Cardiac resynchronization therapy and cardiac sympathetic function
Cristian Martignani1, Igor Diemberger1, Cristina Nanni2
1Institute of Cardiology, University Hospital S. Orsola-Malpighi Bologna, University of Bologna, Bologna, Italy.
Insights
Cardiac resynchronization therapy (CRT) improves cardiac sympathetic nerve activity in heart failure responders. Non-responders show no significant changes, suggesting CRT is most effective when the neuroautonomic system is preserved.
Area of Science:
- Cardiology
- Nuclear Medicine
- Neuroscience
Background:
- Cardiac resynchronization therapy (CRT) improves outcomes in advanced heart failure but mechanisms remain unclear.
- Approximately one-third of patients do not benefit from CRT, highlighting the need to understand response predictors.
- Limited data exist on CRT's impact on sympatho-vagal function, a potential key mechanism.
Purpose of the Study:
- To investigate the effect of CRT on cardiac sympathetic nerve activity using (11)C-hydroxyephedrine positron emission tomography.
- To identify predictors of CRT response related to sympathetic nervous system function.
- To evaluate changes in cardiac sympathetic nerve activity at short and medium term after CRT.
Main Methods:
- Ten patients with dilated cardiomyopathy underwent clinical and echocardiographic assessment before and after CRT.
- (11)C-hydroxyephedrine positron emission tomography was used to evaluate cardiac sympathetic nerve activity.
- Patients were assessed acutely and at 3 months post-CRT.
Main Results:
- CRT responders demonstrated higher left ventricular radiotracer uptake at baseline and post-CRT compared to non-responders.
- Responders showed progressive improvement in the homogeneity of left ventricular tracer uptake.
- Non-responders did not exhibit significant changes in cardiac sympathetic nerve activity.
Conclusions:
- CRT enhances cardiac sympathetic nerve activity in responders, indicating improved sympathetic function.
- Non-responders to CRT do not show significant alterations in cardiac sympathetic nerve activity.
- CRT appears more effective in patients with a structurally preserved but functionally impaired neuroautonomic system.
Background:
Cardiac resynchronization therapy (CRT) is an established therapy for advanced congestive heart failure, improving both survival and hospitalization. The mechanism beneath these improvements still needs to be defined as about one-third of the patients do not benefit from resynchronization. Restoration of sympatho-vagal function can play a significant role in the process, but available data are limited. In this scenario, positron emission tomography scans with (11) C-hydroxyephedrine, a noradrenaline analogous, has the potential to characterize the modifications of the sympathetic nervous system induced by CRT in decompensated patients.
Materials And Methods:
Ten patients (six males, age 68 ± 10 years) with primary dilated cardiomyopathy were studied before and after resynchronization (acutely and after 3 months), from a clinical and echocardiographic point of view. Their cardiac sympathetic nerve activity was evaluated by (11) C-hydroxyephedrine positron emission tomography before resynchronization, at short and medium term after resynchronization.
Results:
Responders to CRT (patients showing ≥ 15% decrease in left ventricular end-systolic volume) showed a higher level of left ventricular radiotracer uptake both at baseline and after resynchronization with respect to nonresponders. This was coupled with a progressive improvement in homogeneity in left ventricular tracer uptake mainly in responders.
Conclusions:
Cardiac resynchronization therapy improves cardiac sympathetic nerve activity in responders since its activation, while nonresponders do not show any significant change at any time of evaluation. CRT seems to be more effective in those patients with a still structurally preserved, yet functionally impaired, neuroautonomic system.
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