Dipyridamole stress echocardiography vs dipyridamole sestamibi scintigraphy for diagnosing coronary artery disease in left bundle-branch block

Study objectives: To evaluate dipyridamole stress echocardiography (DSE) fo r predicting coronary artery diseases (CADS) in patients with complete left bundle-branch block (LBBB). Design: Comparison of DSE and dipyridamole sestamibi myocardial perfusion s cintigraphy (sestamibi). Setting: Tertiary-care cardiac referral center. Patients: Fifty-four consecutive patients (26 men; mean [+/- SD] age, 59 +/ -7 years) with complete LBBB (14 patients with left ventricular [LV] dilata tion) and intermediate probability of CAD. Methods: Simultaneous single pho ton emission CT scan (20 mCi technetium Te 99m stress/rest sestamibi) and e chocardiography (second harmonic imaging) during a two-step (0.56 to 0.84 m g/kg) dipyridamole infusion protocol. Two sestamibi readings were performed . The first reading considered only those studies with reversible defects ( sestamibi-1) to be positive. The second reading considered those studies wi th any defect (sestamibi-2) to be positive. CAD was defined as a greater th an or equal to 50% reduction in diameter in at least one major vessel seen on coronary angiography. Results: CAD was present in 17 patients (31.5%). The global predictive accu racy for CAD was significantly higher for DSE (87.0%) and sestamibi-1 (79.6 %) than for sestamibi-2 (57.4%) [p<0.01 vs DSE; p<0.05 vs sestamibi-1]. No significant differences in sensitivity were present, but specificity was si gnificantly higher for DSE (94.6%) and sestamibi-l (81.1%) than for sestami bi-2 (43.2%; p<0.01 vs both the other two tests). Of 14 patients with LV di latation, 26.8% were falsely positive for CAD (in some cases for posterior defects) as determined by sestamibi-1 and 64.3% were falsely positive for C AD by sestamibi-2 vs none by DSE. Conclusions: DSE is at least as accurate as dipyridamole sestamibi scintigr aphy for predicting CAD in patients with complete LBBB and tends to be more specific in those patients with underlying LV dilatation.