What Is Non-Sustained Ventricular Tachycardia (NSVT)?

Non-sustained ventricular tachycardia (NSVT, or non-sustained V-tach) is an abnormal heart rhythm (arrhythmia) that starts in the lower chambers of the heart (ventricles). NSVT is three or more consecutive heartbeats at a rate of more than 100 beats per minute (bpm) and lasts for less than 30 seconds.

An episode of NSVT can go away on its own, so it is not considered as dangerous as sustained ventricular tachycardia (SVT), which lasts more than 30 seconds. 

Non-sustained VT can be completely harmless in some people, but it’s still important to find out why you have NSVT.

You should also find out if you have risk factors that make you more likely to have NSVT, such as heart disease, electrolyte imbalances, drug use, and taking certain medications.

This article will go over the signs and symptoms of NSVT as well as how it’s diagnosed and treated. 

NSVT Symptoms and Signs

NSVT is an episode of ventricular tachycardia that:

• Involves a heart rate of more than 100 beats per minute
• Persists for at least three heartbeats
• Lasts less than 30 seconds

Most of the time, NSVT does not cause any symptoms. If it does, palpitations—feeling a fast or irregular heartbeat—can be the only symptom a person has of NSVT. The palpitations can also be associated with trouble breathing or chest pain.

Occasionally, NSVT can cause lightheadedness and/or dizziness. Rarely, loss of consciousness (fainting or syncope) may happen with NSVT.

When to Seek Medical Attention

NSVT can be harmless, but it can also be a sign of a more serious sustained ventricular arrhythmia and a risk for sudden death.

It's important to see your healthcare provider if you are having symptoms like:

• Fleeting chest pain
• Lightheadedness
• Heart racing (even if it comes and goes)

Call 911 or go to the ER if you are having:

• Trouble breathing
• Chest pain lasting more than a few minutes
• Chest pain along with other symptoms, like nausea, lightheadedness, and/or cold sweats
  

NSVT Risk Factors and Causes

NSVT can be related to a problem with the structure or function of the heart (which a person may not realize they have). 

NSVT can also be related to problems with the electrical signaling in the heart that helps it beat. 

These problems can lead to more dangerous arrhythmias, such as ventricular fibrillation. This is when the heart stops beating as it should and starts to quiver instead, causing a person to go into cardiac arrest.

It’s not always easy or possible to change structural or electrical heart problems. However, some risk factors for NSVT are things that you can change. 

Structural Heart Disease

The kinds of heart disease most commonly associated with NSVT are:

• Coronary artery disease (CAD). When the blood vessels that supply your heart are narrowed or blocked, which may lead to a heart attack
• Dilated cardiomyopathy heart failure. When your heart chambers get too big and cannot pump blood properly

NSVT is also seen with:

• Hypertrophic cardiomyopathy. An abnormally thick heart muscle
• Heart valve disease (especially aortic stenosis and mitral regurgitation). When one or more of your four heart valves malfunctions

Electrical Instability

NSVT can be caused by an electrical problem in the heart rather than a structural problem.

The most common is repetitive monomorphic ventricular tachycardia (RMVT).

RMVT is a disorder that almost only occurs in young to middle-aged people who do not have structural heart disease.

Common symptoms of RMVT include palpitations and lightheadedness. In this condition, an NSVT episode tends to be triggered by emotional stress or exercise.

Reversible Risk Factors

Many factors that trigger NSVT are things you can take steps to fix, including:

• Electrolyte imbalances (e.g., low potassium or low magnesium levels in the blood)
• Substance use (e.g., cocaine and methamphetamines)
• Low oxygen level in the bloodstream (hypoxia)
  
• A low number of healthy red blood cells in the bloodstream (anemia)
• Certain non-heart conditions (e.g., thyroid disease)
  

How Is It Diagnosed?

NSVT usually does not cause symptoms and is instead found during an electrocardiogram (ECG) that’s being done for another reason. 

If a person is having symptoms, NSVT might be diagnosed during an ambulatory ECG monitoring system.

Heart Rhythm Monitoring

Ambulatory ECG systems record the electrical activity of your heart over days, weeks, or even years. This longer monitoring period allows for heart arrhythmias that may come and go, like NSVT, to be seen and recorded.

A provider who specializes in heart conditions (cardiologist) will look at the recordings from the ambulatory ECG system to see if NSVT or another arrhythmia is on them. 

A Holter monitor is a type of ambulatory ECG system. It is a lightweight and portable monitor that is connected by wires to small discs called electrodes that are taped to your chest. 

The Holter monitor is typically worn for 24 to 48 hours or longer and records your heart rhythm continuously.

Additional Testing

If NSVT is diagnosed, your provider will do more testing to figure out if there are any reversible risk factors you could work on. 

Your provider can do a medical history/physical exam, blood tests like a basic metabolic panel, complete blood count, or thyroid-stimulating hormone (TSH).

Your provider will also check you for any underlying heart problems or diseases. Tests they can use include:

• Exercise stress test
• Echocardiography
• Cardiac magnetic resonance imaging (MRI)
• Coronary angiography

If the results from one or more of these tests show that you have heart disease (such as coronary artery disease), your treatment will be focused on that condition.

If no heart disease is found, you might need to see a heart rhythm specialist (cardiac electrophysiologist) to check if you have RMVT and other conditions.

Non-Sustained VT vs. Sustained VT

Your provider will also check to see if you have NSVT or SVT. The usual way to tell is by looking at how long the arrhythmia lasts.

NSVT Treatment

NSVT does not always need to be treated. If it does, managing NSVT will depend on the underlying cause of the arrhythmia and whether you have symptoms.

If you have no heart disease and no symptoms, no treatment is needed other than following up with your provider routinely or letting them know if anything changes with your health. 

NSVT in people with a healthy heart is usually considered harmless and not something that needs treatment.

Medications

If you do get symptoms from NSVT, medications might be able to help—for example, beta-blockers, calcium channel blockers, or Pacerone (amiodarone).

Amiodarone works to keep your heart in a regular rhythm (an antiarrhythmic drug).

Tambocor (flecainide) and Betapace (sotalol) are also antiarrhythmic drugs, but they are not usually recommended to treat NSVT (especially if the NSVT happens because of a heart attack).

Antiarrhythmic drugs can be used in certain cases when a person has severe symptoms and is under the care of an electrophysiologist.

Ablation Therapy

For people with severe symptoms or people who cannot tolerate or are not being helped b anti-arrhythmic drugs, ablation therapy might be an option. This treatment uses heat or cold energy to destroy the part of the heart that is thought to be the source of abnormal electrical signals.

Ablation therapy is successful at treating NSVT around 80% of the time.

Implantable Cardioverter-Defibrillator

NSVT poses an increased risk of cardiac arrest and sudden death if it occurs with coronary artery disease or heart failure—especially in people with hypertrophic cardiomyopathy.

With these conditions, the risk is from the reduced flow of blood from the left ventricle (ejection fraction) more than from NSVT. To reduce the risk, an implantable cardioverter-defibrillator (ICD) might be recommended.

An ICD is a battery-operated device that is put under the skin on your chest. It monitors the rhythm of your heart and delivers mild electrical currents or shocks if the rhythm becomes abnormal.

Prevention

NSVT cannot be prevented, but some heart conditions that cause it can be. You can also take steps to reduce your risk factors for NSVT.

To optimize your heart health and lower the risk for NSVT, you can make some lifestyle changes:

• Get at least 150 minutes per week of moderate-intensity physical activity (e.g., brisk walking) or 75 minutes per week of vigorous-intensity physical activity (e.g., running)
• Eat a nutritious diet that’s rich in fruits, vegetables, nuts, whole grains, lean protein, and fish
• Limit your intake of dietary trans fats, red meat, processed meats, refined carbohydrates (e.g., pasta and white rice), and sugary drinks
• Achieve and maintain a weight that supports your health
• Quit tobacco use and avoid exposure to secondhand smoke
• See your provider for regular check-ups to see if you have any heart health risk factors like high blood pressure, high cholesterol, and type 2 diabetes
  

Arrhythmias Healthcare Provider Discussion Guide

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Summary

Non-sustained ventricular tachycardia (NSVT) is a kind of heart arrhythmia that usually stops within 30 seconds. In most people, it doesn’t cause any symptoms and is often harmless. In some people, it can develop into a more serious kind of heart problem. 

NSVT may happen in healthy people or people with serious heart disease. It can be diagnosed with special tests to check the heart’s functioning. People with NSVT that do not have any symptoms may not need any treatment. People with heart disease or severe symptoms can be treated with procedures and medications. 

While NVST can’t necessarily be prevented, lifestyle changes that support heart health can be helpful. If you or a loved one is diagnosed with NSVT, see a cardiologist for an assessment.