Comparison of thallium-201 exercise SPECT and dobutamine stress echocardiography for diagnosis of coronary artery disease in patients with left bundle branch block.

The present study assessed and compared the diagnostic accuracy of thallium-201 (Tl-201) exercise myocardial single photon emission computerised tomography (SPECT) and dobutamine stress echocardiography (DSE) for detection of coronary artery disease (CAD) in patients with left bundle branch block (LBBB). Study population consisted of 26 consecutive patients with permanent LBBB who were suffering from chest pain. Patients (8 women, 18 men mean age = 57+/-8 years) were studied with DSE, Tl-201 SPECT and coronary angiography (CAG). Three different approaches for diagnosis of CAD were used to identify CAD in left arterial descending (LAD) coronary artery territories in scintigraphic studies: (1) Approach A (conventional approach): involvement of septal, and/or anterior, and/or apical wall. (2) Approach B: involvement of anterior and septal wall irrespective of apical wall. (3) Approach C: involvement of septum, anterior and apical wall. DSE gave a sensitivity of 91%, specificity of 92% and accuracy of 92% for diagnosis of CAD in the LAD coronary artery territory. Tl-201 SPECT (conventional approach) gave a sensitivity of 100%, specificity of 42% and diagnostic accuracy of 69% for diagnosis of CAD in the LAD coronary artery territory. Sensitivity, specificity and diagnostic accuracy of approach C were 33, 85 and 57% respectively. The specificity of Tl-201 SPECT significantly increased in approach C when compared with approach A and B (p < 0.02). However sensitivity of the Tl-201 SPECT with approach C showed significant decrease when compared with DSE and approach A and B (p < 0.005). Specificity of DSE for diagnosis of CAD in LAD were significantly higher than those of Tl-201 SPECT regarding the approach A and B (p < 0.01). In conclusion the use of DSE for diagnosis of CAD in patients with LBBB seems to be more suitable than Tl-201 SPECT.