Defining left bundle branch block-Is this a roadblock to CRT delivery?
2019; Elsevier BV; Volume: 286; Linguagem: Inglês
10.1016/j.ijcard.2019.03.028
ISSN1874-1754
Autores Tópico(s)Cardiac electrophysiology and arrhythmias
ResumoLeft bundle branch block (LBBB) represents a composite of multiple mechanisms of impaired myocardial conduction that promote a variety of surface ECG morphologies reflected in the plethora of diagnostic criteria which can be confusing [ 1 Brignole M. Auricchio A. Baron-Esquivias G. et al. ESC guidelines on cardiac pacing and cardiac resynchronization therapy: the task force on cardiac pacing and resynchronization therapy of the European Society of Cardiology (ESC). Developed in collaboration with the European Heart Rhythm Association (EHRA). Eur. Heart J. 2013; 34: 2281-2329 PubMed Google Scholar , 2 Surawicz B. Childers R. Deal B.J. et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology. J. Am. Coll. Cardiol. 2009; 53: 976-981 Crossref PubMed Scopus (563) Google Scholar , 3 Bayés De Luna A. Batchvarov V.N. MalikChapter M. 1: the morphology of the electrocardiogram. in: Camm A.J. The ESC Textbook of Cardiovascular Medicine. Blackwell Publishing, 2006: 1-35 Google Scholar , 4 Cosío F.G. Palacios J. Pastor A. Núñez A. Chapter 2 the electrocardiogram. in: Camm A.J. The ESC Textbook of Cardiovascular Medicine. 2 ed. Oxford University Press, 2009: 29-83 Crossref Google Scholar , 5 Strauss D.G. Selvester R.H. Wagner G.S. Defining left bundle branch block in the era of cardiac resynchronization therapy. Am. J. Cardiol. 2011; 107: 927-934 Abstract Full Text Full Text PDF PubMed Scopus (445) Google Scholar ]. The QRS complex in LBBB reflects the failure of optimal myocardial recruitment achieved by the normal functioning His-Purkinje network, a manifestation of a failure in coupling at one or multiple levels: within the left fascicles themselves, fascicular to myocardial conduction or intramyocardial conduction (Fig. 1). The classic M wave pattern in V6 reflects the rotation of an activation wavefront in the LV. Indeed, endocardial and more recently non-invasive ECG Imaging studies have demonstrated that there are 2 main patterns of activation-a Type 1 homogeneous depolarization and Type 2 U shaped pattern as the activation wavefront rotates around a region of fixed or functional block [ 6 Fung J.W. Yu C.M. Yip G. Zhang Y. Chan H. Kum C.C. Sanderson J.E. Variable left ventricular activation pattern in patients with heart failure and left bundle branch block. Heart. 2004 Jan; 90: 17-19 Crossref PubMed Scopus (123) Google Scholar , 7 Lambiase P.D. Rinaldi A. Hauck J. Mobb M. Elliott D. Mohammad S. Gill J.S. Bucknall C.A. Non-contact left ventricular endocardial mapping in cardiac resynchronisation therapy. Heart. 2004 Jan; 90: 44-51 Crossref PubMed Scopus (126) Google Scholar , 8 Varma N. Jia P. Rudy Y. Electrocardiographic imaging of patients with heart failure with left bundle branch block and response to cardiac resynchronization therapy. J. Electrocardiol. 2007 Nov-Dec; 40: S174-S178 Crossref PubMed Scopus (44) Google Scholar ]. There has been a great deal of interest in attempting to predict the exact site of LBBB as this could have important implications not only for the siting of the coronary sinus LV lead but also predicting positive LV remodeling. A number of ECG markers of remodeling have been proposed including QRS duration, QRS area and the morphology of the intrinsicoid deflection [ 9 Nguyên U.C. Claridge S. Vernooy K. Engels E.B. Razavi R. Rinaldi C.A. Chen Z. Prinzen F.W. Relationship between vectorcardiographic QRSarea, myocardial scar quantification, and response to cardiac resynchronization therapy. J. Electrocardiol. 2018 May - Jun; 51: 457-463 Crossref PubMed Scopus (18) Google Scholar , 10 Pastore G. Maines M. Marcantoni L. Zanon F. Noventa F. Corbucci G. Baracca E. Aggio S. Picariello C. Lanza D. Rigatelli G. Carraro M. Roncon L. Barold S.S. ECG parameters predict left ventricular conduction delay in patients with left ventricular dysfunction. Heart Rhythm. 2016 Dec; 13: 2289-2296 Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar , e11 van Stipdonk A.M.W. Ter Horst I. Kloosterman M. Engels E.B. Rienstra M. Crijns H.J.G.M. Vos M.A. van Gelder I.C. Prinzen F.W. Meine M. Maass A.H. Vernooy K. QRS area is a strong determinant of outcome in cardiac resynchronization therapy. Circ. Arrhythm. Electrophysiol. 2018 Dec; 11e006497 Crossref PubMed Scopus (48) Google Scholar , e12 Bryant A.R. Wilton S.B. Lai M.P. Exner D.V. Association between QRS duration and outcome with cardiac resynchronization therapy: a systematic review and meta analysis. J. Electrocardiol. 2013 Mar-Apr; 46: 147-155 Crossref PubMed Scopus (38) Google Scholar ]. Fundamentally, if there is an excess of fibrosed myocardium, it is unlikely there is sufficient myocardial reserve to achieve adequate remodeling even if the lead is targeted outside scar. Large variability in clinical judgement and definitions of left bundle branch block to identify candidates for cardiac resynchronisation therapyInternational Journal of CardiologyVol. 286PreviewLeft bundle branch block (LBBB) morphology is associated with improved outcome of cardiac resynchronisation therapy (CRT) and is an important criterion for patient selection. There are, however, multiple definitions for LBBB. Moreover, applying these definitions seems subjective. We investigated the inter- and intraobserver agreement in the determination of LBBB using available definitions, and clinicians' judgement of LBBB. Full-Text PDF Open Access
Referência(s)