Comparison of Exercise and Dipyridamole Tc-99m Tetrofosmin Scintigraphy for the Diagnosis of Coronary Artery Disease in Patients with Left Bundle-Branch Block

It is well known that the specificity of myocardial perfusion scintigraphy (MPS) for the diagnosis of coronary artery disease (CAD) is low in patients with left bundle branch block (LBBB). It has been suggested that the use of IV dipyridamole (Dp) instead of exercise as a stress modality increases the diagnostic accuracy of the test. Accordingly, symptom-limited treadınili exercise and IV Dp (0.56 mg/kg) Tc-99m tetrofosmin scintigraphies were performed in 29 consecutive patients presented with chest pain and LBBB. MPS were analysed qualitatively with previous knowledge of patients' gender and LBBB status and myocardial segments were defined as normal, with reversible defect, mild persistent defect and severe persistent defect. All patients underwent coronary angiography. Patients having stenoses more than 50% in one or more major coronary arteries or their major branches were considered to have CAD. In 15 patients with CAD, significant perfusion defects (2 reversible, 6 mild persistent and 3 severe persistent) were detected after exercise in ll (73%) and after IV Dp in 10 (67%) (2 reversible, 5 mild persistent and 3 severe persistent). Of 14 patients with normal angiographies 2 (14%) di splayed significant perfusion defects (2 mild persistent) after exercise and 1 (7%) (1 mild persistent) defect after IV Dp. In conclusion, no difference was found between the diagnostic values of exeereise and Dp Tc-99m tetrofosmin MPS when analysed with previous knowledge of patients' gender and LBBB status for the CAD in the patients with LBBB.