PURPOSE: Thallium single photon emission computed tomography (SPECT) has been known as its high incidence of false positive result, even though quantitative perfusion SPECT scans have advantage in differentiating attenuation artifacts from true perfusion defects. Dyssynchrony is one of the causes of false positive result of SPECT and by normal QRS duration, dyssynchrony cannot be excluded. We aimed this study to evaluate the dyssynchrony might be a reason for false positive results of myocardial SPECT in stable angina patients.
METHODS: 30 patients with clinically diagnosed stable angina and positive myocardial SPECT results who underwent coronary angiogram were included. These patients were divided into two groups (group I, patients with positive SPECT results and normal coronary angiography (n=16, mean age=69.4±5.8 years, 8 males), group II patients with positive SEPCT results and significant coronary lesion in coronary angiography (n=14, mean age=71.1±4.3 years, 7 males). We examined conventional echocardiographic parameters and dyssynchrony index. RESULTS: There were no significant differences in conventional echocardiograpic parameters (LV dimension, volume, ejection fraction and E/E’) between two groups. The inter-ventricular (15.4 ±12.6 vs. 17.3 ±12. msec, P=0.784) and intra-ventricular (115.1±20.7 vs. 106.5±27.1msec, P=0.409) electromechanical delay was not significantly different (Time delay between anterior and inferior wall was no significantly different (basal segment : 60.0±50.8 vs. 66.9±49.5, P=0.827, mid segment ; 77.0±58.9 vs. 73.3±51.1msec, P=0.911). But the basal segment time delay between lateral and septal wall peak systolic velocity were significantly delayed in group I (76.9±43.3 vs. 28.8±27.1 P=0.013). CONCLUSIONS: In patients with stable angina, dyssynchrony of left ventricle might be the reason for false positive SPECT results in patients with stable angina. Myocardial SPECT examination with dyssynchrony index measurement might be good tool for screen possible normal coronary angiographic results.
|
