SPC365

Computed Tomography-derived myocardial extracellular volume in patients with severe aortic stenosis: correlation with markers of ventricular dysfunction

Session: Comunicações Orais - Sessão 24 - Tomografia Computorizada Cardíaca
Speaker: Pedro M. Lopes

Congress: CPC 2023
Topic: B. Imaging
Theme: 03. Imaging
Subtheme: 03.2 Computed Tomography
Session Type: Comunicações Orais
FP Number: ---
Authors: Pedro M. Lopes; Rita Reis Santos; Francisco Albuquerque; Pedro Freitas; Cláudia Silva; Sara Guerreiro; João Abecasis; Ana Coutinho Santos; Carla Saraiva; Miguel Mendes; António M. Ferreira

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong>Background: </strong>Myocardial fibrosis is a potential adverse prognostic marker in patients with severe aortic stenosis (AS) and can be quantified using non-invasive imaging measures, such as the extracellular volume fraction (ECV). Although computed tomography (CT) for transcatheter aortic valve replacement (TAVR) planning was originally developed to assess the aortic valve complex and access routes, it has evolved to include the measurement of ECV for myocardial tissue characterization. </span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong>Aim:</strong> This study aimed to determine associations between CT-derived ECV (ECV<sub><span style="color:#222222">C</span>T</sub>) and clinical and echocardiographic markers of ventricular function in patients with severe AS referred for TAVR-planning CT.</span></span></p>

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<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong>Methods: </strong>Single-center prospective study enrolling all consecutive patients with severe symptomatic AS referred for TAVR-planning CT between April and November 2022. CT was performed on a 192-slice dual-source 3<sup>rd</sup> generation scanner (Siemens Somatom Force) and ECV<sub><span style="color:#222222">C</span>T</sub> was acquired during TAVR-planning using an additional 5-minute post-contrast low-radiation-dose prospective acquisition. ECV<sub><span style="color:#222222">C</span>T</sub> was calculated as the ratio of change in CT attenuation (Hounsfield units [HU]) of the septal myocardium and the left ventricle (LV) blood pool before and after contrast administration, according to the equation: ECV<sub>CT</sub> = (1 &ndash; hematocrit) x (<span style="font-family:Symbol">D</span>HU<sub>myo</sub>/<span style="font-family:Symbol">D</span>HU<sub>blood</sub>) &ndash; <strong><span style="color:#0070c0">Figure 1A</span></strong>. </span></span></p>

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<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong><span style="color:black">Results:</span></strong><span style="color:black"> A total of 102 patients were included (</span><span style="color:#222222">mean </span><span style="color:black">age&nbsp;81 &plusmn; 7 years; 46% male</span><span style="color:#222222">; mean valvular transaortic </span><span style="color:black">gradient 51 &plusmn; 14 mmHg</span><span style="color:#222222">; mean aortic valve </span><span style="color:black">area 0.7 &plusmn; 0.2 cm<sup>2</sup></span><span style="color:#222222">; mean LV ejection fraction (EF) by 2D echocardiogram </span><span style="color:black">57 &plusmn; 11%). No patient had a clinical diagnosis of cardiac amyloidosis. </span><span style="color:#222222">Overall, the mean ECV<sub>C</sub></span><sub>T </sub>value was 33.<span style="color:black">4 &plusmn; 7.0%. Myocardial ECV</span><sub><span style="color:#222222">C</span>T</sub><span style="color:black"> values significantly differed between </span><span style="color:#222222">AS subtypes, with higher values in patients with low-gradient AS (n=13, 13%; ECV<sub>C</sub></span><sub>T</sub><span style="color:black"> 40.3 &plusmn; 4.8% vs </span><span style="color:#222222">32.4 </span><span style="color:black">&plusmn; 6.7%, p&lt;0.001</span><span style="color:#222222">) - </span><strong><span style="color:#0070c0">Figure 1B</span></strong><span style="color:#222222">. Additionally, myocardial </span><span style="color:black">ECV</span><sub><span style="color:#222222">C</span>T</sub><span style="color:black"> values correlated with markers of LV and right ventricular (RV) dysfunction, including lower LV EF (r = -0.354, p&lt;0.001), worse LV global longitudinal strain (r = 0.420, p=0.002), reduced TAPSE (r = -0.230, p=0.043) and RV S wave by tissue doppler imaging (r = -0.321, p=0.010) and higher NT-proBNP values (r = 0.347, p=0.002).</span></span></span></p>

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<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong><span style="color:black">Conclusions: </span></strong><span style="color:black">In patients with severe AS scheduled for TAVR-planning CT, ECV</span><sub>CT </sub>values<sub> </sub>are significantly higher in those with low-gradient AS and correlated with several measures of biventricular dysfunction. This CT parameter may be useful to identify a subgroup of patients with higher risk of adverse prognosis.</span></span></p>