Prognostic significance of cardiac sympathetic innervation and contractility in heart failure patients submitted to cardiac resynchronization therapy
Authors: Mishkina A , Zavadovsky K.V , Saushkin V.V , Lebedev D.I , Lishmanov Y.U.B 
Published: November 2020

Abstract

Introduction
In chronic heart failure patients, cardiac resynchronization therapy (CRT) does not lead to the expected result in 30% of cases. There is a lack of prognostic data related to the cardiac sympathetic activity and contractility assessment in ischemic (IHF) and non-ischemic (CHF) heart failure patients.

Purpose
To assess the prognostic value of radionuclide cardiac sympathetic innervation and contractility assessment in IHF and NIHF patients submitted to CRT.

Methods
This study included 38 HF patients (24 male; mean age of 56±11 years), who were submitted to CRT: NYHA class II/III (n=10/28), mean QRS=159.3±17.9ms. The etiology of HF was ischemic in 16 patients and non-ischemic in 22 of them. Before CRT all patients underwent 123I-metaiodobenzylguanidine (123I-MIBG) imaging for cardiac sympathetic activity evaluating. The following indexes were estimated: early and delayed heart to mediastinum ratio (eH/M and dH/M), summed MIBG Score (eSMS and dSMS). Moreover all patients underwent gated myocardial perfusion scintigraphy with the assessments of LV dyssynchrony indexes: standard deviation (SD) and histogram bandwidth (HBW). In addition, all patients underwent gated blood-pool SPECT with both ventricles ejection fraction (EF) and stroke volume (SV) assessment.

Results
One year after CRT all patients were divided into two groups: responders (IHF group n=11; NIHF group n=15) and non-responders (IHF group n=5; NIHF group n=7). Among baseline scintigraphic parameters the following ones showed significant differences between responders vs. non-responders. In IHF patients - HBW: 162 (115.2–180) degree vs. 115.2 (79.2–136.8) degree, p&lt;0.05; RV_EF: 54.5 (41–56)% vs. 44.5 (37–49.5)%, p&lt;0.05; RV_SV: 80 (69–101)ml vs. 55.5 (50–72.5)ml, p&lt;0.05. In group of NIHF patients responders and non-responders were significantly differed in the following preoperative parameters: eH/M: 2.27 (2.02–2.41) vs. 1.64 (1.32–2.16), p&lt;0.05; dH/M: 2.18 (2.11–2.19) vs. 1.45 (1.23–1.61), p&lt;0.05; eSMS: 7 (5–7) vs. 15.5 (10–28.5), p&lt;0.05; dSMS: 10 (10–13) vs. 16.5 (15.5–29), p&lt;0.05, SD: 54.3 (43–58) degree vs. 65 (62–66) degree, p&lt;0.05; HBW: 179.5 (140–198) degree vs. 211 (208–213) degree, p&lt;0.05. Univariate logistic regression in IHF patients showed that LV dyssynchrony indexes – SD (OR=1.55; 95% CI 1.09–2.2; p&lt;0.5) and HBW (OR=1.13; 95% CI 1.02–1.24; p&lt;0.5), as well as RV indexes – RV_EF (OR=1.11; 95% CI 1.001–1.23; p&lt;0.5), RV_SV (OR=1.07; 95% CI 1.003–1.138; p&lt;0.5) were predictors of CRT response. In the group of NIHF patients, dH/M (OR=1.47; 95% CI 1.08–2; p&lt;0.5), SD (OR=0.83; 95% CI 0.73–0.95; p&lt;0.5), HBW (OR=0.96; 95% CI 0.93–0.99; p&lt;0.5) showed the predictive value in terms of CRT response.

Conclusion(s)
The positive response to CRT in IHF patients showed a link with LV dyssynchrony and preserved RV contractility. Whereas in NIHF patients the functional state of cardiac sympathetic activity, as well as LV dyssynchrony, were associated with CRT response.

Funding Acknowledgement
Type of funding source: Public grant(s) – National budget only. Main funding source(s): Russian Foundation for Basic Research