Cardiac sympathetic activity and relationship to cardiac events and left ventricular reverse remodeling in patients with non-ischemic dilated cardiomyopathy

Background: Delayed heart-to-mediastinum ratio (HMR) has been associated with catecholamine levels and contractile reserve in dilated cardiomyopathy (DCM); however, there is scant evidence regarding the association between cardiac sympathetic activity and left ventricular reverse remodeling (LV-RR). We calculated the ¹²³I-metaiodobenzylguanidine (¹²³I-mIBG) HMR and washout rate (WR) in patients with DCM and investigated their associations with LV-RR. Methods: From April 2003 to January 2020, in 120 patients with DCM who underwent ¹²³I-mIBG scintigraphy. 66 patients undergoing follow-up echo and taking a beta-blocker from baseline were examined the relationship between ¹²³I-mIBG and LV-RR. After that, this prognostic value for composite cardiac events was evaluated in the entire 120 patients. Results: In LV-RR analysis, patients were 50.4 ± 12.2 years, with a mean left ventricular ejection fraction of 28.6%. Of 66 patients, 28 (42.4%) achieved LV-RR. Multiple logistic regression analysis of LV-RR revealed that not delayed HMR but the WR (cutoff value: 13.5%) was an independent predictor of LV-RR (odds ratio 6.514, p = 0.002). In the analysis for composite cardiac events, even though WR itself does not have the prognostic capacity, Kaplan–Meier survival curves divided by the cutoff value (delayed HMR = 2.0, WR = 13.5) showed that delayed HMR and WR values enabled the stratification of high-risk patients (log-rank p < 0.001). Conclusions: The ¹²³I-mIBG WR was associated with the prevalence of LV-RR in patients taking 100% of beta-blockers and 98.5% of renin-angiotensin system inhibitors. Reflecting the contractile reserve, the combined assessment of the delayed HMR and WR could be used to further precisely stratify the patients with DCM.