Clinical Significance of Slow Flow Velocity in the Distal Left Anterior Descending Coronary Artery Detected by Transthoracic Doppler Echocardiography

ABSTRACT

BACKGROUND AND OBJECTIVES: The aim of this study was to test whether flow velocity in the distal left anterior descending coronary artery (LAD) measured using transthoracic Doppler echocardiography (TTE) can predict pathologic coronary flow dynamics. SUBJECTS AND METHODS: We prospectively examined 222 subjects (mean age 57+/-9 yrs, MF=13290) including 55 subjects with myocardial infarction (MI group, mean age=57+/-9, MF-4510), 68 with typical angina (Angina group, mean age=62+/-8, MF=4424) and 99 with atypical chest pain and normal coronary angiogram (Control group, mean age=54+/-10, MF=43+/-56). After obtaining tubular color flow signals of the distal LAD using TTE with a special preset program for a low velocity range, the peak (PDV) and mean (MDV) diastolic velocity as well as velocity time integral (VTI) were measured. The echocardiographic parameters of distal LAD flow were compared with the coronary angiographic findings including lesion classification according to ACC/AHA guidelines and the percent diameter stenosis. RESULTS: The average PDV was 20.3+/-9.7 cm/sec in patients with atypical chest pain and normal coronary angiogram, 16.8+/-8.5 cm/sec in patients with typical angina without myocardial infarction and 15.0+/-7.5 cm/sec in those with myocardial infarction (p<0.01 versus the MI group and Angina group, respectively). The PDV was found to be significantly related to the percent diameter stenosis (r=-0.292, p=0.002). The PDV in the group with complex lesion was significantly lower than that of the group with simple lesion. A value of PDV<14 cm/sec had a sensitivity of 76.6% and a specificity of 91.5% for predicting complex lesion of the LAD in groups including myocardial infarction and angina. CONCLUSION: Slow flow velocity in the distal LAD as demonstrated by TTE strongly predicts complex lesions. Baseline coronary flow velocity using TTE provides valuable information about the pathologic condition.