Imaging predictive factors and exercise training in CRT patients
Ana Abreu1, Helena Santa Clara
1Hospital Santa Marta. ananabreu@hotmail.com.
Insights
Predicting cardiac resynchronization therapy (CRT) response in heart failure patients is crucial. Advanced imaging techniques like CMR and nuclear imaging show promise in identifying non-responders and optimizing CRT benefits.
Area of Science:
- Cardiology
- Medical Imaging
- Heart Failure Management
Background:
- Cardiac resynchronization therapy (CRT) benefits patients with chronic heart failure (CHF) and conduction delays, improving function and survival.
- A significant portion (30-40%) of CRT patients are non-responders, lacking clinical or echocardiographic improvement.
- Identifying predictors of CRT response is essential for patient selection and treatment optimization.
Purpose of the Study:
- To review imaging parameters for predicting CRT response in heart failure patients.
- To evaluate the role of cardiac magnetic resonance (CMR) and nuclear imaging (SPECT, PET) in assessing scar burden and mechanical dyssynchrony.
- To explore the potential of exercise training (ExT) in enhancing CRT benefits.
Main Methods:
- Review of existing literature on imaging techniques for CRT response prediction.
- Assessment of cardiac magnetic resonance (CMR) for scar quantification and mechanical dyssynchrony.
- Evaluation of nuclear imaging (SPECT, PET) for scar burden, LV function, and dyssynchrony analysis.
Main Results:
- CMR-derived measures of mechanical dyssynchrony show potential in predicting CRT outcomes but require external validation.
- Nuclear imaging (SPECT) provides data on scar, LV function, and dyssynchrony, though spatial resolution may impact scar extent accuracy.
- Positron emission tomography (PET) may overcome spatial resolution limitations of SPECT.
- Myocardial scar characteristics influence CRT response.
- Exercise training (ExT) may further enhance CRT benefits, with varying aerobic exercise modes and intensities showing potential.
Conclusions:
- Imaging investigations are crucial for better identification of CRT non-responders.
- CMR and nuclear imaging techniques offer valuable insights into factors affecting CRT response.
- Further research is needed to validate imaging parameters and investigate the combined effects of CRT and exercise training.
Abstract:
Cardiac resynchronization therapy (CRT) is an established treatment for patients with moderate-to-severe chronic heart failure (CHF) and intraventricular conduction delay, which is identified by a QRS interval of 120msec or more on a 12-lead electrocardiogram (ECG). CRT improved functional capacity, reduced hospitalizations for worsening CHF and increased survival. However, about 30-40% of patients who underwent CRT were non-responders with no clinical or echocardiographic improvement. Imaging parameters for prediction of CRT response have been reviewed. Cardiac magnetic resonance (CMR), recognized as the gold standard to assess viability, has shown to obtain good results regarding quantification of scar burden. CMR-derived measures of mechanical dyssynchrony appear to predict the outcome of CRT, however they have not been externally validated. Nuclear imaging techniques, namely single-photon emission cardiac tomography (SPECT) provide data on scar burden and location, left ventricular (LV) function, LV contraction and mechanical dyssynchrony from a single scan. The presence, location and burden of myocardial scar have been shown to affect response to CRT. However, compared to CMR, the low spatial resolution of scintigraphy might overestimate the scar extent. This problem can be overcome by positron emission tomography (PET). SPECT has also been used to quantify dyssynchrony, using phase analysis. Imaging investigation is ongoing, trying to better identifying CRT non-responders. The combination of ExT in CRT has not been well investigated; however some data show different aerobic exercise modes and intensities can further improve CRT benefits. Data available on the effects of ExT in patients with CRT have been reviewed.
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