June 2, 2015Open Access
View Full PaperCardiac resynchronization therapy and cardiac sympathetic function
Key Result
Cardiac resynchronization therapy improved cardiac sympathetic nerve activity in responders (≥15% decrease in left ventricular end-systolic volume), while nonresponders showed no significant change.
Study Design
Type
Observational (n=10)
Structured PICO
Does cardiac resynchronization therapy improve cardiac sympathetic nerve activity in patients with primary dilated cardiomyopathy?
P
Population
10 patients (mean age 68 years, 40% female) with primary dilated cardiomyopathy evaluated before and up to 3 months after cardiac resynchronization therapy.
E
Exposure
Cardiac resynchronization therapy (CRT)
C
Comparator
Baseline (pre-resynchronization) and nonresponders to CRT
O
Outcome
Cardiac sympathetic nerve activity evaluated by (11)C-hydroxyephedrine positron emission tomography (radiotracer uptake and homogeneity)surrogate
CRT improves cardiac sympathetic nerve activity in responders, suggesting the therapy is more effective in patients with a structurally preserved but functionally impaired neuroautonomic system.
Abstract
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.