Wearable Defibrillator: How It Works, Uses, Risks and Daily Life
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is a wearable defibrillator?
A wearable defibrillator is a garment and monitor that continuously check the heart's electrical activity and can shock certain life-threatening rhythms. People at risk of sudden cardiac arrest may wear one while awaiting a permanent solution or evaluation. If it detects ventricular tachycardia or fibrillation, it sounds an alarm and, without a response, delivers a shock. [1]
What the research says
In the VEST randomized trial after a heart attack, the wearable defibrillator did not significantly reduce arrhythmic death, though death from any cause was lower. Among 2,302 patients with a recent heart attack and an ejection fraction of 35% or less, arrhythmic death at 90 days occurred in 1.6% with the device versus 2.4% with guideline-directed therapy alone (relative risk 0.67; 95% CI 0.37–1.21; P = 0.18). Death from any cause, a secondary outcome, occurred in 3.1% versus 4.9% (relative risk 0.64; 95% CI 0.43–0.98; uncorrected P = 0.04). Participants wore the device a median of 18.0 hours per day; 1.3% of the device group received an appropriate shock and 0.6% an inappropriate shock (Olgin et al., N Engl J Med, 2018). [2]
Across studies, roughly 5 in 100 wearers received an appropriate treatment over three months, with wide variation between studies. A meta-analysis of 28 studies (33,242 patients) found appropriate wearable-defibrillator therapy in 5 per 100 persons over three months (95% CI 3.0–6.0) and inappropriate therapy in 2 per 100; mortality while wearing the device was 0.7 per 100. Rates were higher in observational studies than in VEST, the results were highly heterogeneous, and the authors call for more randomized trials to justify continued use for primary prevention (Masri et al., JACC Clin Electrophysiol, 2019). [3]
What is a wearable defibrillator?
A wearable defibrillator is a personal device that children and adults at risk for sudden cardiac arrest can wear. It continuously monitors heart rhythm and can deliver a shock if a life-threatening arrhythmia starts. [1]
The system includes a lightweight fabric garment, electrodes and an external monitor. The electrodes pick up the heart's electrocardiogram, or EKG. The monitor is worn around the waist or from a shoulder strap and is about the size of a paperback book. [1]
The garment is worn under clothes and removed only for bathing. It needs to fit well so the electrodes stay in contact with the skin. [1]
How does a wearable defibrillator work?
The monitor reads the EKG continuously. If it detects ventricular tachycardia, a rapid heartbeat, or ventricular fibrillation, a rapid, uncontrolled and ineffective heartbeat, it sounds an alarm to check whether the person is responsive. [1]
If you are conscious, you have less than one minute to respond to the alarms by pressing two buttons to stop treatment. This response is important because not every alarm necessarily means that you need a shock. Follow the instructions provided by the treating team for your specific device. [1]
If you do not respond, the device warns people nearby that a shock is about to occur. The warning tells bystanders not to touch you so they avoid injury. [1]
If the dangerous rhythm continues and you still do not respond, the device delivers a treatment shock through the garment electrodes. When you are unconscious, you will not feel the shock. [1]
If the heartbeat returns to normal, the alarms stop and the device returns to normal monitoring. If the rhythm does not return to normal, the treatment cycle can repeat, with up to five treatment shocks possible. [1]
Stage | What happens |
Continuous monitoring | Electrodes pick up the EKG while the garment is worn. |
Rhythm detection | The monitor looks for ventricular tachycardia or ventricular fibrillation. |
Alarm | The device sounds an alarm to check whether the person is responsive. |
Conscious response | A conscious person has less than one minute to press two buttons to stop treatment. |
Bystander warning | If there is no response, nearby people are warned not to touch the wearer during a shock. |
Treatment shock | If the rhythm continues, the garment electrodes deliver a shock. |
Return to monitoring | If the rhythm returns to normal, alarms stop and monitoring resumes. |
What happens if the device alarms?
A conscious person has less than one minute to respond by pressing two buttons to stop treatment. The specific instructions supplied with the device and by the healthcare team should guide what you do. [1]
If the person does not respond, bystanders should not touch them during the warning and shock sequence. Family members and other people who may be nearby should understand how the device works and how to avoid contact during a shock. [1]
This article does not replace the instructions provided by the treating team or the device manufacturer. Ask the healthcare provider to demonstrate the alarm response and explain what family members should do.
Why might someone use a wearable defibrillator?
A wearable defibrillator may provide protection from sudden cardiac arrest while a person waits for an implantable cardioverter defibrillator, a heart transplant or a decision about whether an ICD is needed. It may also be used while waiting for another ICD after an infection or device malfunction. [1]
It is listed as an option for people who are not candidates for an ICD, have had a heart attack with reduced left-ventricular ejection fraction, will have or have had bypass surgery or stent placement, or have cardiomyopathy or heart failure.
The device's role and wear duration depend on the person's rhythm risk, heart function, planned treatment and clinical course. An online article cannot determine whether it is appropriate for an individual.
Situation | Possible role of a wearable defibrillator |
Waiting for an ICD | Provides temporary protection while an implantable device is being considered or arranged. |
Waiting for a heart transplant | Provides protection during the waiting period. |
Watching for improvement | Provides protection while the team sees whether the condition improves enough to avoid an ICD. |
After ICD infection or malfunction | Provides protection while waiting for another ICD. |
Not an ICD candidate | May be considered when an ICD is not an option. |
Heart attack with reduced ejection fraction | May be an option when left-ventricular pumping function is reduced. |
Bypass surgery or stent placement | May be considered around these procedures. |
Cardiomyopathy or heart failure | May be an option depending on the clinical situation. |
Ejection fraction and wearable defibrillators
Ejection fraction describes how well the left ventricle pumps. Clinical references say a person may need a wearable defibrillator when ejection fraction is less than or equal to 35%, and describe a normal ejection fraction as 55% to 70%. [1]
These values are context, not a self-diagnosis rule or automatic prescription threshold. The cardiology team considers the full clinical picture and decides whether temporary wearable protection is appropriate.
Wearable defibrillator vs AED vs ICD
A wearable defibrillator and an implantable cardioverter defibrillator both provide continuous protection. An ICD is placed under the skin and in the veins, while a wearable defibrillator is worn under clothing. [1]
An automated external defibrillator requires someone nearby to recognize the abnormal rhythm, operate the AED and provide the shock. With a wearable defibrillator, a bystander is not required for the device to monitor the EKG or deliver treatment. [1]
An AED can be effective only when someone acts quickly after the event, while a wearable defibrillator can monitor continuously and typically deliver a treatment shock within one minute. It can protect someone who is alone or sleeping.
Feature | Wearable defibrillator | AED | ICD |
Location | Worn under clothing. | Kept nearby and used during an event. | Placed under the skin and in the veins. |
Monitoring | Continuously monitors the EKG while worn. | Does not continuously monitor a person. | Provides continuous protection. |
Bystander needed | No bystander is needed for monitoring or treatment. | Yes; someone must recognize the event and operate it. | No bystander is needed for the implanted device to treat. |
Use period | Often weeks or months; duration is individualized. | Used during an emergency event. | A more permanent implanted solution. |
Bathing | Removed for bathing. | Not worn. | Implanted. |
Fit and contact | Must fit well so electrodes touch the skin. | Pads must be positioned during use. | Implanted leads contact the heart. |
How long might someone wear one?
Many people wear a wearable defibrillator for a few weeks or months. People have also worn one for as long as about seven years. The treating team decides the duration based on the person's risk and treatment plan. [1]
Do not stop wearing the device or change the schedule because of an online article. Ask the healthcare provider when the device can be removed permanently, how much daily wear is expected and what to do while bathing.
Daily life with a wearable defibrillator
The garment is worn under clothing and the monitor is worn around the waist or from a shoulder strap. The device must fit well for the electrodes to maintain contact with the skin. [1]
The device is removed for bathing and the battery must be changed every day. You also need to be ready to respond to alarms at any time. [1]
Family members should understand how the device works. They should know that they must not touch the wearer during a shock and should ask the healthcare team questions if they are unsure about the device. [1]
Daily-life topic | Key point |
Clothing | Wear the lightweight garment under your clothes. |
Monitor | Wear it around the waist or from a shoulder strap. |
Skin contact | The device needs to fit well to contact the skin. |
Bathing | Remove it for a shower or bath. |
Battery | Change the battery every day. |
Alarms | Be ready to respond at any time. |
Family | Family should understand how the device works and how to care for it. |
Benefits, risks and limitations
Potential advantages include protection from sudden cardiac arrest while the device is worn, no need for help from someone nearby, a short-term solution until an ICD, and EKG recordings for the healthcare provider. [1]
The main limitation is that it does not work if you do not wear it. Other disadvantages include needing to respond to alarms at any time, removing it for bathing and changing the battery daily. [1]
People nearby may be injured if they touch you while you are receiving a shock. Make sure the people who live with you or spend time with you understand the warning and know not to touch you during a shock. [1]
Potential benefit | Limitation or safety consideration |
Protection while worn | It does not work if you do not wear it. |
Independent monitoring and treatment | You need to be ready to respond to alarms. |
Short-term protection | It may be temporary while another solution is planned. |
EKG recordings | It still requires follow-up with the healthcare team. |
Wearable design | It must fit correctly and be removed for bathing. |
External power | The battery must be changed every day. |
Automatic shock capability | People nearby must not touch you during a shock. |
Success rate: what clinical references report
Clinical reference material reports that researchers found a 99% success rate for treating ventricular tachycardia or ventricular fibrillation occurrences and that treatment usually took only one shock to correct an abnormal rhythm. This is a reported result, not a guarantee for an individual. [1]
A result from a study or summary cannot predict what will happen to a particular person. As the research above shows, results vary across studies, so ask the cardiology team how the device works in your situation and what to do after an alarm or shock.
When should I contact the healthcare provider?
Contact the healthcare provider if you awaken after receiving a shock, have questions about the device, or notice that it is not working normally or does not fit correctly. [1]
After a shock, follow the instructions from the treating team and contact the provider even if you feel well after waking. Waking after a shock is specifically listed as a reason to contact the provider.
If you think someone is experiencing a life-threatening emergency, follow the emergency instructions given by the treating team and local emergency services. This article cannot replace an individualized emergency plan.
Questions to ask before going home with a wearable defibrillator
Topic | Example question |
Purpose | What risk is the device addressing in my situation? |
Duration | How long should I wear it, and what would change that plan? |
Fit | How should the garment fit, and how do I know the electrodes are contacting my skin? |
Monitor | Where should I wear the monitor, and how should I secure it? |
Alarms | What exactly should I do if the device alarms while I am conscious? |
Family | How should family members respond, and when must they avoid touching me? |
Bathing | When can I remove the device for bathing, and how should I put it back on? |
Battery | How and when should I change the battery? |
Shock | Who should I contact if I wake up after a shock? |
Fit or function | Who should I call if the device is uncomfortable, loose, damaged or not working normally? |
Follow-up | When is my next appointment, and what EKG information will be reviewed? |
Long-term plan | What would lead to an ICD, transplant plan or stopping the wearable device? |
Conclusion: Understand how it works, how to wear it and when to call
A wearable defibrillator is an external garment-and-monitor system that continuously reads the EKG and can deliver a shock for certain life-threatening heart rhythms. It may protect people at risk of sudden cardiac arrest while they wait for an ICD, heart transplant or a decision about longer-term treatment. [1]
The device must be worn to work, fit well for electrode contact, be removed for bathing and be powered with a battery that is changed daily. If it detects ventricular tachycardia or ventricular fibrillation, it sounds alarms, checks for a response and may deliver a shock if the person does not respond. It differs from an AED, which requires a nearby operator, and from an ICD, which is implanted. [1]
Ask the cardiology team to explain why the wearable defibrillator is recommended, how to respond to alarms, what family members should know, how to manage bathing and batteries, how long it may be needed and who to contact after a shock or device problem.
Frequently Asked Questions
Is a wearable defibrillator the same as an ICD?
No. Both can provide continuous protection, but an ICD is placed under the skin and in the veins, while a wearable defibrillator is worn under clothing.
Is a wearable defibrillator the same as an AED?
No. An AED requires a nearby person to recognize the event, operate the device and provide treatment. A wearable defibrillator continuously monitors the EKG and can deliver a shock without a bystander.
Can a wearable defibrillator work while I sleep?
Yes. It can protect you when you are alone or sleeping because it continuously monitors the EKG and does not require a bystander.
What heart rhythms can it treat?
Clinical references discuss ventricular tachycardia and ventricular fibrillation. The device sounds an alarm and may deliver a shock if the dangerous rhythm continues and the wearer does not respond.
Can I stop the shock if I am awake?
If you are conscious, you have less than one minute to press two buttons to stop treatment. Follow the instructions provided by your treating team.
What happens if I do not respond to the alarm?
The device warns bystanders not to touch you and delivers a shock through the garment electrodes if the arrhythmia continues. Up to five treatment shocks may occur if the rhythm does not return to normal.
Do people feel the shock?
When you are unconscious, you will not feel the shock from the device.
How often do I change the battery?
The battery needs to be changed every day. Ask the device team for the exact battery routine and backup plan.
Can I bathe while wearing it?
No. The garment and monitor are removed for showering or bathing.
What if the vest does not fit correctly?
Contact the healthcare provider if the device does not fit right. Good fit matters because the electrodes need contact with the skin.
How long will I need to wear it?
Many people wear one for a few weeks or months, but people have worn one for about seven years. Duration is determined by the treating team.
What ejection fraction may lead to a wearable defibrillator?
A person may need one when ejection fraction is less than or equal to 35%, while normal ejection fraction is 55% to 70%. This is not an automatic treatment rule.
Why might someone use one after a heart attack?
A heart attack with reduced left-ventricular ejection fraction is one situation in which a wearable defibrillator may be an option.
Can children wear a wearable defibrillator?
Children and adults at risk for sudden cardiac arrest can wear a personal defibrillator. The cardiology team decides whether it is appropriate.
What happens after a shock?
Contact the healthcare provider if you awaken after receiving a shock. The provider can review what happened and advise on next steps.
What should my family know?
Family members should understand how the device works and know not to touch the wearer during a shock. Encourage them to ask the healthcare team questions.
What are the main disadvantages?
It does not work if you do not wear it, you must be ready to respond to alarms, you cannot wear it while bathing, the battery must be changed daily and people nearby may be injured if they touch you during a shock.
Does the device record heart information?
Keeping EKG recordings for the healthcare provider is listed as an advantage.
Related guides
Related Reading
Subcutaneous ICD (S-ICD): How It Works, Procedure and Recovery explains the subcutaneous ICD.
References
Cleveland Clinic. LifeVest. Cleveland Clinic. Last updated May 19, 2022. https://my.clevelandclinic.org/health/treatments/17173-lifevest
Olgin JE, Pletcher MJ, Vittinghoff E, et al. Wearable cardioverter-defibrillator after myocardial infarction. N Engl J Med. 2018;379(13):1205-1215. PMID 30280654. https://doi.org/10.1056/NEJMoa1800781
Masri A, Altibi AM, Erqou S, et al. Wearable cardioverter-defibrillator therapy for the prevention of sudden cardiac death: a systematic review and meta-analysis. JACC Clin Electrophysiol. 2019;5(2):152-161. PMID 30784684. https://doi.org/10.1016/j.jacep.2018.11.011
Disclaimer
This article is for general educational purposes and is not a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified healthcare professional with any questions about a medical condition or treatment.
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