Prognostic value of exercise echocardiography in patients with left bundle branch block.

Objectives: Our aim was to evaluate the role of exercise echocardiography for predicting outcome in a cohort of patients with left bundle branch block (LBBB).

Background: Although the prognostic value of exercise echocardiography has been well established in several subgroups of patients, it has not been specifically assessed in patients with LBBB.

Methods: Of the 8,050 patients who underwent treadmill exercise echocardiography, 618 demonstrated complete LBBB. Nine patients were lost to follow-up and 609 patients were included in this study. Wall motion score index (WMSI) was evaluated at rest and at peak exercise, and the difference (DeltaWMSI) was calculated. Ischemia was defined as the development of new or worsening wall motion abnormalities with exercise. End points were all-cause mortality and major cardiac events (including cardiac death, myocardial infarction, or cardiac transplantation). Mean follow-up was 4.6 +/- 3.4 years.

Results: Mean age was 66 +/- 10 years, and 331 patients (54%) were men. A total of 177 patients (29%) developed ischemia with exercise. During follow-up, 124 deaths occurred, and 74 patients had a major cardiac event before any revascularization procedure. Patients with ischemia had a greater 5-year mortality rate (24.6% vs. 12.6%, p < 0.001) and 5-year major cardiac events rate (18.1% vs. 9.7%, p = 0.003). In multivariate analysis, DeltaWMSI remained an independent predictor of mortality (hazard ratio: 2.42, 95% confidence interval: 1.21 to 4.82, p = 0.012) and major cardiac events (hazard ratio: 3.38, 95% confidence interval: 1.30 to 8.82, p = 0.013). Exercise echocardiographic results also provided incremental value over clinical, resting echocardiographic, and treadmill exercise data for the prediction of mortality (p = 0.014) and major cardiac events (p = 0.017).

Conclusions: Exercise echocardiography provides significant prognostic information for predicting outcome in patients with LBBB. As compared to patients with normal exercise echocardiograms, patients with abnormal results are at increased risk of mortality and major cardiac events.