Relationship between impaired cardiac sympathetic activity and spatial dyssynchrony in patients with non-ischemic heart failure: Assessment by MIBG scintigraphy and tagged MRI

Background: Impairment of cardiac sympathetic activity has various detrimental effects on cardiac function. The purpose was to investigate the relationship between left ventricular (LV) dyssynchrony and cardiac sympathetic activity in non-ischemic heart failure (HF). Methods: Twenty-seven patients with non-ischemic HF were enrolled. Cardiac sympathetic activity was assessed by heart-to-mediastinum ratio (H/M ratio) on ¹²³I- Metaiodobenzylguanidine scintigraphy. LV dyssynchrony was assessed by cross-correlation analysis of time curves of myocardial circumferential strains delivered from cine-tagging MR images. Temporal dyssynchrony was defined as contraction delay between septal and lateral segments >110 milliseconds. Spatial dyssynchrony was defined as the negative value of the maximum correlation for the two strain time curves. Results: H/M ratio was significantly lower for patients with spatial dyssynchrony compared to patients without (1.8 ± 0.3 vs 2.1 ± 0.3, P <.05). There was no difference between patients with and without temporal dyssynchrony (2.0 ± 0.2 vs 2.0 ± 0.3). The incidence of spatial dyssynchrony was significantly higher in patients with H/M ratio <2.0 than those whose ratios were ≥2.0 (75% vs 20%, P =.001). There was no difference in the incidence of temporal dyssynchrony between the two groups (17% vs 20%). Conclusion: Impairment of cardiac sympathetic activity was found to be associated with spatial dyssynchrony in patients with non-ischemic HF.