Prevalence and Long-Term Prognosis of Patients with Complete Bundle Branch Block (Right or Left Bundle Branch) with Normal Left Ventricular Ejection Fraction Referred for Stress Echocardiography

BackgroundThe prognostic value of stress echocardiography (SE) in patients with complete bundle branch blocks (BBB) with normal left ventricular ejection fraction (LVEF) has not been well described. We sought to determine the prognostic value of SE in patients with BBB and normal LVEF. MethodsWe analyzed 7214 patients (5814years; 57% female) with a mean follow-up time of 94years. Dobutamine SE was performed in 51% of patients and exercise SE was performed in 49%. All-cause mortality data were obtained from the Social Security Death Index. ResultsThere were 222 (3%) patients with right bundle branch block (RBBB) and 50 (0.7%) patients with left bundle branch block (LBBB). Patients with LBBB were 3 times more likely to have an abnormal stress test after adjusting for age, gender, mode of stress test, and coronary artery disease risk factors (OR=3.3; 95% CI: 1.86-5.92; P<0.001). The mortality rates were 4.5%/year for patients with LBBB, 2.5%/year for patients with RBBB, and 1.9%/year for patients without BBB (P<0.001). Among patients with a normal SE, those with LBBB had similar mortality to those without LBBB (HR=0.9; 95% CI: 0.4-2.2; P=0.8). Patients with LBBB and abnormal SE had more than 2 times greater risk of all-cause mortality (HR=2.4; 95% CI: 1.4-4.2; P=0.002). ConclusionA normal stress echocardiogram in LBBB is associated with benign prognosis while those with LBBB and abnormal SE have the worst outcomes.