Intraventricular conduction defects in patients with st-segment elevation myocardial infarction – the paradox of right bundle branch block

Abstract

Abstract Intraventricular conduction defects (IVCD) in patients with acute myocardial infarct (AMI) are predictors of a worse prognosis. When acquired they can be the result of an extensive myocardial damage. Purpose To assess the impact of IVCD, regardless of being previously known or presumed new, on in-hospital outcomes of patients with AMI with ST segment elevation (STEMI) or undetermined location. Methods From a series of patients included in the National Registry of Acute Coronary Syndrome between 10/1/2010 and 9/1/2019, were selected patients with STEMI or undetermined AMI, undergoing coronary angiography. Results 7805 patients were included: 461 (5.9%) presenting left bundle branch block (LBBB), 374 (4.8%) with right bundle branch block (RBBB) and 6970 (89.3%) with no IVCD. Clinical characteristics as well as in-hospital outcomes are described in the table 1. An unexpected worse prognosis in patients with RBBB has motivated a multivariate analysis. RBBB remained an independent predictor of in-hospital mortality (OR 1.91, 95% CI 1.04–3.50, p=0.038), along with female gender (OR 1.73, 95% CI 1.11–2.68, p=0.015), Killip Class>1 (OR 2.26, 95% CI 1.45–3.53, p<0.001), left ventricular ejection fraction <50% (OR 3.93, 95% CI 2.19–7.05, p<0.001) and left anterior descending artery as the culprit lesion (OR 1.85, 95% CI 1.16–2.91, p=0.009). Conclusion In spite of an apparent better clinical profile, in the current large series of unselected STEMI patients, the presence of RBBB is associated with the worst in-hospital outcome. RBBB doubles the risk of death, being an independent predictor of in-hospital mortality. Funding Acknowledgement Type of funding source: None