913-122 Detection of Left Anterior Descending Artery Stenosis in Patients with Left Bundle Branch Block: Exercise, Adenosine or Dobutamine Imaging?

In patients with left bundle branch block, false positive septal perfusion defects occur commonly during exercise perfusion tomography (ExT) and this problem appears to be less frequent during pharmacologic stress using adenosine (AdT) or dipyridamole. No data exist on the value of dobutamine tomography (DobT) in this setting. Accordingly, we studied 378 consecutive patients with left bundle branch block referred for perfusion imaging during the period of January 1990 and June 1994. ExT was performed in 206, AdT in 124 and DobT in 48 patients. Coronary angiography was performed in 77, 47, and 25 patients, respectively, in these 3 groups within 1 month of the nuclear study. ExT, AdT and DobT had similar sensitivity and specificity for the detection of >50% stenosis in the circumflex (74% and 96%; 50% and 100%; 57% and 91%, respectively) and the right coronary artery (96% and 86%; 81% and 90%; 74% and 100%, respectively) and similar sensitivity in left anterior descending artery stenoses (88%, 78% and 100%, respectively). However, the false positive rate for septal defects was higher by ExT (26/57, 46%) compared to pharmacologic methods (5/42,12%, P=0.008) and there was no significant difference between AdT (4/32, 13%) and DobT (1/10,10%, P=NS).ConclusionIn the presence of left bundle branch block, pharmacologic stress imaging is more specific than ExT in the diagnosis of left anterior descending artery stenosis. DobT and AdT appear to be equally specific in these patients