Serial changes in cardiac sympathetic nervous function after transcatheter aortic valve replacement: A prospective observational study using 123I-meta-iodobenzylguanidine imaging

Purpose:Transcatheter aortic valve replacement (TAVR) can rapidly improve cardiac sympathetic nervous function (CSNF) within 2 weeks in patients with aortic stenosis (AS). However, it remains unclear whether such short-term improvements will be sustained thereafter. The present study aimed to investigate the mid-term (i.e., 6–12 months) effects of TAVR on CSNF in patients with severe AS using 123I-meta-iodobenzylguanidine (MIBG) imaging.Methods:Patients with severe AS who were scheduled to undergo TAVR between October 2017 and June 2019 were enrolled in this single-centre, prospective, observational study. MIBG imaging was performed at baseline, within 2 weeks after TAVR, and at 6–12 months post-TAVR to evaluate the heart–mediastinum ratio (H/M) and washout rate (WR). Differences between each MIBG parameter at three time points were analysed, and factors involved in the long-term improvement in the late H/M were investigated. Results:Of 183 consecutive patients, 75 (19 men; median age: 86 years) were evaluated. The late H/M significantly improved within 2 weeks after TAVR (P=0.041) and further improved over 6–12 months after TAVR (P=0.041). The WR rapidly improved immediately after TAVR (P=0.003) but remained unchanged at 6–12 months (P=0.827). Multivariate analysis revealed that the baseline mean aortic valve pressure gradient (mPG) was an independent predictor of mid-term improvement in the late H/M (>0.1) (adjusted odds ratio: 0.035; 95% confidence interval: 0.004–0.070; P=0.037). Patients with a high baseline mPG (≥58 mmHg) exhibited a significantly greater increase in the late H/M than those with a low baseline mPG (P=0.029).Conclusions:CSNF, as denoted by the late H/M, demonstrated sustained improvement from within 2 weeks after TAVR until 6–12 months later. Such improvement was related to baseline hemodynamic AS severity.