Can transthoracic Doppler echocardiography be used to detect coronary slow flow phenomenon?

Background Coronary slow flow phenomenon （CSFP） is an important, angiographic clinical entity but is lacking non-invasive detecting techniques. This study aimed to elucidate the value of transthoracic Doppler echocardiography （TTDE） in the diagnosis and monitoring of coronary slow flow in left anterior descending （LAD） coronary artery.Methods We consecutively enrolled 27 patients with CSFP in LAD detected by coronary arteriography from August 2009 to April 2010. Thirty-eight patients with angiographically normal coronary flow served as control. Corrected thrombolysis in myocardial infarction （TIMI） frame count （CTFC） was used to document coronary flow velocities. All subjects underwent TTDE within 24 hours after coronary angiography. LAD flow was detected and the coronary diastolic peak velocities （DPV） and diastolic mean velocities （DMV） were calculated.Results Sixty of 65 （92.3%） subjects successfully underwent TTDE. Baseline clinical characteristics were similar between the two groups. Coronary DPV and DMV of LAD were significantly lower in the CSFP group than in the control group （（0.228±0.029） m/s vs. （0.302±0.065） m/s, P=0.000; （0.176±0.028） m/s vs. （0.226±0.052） m/s, P=0.000,respectively）. There was a high inverse correlation between CTFC and coronary DPV and DMV （r=-0.727, P=0.000;r=-0.671, P=0.000, respectively）. Receiver operating characteristic （ROC） curve showed that the area under the curve （AUC） was less than one half for coronary DPV （AUC=0.104） and DMV （AUC=0.204）, respectively.Conclusions In patients with CSFP, there is a high inverse correlation between CTFC and coronary diastolic flow velocities in the LAD coronary artery, as measured by TTDE. The value of TTDE in the monitoring and evaluation of coronary flow in patients with CSFP deserves further investigation.