Transcatheter Aortic Valve Implantation Improves Cardiac Sympathetic Nerve Activity on ¹²³I-Metaiodobenzylguanidine Myocardial Scintigraphy in Severe Aortic Valve Stenosis

Abstract

Background: There is a consensus that overactivation of the cardiac sympathetic nervous system (CSN) proportionately increases the severity of heart failure and is accompanied by worse prognosis. Because it is unknown whether patients with aortic valve stenosis (AS) have similar CSN activation, we investigated the effect of transcatheter aortic valve implantation (TAVI). Methods and Results:We enrolled 31 consecutive patients with AS treated by TAVI. 123 I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy was performed at baseline and at 2 weeks after TAVI. At baseline, the early heart-mediastinum ratio (H/M) was within normal limits (3.0±0.5), but the delayed H/M was low (2.6±0.6) and the washout rate (WR) was high (34±13%). WR negatively correlated with aortic valve area (r=−0.389, P<0.01) and cardiac output (r=−0.595, P<0.01) and positively correlated with norepinephrine (r=0.519, P<0.01) and log NT-proBNP level (r=0.613, P<0.01). After TAVI, there were significant decreases in the norepinephrine level (366±179 ng/mL vs. 276±125 ng/mL, P<0.01) and WR (34±13 vs. 26±11%, P<0.01). Conclusions:The WR of MIBG was a useful marker of CSN activity and severity of AS. Immediate improvement of CSN activity after TAVI implied that AS hemodynamics per se enhanced CSN.

Prognostic value of cardiac 123I‐metaiodobenzylguanidine imaging for predicting cardiac events after transcatheter aortic valve replacement

“…Recently, aortic valve stenosis (AS) has become one of the most important cardiac diseases causing HF among elderly patients 7 . In patients with AS, CSN overactivation associated with decreased cardiac index and increased left ventricular volume or left ventricular hypertrophy has been reported in previous studies 8–10 . Furthermore, prior studies 9,10 have suggested that transcatheter aortic valve replacement (TAVR), a less invasive treatment option for patients at intermediate or high operative risk, 11 can improve CSN function in patients with AS.…”

“…7 In patients with AS, CSN overactivation associated with decreased cardiac index and increased left ventricular volume or left ventricular hypertrophy has been reported in previous studies. [8][9][10] Furthermore, prior studies 9,10 have suggested that transcatheter aortic valve replacement (TAVR), a less invasive treatment option for patients at intermediate or high operative risk, 11 can improve CSN function in patients with AS. In our previous study, 10 we demonstrated that CSN function denoted by L-H/M, rapidly improved within 2 weeks after TAVR.…”

Impact of Prosthesis-Patient Mismatch After Transcatheter Aortic Valve Replacement on Changes in Cardiac Sympathetic Nervous Function

“…22) Several studies have demonstrated CSN overactivation among patients with AS due to various hemodynamic and mechanical changes such as pressure overload and LV hypertrophy. 4,12,23) Although Sobajima, et al and Kadoya, et al have reported the early effects of TAVR on CSN function using 123I-MIBG scintigraphy, 4,12) the impact of PPM after TAVR on changes in CSN function is not well established. Thus, we conducted the present study to address this gap in the knowledge.…”

“…Early and delayed H/M ratios were calculated by measuring the average counts in each region. 4,12) The washout rate (WR) was calculated using the following equation: [(H − M) early − (H − M) delayed/k] × 100/(H − M) early, with background subtraction and time decay correction (k = time decay coefficient). 4,12) Changes between pre-and post-procedural 123I-MIBG parameters were calculated using the following formulas: (1) ΔH/M ratio = (post-procedural H/M ratio) − (baseline H/M ratio) and (2) ΔWR = (baseline WR) − (postprocedural WR).…”

SPECT vs. PET in cardiac innervation imaging: clash of the titans

“…Apart from that, Sobajima et al demonstrated immediate improvement of SNS activity (assessed by 123 I-mIBG washout rate) after transcatheter aortic valve implantation (TAVI) in patients suffering from aortic valve stenosis. Hence, 123 I-mIBG might serve as a risk stratification tool or could also monitor the therapeutic efficacy of TAVI [ 30 ]. Moreover, 123 I-mIBG imaging has also been used to evaluate cardiac involvement in multiorgan diseases: On a small cohort of 5 patients, Yamamoto et al demonstrated that cardiac sympathetic nerve activity is reduced in subjects diagnosed with Anderson-Fabry Disease (AFD) [ 31 ].…”