Prognostic value of pharmacologic stress echocardiography in patients withleft bundle branch block

PURPOSE: Although coronary artery disease is a frequent cause of left bundl e branch block, the prognostic value of myocardial ischemia in patients wit h this conduction abnormality has not been defined. We investigated the val ue of pharmacologic stress echocardiography ill risk stratification of pati ents with left bundle branch block. PATIENTS AND METHODS: Three hundred eighty-seven patients [230 men and 157 women, mean (+/- SD) age, 64 +/- 9 years] with complete left bundle branch block on the resting electrocardiogram underwent dobutamine (n = 217) or di pyridamole (n = 170) stress echocardiography to evaluate suspected or known coronary artery disease. A summary wall motion score ton a one to four sca le) was calculated. The primary end points were cardiac death and nonfatal myocardial infarction. RESULTS: A positive echocardiographic result (evidence of ischemia) was det ected in 109 (28%) patients, During a mean follow-up of 29 +/- 26 months, t here were 21 cardiac deaths and 20 myocardial infarctions, 63 patients unde rwent coronary revascularization, and 1 patient received a heart transplant . In a multivariate analysis, four clinical and echocardiographic variables were associated with increased risk of cardiac death: resting wall motion score index [hazard ratio (I-IR) = 7.5 per unit; 95% confidence interval (C I), 2.8 to 20; P = 0.001], previous myocardial infarction (HR = 2.9; 95% CI , 1.1 to 7.3; P = 0.02), diabetes (HR = 2.7; 95% CI, 1.1 to 6.6; P = 0.03), and the change in wall motion score index from rest to peak stress (HR = 3 .0 per unit; 95% CI, 1.0 to 8.6; P = 0.04). The 5-year survival was 77% in the ischemic group and 92% in the nonischemic group (P = 0.02). Four variab les were associated with increased risk of cardiac death or infarction: pre vious myocardial infarction (HR = 3.4; 95% CI, 1.7 to 6.8; P = 0.0005), dia betes (HR = 2.4; 95% CI, 1.2 to 4.6; P = 0.01), resting wall motion score i ndex (HR = 2.2 per unit; 95% CI, 1.1 to 4.1;P = 0.02), and positive echocar diographic result (HR = 2.2; 95% CI, 1.1 to 4.5; P = 0.03). The 5-year infa rction-free survival was 60% in the ischemic group and 87% in the nonischem ic group (P < 0.0001). Stress echocardiography significantly improved risk statification in patients without previous myocardial infarction (P = 0.000 1), but not in those with previous myocardial infarction (P = 0.08). In par ticular, it provided additional value over clinical and resting echocardiog raphic findings in predicting cardiac events among patients without previou s infarction. CONCLUSIONS: Myocardial ischemia during pharmacologic stress echocardiograp hy is a strong prognostic predictor in patients with left bundle branch blo ck, particularly in those without previous myocardial infarction. <(c)> 200 1 by Excerpta Medica, Inc.