Heart with synchronized electrical impulses

CRT: Can This Heart Therapy Improve Your Long-Term Health?

Kai Mendoza in Health & Wellness June 2025 • 4 min read.

"Explore how cardiac resynchronization therapy (CRT) can help patients with heart failure, focusing on echocardiographic assessments and long-term outcomes."

Heart failure (HF) is a significant global health concern, affecting millions worldwide and leading to frequent hospitalizations. In Brazil alone, tens of thousands are admitted each year due to HF. A common issue among HF patients is intraventricular conduction disturbances, where electrical signals in the heart are not properly synchronized. This often leads to a condition called cardiac dyssynchrony, impairing the heart's ability to pump blood efficiently.

Cardiac resynchronization therapy (CRT) has emerged as a valuable treatment option for individuals with advanced heart failure. CRT involves implanting a device that helps to coordinate the contractions of the heart's ventricles, improving its overall function. Identifying which patients will benefit most from CRT has been a key focus of research, with echocardiography playing a crucial role in both patient selection and therapy assessment.

Echocardiography, a non-invasive imaging technique using ultrasound, allows doctors to visualize the heart's structure and function. It helps in determining the extent of dyssynchrony and assessing the impact of CRT on cardiac performance. A recent study investigated the use of echocardiography to evaluate CRT outcomes over a two-year period, providing insights into the therapy's effectiveness and potential predictors of success.

How Does Echocardiography Help Assess CRT Effectiveness?

Heart with synchronized electrical impulses

The study, published in the Arq Bras Cardiol in 2010, followed 20 patients who underwent CRT, with assessments conducted over two years. Researchers used echocardiography to evaluate various parameters, including the heart's ejection fraction (the percentage of blood pumped out with each contraction), the degree of intraventricular dyssynchrony, and overall heart function. Patients also completed questionnaires to assess their quality of life and underwent walking tests to measure their exercise capacity.

Key findings from the study revealed:

Mortality: 25% of patients (5 individuals) died during the two-year follow-up. A significant number of these deaths were linked to cardiomyopathy caused by Chagas' disease.
Ejection Fraction: While there was no immediate change in ejection fraction after CRT implantation, a significant improvement was observed two years later.
Intraventricular Dyssynchrony: An initial worsening of dyssynchrony was noted shortly after the procedure, but long-term assessments showed that tissue Doppler imaging could predict CRT efficiency in relation to death rate.
Quality of Life: Patients who died reported a higher score on the “Minnesota Living with Heart Failure Questionnaire,” indicating a poorer quality of life.

The study highlighted the importance of intraventricular dyssynchrony assessment using tissue Doppler imaging as a predictor of CRT success. While other echocardiographic parameters showed changes over time, only dyssynchrony assessment was directly linked to mortality rates. This suggests that closely monitoring and managing dyssynchrony is critical for optimizing CRT outcomes.

The Future of CRT Assessment

While this study provides valuable insights, the authors acknowledge limitations such as a small sample size and the absence of a control group. They also point out that more advanced echocardiography techniques, like three-dimensional imaging and strain analysis, could further enhance CRT evaluation. As technology evolves, these advanced methods may play a more significant role in optimizing patient selection and improving long-term outcomes for individuals undergoing cardiac resynchronization therapy.

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Everything You Need To Know

What exactly is Cardiac Resynchronization Therapy (CRT), and why is it used in heart failure?

Cardiac Resynchronization Therapy (CRT) is a treatment for advanced heart failure. It involves implanting a device to coordinate the contractions of the heart's ventricles. This synchronization aims to improve the heart's overall pumping efficiency, which is often impaired in individuals with intraventricular conduction disturbances leading to cardiac dyssynchrony. CRT doesn't cure heart failure, but it can alleviate symptoms and improve the patient's quality of life. Its significance lies in its ability to address the specific issue of uncoordinated heart contractions, a common problem in heart failure patients.

How does echocardiography play a role in determining if Cardiac Resynchronization Therapy (CRT) is working for a patient?

Echocardiography is a non-invasive imaging technique that uses ultrasound to visualize the heart's structure and function. It is crucial in assessing Cardiac Resynchronization Therapy (CRT) effectiveness by allowing doctors to determine the extent of dyssynchrony and evaluate the impact of CRT on cardiac performance. Echocardiography helps in selecting suitable candidates for CRT and monitoring the therapy's success by measuring parameters like ejection fraction and intraventricular dyssynchrony. Without echocardiography, it would be difficult to accurately assess the need for CRT or its impact on heart function.

What does intraventricular dyssynchrony mean, and why is it important to measure it in heart failure patients?

Intraventricular dyssynchrony refers to the uncoordinated electrical signals within the heart's ventricles, leading to inefficient pumping. This is significant because it impairs the heart's ability to pump blood effectively, contributing to the symptoms and progression of heart failure. Assessing intraventricular dyssynchrony, particularly using tissue Doppler imaging, is vital for predicting the success of Cardiac Resynchronization Therapy (CRT). Managing dyssynchrony is crucial for optimizing CRT outcomes and improving patient survival rates. The presence and severity of intraventricular dyssynchrony can greatly affect the long-term prognosis of heart failure patients.

What is ejection fraction, and why did the study show it may not be the best immediate indicator of Cardiac Resynchronization Therapy (CRT) success?

Ejection fraction is the percentage of blood that the heart pumps out with each contraction. While it is an important measurement, the study indicates that changes in ejection fraction might not be immediately apparent after Cardiac Resynchronization Therapy (CRT) implantation, with improvements potentially occurring over a longer period. More importantly, the degree of intraventricular dyssynchrony appears to be a more direct predictor of mortality rates than ejection fraction changes. This suggests that while ejection fraction is a valuable indicator of overall heart function, it may not be the most sensitive marker for evaluating the immediate impact of CRT.

Besides the therapy itself, what other factors can impact how well Cardiac Resynchronization Therapy (CRT) works for someone?

Several factors can influence the success of Cardiac Resynchronization Therapy (CRT). These include the presence of cardiomyopathy (particularly that caused by Chagas' disease), the degree of intraventricular dyssynchrony, and the patient's overall quality of life. Advanced echocardiography techniques, such as three-dimensional imaging and strain analysis, could further refine patient selection and therapy assessment. Addressing these factors and utilizing advanced assessment methods may improve long-term outcomes for individuals undergoing CRT. Future research should focus on these areas to optimize patient care.