Preventing Sudden Death After a Heart Attack

If you've 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, they need electric shocks to the heart with a defibrillator immediately because 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.

man in cardiac arrest
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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 of acute 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 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 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 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 arrhythmia
  • You have long QT syndrome
  • You 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.

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7 Sources
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  1. American Heart Association. Heart attack or sudden cardiac arrest: how are they different?

  2. 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

  3. American Heart Association. Understand your risk for cardiac arrest.

  4. Intermountain Healthcare. Sudden cardiac arrest: know your ejection fraction.

  5. 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

  6. 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

  7. 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

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