Canadian Genetic Heart Rhythm Network

For Patients & The Public

Cardiac Arrest

What is cardiac arrest?

Cardiac arrest is the sudden, abrupt loss of heart function. The victim may or may not have diagnosed heart disease. It's also called sudden cardiac arrest or unexpected cardiac arrest. Sudden death (also called sudden cardiac death) occurs within minutes after symptoms appear.

What causes cardiac arrest?

The most common underlying reason for patients to die suddenly from cardiac arrest is coronary heart disease. Most cardiac arrests that lead to sudden death occur when the electrical impulses in the diseased heart become rapid (ventricular tachycardia) or chaotic (ventricular fibrillation) or both. This irregular heart rhythm (arrhythmia) causes the heart to suddenly stop pumping blood. Some cardiac arrests are due to extreme slowing of the heart. This is called bradycardia.

Other factors besides heart disease and heart attack can cause cardiac arrest. These can be inherited problems that lead to rare heart muscle or heart electrical system disorders, such as Long QT Syndrome (LQTS) or Arrhythmogenic right ventricular cardiomyopathy (ARVC). Other causes of cardiacarrest include respiratory arrest, electrocution, drowning, choking and trauma. Cardiac arrest can also occur without any known cause.

Can cardiac arrest be reversed?

Brain death and permanent death start to occur in just 4 to 6 minutes after someone experiences cardiac arrest. Cardiac arrest can be reversed if it's treated within a few minutes with an electric shock to the heart to restore a normal heartbeat. This process is called defibrillation. A victim's chances of survival are reduced by 7 to 10 percent with every minute that passes without CPR and defibrillation. Few attempts at resuscitation succeed after 10 minutes. The difference between cardiac arrest and sudden death is rapid resuscitation.

How many people survive cardiac arrest?

No statistics are available for the exact number of cardiac arrests that occur each year. It's estimated that more than 95 percent of cardiac arrest victims die before reaching the hospital. In cities where defibrillation is provided within 5 to 7 minutes, the survival rate from sudden cardiac arrest is considerably higher.

What can be done to increase the survival rate?

Early CPR and rapid defibrillation combined with early advanced care can result in high long-term survival rates for witnessed cardiac arrest. If bystander CPR was initiated more consistently, if AEDs were more widely available, and if every community could achieve a 20 percent cardiac arrest survival rate, an estimated 4000 more lives could be saved in Canada each year. Death from sudden cardiac arrest is not inevitable. If more people react quickly by calling 9-1-1 and performing CPR, more lives can be saved.