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Defining Left Bundle Branch Block in the Era of Cardiac Resynchronization Therapy

      Cardiac resynchronization therapy (CRT) has emerged as an attractive intervention to improve left ventricular mechanical function by changing the sequence of electrical activation. Unfortunately, many patients receiving CRT do not benefit but are subjected to device complications and costs. Thus, there is a need for better selection criteria. Current criteria for CRT eligibility include a QRS duration ≥120 ms. However, QRS morphology is not considered, although it can indicate the cause of delayed conduction. Recent studies have suggested that only patients with left bundle branch block (LBBB) benefit from CRT, and not patients with right bundle branch block or nonspecific intraventricular conduction delay. The authors review the pathophysiologic and clinical evidence supporting why only patients with complete LBBB benefit from CRT. Furthermore, they review how the threshold of 120 ms to define LBBB was derived subjectively at a time when criteria for LBBB and right bundle branch block were mistakenly reversed. Three key studies over the past 65 years have suggested that 1/3 of patients diagnosed with LBBB by conventional electrocardiographic criteria may not have true complete LBBB, but likely have a combination of left ventricular hypertrophy and left anterior fascicular block. On the basis of additional insights from computer simulations, the investigators propose stricter criteria for complete LBBB that include a QRS duration ≥140 ms for men and ≥130 ms for women, along with mid-QRS notching or slurring in ≥2 contiguous leads. Further studies are needed to reinvestigate the electrocardiographic criteria for complete LBBB and the implications of these criteria for selecting patients for CRT.
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      References

        • Strauss D.G.
        • Selvester R.H.
        The QRS complex—a biomarker that “images” the heart: QRS scores to quantify myocardial scar in the presence of normal and abnormal ventricular conduction.
        J Electrocardiol. 2009; 42: 85-96
        • Strauss D.G.
        • Selvester R.H.
        • Lima J.A.
        • Arheden H.
        • Miller J.M.
        • Gerstenblith G.
        • Marban E.
        • Weiss R.G.
        • Tomaselli G.F.
        • Wagner G.S.
        • Wu K.C.
        ECG quantification of myocardial scar in cardiomyopathy patients with or without conduction defects: correlation with cardiac magnetic resonance and arrhythmogenesis.
        Circ Arrhythm Electrophysiol. 2008; 1: 327-336
        • Bristow M.R.
        • Saxon L.A.
        • Boehmer J.
        • Krueger S.
        • Kass D.A.
        • De Marco T.
        • Carson P.
        • DiCarlo L.
        • DeMets D.
        • White B.G.
        • DeVries D.W.
        • Feldman A.M.
        Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure.
        N Engl J Med. 2004; 350: 2140-2150
        • Cleland J.G.
        • Daubert J.C.
        • Erdmann E.
        • Freemantle N.
        • Gras D.
        • Kappenberger L.
        • Tavazzi L.
        The effect of cardiac resynchronization on morbidity and mortality in heart failure.
        N Engl J Med. 2005; 352: 1539-1549
        • Egoavil C.A.
        • Ho R.T.
        • Greenspon A.J.
        • Pavri B.B.
        Cardiac resynchronization therapy in patients with right bundle branch block: analysis of pooled data from the MIRACLE and Contak CD trials.
        Heart Rhythm. 2005; 2: 611-615
        • Bilchick K.C.
        • Kamath S.
        • DiMarco J.P.
        • Stukenborg G.J.
        Bundle-branch block morphology and other predictors of outcome after cardiac resynchronization therapy in medicare patients.
        Circulation. 2010; 122: 2022-2030
        • Moss A.J.
        • Hall W.J.
        • Cannom D.S.
        • Klein H.
        • Brown M.W.
        • Daubert J.P.
        • Estes III, N.A.
        • Foster E.
        • Greenberg H.
        • Higgins S.L.
        • Pfeffer M.A.
        • Solomon S.D.
        • Wilber D.
        • Zareba W.
        Cardiac-resynchronization therapy for the prevention of heart-failure events.
        N Engl J Med. 2009; 361: 1329-1338
        • Zareba W.
        • Klein H.
        • Cygankiewicz I.
        • Hall J.
        • Goldberger J.
        • Daubert J.P.
        • Gold M.R.
        • Rashtian M.
        • Viskin S.
        • Kargul W.
        • Pitschner H.
        • McNitt S.
        • Moss A.J.
        CRT-D effectiveness by QRS duration and morphology in the MADIT-CRT patients.
        Heart Rhythm. 2010; 7: S24-S25
        • Eppinger H.
        • Rothberger J.
        Zur Analyse des Elektrokardiograms.
        Wien Klin Wschnschr. 1909; 22: 1091
        • Carter E.P.
        Clinical observations on defective conduction in the branches of the A-V bundle.
        Arch Int Med. 1914; 13: 803
        • Wilson F.N.
        Concerning the form of the QRS deflections of the electrocardiogram in bundle branch block.
        J Mount Sinai Hosp N Y. 1941; 8: 1110
        • Wilson F.N.
        • Herrmann G.R.
        Bundle branch block and arborization block.
        Arch Int Med. 1920; 26: 153-191
        • Oppenheimer B.S.
        • Pardee H.E.B.
        The site of the cardiac lesion in two instances of intraventricular heart-block.
        Proc Soc Exper Biol Med. 1920; 17 (117)
        • Barker P.S.
        • Macleod A.G.
        • Alexander J.A.
        The excitatory process observed in the exposed human heart.
        Am Heart J. 1930; 5: 720-742
        • Macleod A.G.
        • Wilson F.N.
        • Barker P.S.
        The form of the Electrocardiogram.
        Proc Soc Exper Biol Med. 1930; 27 (586)
        • Grant R.P.
        • Dodge H.T.
        Mechanisms of QRS complex prolongation in man; left ventricular conduction disturbances.
        Am J Med. 1956; 20: 834-852
        • Selvester R.H.S.
        • Solomon J.C.
        Computer simulation of ventricular depolarization, QRS duration and quantification of wall thickness.
        in: Willems J.L. Van Bemmel J.H. Zywitz C. Computer ECG Analysis: Toward Standardization. North Holland, Amsterdam, The Netherlands1986: 221-272
        • Padanilam B.J.
        • Morris K.E.
        • Olson J.A.
        • Rippy J.S.
        • Walsh M.N.
        • Subramanian N.
        • Vidal A.
        • Prystowsky E.N.
        • Steinberg L.A.
        The surface electrocardiogram predicts risk of heart block during right heart catheterization in patients with preexisting left bundle branch block: implications for the definition of complete left bundle branch block.
        J Cardiovasc Electrophysiol. 2010; 21: 781-785
        • Vassallo J.A.
        • Cassidy D.M.
        • Marchlinski F.E.
        • Buxton A.E.
        • Waxman H.L.
        • Doherty J.U.
        • Josephson M.E.
        Endocardial activation of left bundle branch block.
        Circulation. 1984; 69: 914-923
        • Vassallo J.A.
        • Cassidy D.M.
        • Miller J.M.
        • Buxton A.E.
        • Marchlinski F.E.
        • Josephson M.E.
        Left ventricular endocardial activation during right ventricular pacing: effect of underlying heart disease.
        J Am Coll Cardiol. 1986; 7: 1228-1233
        • Auricchio A.
        • Fantoni C.
        • Regoli F.
        • Carbucicchio C.
        • Goette A.
        • Geller C.
        • Kloss M.
        • Klein H.
        Characterization of left ventricular activation in patients with heart failure and left bundle-branch block.
        Circulation. 2004; 109: 1133-1139
        • Fantoni C.
        • Kawabata M.
        • Massaro R.
        • Regoli F.
        • Raffa S.
        • Arora V.
        • Salerno-Uriarte J.A.
        • Klein H.U.
        • Auricchio A.
        Right and left ventricular activation sequence in patients with heart failure and right bundle branch block: a detailed analysis using three-dimensional non-fluoroscopic electroanatomic mapping system.
        J Cardiovasc Electrophysiol. 2005; 16: 112-119
        • Wagner G.S.
        Marriott's Practical Electrocardiograpy.
        Lippincott Williams & Wilkins, Philadelphia, Pennsylvania2008
        • Surawicz B.
        • Childers R.
        • Deal B.J.
        • Gettes L.S.
        • Bailey J.J.
        • Gorgels A.
        • Hancock E.W.
        • Josephson M.
        • Kligfield P.
        • Kors J.A.
        • Macfarlane P.
        • Mason J.W.
        • Mirvis D.M.
        • Okin P.
        • Pahlm O.
        • Rautaharju P.M.
        • van Herpen G.
        • Wagner G.S.
        • Wellens H.
        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
        • Selvester R.H.
        • Wagner G.S.
        • Ideker R.E.
        Myocardial Infarction.
        in: Macfarlane P.W. Lawrie T.D.V. Comprehensive Electrocardiology: Theory and Practice in Health and Disease. Pergamon Press, New York, New York1989: 565-629
        • Macfarlane P.
        • Lawrie T.D.V.
        Appendix 1: normal limits.
        in: Macfarlane P. Lawrie T.D.V. Comprehensive Electrocardiology: Theory and Practice in Health and Disease. Pergamon Press, New York1989: 1441-1526
        • Strauss D.G.
        • Poole J.E.
        • Wagner G.S.
        • Selvester R.H.
        • Miller J.M.
        • Anderson J.
        • Johnson G.
        • McNulty S.E.
        • Mark D.B.
        • Lee K.L.
        • Bardy G.H.
        • Wu K.C.
        An ECG index of myocardial scar enhances prediction of defibrillator shocks: an analysis of the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT).
        Heart Rhythm. 2011; 8: 38-45
        • Sweeney M.O.
        • van Bommel R.J.
        • Schalij M.J.
        • Borleffs C.J.
        • Hellkamp A.S.
        • Bax J.J.
        Analysis of ventricular activation using surface electrocardiography to predict left ventricular reverse volumetric remodeling during cardiac resynchronization therapy.
        Circulation. 2010; 121: 626-634