Clinical Study Of Myocardial Perfusion In Patients With Hypertension By CT Myocardial Perfusion Imaging

BackgroundHypertension,as one of the important risk factors for cardio-cerebrovascular diseases,is closely related to acute and chronic cardiovascular events.Hypertension is often associated with the occurrence and development of myocardial ischemia,especially in hypertensive patients with left ventricular hypertrophy.The studies found that,using different myocardial perfusion imaging techniques(including magnetic resonance imaging,single-photon emission computed tomography and positron emission tomography),hyperemic myocardial blood flow(MBF)was significantly decreased in hypertensive patients with non-obstructive coronary artery stenosis.Thus,quantifying myocardial perfusion can identify myocardial ischemia in hypertensive patients as early as possible and provide more information for more reasonable clinical treatment and prognosis.As a newly developed imaging modality,stress dynamic CT myocardial perfusion imaging(CT-MPI)can quantify myocardial perfusion and provide a one-stop evaluation of coronary artery morphology and myocardial perfusion function.However,few studies have used CT-MPI to evaluate the effect of hypertension on myocardial perfusion in hypertensive patients with non-obstructive coronary artery stenosis.The relationship between CT-MPI-derived myocardial perfusion parameters and cardiovascular risk factors has not been clearly reported.Therefore,this study aims to explore the characteristics and the influencing factors of myocardial perfusion by CT-MPI in hypertensive patients with non-obstructive epicardial coronary stenosis.Objectives1.To explore the feasibility of CT-MPI in evaluating myocardial perfusion in patients with hypertension.2.To explore the characteristics of myocardial perfusion by CT-MPI in hypertensive patients with non-obstructive epicardial coronary stenosis.3.To evaluate the influencing factors of myocardial perfusion by CT-MPI in hypertensive patients with non-obstructive epicardial coronary stenosis.Methods1.Study population and groupingNinety-five patients with stable chest pain and confirmed coronary stenosis<50%by coronary computed tomography angiography(cCTA)in Qilu Hospital of Shandong University were selected and underwent CT-MPI examination.According to the 2018 ESC/ESH Clinical Practice Guidelines for the Management of Arterial Hypertension,all enrolled populations were divided into the hypertension group(HTN,systolic blood pressure>140 mmHg or diastolic blood pressure>90 mmHg)and the non-hypertension group(non-HTN,systolic blood pressure<140 mmHg and diastolic blood pressure<90 mmHg).Patients with HTN were further divided into left ventricular hypertrophy group[LVH,left ventricular mass index(LVMI)of>108 g/m2 for men or>99 g/m2 for women]and non-hypertrophy group(non-LVH,LVMI of≤108 g/m2 for men or≤99 g/m2 for women).2.Clinical dataTake notes of age,sex,height,weight,systolic blood pressure,diastolic blood pressure,heart rate,smoking,alcohol intake,diabetes mellitus,hyperlipidemia and family history of coronary heart disease(CHD)of all enrolled subjects.Calculating body mass index(BMI)and body surface area(BSA)based on height and weight.Duration of hypertension and anti-hypertension medication were collected in hypertensive patients.3.EchocardiographyAll subjects underwent echocardiography taking left lateral decubitus position,and connected with an synchronized limb lead electrocardiogram.The linear measurements of septal wall thickness diastole(SWTd),left ventricular end diastolic distance(LVEDd)and post wall thickness diastole(PWTd)are made from the parasternal long-axis acoustic window at the end of diastole.Left ventricular mass index(LVMI)was calculated according to the formula.4.CT-MPICT-MPI and cCTA scanning were performed successively in all enrolled subjects with third-generation dual-source CT.The data derived from CT-MPI scanning were processed by workstation(Volume Perfusion CT Body,Syngo MMWP workstation,Siemens Healthcare)to quantify the global left ventricular MBF and myocardial blood volume(MBV).The data of cCTA scanning were reconstructed using curved multiplanar reformats by the software(Circulation,Syngo MMWP workstation,Siemens Healthcare)to assess the degree of coronary stenosis.This study enrolled patients with coronary stenosis<50%of the luminal diameter in each coronary.5.Statistical analysisStatistical analysis involved use of SPSS version 20.0(IBM Corp.,Armonk,NY)statistical software.Categorical variables were presented as numbers(n)and percentages and compared using the χ2 test.The Shapiro-Wilk test was used to test the normality for continuous variables.Continuous normally distributed variables were presented as the mean ± SD and were compared using the independent samples t-test.Non-normally distributed variables were presented as the median and interquartile range(25-75 percentiles).For the non-normally distributed data of MBF and MBV,we transformed them to normally distributed data(nMBF and nMBV,respectively)using the normal score of case order,which were compared using the independent samples t-test.Both univariate linear regression analysis and multivariate stepwise linear regression analysis were performed to analyze the relationship between nMBF,nMBV and general clinical variables or echocardiography data.Spearman correlation coefficients were calculated for the relationship between continuous variables and MBF,MBV.A two-tailed p<0.05 was considered statistically significant for all statistics.Results1.Clinical data1.1.The comparison between HTN and non-HTN groupOf the 95 enrolled subjects,31 individuals were in the HTN group and 64 were in the non-HTN group.HTN group had significant higher systolic blood pressure,diastolic blood pressure,age,BMI,BSA,smoking history and hyperlipidemia prevalence than non-HTN group(P<0.05).Significant differences were not found between the groups in sex,heart rate,alcohol intake,diabetes mellitus and family history of CHD(P>0.05).1.2.The comparison between LVH and non-LVH groupNo significant differences were found between LVH and non-LVH group in age,sex,BMI,BSA,systolic blood pressure,diastolic blood pressure,heart rate,smoking,alcohol intake,diabetes mellitus,hyperlipidemia,family history of CHD,duration of hypertension and treated HTN prevalence(P>0.05).LVH group had higher calcium channel blockers intake prevalence(P<0.05),but no significant differences were found in angiotensin converting enzyme inhibitors/angiotensin receptor inhibitors,beta-blockers and diuretics intake prevalence(P>0.05).2.Echocardiography data2.1.The comparison between HTN and non-HTN groupBoth HTN and non-HTN groups had similar LVEDd(P>0.05).However,subjects with HTN showed significant increases in SWTd,PWTd and LVMI than those withnon-HTN(P<0.05).2.2.The comparison between LVH and non-LVH groupThe LVH group had significantly higher LVEDd,SWTd and PWTd than non-LVH group,resulting in a higher LVMI(P<0.05).3.CT-MPI parameters3.1.The comparison between HTN and non-HTN groupThe MBF in HTN group was significant lower than that of non-HTN group(P<0.05),but there was no significant difference in MBV(P>0.05).3.2.The comparison between LVH and non-LVH groupThe LVH group showed significantly lower MBF than the non-LVH group(P<0.05),but there was no significant difference in MBV(P>0.05).4.Correlation analysis of CT-MPI parameters with clinical and echocardiography data4.1.Correlation analysis in all enrolled populationMBF was negatively correlated with age,BMI,BSA,SBP,LVEDd,SWTd,PWTd and LVMI(P<0.05 for all).MBV was negatively correlated with age and PWTd(P<0.05 for all).4.2.Correlation analysis in HTN groupMBF was negatively correlated with BMI,SWTd and LVMI(P<0.05 for all).MBV was positively correlated with SBP(P<0.05).5.The linear regression analysis between CT-MPI parameters and clinical and echocardiography data5.1.The linear regression analysis in all enrolled population5.1.1.The linear regression analysis between nMBF and clinical and echocardiography dataUnivariate linear regression analysis revealed that nMBF was associated with age,sex,BMI,BSA,SBP,smoking,LVEDd,SWTd,PWTd and LVMI(P<0.05).Multivariate stepwise linear regression analysis showed that both BSA and LVMI were the independent predictors of nMBF(R=0.525 for combination,P<0.001).5.1.2.The linear regression analysis between nMBV and clinical and echocardiography dataUnivariate linear regression analysis revealed that nMBV was associated with age and PWTd(P<0.05).Multivariate stepwise linear regression analysis showed that age was the independent predictor of nMBV(R=0.343 for combination,P=0.001).5.2.The linear regression analysis in HTN group5.2.1.The linear regression analysis between nMBF and clinical and echocardiography dataUnivariate linear regression analysis showed that nMBF was associated with sex,BMI,smoking,SWTd,PWTd and LVMH(P<0.05).Multivariate linear regression analysis found that both female and LVMI were independent predictors of nMBF(R＝0.658 for combination,P<0.001).5.2.2.The linear regression analysis between nMBV and clinical data and echocardiography parametersUnivariate linear regression analysis showed that no factor was associated with nMBV(P>0.05).Conclusion1.CT-MPI can be used as a new noninvasive modality to evaluate myocardial perfusion in hypertensive patients.2.MBF was decreased in hypertensive patients with non-obstructive epicardial coronary stenosis,while MBV was not found significant difference.MBF was further reduced in patients with left ventricular hypertrophy,while MBV remained unchanged.3.In hypertensive patients with non-obstructive epicardial coronary stenosis,decreased MBF is significantly correlated with increased LVMI.