Características electrocardiográficas del bloqueo de rama izquierda y su capacidad para predecir fracción de eyección disminuida del ventrículo izquierdo

Introduction: Left bundle branch block it’s an uncommon entity, that has been associated with adverse cardiovascular outcomes and structural abnormalities in cardiac chambers. Some electrocardiographic criteria have been associated independently with reduced left ventricle ejection fraction. Nevertheless, it is uncertain whether ventricular hypertrophy, left auricular enlargement, QRS duration, and Strauss criteria can predict reduced left ventricle ejection fraction. Objectives: to evaluate the capacity of Strauss criteria, ventricular hypertrophy, left auricular enlargement, QRS duration, and Strauss criteria to predict reduced left ventricle ejection fraction. Methods: the authors conducted an observational descriptive, transversal study in which they included adults with left bundle branch block by traditional criteria in which left ventricle ejection fraction was evaluated with transthoracic echocardiography. Univariated, bivariated and multivariated analysis were done and Oliveira score was validated. Additionally, prediction models as logistic regression were applied and operative characteristics of the electrocardiographic signs were determined. Results: 133 patients were included in the analysis, of them 46 (34.5%) presented with reduced left ventricle ejection fraction. In the bivariated analysis, Cornell index, left auricular enlargement and Strauss criteria showed the highest sensitivity (80, 78 y 76 % respectively), and Sokolow index the highest specificity (95%). In regression models, that included electrocardiographic and clinical variables, the authors found that the variables that best predict reduced left ventricle ejection fraction were QRS amplitude, left axis deviation, arterial hypertension, age and functional class according to NYHA 1. Conclusions: prediction capacity of electrocardiographic and clinical variables is modest in this study, as the Oliveira score with cut points for reduced left ventricle ejection fraction of 40 and 45 %, respectively.