| Objective: The main clinical manifestations of patients with coronary slow flow phenomenon are atypical chest pain.Although there are abnormalities in objective examinations,such as ST-T changes in electrocardiogram,its report of coronary angiography showed the coronary artery vessel wall was smooth or only with slight atherosclerosis.These patients are offten associated with multiple cardiovascular risk factors,such as hypertension,diabetes,smoking and so on.They can develop into acute coronary syndrome and sudden death.However,it is still not clear about the risk factors may affect the coronary slow flow and the effect on cardiac function caused by coronary slow flow phenomenon currently.Methods: By analyzing the clinical data of the population with coronary slow phenomenon and comparing with the population who was non-coronary slow phenomenon,to reveal the related risk factors which can cause the coronary slow phenomenon in the special population in the first part;in the second part,to investigate the changes of left ventricular function and related factors in patients with coronary slow flow phenomenon under dobutamine stress test,and to evaluate the safety of dobutamine stress test in the patients with coronary slow flow phenomenon.Materials and methods: All the patients were underwent the examination of coronary angiography for the reason of chest pain.According to the results of coronary angiography,152 CSFP patients(106 males and 51 females),were enrolled by TIMI frame number method.The control group consisted of 96 patients(45 males and 51 females),whose epicardial coronary artery had no severe stenosis and normal blood flow confirmed by coronary angiography at the same time.The relationship between cardiovascular risk factors and CSFP was analyzed between the two groups.In the second part,142 patients in CSFP group(103 males and 39 females)and 44 patients in control group(25 males and 19 females)were re-screened after coronary angiography.All patients underwent routine transthoracic echocardiography and two-dimensional speckle tracking echocardiography.CSFP patients underwent two-dimensional speckle tracking echocardiography under dobutamine stress loading to measure left ventricular strain and strain rate at different doses of stress loading.Results:The first part:1.The comparison of baseline characterics and TIMI Frame Counts(TFC)between the CSFP group and the control group: there were significant differences in male,diastolic blood pressure,pulse pressure,smoking history,waist circumference(WC)and lipid accumulation product(LAP)between the groups,and no significant difference was observed between the groups in baseline characteristics including age,hypertension history,systolic blood pressure,diabetes history,uric acid,total cholesterol,low density lipoprotein,high density lipoprotein,triglyceride and body mass index(BMI)).The use of aspirin,beta-blocker,CCB,ACEI/ARB,nitrate and statins was no significant difference between the CSFP group and the control group.The value of TFC for LAD,LCX,and RCA,as well as mean TFC were significantly higher in the CSFP group compared with the control group.2.Multivariate linear regression analysis of factors effect on coronary slow flow: With the frame number of coronary slow flow as dependent variable,the risk factors of cardiovascular diseases with statistical differences between the two groups were taken as independent variables(male,diastolic blood pressure,pulse pressure,smoking history,waist circumference,LAP).Multivariate linear regression method was used to analyze the risk factors.The results showed that pulse pressure and LAP were independent predictors of coronary slow flow.3.Distribution of vessels involved in coronary slow flow: Single vessel involvement was more common in coronary slow flow(94.7%)than double vessel involvement(5.2%).Simultaneous involvement of three coronary arteries was not observed.Among them,131 cases(86.2%)were involved in LAD,10 cases(6.6%)in LCX,3 cases(2.0%)in RCA and 8 cases(5.2%)in LAD with LCX.The second part:1.The occurrence of arrhythmia in patients with different doses of drug load: No atrial fibrillation or atrial flutter arrhythmia occurred in all patients.The incidence of atrial premature beats and ventricular premature beats increased with the increase of dose when given different doses of drug loading.Under the drug loading of 20 ug/kg·min,there were 3 cases(2%)of paroxysmal ventricular tachycardia,including 1 case of LAD slow blood flow and 2 cases of LAD combined with LCX.2.Analysis of termination of drug load test in CSFP group: When the dosage of dobutamine reached 15-20 ug/kg·min,the incidence of non-cardiac side effects(headache,nausea,palpitation,etc.)increased significantly(14.7%,30.9%);3 cases of new abnormal ventricular wall motion(2.0%);when the dosage reached 10 ug/kg·min,the incidence of chest distress increased with the increase of dosage(2.1%,11.9%,29.5%);The incidence of ST-segment depression(> 1 mm)in ECG was 9.1% and 16.9% respectively in the drug loading stage of 15-20/kg·min,while the incidence of abnormal systolic increase was low,only in the drug loading stage of 15-20 ug/kg·min,the incidence was 0.7% and 2.8% respectively.3.Changes of left ventricular function parameters under different drug loading doses: There was no significant difference in left ventricular longitudinal strain,circumferential strain and strain rate parameters between CSFP patients and control group at rest.The results of different dosage loads of dobutamine in CSFP patients showed that the longitudinal strain and strain rate of left ventricle increased with the increase of the dose of dobutamine,and then LS and LSRS decreased with the increase of the dose.The change of LSRed was the earliest in the dobutamine drug load test.Indicators reflecting left ventricular circumferential strain and strain rate decreased significantly when the drug dose was 20 ug/kg·min compared with the previous stress loading doses.4.The correlation between cardiovascular risk factors and left ventricular strain and multivariate linear regression analysis: Cardiovascular risk factors in CSFP group: diastolic pressure,waist circumference,pulse pressure,LAP,body mass index were correlated with left ventricular strain_.Further multiple linear regression analysis showed that pulse pressure and LAP were independent predictors of left ventricular strain.ConclusionThe first part:1.There was no significant difference in sex ratio,age,smoking,body mass index,low density lipoprotein cholesterol,high density lipoprotein cholesterol,total cholesterol,hypertension and diabetes between the two groups.2.The index of arterial stiffness has a good correlation with coronary slow flow,which is an independent predictor of the occurrence of coronary slow flow.3.The lipid accumulation product reflecting visceral fat is better than BMI and waist circumference.It is an independent predictor of coronary slow flow.4.In this study,coronary slow flow was observed to be the most common phenomenon in LAD,followed by LCX and RCA,and bilateral and multivessel involvement was rare.The second part:1.Low-dose dobutamine loading test is safe in patients with single vessel involvement of coronary slow flow.2.Compared with the control group,the left ventricular systolic and diastolic function of the patients with coronary slow flow at rest did not decrease significantly.3.Coronary slow blood flow has an effect on left ventricular function.Myocardial ischemia can be induced by dobutamine loading test.4.Speckle Tracking Echocardiography(STE)combined with dobutamine loading test can accurately evaluate left ventricular function in patients with coronary slow flow and detect subtle changes in heart function.5.In the condition of myocardial ischemia,the left ventricular longitudinal strain and diastolic function first decreased,followed by the longitudinal systolic strain.Longitudinal strain is superior to circumferential strain in sensitivity to ischemia. |
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