Study objectives: To evaluate dipyridamole stress
echocardiography (DSE) for predicting coronary artery diseases (CADs)
in patients with complete left bundle-branch block (LBBB).
Design: Comparison of DSE and dipyridamole sestamibi
myocardial perfusion scintigraphy (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] dilatation) and intermediate probability of
Methods: Simultaneous single photon emission CT
scan (20 mCi technetium Tc 99m stress/rest sestamibi) and
echocardiography (second harmonic imaging) during a two-step (0.56 to
0.84 mg/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 with any defect (sestamibi-2) to be
positive. CAD was defined as a ≥ 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 accuracy 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
significantly higher for DSE (94.6%) and sestamibi-1 (81.1%) than for
sestamibi-2 (43.2%; p < 0.01 vs both the other two tests). Of 14
patients with LV dilatation, 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 CAD by sestamibi-2 vs none by
Conclusions: DSE is at least as accurate
as dipyridamole sestamibi scintigraphy for predicting CAD in patients
with complete LBBB and tends to be more specific in those patients with
underlying LV dilatation.