ABC | Volume 115, Nº1, Suplement, July 2020

Case Report Guimarães & Bocchi Left Bundle Branch Block Arq Bras Cardiol 2020; 115(1Suppl.1):10-13 This is an open-access article distributed under the terms of the Creative Commons Attribution License CPX. On the other hand, exercise-induced left bundle branch block may be related or not to apparent cardiac abnormalities. However, patients with this finding have significantly higher all-cause mortality rates compared to those without exercise- induced left bundle branch block. 11 This apparent decrease in cardiac function during exercise may be due to a transitory decrease in stroke volume, probably related toworsening left ventricular (LV) function associatedwith an abrupt increase in the VE/VCO 2 slope, giving rise to a higher dead space to tidal volume ratio and an early increase in the respiratory rate, as compensatory mechanisms. 1,3,5,10 This disturbance in pathophysiology is linkedwith LVdysfunction, causedorworsened by LBBB, may indirectly lead to right ventricular dysfunction through increased left-sided filling pressure, causing changes in the function of the lungs’ airways, and to the development of abnormal gas exchange due to alveolar-capillary dysfunction. 3,4 In addition, a higher VE/VCO 2 slope is suggestive of secondary pulmonary hypertension, as a consequence of another primary condition, such as heart failure or pulmonary disease. 3,4 Consideration Cardiopulmonary exercise testing in LBBB, in the absence of other heart diseases, should be considered as a technique to evaluate the exercise capacity in patients with unexplained symptoms. Author Contributions Conception and design of the research, Acquisition of data and Critical revision of the manuscript for intellectual content: Guimarães GV; Analysis and interpretation of the data and Writing of the manuscript: Guimarães GV, Bocchi EA. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding GV Guimarães was supported by National Council f o r S c i en t i f i c and Te chno l og i c a l De v e l opmen t (CNPq:301957/2017-7). Study Association This study is not associated with any thesis or dissertation work. Ethics Approval and Consent to Participate This article does not contain any studies with human participants or animals performed by any of the authors. 1. Belli JFC, Bacal F, Bocchi EA, Guimaras GV. “Ergoreflex activity in heart failure.” Arq Bras Cardiol.2011;97(2):171-8. 2. Breithardt G, Breithardt OL. Left bundle branch block, an old–new entity. J Cardiovasc Transl Res.2012;5(2):107-16. 3. Farina S, Correale M, Bruno N, Paolillo S, Salvioni E, Badagliacca R, et al., Stefania, et al. The role of cardiopulmonary exercise tests in pulmonary arterial hypertension.”Eur Respir Rev. 2018;27(148):17034. 4. Guazzi M, Cahalin L, Arena R. Cardiopulmonary exercise testing as a diagnostic tool for the detection of left-sided pulmonary hypertension in heart failure. J Card Fail. 2013;19(7):461-7. 5. Guimarães GV, Belli JC, Bacal F, Bocchi EA. Behavior of Central and Peripheral Chemoreflexes in Heart Failure. 2011; 96(2):161-7. 6. Kim JH, Baggish A L. Electrocardiographic right and left bundle branch block patterns in athletes: prevalence, pathology, and clinical significance. J Electrocardiogr.2015;48(3):380-4. 7. Kim JH, Baggish AL. Significance of electrocardiographic right bundle branch block in trained athletes. Am J Cardiol. 2011;107(7):1083-9. 8. Koepfli P,Wyss C, Gaemperli O, Siegrist PT, Klainuti M , Schepis T, et al. “Left bundle branch block causes relative but not absolute septal underperfusion during exercise. Eur Heart J. 2009;30(24): 2993-9. 9. Lamberti M, Ratti G, Di Miscio G, Franciolini E. Cardiovascular risk in young workers with left bundle branch block. Open J PrevMed. 2014;4(5):270-4. 10. Lim HS, Hoong S, Theodosiou M. Exercise ventilatory parameters for the diagnosis of reactive pulmonary hypertension in patients with heart failure. J Card Fail. 2014;20(9):650-7. 11. Stein R, Ho M, Oliveira CM,Ribeiro JP, Lata K, Abella J, et al. Exercise- induced left bundle branch block: prevalence and prognosis. Arq Bras Cardiol.2011;97(1):26-32. References 13