How is sudden cardiac arrest diagnosed?

Sudden cardiac arrest is diagnosed after the event, and may appear as ventricular fibrillation on an electrocardiogram (ECG). If you are risk for sudden cardiac arrest, your doctor may suggest one or more of the tests listed below. Some of the tests check the electrical system in your heart. Other tests check to see how your heart is pumping. The test results can also help your doctor choose the best treatment for you. In some cases you may be sent to specialists for diagnosis, testing and treatment.

  • Electrocardiogram (ECG): The ECG can show how your heart’s electrical system is working. It senses and records your heartbeats.
  • Echocardiogram: This test (also called an echo) uses ultrasound to create images of your heart as it beats. The echo helps your doctor learn about the shape and size of your heart, how well your heart valves are working, and the amount of blood pumped with each heart beat. This is called your ejection fraction (also called EF).
  • Electrophysiology study: The EP study involves checking how electrical impulses travel through the heart muscle. It can help find out about abnormal heart rhythms.

Your ejection fraction (EF)

Your doctor can determine your risk of SCA by measuring your ejection fraction, or EF. The EF is the amount of blood pumped (ejected) by your heart with each beat.
The heart normally ejects at least one-half of the blood (50-60%) it holds with each beat. One or more heart attacks can cause a decrease in the ejection fraction. When less than one-third of the blood is ejected (30-35%), the risk for sudden cardiac death increases.1
If you have a low ejection fraction, your doctor may recommend that you visit a heart rhythm specialist. Your heart rhythm specialist may recommend that you receive a pacemaker-like device called an implantable cardioverter defibrillator that can prevent sudden cardiac death.

Brochure for Patients who have been prescribed an Impantable Defibrillator

Guide for Patients who have an Implanted Defibrillator