
• Counselling to quit smoking and manage stress, anxiety and depression

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A heart attack is a serious event with long-lasting consequences and complications. Potential complications from a heart attack can vary widely, from mild to life threatening. These complications include:

• Arrhythmia

  An arrhythmia occurs when an abnormal heart beat either too fast, too slow or irregular. This affects the flow of blood and oxygen to the heart and can lead to palpitations, chest pain, dizziness, fatigue or breathlessness.

• Heart failure

  Heart failure happens when heart is unable to pump blood effectively to the rest of the body. It can lead to breathlessness, fatigue, build-up of fluid in the arms and legs (oedema).

• Heart rupture or cardiac rupture

  Heart rupture or cardiac rupture is rare complication following a heart attack where the damage or trauma caused by a prior heart attack has created a weaken area that can lead to a tear or rupture.

• Cardiogenic shock

  Cardiogenic shock is similar to a heart failure but in a more severe form. Symptoms can include mental confusion, cold hands and feet, rapid heartbeat, pale skin and difficulty breathing.