Causes of Cardiac Arrest

Cardiac arrest may be caused by many different heart conditions.

Most cardiac arrests occur when the heart’s electrical system suddenly stops working normally. This can lead to dangerous heart rhythms, such as ventricular tachycardia or ventricular fibrillation. Some cardiac arrests are also caused by extreme slowing of the heart’s rate, bradycardia.

Irregular heartbeats such as these are life-threatening.

Other causes of cardiac arrest include:

• Scarring of the heart tissue – It may come from a prior heart attack or other cause. A heart that’s scarred or enlarged is prone to develop life-threatening ventricular arrhythmias. The first six months after a heart attack is a high-risk period for sudden cardiac arrest in patients with atherosclerotic heart disease. This type of heart disease is caused by the buildup of fatty deposits, or plaque, in the arteries.
• Thickened heart muscle (cardiomyopathy) – Damage to the heart muscle can come from high blood pressure, heart valve disease or other causes. Problems that weaken or hurt the heart muscle can make sudden cardiac arrest more likely, especially when heart failure is present. Learn more about cardiomyopathy. 
• Heart medications – Some heart medications may cause arrhythmias that lead to sudden cardiac arrest.
  • Even medications meant to treat arrhythmias can sometimes cause ventricular arrhythmias. This is called a “proarrhythmic” effect.
  • Big changes in your levels of potassium and magnesium can also cause arrhythmias and cardiac arrest. This can happen when taking water pills, or diuretics.
• Electrical abnormalities – These may cause sudden cardiac arrest in children and young adults. They include:
  • Wolff-Parkinson-White syndrome
  • Long QT syndrome     
• Blood vessel abnormalities – These rare cases occur particularly in the coronary arteries and aorta. Adrenaline released during intense physical activity can cause sudden cardiac arrest when these blood vessel issues are present. 
• Recreational drug use – This can be related to cardiac arrest in otherwise healthy people.
• Commotio cordis – Commotio cordis occurs after a blow to the left side of the chest during a narrow window in the heart rhythm. Learn more about commotio cordis.