Impact of an exercise training program on cardiac neuronal function in heart failure patients on optimal medical therapy : A randomized Iodine-123 metaiodobenzylguanidine scintigraphy study

Abstract

Background: The syndrome of heart failure (HF) is characterized by left ventricular dysfunction and a compensatory chronic over activation of the sympathetic nervous system. We wanted to investigate if the beneficial effects of exercise training (ET) in HF patients on optimal medical therapy (OMT) are associated with alterations in cardiac sympathetic activity.

Methods: Cardiac sympathetic activity was evaluated at baseline and after 12 weeks using metaiodobenzylguanidine scintigraphy in 23 patients with stable HF participating in the SmartEx trial. Patients with HF in New York Heart Association class II or III and left ventricular ejection fraction <35 % were randomized to three different ET groups.

Results: We found no statistically significant changes in cardiac sympathetic activity after 12 weeks of ET. Heart to mediastinum (H/M) ratio at 15 minutes (0.00174 ± 0.0841, P = 0.922), H/M ratio at 4 hours (-0.00565 ± 0.1163, P = 0.818) and washout ratio (WR) (-1.2666 ± 16.5412, P = 0.717). A further group-wise analysis of the three ET groups did not show any difference between the groups.

Conclusion: A 12-week ET program did not alter the abnormal cardiac sympathetic activity in stable HF patients on modern OMT.

Trial registration: ClinicalTrials.gov NCT00917046.

Keywords: Exercise; heart failure; nervous system; norepinephrine; nuclear medicine; sympathetic.