Sudden Cardiac Death What is sudden cardiac death? Sudden cardiac death (also known as sudden cardiac arrest) is most commonly caused by a rapid, erratic heart rhythm. If not treated, death occurs within minutes. Approximately 95% of people do not survive sudden cardiac death. Sudden cardiac death (SCD) is different from a heart attack. A heart attack results when blood flow is blocked to part of the heart muscle. SCD occurs when the electrical impulses that control the heart’s rhythm speed up and/or become chaotic. Who is at risk? People who’ve been treated for heart attacks and chronic heart failure are at greatly increased risk for SCD. High-risk patients are defined as those who have an ejection fraction (the amount of blood ejected from the heart during each beat) of less than 35%. But SCD can—and does—happen in people who look and feel healthy and who have not been diagnosed with heart disease or other risk factors. How can you avoid SCD? Heart doctors called electrophysiologists perform tests that show if a person is at increased risk. An implantable defibrillator device (ICD) can reduce the chance of SCD. The ICD monitors the heart for abnormal rhythms and delivers an electrical shock to restore the heart’s normal rhythm. People who have been hospitalized for a coronary intervention (such as angioplasty), coronary bypass, or a newly diagnosed heart failure should be re-evaluated 90 days after they are discharged. A patient who has suffered a heart attack should be re-evaluated at 40 days. This delay gives the heart time to heal and can make preventive procedures safer. If the heart is still weak, an ICD may be needed to reduce the chance of sudden cardiac death. What else can you do? A heart-healthy lifestyle—regular exercise, avoiding smoking, eating a healthy diet, and staying at a healthy weight—can help reduce the risk of SCD and other heart disease. It also helps to treat conditions that contribute to heart problems, such as high blood pressure, high cholesterol, and diabetes. To learn more about sudden cardiac death, visit the American Heart Association’s Sudden Cardiac Death page. The Heart Rhythm Society has a sudden cardiac death risk assessment tool. Visit their website to learn more.