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) 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 CAD.

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 >or= 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 DSE.

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.