Impact of visceral adipose tissue on mortality in patients undergoing transcatheter aortic valve implantation
Authors: Somaschini A , Casirati A , Olivotti L , Cornara S , Giachello V , Astuti M , Ghione M , Botta M , Buscemi M , Caccialanza R , Bellone P , Cordone S 
Published: November 2023

Abstract

Background
Computed tomography (CT) is a recognized method to assess body composition. The analysis of CT-scans at third lumbar vertebra level (L3-CT) allows to detect sarcopenia, which plays a negative prognostic role in patients undergoing Transcatheter Aortic Valve Implantation (TAVI). Conversely, the effect of visceral adipose tissue (VAT), a pro-inflammatory and metabolically active organ associated with unfavorable cardiovascular outcomes, is still poorly explored.

Purpose
We investigated the association between preoperative VAT and 30-days and 1-year mortality in patients undergoing TAVI.

Methods
Anamnestic, laboratory and clinical data of patients who underwent TAVI in 2010-2020 were collected. Preoperative CT were analyzed to measure VAT area (cm2), normalized for stature obtaining VAT index (VATi, cm2/m2). The sample was classified according to VATi values into two groups: low VATi [1st quartile] vs. high VATi [2nd to 4th quartiles]. The two groups were compared by T-test for continuous variables (expressed as mean ± SD) and Chi-square test for categorical variables (expressed as%). Mortality analyses were performed through Kaplan-Meier curves with log rank test. To address for potential confounding factors a propensity score (1:1 matching)based on STS mortality score and Euroscore II values was calculated in order to create two comparable groups.

Results
We enrolled 168 patients (45.8%males), 150 of whom had CT images available. Mean value of VATi was 58.6±37.2cm2/m2(range1.7-172.3). Patients with higher VATi presented higher levels of glycemia (124±40vs111±23mg/dl,p=0.021), HbA1c (6±0.8vs.5.6± 0.5%,p=0.001) and neutrophils (5.4±2.7vs4.5±1.8x103/µl,p=0.028). No differences were found between the two groups in terms of age, CKD (GFR&lt;30ml/min), previous stroke/myocardial infarction/ surgical or percutaneous revascularization, intra-hospital complications and presence of comorbidities such as cancer, atrial fibrillation, diabetes, and COPD. Overall, 1-year and 30-days mortality were 16.1%and5.4%, respectively. High VATi group [range25.9-172.3cm2/m2] presented higher 1-year mortality (19.5%vs5.4%,OR= 4.2, p=0.046) as compared with low VATi group [range 1.7-25.7cm2/m2], while no significant differences were found in 30-days mortality (6.2%vs2.7%,p=0.421); survival curves are shown in Fig.1A and 1B. After propensity score creation, 37 pairs of patients were successfully matched; in the matched population, high VATi was significantly associated with a higher 1-year mortality (21.6%vs5.5%, p=0.041,Fig.2).

Conclusions
High levels of VATi are independently associated with a four-fold increased risk of 1-year mortality in patients treated by TAVI, possibly mediated by enhanced inflammatory status and augmented incidence of metabolic complications related with abundant abdominal VAT. Adding VAT evaluation to the scores currently used in clinical practice could help to optimize pre-operative risk stratification in patients undergoing TAVI.