Causes and Risk Factors

What are the causes and risk factors of sudden cardiac arrest?

Sudden cardiac arrest is usually caused by a problem with the electrical system of the heart, which may be the result of coronary artery disease, a heart attack or other heart problems.

SCA can strike persons of any age, gender, race, and even those who seem in good health. You may remember a world class professional athlete at the peak of fitness who died suddenly during a sporting event. This is often caused by sudden cardiac arrest.

Usually, sudden cardiac arrest is caused by a problem with the electrical system of your heart. If the electrical signals in your heart are abnormal, this can create an irregular heart rhythm called an arrhythmia.

In some cases, an arrhythmia may cause your heart rate to change to a serious fast heart rate, called ventricular tachycardia or VT. If the heart rate becomes very fast, unstable, and irregular, it may become a much more dangerous rhythm, called ventricular fibrillation or VF. With VF, the heart quivers rapidly and cannot pump blood throughout the body. This is called sudden cardiac arrest.

What triggers the heart's electrical system to malfunction? Most heart and blood vessel diseases can lead to sudden cardiac arrest.

  • Cardiac Arrest Survivors: Most people who experience a sudden cardiac arrest do not survive the first event. If you survived one sudden cardiac arrest, you are at risk for having another one.1
  • Heart Attack Survivors: A heart attack can damage your heart and create an area of scar tissue. If large enough, this scar can cause a fast, dangerous heart rhythm to occur.
  • Spontaneous fast rhythms: Normal hearts can have fast heart rhythms that cause patient symptoms. If medicine is not helpful in treating the arrhythmias, an ICD device may be recommended to treat them.2
  • Congenital heart defects: Five heart defects increase the risk of having a sudden cardiac arrest. These include tetralogy of Fallot, transposition of the great arteries, aortic stenosis, functional single ventricle, and congenital Long QT Syndrome (LQTS). The defect itself, or its surgical repair, may make the patient at risk of dangerous heart rhythm.1

Factors increasing the risk for SCA include: 

  • A family history of coronary heart disease
  • High blood pressure
  • High cholesterol
  • Obesity
  • Diabetes
  • Sedentary lifestyle
  • Smoking
  • Excessive alcohol intake
  • Age

Other factors increasing the risk for SCA include:

  • A personal or family history of arrhythmias
  • A personal or family history of SCA
  • Previous heart attack
  • Previous heart failure
  • Drug abuse
  • Heart Attack Survivors: A heart attack can damage your heart and create an area of scar tissue. If large enough, this scar can cause a fast, dangerous heart rhythm to occur.
  • Spontaneous fast rhythms: Normal hearts can have fast heart rhythms that cause patient symptoms. If medicine is not helpful in treating the arrhythmias, an ICD device may be recommended to treat them.2
  • Congenital heart defects: Five heart defects increase the risk of having a sudden cardiac arrest. These include tetralogy of Fallot, transposition of the great arteries, aortic stenosis, functional single ventricle, and congenital Long QT Syndrome(LQTS). The defect itself, or its surgical repair, may make the patient at risk of dangerous heart rhythm.1

Given that SCA is often linked with coronary heart disease, many of the risk factors for heart disease are also risk factors for SCA. These would include such factors as:

  • A family history of coronary heart disease
  • High blood pressure
  • High cholesterol
  • Obesity
  • Diabetes
  • Sedentary lifestyle
  • Smoking
  • Excessive alcohol intake
  • Age

Other factors increasing the risk for SCA include:

  • A personal or family history of arrhythmias
  • A personal or family history of SCA
  • Previous heart attack
  • Previous heart failure
  • Drug abuse
  • Cardiac Arrest Survivors: Most people who experience a sudden cardiac arrest do not survive the first event. If you survived one sudden cardiac arrest, you are at risk for having another one.1
  • Heart Attack Survivors: A heart attack can damage your heart and create an area of scar tissue. If large enough, this scar can cause a fast, dangerous heart rhythm to occur.
  • Spontaneous fast rhythms: Normal hearts can have fast heart rhythms that cause patient symptoms. If medicine is not helpful in treating the arrhythmias, an ICD device may be recommended to treat them.2
  • Congenital heart defects: Five heart defects increase the risk of having a sudden cardiac arrest. These include tetralogy of Fallot, transposition of the great arteries, aortic stenosis, functional single ventricle, and congenital Long QT Syndrome(LQTS). The defect itself, or its surgical repair, may make the patient at risk of dangerous heart rhythm.1

Given that SCA is often linked with coronary heart disease, many of the risk factors for heart disease are also risk factors for SCA. These would include such factors as:

  • A family history of coronary heart disease
  • High blood pressure
  • High cholesterol
  • Obesity
  • Diabetes
  • Sedentary lifestyle
  • Smoking
  • Excessive alcohol intake
  • Age

Other factors increasing the risk for SCA include:

  • A personal or family history of arrhythmias
  • A personal or family history of SCA
  • Previous heart attack
  • Previous heart failure
  • Drug abuse

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Some heart attack survivors are at increased risk due to the extent of the scar from the attack. The scar disrupts the normal electrical conduction and can do so without warning. When this happens, it creates a fatal heart rhythm called ventricular fibrillation.

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