J. Federman*, PA. Pellikka, JB. Seward.

Mayo Clinic, Rochester, Minnesota, USA.

LBBB is associated with an increased incidence of coronary artery disease )CAD) or cardiomyopathy and management decisions will be affected by the specific diagnosis.  Various nuclear stress procedures have been used to try to distinguish between these 2 diagnoses but there are problems with sensitivity and specificity.  Echocardiography (echo) demonstrates changes in septal motion with a LBBB which can make the interpretation of stress studies difficult.  If wall thickening is also assessed the sensitivity and specificity should improve.  To evaluate the true accuracy of Dobutamine stress echo (DSE) in excluding significant coronary artery disease in a group of patients (Pt) with LBBB we retrospectively assessed a group who had no prior significant CAD.  Of these 4801 Pt with stress DSE between 1/1/94 .1/1/99, 207 Pt had a LBBB.  Of these 20 Pt had coronary angiography (CA) within 30 days post DSE (0 .24 mean 6.1 days), with no prior acute myocardial infarction, coronary bypass graft surgery, coronary angioplasty or CA within 5 yrs.  There were 9 males and 11 females aged 37‑-85 (mean 66.7) yr and all were in sinus rhythm.  Echo left ventricular ejection fraction was <30% in 7 Pt, 30‑-50% in 5 Pt and >50% in 8 Pt.  Indications for DSE were chest pain 8, pre surgery in 7, aortic valve disease in 2 and dyspnoea in 3.  In 15 Pt DSE suggested CAD with 2 Pt being normal and 3 Pt having lesions <50%.  In 10 Pt, lesions >50% were present (>70% in 5 Pt).  In 5 Pt with DSE suggesting no CAD, 1 Pt had no CAD, 3 Pt lesions <50% and 1 Pt lesions >70%.

LAD‑-Left anterior descending, LCX‑-Left circumflex, RCA‑-Right coronary, PPA‑-Positive predictive accuracy, NPA‑-Negative predictive accuracy.

Conclusion:  DSE has limited specificity in the diagnosis of CAD in patients with LBBB with its greatest benefit being in its negative productive accuracy.

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