56-62: Response to cardiac resynchronization: the impact of baseline autonomic nervous system function

Abstract

Background: Nonresponse to cardiac resynchronization therapy (CRT) occurs in around one third of the patients. Autonomic nervous system (ANS) dysfunction in heart failure (HF) contributes to its progression and confers a dismal prognosis. Purpose: We aim to evaluate the association of baseline ANS severity dysfunction in HF with CRT response. Methods: Consecutive patients submitted to CRT device implantation, in a terciary centre were included. Pre and 6 months post-CRT device implantation echocardiography was performed to assess left ventricular ejection fraction (LVEF) and left ventricle volumes. CRT response was defined as an absolute 5% increase in LVEF, from baseline. Pre-CRT 123-i-MIBG cardiac scintigraphy with determitation of heart to mediastinum ratio early (HMRe), heart to mediastinum ratio late (HMRl) and 24h Holter monitoring with evaluation of heart rate variability, were performed for the evaluation of ANS. Results: From 121 patients were included (68.6% males and mena age 68.4 ± 12.3 years old) 30.5% presented ischemic etiology and 74.3% were in NYHA class > III. Mean LVEF pre-CRT was 26.2 ± 7.1% and 70% were considered responders by echocardiography. Mean values obtained for the ANS variables were: HMRe 1.5 ± 0.2, HMRl 1.4 ± 0.2, SDNN 124 ± 68. Logistic regression demonstrated that HMRe (OR 15.1 95% CI 1.0-25.8, p = 0.05) and HMRl (OR 17.7 95% CI 1.2-26.2, p = 0.037) were independent predictors of CRT response by echocardiography. SDNN was not statistically associated with CRT response. Conclusion: Sympathetic innervation status in heart failure pre-CRT implantation, assessed by 123-i-MIBG cardiac scintigraphy, showed to be independently associated with CRT response. This finding might improve patients selection for resynchronization therapy.