Changes Of Left Ventricular Function In Patients With Coronary Slow Flow And Different Exercise Stress Test Result

Objective: Coronary slow flow(CSF)is a kind of coronary microvascular disease,which often causes resting angina pectoris,sometimes may cause exertional angina pectoris or mixed angina pectoris,and can lead to left ventricular dysfunction.Some of patients with CSF have positive results in exercise stress test,but it has not been clear whether there are differences in left ventricular function among patients with CSF and different exercise test results.This study was carried out to compare the differences of clinical characteristics and left ventricular function among patients with CSF and different exercise test results for the purpose of risk stratification of patients with CSF and aiding in the individual management.Method: Patients with coronary artery stenosis no more than 30% were selected from June 2019 to November 2020 who were admitted to cardiology department of the first affiliated Hospital of China Medical University and underwent selective coronary angiography.Coronary blood flow velocity was evaluated by TIMI Frame Count(TFC)method,and left ventricular function was assessed by conventional echocardiography,tissue Doppler echocardiography and two-dimensional speckle-tracking technique.Finally,63 patients with CSF were included,61 same-period and age-matched patients with normal coronary blood flow were included as controls.The differences of general clinical data and left ventricular function between the two groups were compared.There were 31 patients with CSF and 19 patients in the control group received ECG exercise stress test.According to exercise test result,the patients were subdivided into three subgroups: positive exercise test CSF group,negative exercise test CSF group,and control group.The differences of general clinical data and left ventricular function among the three groups were compared.Result: 63 patients with CSF and 61 patients with normal coronary flow as controls were enrolled in the study.The proportion of male patients in CSF group was significantly higher than controls(P=0.001).Compared with controls,the patients in CSF group had significantly increased hematocrit(HCT),uric acid(UA)and homocysteine(Hcy)(P<0.001,P < 0.001 and P=0.022,respectively).Left ventricular end-diastolic volume(LVEDV)was significantly increased in CSF group than in controls(P=0.038),while left ventricular global systolic longitudinal strain(LVGLS)was significantly decreased in CSF group than in controls(P=0.015).Correlation analysis showed that mean TIMI frame count was positively correlated with HCT and UA(r=0.417,P<0.001 and r=0.299,P<0.001,respectively),while negatively correlated with LVGLS(r=-0.228,P=0.018).A total of 50 patients underwent ECG exercise stress test.In CSF group,8 cases were positive,21 cases were negative,2 cases were forced to suspend the test ahead of time due to lack of physical strength,the positive rate of exercise test was about 26%.In controls,1 case was positive,18 cases were negative,and the positive rate of exercise test was about 5%.According to exercise test result,these patients were subdivided into positive exercise test CSF group(n=8),negative exercise test CSF group(n=21)and control group(n=18).Subgroup analysis showed that there was no difference in TIMI frame count between the positive exercise test CSF group and the negative exercise test CSF group(P≥0.05),and there was also no difference in general clinical information and blood biochemical indexes among the three groups(P≥0.05).Compared with the negative exercise test CSF group and the control group,LVGLS was significantly lower in the positive exercise test CSF group(P=0.004 and P=0.009,respectively),while left atrial end-systolic dimension(LAD)in the negative exercise test CSF group was significantly larger than that in controls(P=0.037).Conclusion: CSF is more common in male patients.HCT,UA and Hcy were significantly increased and left ventricular systolic function was significantly decreased in patients with CSF.There were differences in left ventricular function among CSF patients with different exercise test results.Left ventricular systolic function was impaired more seriously in patients with CSF and positive exercise test.In patients with CSF and negative exercise test,the left atrium was significantly enlarged,while the left ventricular function was not impaired significantly.