The Survey Of Coronary Atherosclerotic Plaque Detected By MSCT And The Analysis Of Its Risk Factors In Asymptomatic Subjects In Guangzhou

BackgroundCoronary atherosclerosis (coronary artery disease, CAD) is one of major diseases hazarding human health,with the improvement of living standards and the average life expectancy, its morbidity and mortality rates increasing year by year, the potential incidence is more and more larger crowd and the age of onset is more younger.From 1984 to 1993,China MONICA program showed standardized incidence of acute CAD event rate of average annual growth rate of 2.3%. In most heart disease patients with sudden death or myocardial infarction, there is none chest pain or dyspnea symptoms of fatigue, which more emphasis on early detection of plaque and the coronary atherosclerosis treatment. More and more literatures reported that Coronary risk stratification using a risk factor only-based scheme is a weak discriminator of so the use of imaging methods to detect occult coronary artery plaques is very important.Current conventional coronary angiography can show the stenosis of coronary artery lumen,but it can not display the characteristic of coronary atherosclerotic plaque,and there is an obvious underestimate the potential. Intravascular ultrasound (intravascular ultrasound, IVUS) through selective operation in detail to determine plaque volume, vascular wall remodeling in the overall status and plaque characteristics, is now considered as "the gold standard" for detection and diagnosis of coronary artery atherosclerotic plaques. However, IVUS examination need to adopt intrusive inspection methods and equipment, and it is high cost, so it is not adopt for large-scale population studies. At present, the Application of non-invasive method to identify and assess the mild stenosis of the coronary atherosclerotic plaque imaging technology has become a hot spot. Although MRI can better show coronary artery stenosis, it can only show fewer display segments with limited value.64-slice CT greatly improved time resolution, combined with ECG-gated techniques and powerful image post-processing functions of CT coronary angiography, is of vital value in the detection of the plaque and the evaluation of plaque type, and MSCT is a non-invasive examination with relatively lower cost. Multiple single-center study confirmed that 64-slice spiral CT (64-MSCT) is a safe,effective,relatively economically method for screening and diagonsing of early coronary heart disease investigation. Coronary CT angiography (CT angiography, CTA) assessed the plaques mainly by measuring the CT values. Studies indicated that plaque CT value of different types and IVUS echo characteristics show a strong correlation. A previous study by Leber et al. demonstrated that MSCT found that the sensitivity of the three kinds of plaques were 78%,78%,95%.There are many literatures on coronary artery plaque characteristics in the clinical CAD patients, but there is a paucity of data regarding the prevalenc and characteristics of coronary atherosclerotic plaques in asymptomatic subjects. The latest literature abroad reported Coronary atherosclerosis plaque incidence in asymptomatic population by MSCT arrived to 22%, and 25% individuals diagnosed as having coronary heart disease by MSCT were classified in the low-risk group. As the incidence of occult CAD is so high, strengthening the prevention of CAD is particularly important. there is no reported in the literature about the features of coronary atherosclerostic plaques in asymptomatic middle-aged subjects in Guangzhou, This research is aimed to investigate MSCT findings and features of coronary artery atherosclerostic plaques in asymptomatic subjects in Guangzhou.According MONICA study in Beijing, we should emphasis on primary prevention in the formulation of coronary heart disease prevention strategies, it needs to quickly find out what the factors related with CAD mostly. More and more evidence indicated that non-calcified plaque and the occurrence of acute coronary syndrome has a strong correlation. Thus, prevention of non-calcified plaque is particularly important. The research on traditional risk assessment tools for research is a hot issue today, some literatures have confirmed that the different species in different areas, risk factors are not the same, and coronary risk stratification using a risk factor only-based scheme is a weak discriminator. Patients with little or no plaque might be subjected to lifelong drug therapy, whereas many others with substantial plaque might be undertreated or not treated at all. On earth which independent risk factors of cononary atherosclerotic plaques in Guangzhou are, and which non-calcified plaque independent risk factors are, MCAP and CAP are the same? Another purpose of this study is to assess the relationship between clinical risk factors with cononary atherosclerosis plaques, to provide a reference.for making strategies of cardiovascular disease in Guangzhou.PurposePart oneTo investigate MSCT findings and features of coronary artery atherosclerostic plaques in asymptomatic middle-aged subjects in Guangzhou.Part two To assess the Relationship between cardiovascular risk factors and extent of noncalcified Coronary Atherosclerotic Plaque(NCAP), mixed Coronary Atherosclerotic Plaque(MCAP), and calcified coronary atherosclerotic plaque (CAP) in people with no history of cardiovascular disease in Guangzhou..Material and MethodsPart one280 middle-aged asymptomatic subjects (age 52±6,53% years,53% men) who underwent CTA (64-slice multidetector row computed tomography) as part of a general health evaluation were consecutively enrolled. To analysis the morbidity and clinical epidemiology of coronary Artery atherosclerostic plaques, all plaques were classified as NCAP, MCAP and CAP. All plaque components were assessed on 17 segment.Part twoBlood biochemical examination were done on the 280 middle-aged subjects in one month after having CTA examination.Statistical analysisThe statistical analysis were performed with the statistcal software packgae SPSS for Widow,version 13.0.Part one1. All subjects were divided into two groups:men and women.Chi-square test was applied for numeration data, T-test or Wilcoxon signed-rank test was used for T-test or Wilcoxon signed-rank test was used.2. Age quartiles (,45 to 52,53 to59, and>59 years of age) were selected to serve as cutoff values to assess differences in the extent of NCAP, MAP, and CAP according to age and ANOVA were performed.If the variance in each group missing, using Welch correction methods, to compare two groups using the Dunnett T3 method. And analyze the age and the number of segmental plaque occurrence correlationy.Part two1. To assess whether the risk factor profiles were different across the 4 groups of subjects with no plaque, exclusively NCAP, MCAP, oCAP we performed ANOVA for normally distributed variables Chi-square test was applied for numeration data.2. Further, we performed multivariable logistic regression analysis to determine the association between NCAP, MCAP, or CAP and the individual risk factors.3. we performed multivariable logistic regression analysis to determine the association between CHD and the individual risk factors.ResultsPart onePlaques were found in 105 of 280 (38%) patients.27 subjects were diagnosed by MSCT as coronary heart disease(CHD), and 6 subjects (22%) were graded as severe diameter narrowing in these subjects. Morbidity of plaques were significantly higher in male than that in female in less than 60 years old subjects, but in subjects older than 60 years old, no significantly difference was found in the morbidity of CHD. The plaques were detected in 189 segments of 4760 segments of 280 subjects. The left anterior descending coronary artery (LAD) was affected in 110 segments (58%) and CAP emerged as the most frequent type of atherosclerotic plaque(50%).Plaques were found in 105 of 280 (38%) subjects. NCAP,MCAP and CAP were detected respectively in 53,42 and 94 segments. The extent of NCAP decreased (F=38.36, P<0.001)and the extent of MCAP and CAP increased with age(F=6.95, F=9.35,P=0.001,P<0.001)Part two The number of four groups for subjects with no plaque, exclusively NCAP, MCAP, and CAP is respectively 175,14,42 and 49.Among individual risk factors, male and triglyceride may be independent risk factors of the extent of NCAP,age and triglyceride may be independent risk factors of the extent of MCAP, while HDL may be an independent protect factor, age may be independent risk factor of the extent of CAP, inversely HDL may be independent protect factor.Total cholesterol may be independent risk factor of CAD, inversely HDL may be also an independent protect factor.ConclusionPart oneAccording to CT finding,the morbidity of coronary artery atherosclerostic plaques in asymptomatic middle-aged subjects in Guangzhou is 38%, and the prevalence of occult CAD in apparently healthy individuals was not negligible.Part twoThe occurrence of non-calcified plaques may not be impacted by age, and it may be more likely occurred on the male population. Male population should pay attention to the prevention in the early years and control of triglycerides; Reduce triglycerides and increase HDL-C is a patch to prevent atherosclerotic plaques. The he role of high-density lipoprotein should be concerned.