SPC365

Idiopathic Isolated Left Bundle Branch Block – A Benign Finding or Something More?

Session: Comunicações Orais - Sessão 13 - Taquicardia Ventricular e Morte Súbita Cardíaca
Speaker: Catarina Amaral Marques

Congress: CPC 2023
Topic: C. Arrhythmias and Device Therapy
Theme: 08. Ventricular Arrhythmias and Sudden Cardiac Death (SCD)
Subtheme: 08.7 Ventricular Arrhythmias and SCD - Other
Session Type: Comunicações Orais
FP Number: ---
Authors: Catarina Amaral Marques; André Cabrita; Miguel Martins de Carvalho; João Calvão; Catarina Martins da Costa; Ana Filipa Amador; Ana Isabel Pinho; Cátia Oliveira; Luís Daniel Santos; Miguel Rocha; Helena Santos Moreira; Pedro Mangas Palma; Elisabete Martins; Filipe Macedo

<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong><span style="font-family:&quot;Times New Roman&quot;,serif">Introduction and Objectives:</span></strong><span style="font-family:&quot;Times New Roman&quot;,serif"> Idiopathic isolated left bundle branch block (LBBB) is a rare diagnosis, implying exclusion of structural heart disease&nbsp;and/or ischemia, mainly in patients (pts) with cardiovascular risk factors (CVRF). Natural history and prognosis of this entity remain poorly studied. Our aim was to characterize a population of pts with idiopathic LBBB and preserved left ventricular ejection fraction (LVEF &gt;50%). </span></span></span></span></p>

<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong><span style="font-family:&quot;Times New Roman&quot;,serif">Methods: </span></strong><span style="font-family:&quot;Times New Roman&quot;,serif">Retrospective study of LBBB adult pts screened from a large tertiary care hospital electrocardiographic database from 2011 to 2017. Only idiopathic LBBB pts with LVEF&gt;50% and follow-up (FU) echocardiographic and clinical data were included in the analysis. </span></span></span></span></p>

<p style="text-align:justify"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong><span style="font-family:&quot;Times New Roman&quot;,serif">Results: </span></strong><span style="font-family:&quot;Times New Roman&quot;,serif">39% of all 641 LBBB pts were identified as idiopathic cases. Final cohort study (LVEF&gt;50%) had 152 pts. 61% were female, median age at pts&rsquo; first-ever LBBB report was 61 years and 87% presented at least 1 CVRF. Median FU time was 8 years. During FU, 35 pts developed left ventricular dysfunction (2/3 mild dysfunction; 1/3 moderate or severe dysfunction). Causes for dysfunction (Figure 1) were identified in 13 pts, while the remaining 23 were possible LBBB-induced. All latter pts were submitted to additional testing (non-invasive ischemia testing in 78%; coronariography in 70%; cardiac magnetic resonance in 35%) to exclude other causes of LBBB. Overall median time-to-dysfunction was 8 years after first-ever LBBB report. Regarding clinical presentation of all idiopathic LBBB pts with LVEF&gt;50%, 60% were asymptomatic, while 17%, 14% and 7% presented with chest pain, heart failure symptoms and syncope/pre-syncope, respectively. 25 pts needed cardiac implantable electronic devices (CEID), namely 15 pacemakers, 1 implantable cardioverter defibrillator and 7 cardiac resynchronization therapy devices. Focusing pts outcomes, 18% presented at least 1 cardiovascular (CV) event needing hospitalization: 9% due to advanced conduction disturbances/complete heart block, 4% ischemic cerebrovascular event, 1% acute myocardial infarction, and 4% heart failure hospitalization. Only one patient died during FU due to CV cause. <span style="color:black">Baseline characteristics (age, sex, CVRF) were comparable between patients with and without LVEF drop, as well as between patients with known causes for LVEF drop versus possible LBBB-induced. No differences in time-to-dysfunction were found between the latter (Log-rank=0.713). </span></span></span></span></span></p>

<p><strong><span style="font-size:12pt"><span style="font-family:&quot;Times New Roman&quot;,serif">Conclusion: </span></span></strong><span style="font-size:12pt"><span style="color:#000000"><span style="font-family:&quot;Times New Roman&quot;,serif">Our data show that about one-quarter of pts with idiopathic LBBB and preserved LVEF later develop ventricular dysfunction and an important proportion are possible LBBB-induced. Additionally, 18% presented at least one CV event needing hospitalization, and 16% needed a CEID. Our study sheds some light on a largely unknown topic, bringing to discussion whether isolated idiopathic LBBB is, as it has been increasingly suggested, a not-so benign finding that may require follow-up.</span></span></span></p>