Usefulness and limitations of dobutamine-atropine stress echocardiography for the diagnosis of coronary artery disease in patients with left bundle branch block. A multicentre study.

BACKGROUND: Patients with left bundle branch block exhibit abnormal septal motion which may limit the interpretation of stress echocardiograms. This study sought to assess the diagnostic value of dobutamine-atropine stress echocardiography in left bundle branch block patients. METHODS AND RESULTS: Sixty-four left bundle branch block patients (mean age 59 years, 24 men) with suspected coronary artery disease underwent dobutamine-atropine stress echocardiography and coronary arteriography. Myocardial ischaemia was defined as new or worsening wall thickening abnormalities. Coronary artery disease was quantitatively defined as a diameter stenosis >/=50% in a major epicardial artery. Rest septal motion was normal (apart from the early systolic septal notch) in 34 patients (53%) and abnormal in 30 patients (47%). Rest septal thickening was normal in 32 patients (50%) and abnormal in 32 patients (50%). All seven patients with a QRS duration >/=160 ms and an abnormal QRS axis had abnormal rest septal motion and thickening. Inter-observer agreement for ischaemia was 88%. In all but one patient disagreement was in the septum. For the anterior and posterior circulation, respectively, sensitivity was 60% (9/15) and 67% (8/12), specificity was 94% (46/49) and 98% (51/52), and accuracy was 86% (55/64) and 92% (59/64). Sensitivity for the anterior circulation tended to be better in patients with normal rest septal thickening (83% vs 44%). CONCLUSIONS: Dobutamine-atropine stress echocardiography has excellent diagnostic specificity in left bundle branch block patients with suspected coronary artery disease. In patients with abnormal rest septal thickening, however, dobutamine-atropine stress echocardiography may lack good sensitivity for detection of coronary artery disease in the anterior circulation. Left bundle branch block patients who potentially most benefit from dobutamine-atropine stress echocardiography may initially be selected by their resting electrocardiogram.

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