Cardiac Resynchronization Therapy

Cardiac resynchronization therapy, or CRT, is a device-based treatment used in selected people with heart failure when the heart’s chambers are not beating in a coordinated way. By improving electrical synchrony, CRT may help symptoms, function, and outcomes in the right patient group.

What is CRT?

CRT is a form of pacing therapy in which a specialized device stimulates the heart in a coordinated way to improve the timing of contraction between the ventricles. It is often referred to as biventricular pacing. The goal is not simply to prevent a slow pulse, but to improve inefficient pumping caused by electrical dyssynchrony in certain forms of heart failure. ^[1][2][3]

In whom is it considered?

CRT is considered in selected patients with heart failure, reduced ejection fraction, persistent symptoms despite guideline-directed medical therapy, and specific ECG features such as a widened QRS complex—especially certain left bundle branch block patterns. It is not intended for every person with heart failure. ^[1][3][4]

How is evaluation done before implantation?

Before implantation, clinicians assess the severity of heart failure, medications already in use, ECG pattern, echocardiography findings, kidney function, other comorbidities, and whether the patient may also need defibrillator capability. Optimized medical therapy remains a core part of treatment even when a device is being considered. ^[1][2][4]

How is the CRT device implanted?

Implantation is usually similar in general concept to pacemaker placement. Leads are positioned to stimulate the right atrium or right ventricle as needed and, importantly, the left ventricle via the coronary sinus system or another strategy depending on anatomy. The generator is placed under the skin. ^[2][3][5]

What benefits can be expected?

In appropriate patients, CRT may reduce symptoms, improve exercise tolerance, enhance quality of life, reduce hospitalization risk, and in some cases improve survival. It may also improve heart pumping efficiency over time. The benefit is strongest when the patient selection criteria are appropriate. ^[1][3][4]

What are the risks and complications?

Risks include bleeding, infection, lead displacement, pneumothorax in some cases, vascular complications, device malfunction, and the possibility that a patient may not respond as much as hoped. Not every implanted patient becomes a “CRT responder.” ^[2][4][5]

How is follow-up done?

Follow-up includes wound checks, device interrogation, battery and lead review, rhythm assessment, and continued heart failure management. Device therapy does not replace guideline-based medication, lifestyle measures, and broader clinical care. ^[1][3][5]

When is urgent evaluation needed?

Urgent review is needed for fever, redness or drainage at the device site, worsening shortness of breath, fainting, severe palpitations, chest pain, or swelling and pain suggesting a vascular complication. ^[2][4][5]

How should lifestyle and expectations be managed after CRT?

Patients should understand that recovery and benefit may take time and that the device is part of a broader heart failure treatment strategy. Activity guidance, medication adherence, salt and fluid recommendations when relevant, and regular follow-up remain essential. The aim is coordinated care, not reliance on the device alone. ^[1][3][4]

This content is intended for general information only. Device decisions require individualized cardiology evaluation.