Left bundle branch block tied to left ventricular dysfunction

(HealthDay)—Left bundle branch block (LBBB) is associated with a smaller degree of left ventricular ejection fraction (LVEF) improvement compared with other QRS morphologies, according to a study published in the Jan. 23 issue of the Journal of the American College of Cardiology.

Edward Sze, M.D., from Duke University in Durham, N.C., and colleagues used data from the Duke Echocardiography Laboratory Database to identify patients with baseline electrocardiography and LVEF ≤35 percent with follow-up LVEF three to six months later. The authors sought to assess rates of LVEF improvement for patients with LBBB versus other QRS morphologies.

The researchers found that of the 659 included patients, 111 had LBBB, 59 had wide QRS duration ≥120 ms (but not LBBB), and 489 had narrow QRS duration. In the three groups, the adjusted mean increase in LVEF over three to six months was 2.03, 5.28, and 8.00 percent, respectively (P < 0.0001). After adjusting for interim revascularization and myocardial infarction, results remained similar. There was virtually no difference when comparing mean LVEF improvement between patients with LBBB on guideline-directed medical therapy and those not on that treatment (3.50 versus 3.44 percent). Patients with LBBB had the highest combined end point of heart failure hospitalization or mortality.

"LBBB is associated with a smaller degree of LVEF improvement compared with other QRS morphologies, even with guideline-directed medical therapy," the authors write. "Some patients with LBBB may benefit from cardiac resynchronization therapy earlier than guidelines currently recommend."

Several authors report financial ties to the medical device industry.