Should You Get an Implantable Defibrillator?

Implantable defribillator

Paul T/Wikimedia Commons/CC BY 3.0

Implantable defibrillators, also known as implantable cardioverter-defibrillator (ICD), are highly effective at preventing sudden cardiac death from heart arrhythmias (irregular heart rhythm). But, unfortunately, at least 25% of the more than 350,000 Americans who die suddenly each year never learn that their risk is high. Therefore, they never have the opportunity to consider an ICD.

Anyone with significant heart disease or close family members who have had a sudden death should talk to their doctor about their own risk of sudden death. If your risk is high, you should discuss an ICD.

This article explains the risk factors for sudden death and when ICD may be indicated as a preventative measure.

Significant Coronary Artery Disease (CAD)

People with significant coronary artery disease (CAD) have an increased risk of having a life-threatening arrhythmia. That's because the plaques associated with CAD can suddenly rupture, producing a spectrum of conditions called acute coronary syndrome (ACS).

One of the possible outcomes of ACS is cardiac arrest (when the heart stops pumping blood). That's because when plaque ruptures, it can acutely disrupt the cardiac electrical system. When this happens, it can suddenly produce heart disturbances, such as:

  • Ventricular tachycardia (VT ): Sudden, rapid, irregular heartbeat that originates in the ventricles (the lower chambers of the heart)
  • Ventricular fibrillation (VF): Heart rhythm disturbance where the heart stops beating normally and instead starts quivering uncontrollably

Unfortunately, for many people who have significant CAD, sudden death is the first sign that the disease is present.

However, generally speaking, the overall risk of sudden death in people who have CAD but have not yet had a myocardial infarction (heart attack) is not high enough to require an ICD.

Instead, doctors generally recommend aggressive measures to control the risk factors known to accelerate CAD and make plaque rupture more likely. Good medical care and effective lifestyle modification can significantly reduce the risk of heart attacks, angina, and sudden death.


CAD is a risk factor for sudden death. However, ICD is not usually recommended for CAD alone unless you have also had a heart attack.

Episodes of VT or VF

People who have already had episodes of VT or VF have an unacceptably high risk of having another ventricular arrhythmia — which may be fatal. This risk is especially high if the arrhythmia has caused cardiac arrest or loss of consciousness.

Unless a doctor has identified some underlying, totally reversible cause for cardiac arrest, almost all people with VT or VF should be offered an ICD.

Heart Failure

People with heart failure with a significantly reduced left ventricular ejection fraction (a measurement that assesses heart strength) are at increased risk for sudden death.

Current guidelines recommend that ICDs be considered for people with heart failure whose ejection fractions are reduced to 35% or lower. Many of these individuals benefit from an ICD that also includes cardiac resynchronization therapy (treatment with a biventricular pacemaker).

If you have heart disease of almost any type, it is important to know your ejection fraction.

Previous Heart Attack

People who have had heart attacks and other risk factors are at increased risk of sudden death. Risk factors that may warrant an ICD include:

  • A heart attack which has left a person with a left ventricular ejection fractions of 35% or lower
  • Certain arrhythmias, like ventricular tachycardia
  • Other high risks of sudden death

Inherited Heart Defects

People who have inherited heart defects that make VT or VF likely to occur are at risk of sudden death. Such conditions include: 

ICDs can prevent sudden death in these inherited conditions. Therefore, people with these health conditions should strongly consider an ICD.

Is an ICD Right for You?

Anyone with a strong family history of sudden death should discuss their family history with their doctor and ask whether they should do any special testing. In most cases, a simple electrocardiogram (ECG) and perhaps an echocardiogram would be sufficient to rule out the most common inherited cardiac disorders that increase the risk of sudden death.

If you believe you may be at increased risk, you need to have a serious conversation with your doctor about evaluating your likelihood of sudden cardiac death.

Since there are many factors involved, an app is available to help doctors navigate the recommendations.

A Word From Verywell

ICDs are not for everyone. There are risks with these devices as well as benefits. Whether to have one — even if you have an elevated risk and a formal "indication" for an ICD — is always an individual decision. 

However, before you can even have the opportunity to make this decision, you need to be aware of your elevated risk for sudden death. Unfortunately, many doctors are (understandably) reluctant to broach this topic with their patients. So, if you are concerned that you might be at increased risk, break the ice yourself — ask your doctor to talk with you about it.

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