Most cases of ventricular fibrillation (VF) are caused by a heart attack. A blockage in a coronary artery reduces blood flow to the heart and causes the heart attack. If the VF occurs within 48 hours of the original heart attack, it is known as primary ventricular fibrillation. Other known causes include low blood pressure and shock, an electrical shock to the body and conditions that change the electrical activity in the heart, such as low potassium levels or some drugs.

Knowing the most common risk factors for ventricular fibrillation (VF) can be helpful in preventing or recognizing symptoms before an episode occurs. These risk factors, which can be identified over time, include:

• Coronary artery disease
  
  
• Certain types of congenital heart disease
  
  
• Cardiomyopathy (enlargement of the heart muscle)
  
  
• Arrhythmogenic right ventricular dysplasia
  
  
• Family history of either VF or unexplained fainting (syncope)
  
  
• Long QT syndrome (rare, inherited disorder that affects the heart’s electrical system)
  
  
• Brugada Syndrome (rare genetic cause of sudden unexplained ventricular fibrillation)
  
  
• Electrolyte imbalance in the blood (often caused by low levels of potassium and magnesium)
  
  
• Excessive toxins, such as alcohol or recreational drugs (e.g., cocaine)
  
  
• Overuse of caffeine or decongestants
  
  
• Valve dysfunction
  
  
• Electric shock