Heart failure

Cardiac resynchronization therapy (CRT) and heart failure

Cardiac resynchronization therapy (CRT) is a treatment that helps restore a synchronized heart rhythm when your heart has weakened and is no longer beating in sync.

CRT involves the use of a pacemaker implanted in the chest.

Although CRT can be a life-saving therapy, it is not effective for everyone with heart failure or a heart rhythm disorder called arrhythmia.

This article will take a closer look at CRT, what it involves, its effectiveness, and potential risks.

A healthy heart beats at a rate that allows the upper chambers of the heart (atria) to fill with blood while the lower chambers (ventricles) pump blood to the body. Once the ventricles are empty, the atria fill them with blood and the process begins again.

Although the electrical system that keeps your heart going may seem tireless, it is nevertheless vulnerable to problems, especially when heart failure weakens the pumping force of the heart muscle.

CRT helps maintain the heartbeat with a healthier coordinated rhythm in a person with heart failure. Treatment involves the surgical implantation of a small, battery-powered CRT pacemaker in the chest.

The device also has thin, flexible wires (called leads) that extend into the heart muscle itself. The pacemaker sends electrical impulses through the leads and into the heart to stimulate the heart in a pattern that supports a strong, steady rhythm.

There are actually two main types of CRT pacemakers: CRT-P and CRT-D. Which one is right for you depends on the nature of your heart condition.


A CRT pacemaker (CRT-P) has two main functions. It delivers electrical impulses to overcome slow, weak heartbeats, and it sends separate signals to the right and left ventricles to ensure they contract simultaneously.

By doing so, the heart pumps blood to the lungs and the rest of the body more efficiently.


A CRT-D is a pacemaker that also acts as an automatic defibrillator, sending an electric shock to the heart if the device detects an abnormal rhythm. This abnormal rhythm could signal that the person may be in cardiac arrest.

A study 2022 looked at the use of CRT in people with reduced ejection fraction (HFrEF), a type of heart failure in which the left side of the heart does not pump enough blood to meet the body’s needs. According to this study, CRT-D is associated with a lower mortality risk, but it was not used as often in older people.

The results also suggest that CRT-D may be a better option than CRT-P for people with severe HFrEF.

A study 2017 suggests that heart failure puts people at a much higher risk of developing an arrhythmia and that CRT can effectively reduce their mortality risk.

When an arrhythmia develops in a person with heart failure, CRT is considered an appropriate treatment if other options, such as medications, are not able to maintain a healthy heart rhythm.

Some of the other benefits of CRT include:

  • improved quality of life
  • increased circulation throughout the body
  • lower mortality risk
  • reduction in symptoms of heart failure, such as dizziness and water retention

Depending on the general health of the person receiving a CRT device, the procedure may be performed on an outpatient basis or as part of a hospital stay. The process can take 2-5 hours.

In the hospital, you will be given medicine to help you relax or sleep, but general anesthesia is usually not necessary.

The doctor then makes a small incision in the chest just under the skin. The device and battery are placed in this “pocket” and then the leads (wires) are placed in the veins leading to the heart. When they are in the right place, the doctor attaches the wires to the CRT and tests to make sure everything is working properly.

The doctor will then close the incision. Once you are fully alert, you will receive instructions on living with CRT and any side effects or complications that may occur, as well as what to do if you notice any problems.

In addition to limiting strenuous activities for the first few weeks and keeping the incision clean while it heals, you should be able to follow your usual diet, work, and carry on with your daily activities.

CRT is most effective in people with heart failure when treatment is started earlier in disease progression.

Patients most likely to respond well to CRT generally have:

Also, CRT is not effective for everyone with heart failure. About 30 percent of patients with heart failure do not respond to CRT and, in some cases, patients may be considered “negative responders” and require deactivation of the device.

A study 2019 suggests that CRT was effective in keeping people alive and out of hospital with heart failure complications in about 50% of people younger than 75. And for people 75 or older, the 1-year survival rate was 47%.

In this same study, complications occurred in only 19% of people with heart failure and CRT pacemakers.

It should be noted that people with heart failure often have other health conditions that cannot be treated with CRT, such as kidney damage or liver disease. So, although the CRT can work effectively, a person with heart failure may still have to deal with several other health complications.

In general, surgery to implant a CRT pacemaker and subsequent therapy are safe and well tolerated.

But as with any medical procedure and long-term treatment, there are some risks associated with CRT, such as:

  • additional arrhythmias
  • bleeding
  • infection
  • mechanical difficulties with pacemaker or CRT leads
  • swelling in the area of ​​the chest housing the device

For people with heart failure and arrhythmia, cardiac resynchronization therapy (CRT) can be a life-saving treatment and improve daily life.

The therapy, which is usually prescribed after other treatment options have proven ineffective, can often relieve heart failure symptoms and prolong a person’s life.

The key, once you have a CRT pacemaker, is to keep up with your appointments with the cardiologist. This is important to ensure that the device is working properly and to spot signs that it may need to be replaced long before there are problems.