Heart Health Heart Disease Heart Attack Preventing Sudden Death After a Heart Attack By Richard N. Fogoros, MD Richard N. Fogoros, MD Facebook LinkedIn Richard N. Fogoros, MD, is a retired professor of medicine and board-certified internal medicine physician and cardiologist. Learn about our editorial process Medically reviewed by Yasmine S. Ali, MD, MSCI Medically reviewed by Yasmine S. Ali, MD, MSCI on March 27, 2020 Facebook LinkedIn Twitter Yasmine Ali, MD, is board-certified in cardiology. She is an assistant clinical professor of medicine at Vanderbilt University School of Medicine and an award-winning physician writer. Learn about our Medical Review Board on March 27, 2020 Print If you've already had a heart attack, you're at high risk of having a sudden cardiac arrest. Dying from sudden cardiac arrest after a heart attack is, unfortunately, all too common. When a person goes into sudden cardiac arrest, he or she needs electric shocks to the heart with a defibrillator immediately because of the chances of survival decrease with every minute, eventually leading to sudden cardiac death, which claims the lives of around 325,000 adults in the United States each year. Jupiterimages / Getty images Sudden Cardiac Death Most victims of sudden cardiac death have had a prior myocardial infarction (heart attack) weeks, months, or even years earlier. Heart attacks, the most severe form of the acute coronary syndrome, are produced when a coronary artery becomes suddenly blocked, usually due to the rupture of coronary artery plaque, thus causing the death of a portion of the heart muscle. The damaged heart muscle eventually heals following a heart attack, but always produces a permanent scar. The scarred portion of the heart can become electrically unstable and the electrical instability can produce a life-threatening heart arrhythmia called ventricular tachycardia (fast heartbeat), which can lead to ventricular fibrillation. Unfortunately, these arrhythmias can occur quite suddenly, without any warning whatsoever, and people can experience them even if everything seems to be going well from a medical standpoint. The arrhythmia can then lead to a sudden cardiac arrest, which often results in death. The Risk of Sudden Cardiac Arrest After a Heart Attack The risk of sudden cardiac arrest after you've had a heart attack is highest within the six months following your heart attack. In fact, 75% of people who have sudden cardiac arrest had a previous heart attack. The highest risk occurs in people who have already survived a cardiac arrest and have been successfully resuscitated. The risk is also relatively high in people whose heart attacks are considered large, that is, whose heart attacks produce a lot of heart muscle scarring. Ejection Fraction One good measure that reflects the amount of scarring is the ejection fraction, a measurement to determine how well your heart is pumping blood. The more scarring you have, the lower the ejection fraction. After a heart attack, those with an ejection fraction above 40% (a normal ejection fraction is 55% or higher) seem to have a relatively low risk of sudden death. The risk of sudden death increases with lower ejection fractions and becomes substantially higher with values of 35% or below. For this reason, anyone who has had a heart attack should have their ejection fractions measured. Reducing the Risk of Sudden Cardiac Arrest After a Heart Attack The risk of sudden death after a heart attack can be greatly reduced by two general kinds of measures: Standard medical treatments including beta-blockers, ACE inhibitors, and statin therapy. Identifying people who are still at high risk despite medical treatment, and considering an implantable cardioverter-defibrillator (ICD) in these individuals. Medications to Reduce the Risk of Sudden Cardiac Arrest Beta-blockers, ACE inhibitors, and statins have all been shown to reduce the risk of dying after a heart attack. While much of this mortality reduction is related to reducing the chances of developing heart failure or further heart attacks, these drugs also modestly reduce the risk of cardiac arrest and sudden death. All survivors of heart attacks should be placed on these drugs unless there's a very good reason not to. Implantable Cardioverter Defibrillator (ICD) to Reduce the Risk of Sudden Cardiac Arrest Despite the use of aggressive medical therapy, in some people, the risk of sudden death due to cardiac arrest remains high. You may be a good candidate for an ICD if any of the following is true: You've had a prior sudden cardiac arrest, heart attack, or a ventricular arrhythmiaYou have Long Q-T syndromeYou have congenital heart disease or other conditions that could lead to sudden cardiac arrest Clinical studies have shown that in any of these circumstances, having an ICD can help prevent sudden cardiac arrest. Was this page helpful? Thanks for your feedback! Did you know the most common forms of heart disease are largely preventable? Our guide will show you what puts you at risk, and how to take control of your heart health. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. American Heart Association. Heart attack or sudden cardiac arrest: how are they different? Updated July 31, 2015. Richardson WJ, Clarke SA, Quinn TA, Holmes JW. Physiological implications of myocardial scar structure. Compr Physiol. 2015;5(4):1877-909. doi:10.1002/cphy.c140067 American Heart Association. Understand your risk for cardiac arrest. Updated March 10, 2017. Intermountain Healthcare. Sudden cardiac arrest: know your ejection fraction. Updated February 20, 2013. Elayi CS, Charnigo RJ, Heron PM, Lee BK, Olgin JE. Primary prevention of sudden cardiac death early post-myocardial infarction: root cause analysis for implantable cardioverter-defibrillator failure and currently available options. Circ Arrhythm Electrophysiol. 2017;10(6). doi:10.1161/CIRCEP.117.005194 Rossello X, Pocock SJ, Julian DG. Long-term use of cardiovascular drugs: challenges for research and for patient care. J Am Coll Cardiol. 2015;66(11):1273-1285. doi:10.1016/j.jacc.2015.07.018 Poole JE. Present guidelines for device implantation: clinical considerations and clinical challenges from pacing, implantable cardiac defibrillator, and cardiac resynchronization therapy. Circulation. 2014;129(3):383-94. doi:10.1161/CIRCULATIONAHA.112.000762 Additional Reading American Heart Association. Implantable Cardioverter Defibrillator (ICD). American Heart Association. Ejection Fraction Heart Failure Measurement. National Heart, Lung, and Blood Institute. How Can Death Due to Sudden Cardiac Arrest Be Prevented? U.S. Department of Health and Human Services. Cleveland Clinic. Sudden Cardiac Death (Sudden Cardiac Arrest): Risk Factors.