Ejection fraction in left bundle branch block is disproportionately reduced in relation to amount of myocardial scar

Jimmy Axelsson, Björn Wieslander, Robert Jablonowski, Igor Klem, Robin Nijveldt, Erik B. Schelbert, Peder Sörensson, Andreas Sigfridsson, Uzma Chaudhry, Pyotr G. Platonov, Rasmus Borgquist, Henrik Engblom, David G. Strauss, H. kan Arheden, Brett D. Atwater, Martin Ugander

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Abstract

Introduction: The relationship between left ventricular (LV) ejection fraction (EF) and LV myocardial scar can identify potentially reversible causes of LV dysfunction. Left bundle branch block (LBBB) alters the electrical and mechanical activation of the LV. We hypothesized that the relationship between LVEF and scar extent is different in LBBB compared to controls. Methods: We compared the relationship between LVEF and scar burden between patients with LBBB and scar (n = 83), and patients with chronic ischemic heart disease and scar but no electrocardiographic conduction abnormality (controls, n = 90), who had undergone cardiovascular magnetic resonance (CMR) imaging at one of three centers. LVEF (%) was measured in CMR cine images. Scar burden was quantified by CMR late gadolinium enhancement (LGE) and expressed as % of LV mass (%LVM). Maximum possible LVEF (LVEFmax) was defined as the function describing the hypotenuse in the LVEF versus myocardial scar extent scatter plot. Dysfunction index was defined as LVEFmax derived from the control cohort minus the measured LVEF. Results: Compared to controls with scar, LBBB with scar had a lower LVEF (median [interquartile range] 27 [19–38] vs 36 [25–50] %, p < 0.001), smaller scar (4 [1–9] vs 11 [6–20] %LVM, p < 0.001), and greater dysfunction index (39 [30–52] vs 21 [12–35] % points, p < 0.001). Conclusions: Among LBBB patients referred for CMR, LVEF is disproportionately reduced in relation to the amount of scar. Dyssynchrony in LBBB may thus impair compensation for loss of contractile myocardium.
Original languageEnglish
Pages (from-to)1071-1076
JournalJournal of Electrocardiology
Volume51
Issue number6
DOIs
Publication statusPublished - 2018

Cite this

Axelsson, J., Wieslander, B., Jablonowski, R., Klem, I., Nijveldt, R., Schelbert, E. B., ... Ugander, M. (2018). Ejection fraction in left bundle branch block is disproportionately reduced in relation to amount of myocardial scar. Journal of Electrocardiology, 51(6), 1071-1076. https://doi.org/10.1016/j.jelectrocard.2018.09.009