If you’ve had aheart 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, they may need electric shocks to the heart with a defibrillator immediately (depending on the underlying heart rhythm, which the defibrillator analyzes).
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.
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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 ofacute coronary syndrome, occur when a coronary artery is 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 may produce 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 without any warning, 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 theejection 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
Medications to Reduce the Risk of Sudden Cardiac Arrest
Beta-blockers, ACE inhibitors, statins, and SGLT2 inhibitors 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 developingheart failureor 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 remains high. After a heart attack, serious consideration should be given to implanting an ICD, in addition to medical treatment, when:
Clinical studies have shown that in any of these circumstances, having an ICD can help prevent sudden cardiac arrest.
7 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto 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?Richardson WJ, Clarke SA, Quinn TA, Holmes JW.Physiological implications of myocardial scar structure.Compr Physiol. 2015;5(4):1877-1909. doi:10.1002/cphy.c140067American Heart Association.Understand your risk for cardiac arrest.Intermountain Healthcare.Sudden cardiac arrest: know your ejection fraction.Heidenreich PA, Bozkurt B, Aguilar D, et al.2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines [published correction appears in Circulation. 2022 May 3;145(18):e1033].Circulation. 2022;145(18):e895-e1032. doi:10.1161/CIR.0000000000001063Heidenreich PA, Bozkurt B, Aguilar D, et al.2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines.J Am Coll Cardiol. 2022;79(17):e263-e421. doi:10.1016/j.jacc.2021.12.012Poole JE.Present guidelines for device implantation: clinical considerations and clinical challenges from pacing, implantable cardiac defibrillator, and cardiac resynchronization therapy.Circulation. 2014;129(3):383-394. doi:10.1161/CIRCULATIONAHA.112.000762Additional ReadingAmerican 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?
7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto 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?Richardson WJ, Clarke SA, Quinn TA, Holmes JW.Physiological implications of myocardial scar structure.Compr Physiol. 2015;5(4):1877-1909. doi:10.1002/cphy.c140067American Heart Association.Understand your risk for cardiac arrest.Intermountain Healthcare.Sudden cardiac arrest: know your ejection fraction.Heidenreich PA, Bozkurt B, Aguilar D, et al.2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines [published correction appears in Circulation. 2022 May 3;145(18):e1033].Circulation. 2022;145(18):e895-e1032. doi:10.1161/CIR.0000000000001063Heidenreich PA, Bozkurt B, Aguilar D, et al.2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines.J Am Coll Cardiol. 2022;79(17):e263-e421. doi:10.1016/j.jacc.2021.12.012Poole JE.Present guidelines for device implantation: clinical considerations and clinical challenges from pacing, implantable cardiac defibrillator, and cardiac resynchronization therapy.Circulation. 2014;129(3):383-394. doi:10.1161/CIRCULATIONAHA.112.000762Additional ReadingAmerican 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?
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto 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?Richardson WJ, Clarke SA, Quinn TA, Holmes JW.Physiological implications of myocardial scar structure.Compr Physiol. 2015;5(4):1877-1909. doi:10.1002/cphy.c140067American Heart Association.Understand your risk for cardiac arrest.Intermountain Healthcare.Sudden cardiac arrest: know your ejection fraction.Heidenreich PA, Bozkurt B, Aguilar D, et al.2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines [published correction appears in Circulation. 2022 May 3;145(18):e1033].Circulation. 2022;145(18):e895-e1032. doi:10.1161/CIR.0000000000001063Heidenreich PA, Bozkurt B, Aguilar D, et al.2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines.J Am Coll Cardiol. 2022;79(17):e263-e421. doi:10.1016/j.jacc.2021.12.012Poole JE.Present guidelines for device implantation: clinical considerations and clinical challenges from pacing, implantable cardiac defibrillator, and cardiac resynchronization therapy.Circulation. 2014;129(3):383-394. doi:10.1161/CIRCULATIONAHA.112.000762
American Heart Association.Heart attack or sudden cardiac arrest: how are they different?
Richardson WJ, Clarke SA, Quinn TA, Holmes JW.Physiological implications of myocardial scar structure.Compr Physiol. 2015;5(4):1877-1909. doi:10.1002/cphy.c140067
American Heart Association.Understand your risk for cardiac arrest.
Intermountain Healthcare.Sudden cardiac arrest: know your ejection fraction.
Heidenreich PA, Bozkurt B, Aguilar D, et al.2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines [published correction appears in Circulation. 2022 May 3;145(18):e1033].Circulation. 2022;145(18):e895-e1032. doi:10.1161/CIR.0000000000001063
Heidenreich PA, Bozkurt B, Aguilar D, et al.2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines.J Am Coll Cardiol. 2022;79(17):e263-e421. doi:10.1016/j.jacc.2021.12.012
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):383-394. doi:10.1161/CIRCULATIONAHA.112.000762
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?
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?
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