SPC365

Left ventricular mechanics in patients with left bundle branch block assessed by cardic magnetic resonance – influence of etiology and presence of fibrosis

Session: Posters (Sessão 6 - Écran 1) - Imagem 3 - RM Cardíaca e Cardiologia Nuclear
Speaker: Mariana da Silva Santos

Congress: CPC 2022
Topic: B. Imaging
Theme: 03. Imaging
Subtheme: 03.3 Cardiac Magnetic Resonance
Session Type: Pósters Electrónicos
FP Number: ---
Authors: Mariana da Silva Santos; Marina Santos; Sara Guerreiro; Daniel Gomes; Bruno Rocha; Gonçalo Cunha; Pedro Freitas; João Abecasis; Ana Santos; Carla Saraiva; Miguel Mendes; António Ferreira

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong>Introduction</strong>: Cardiovascular magnetic resonance (CMR) is the gold standard to evaluate myocardial structure and function, and recent advances have allowed the assessment of myocardial deformation by feature tracking CMR (FT-CMR). Our aim is to evaluate the impact of left bundle branch block (LBBB) on left ventricle (LV) function and mechanics as measured by FT-CMR in patients with non-ischemic cardiomyopathy (NICM) vs. ischemic cardiomyopathy (ICM).</span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong>Methods</strong>: Single center registry including LBBB pts referred to CMR to assess structural cause of LV dysfunction from 2015 to 2021. LBBB was defined according to Strauss criteria <span style="background-color:white"><span style="color:black">as strict LBBB and non-strict LBBB</span></span><span style="background-color:white"><span style="color:black">. </span></span><span style="background-color:white"><span style="color:#232323">Myocardial mechanics including longitudinal (GLS), circumferential (GCS) and radial (GRS) global strain were assessed using a </span></span><span style="background-color:white"><span style="color:#333333">semi-automated FT-CMR </span></span><span style="background-color:#fcfcfc"><span style="color:#333333">(Circle CVI42&reg;). </span></span>Late gadolinium enhancement (LGE)<span style="background-color:#fcfcfc"><span style="color:#333333"> pattern was used to distinguish ICM and NICM (NICM-LGE). Patients with no LGE </span></span>were classified as having isolated LBBB-related septal dyssynchrony (LBBB-SD).</span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong>Results</strong>: We included 104 LBBB patients (53% male; mean age 66&plusmn;12 years; mean QRS 153&plusmn;18ms and mean LV ejection fraction (LVEF) was 35&plusmn;12%). <span style="background-color:white"><span style="color:#212121">Compared with NICM, those with ICM were more often male (73.1% vs 46.2%, p = 0.015), and had lower LVEF (31&plusmn;8% vs 36&plusmn;12%, p=0.023), lower </span></span>absolute global strain values (p=0.012 for GLS, p=0.007 for GCS and p=0.003 for GRS), and shorter septal-lateral delay (183<span style="background-color:white"><span style="color:black">&plusmn;109 vs 241&plusmn;108ms, p=0.021). </span></span><span style="background-color:white"><span style="color:#212121">Among </span></span>LBBB-SD patients, all myocardial strain components were significantly less impaired in comparison with ICM patients (GLS: -9.5&plusmn;3.1 vs -7.0&plusmn;3.2, p=0.007; GRS: 17.1&plusmn;6.8 vs 11.8&plusmn;4.1, p=0.004; GCS: -11.7&plusmn;3.5 vs -8.7&plusmn;2.5, p=0.003) but this difference was not detected between NICM-LGE and ICM. Furthermore, in LBBB-SD group, LV dimensions were smaller and LVEF higher than NICM-LGE - <strong>Table</strong>.</span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">LGE was found in 53% of patients and all types of global strain values were lower in this group <span style="background-color:white"><span style="color:#212121">(p&lt;0.05 for all).</span></span> <span style="background-color:white"><span style="color:#212121">Within NICM, LGE was mainly distributed as an </span></span>intramural pattern (n=22; 69%)<span style="background-color:white"><span style="color:#212121"> and </span></span><span style="background-color:white"><span style="color:#212121">more often located in the ventricular septum (</span></span>n=23; <span style="background-color:white"><span style="color:#212121">72%). </span></span></span></span></p>

<p style="text-align:justify"><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><strong>Conclusion: </strong>Among LBBB patients, myocardial strain analyzed by FT-CMR was independently associated with LV remodeling. LBBB patients with NICM without LGE seem to present a distinct phenotype in terms of LV mechanics, characterized by less severe compromise of LVEF and strain parameters. </span></span></p>