EP News: Clinical

Abstract

Sze et al (J Am Coll Cardiol 2018;71:306–317, PMID 29348023) examined patients with cardiomyopathy and assessed rates of left ventricular ejection fraction (LVEF) improvement in patients with left bundle branch block (LBBB) compared to other QRS morphologies on guideline-directed medical therapy (GDMT). In patients with LVEF ≤35%, QRS morphology was classified as LBBB, QRS duration <120 ms (narrow QRS duration), or wide QRS duration ≥120 ms but not LBBB. There were 659 patients who met the criteria: 111 LBBB (17%), 59 wide QRS duration ≥120 ms but not LBBB (9%), and 489 narrow QRS duration (74%). Increases in LVEF over 3 to 6 months in the 3 groups were 2.03%, 5.28%, and 8.00%, respectively (P <.0001). Comparison of mean LVEF improvement between patients with LBBB on GDMT and those not on GDMT showed virtually no difference (3.50% vs 3.44%). The combined endpoint of heart failure hospitalization or mortality was highest for patients with LBBB. The authors conclude that LBBB is associated with a lower degree of LVEF improvement compared with other QRS morphologies, even with GDMT.