PREDICTORS OF SUBCLINICAL ATHEROSCLEROSIS IN PREMENOPAUSAL WOMEN

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1 Acta Medica Mediterranea, 2014, 30: 941 PREDICTORS OF SUBCLINICAL ATHEROSCLEROSIS IN PREMENOPAUSAL WOMEN MESUT AYDIN*, RECAI ALEMDAR 1, HABIB CIL 2, FAHRI HALIT BESIR 3, HAKAN OZHAN 4, YUSUF AYDIN 5, SERKAN BULUR 6, ÖMER YAZGAN 7, AHMET KAYA 8, CENGIZ BASAR 9, for the Melen Investigators. 1 Atatürk hospital, cardiology - 2 Dicle University Medical Faculty, Cardiology - 3 Düzce university medical faculty, cardiology - 4 Duzce University, Medical School, Department of Cardiology - 5 Duzce university medical faculty, Internal medicine - 6 Medeniyet University, Medical school, Department of Cardiology - 7 Bülent Ecevit University, Medical School, Department of Radiology - 8 Ordu University, Medical School, Department of Cardiology - 9 Duzce University, Medical School, Department of Cardiology ABSTRACT Aims: We aimed to investigate the predictors of Carotid intima media thickness (CIMT) in premenopausal women. Background: CIMT was shown to be a strong coronary artery disease predictor in both pre- and postmenopausal women. Materials and methods: The study was conducted on 2298 participants. The final cohort included 783 pre-menopausal women (with a mean age of 39 ± 11). Carotid intima media thickness was measured in all of the participants. Results: Mean CIMT of premenopausal women was 0.51 ± 0.14 mm. Age- adjusted correlates of CIMT was SBP (r = 0.138; p=<0.001), DBP (r=0.095; p=0.012) and LDL/HDL (r =0.077; p=0.041) ratio. Linear regression analysis was done in order to find independent covariates of carotid intima media thickness in two different models. Only age and systolic blood pressure were independently associated with CIMT. Logistic regression analysis revealed that only age was an independent predictor of subclinical atherosclerosis. Hypertension had the highest Odds ratio with borderline significance. Conclusion: The age and systolic blood pressure were independently associated with CIMT in premenopausal healthy Turkish women. Hypertension might be the best target for a modifiable risk factor for CIMT and future cardiovascular risk in this population. Key words: Premenopause, Atherosclerosis, Hypertension, Blood Pressure. Received February 18, 2014; Accepted May 19, 2014 Introduction Measurement of carotid intima media thickness (CIMT) is assessed by a noninvasive ultrasound imaging technique that can measure the extent of generalized atherosclerosis detected in the arterial wall. Intima-media thickness is highly predictive of the development of atherosclerosis (1). It is believed that estrogens may exert a protective impact on atherosclerosis in regularly menstruating women (2). However, CIMT was shown to be a strong CAD predictor in both pre- and postmenopausal women, in contrast to the menopausal status (3,4). Moreover, the predictors of CIMT as marker of subclinical atherosclerosis has been studied in postmenopausal women. However, the predictors of subclinical atherosclerosis in premenopausal women have not been studied before. Therefore we aimed to investigate the predictors of CIMT in a large cohort of premenopausal women. Materials and methods Study population: The MELEN Study is a prospectively designed survey on the prevalence of cardio metabolic risk factors in Turkish adults. The baseline visits were carried out in May and June, 2010 and biennial follow-up visits were planned. The name of the study comes from the geographic valley in north-east of Duzce, Turkey which is inhabitant of people. There is a town centre (Yigilca) and 37 villages. Health service of the region was supplied by six family physicians, each following up almost 2500 adults. The study was conducted in May and June, 2010 in the Social health center located in the town center. 400 sub-

2 942 Mesut Aydin, Recai Alemdar et Al jects from each family physician representatively stratified for sex, age and for rural-urban distribution were randomly assigned and invited to participate the study. A total of 2298 subjects with a mean age of 50 (age range 18 to 92) were interviewed. The participants who refused CIMT measurement or blood sampling (n=68), male subjects (n=827) and postmenopausal women (n=620), were excluded. Menopausal status was obtained from the answers of individuals to questions via investigator. Investigators asked the questions and filled the answer form. Totally, 783 premenopausal women were include the study. The study protocol was approved by the Ethics Committee of Duzce University and every subject signed a consent form. Data were obtained by a questionnaire, physical examination of the cardiovascular system, sampling of blood, recording of a resting electrocardiogram and measurement of carotid-intima media thickness. Definitions Presence of subclinical atherosclerosis was defined as CIMT mean ± 1SD (>0.8 mm). Hypertension was defined as the blood pressure is higher than 140/90 mmhg without diabetes or renal failure, or higher than 130/80 with diabetes and or renal failure or presence of using of antihypertensive drug (5). Diabetes was defined as fasting glucose level is higher than 126 mg/dl or presence of using of antidiabetic drug (6). Insulin resistance was estimated by homeostasis model assessment (HOMA). The HOMA insulin resistance index was calculated using the formula: Fasting insulin (μu/l) fasting glucose (mmol/l)/22.5 (7). Measurements Blood pressure was measured in the sitting position on the right arm, and the mean of two recordings at least 3 min apart was recorded. Weight was measured without shoes in light indoor clothes using a bio-impedance meter (Omron BF 510; Omron Corp. Kyoto, Japan). Waist circumference was measured with a tape, the subject standing and wearing only underwear, at the level midway between the lower rib margin and the iliac crest. Body mass index was calculated as weight divided by height squared (kg/m2). The participants underwent a Doppler Ultrasound examination (M Turbo, SonoSite Inc., Bothell, WA, USA) with a 5-12 MHz linear-array transducer. Ultrasonography was performed with the subject in the supine position. A careful search was performed to obtain optimal visualization of the vessel wall demonstrating the typical double lines representing the intima media layer. At least three consecutive longitudinal images of the common carotid artery were obtained. Measurements involved common carotid artery, bifurcation and origin (first 2 cm) of the internal carotid arteries. Carotid intima media thickness was measured from the thickest point on the far wall between the lumen intima interface and the media-adventitia interface, using visual assessment (8). Measurements were done 3 times at a site free of plaque and the mean of the three measurements was recorded. No software analysis was used during and after the measurement process. All measurements were made by two experienced radiologist (F.H.B. and O.Y.). The interobserver coefficient of variation was 4.1%. Sample Collection Ten milliliters of blood were drawn from the antecubital vein of each subject by applying minimal tourniquet force. Eight ml of blood was drawn into a vacutainer tube without anticoagulant. These blood samples were allowed to clot for 20 minutes prior to centrifugation. The blood tubes were centrifuged for 10 min at 1500 x g and were processed within 30 minutes in place. Sera were shipped within a few hours on cooled gel packs at 2-5 0C, reached to the Duzce University central laboratory and were kept at - 80 C until the final analyses. Biochemical analysis: Serum concentrations of cholesterol, fasting triglycerides, HDL-cholesterol, glucose, electrolytes, liver function tests and other biochemical variables were measured by a Cobas 6000 auto analyzer using commercially available kits (Roche Diagnostics GmbH, Mannheim, Germany). LDL-cholesterol values were computed according to the Friedewald formula. Statistical Analyses Statistical Package for Social Sciences software (SPSS 12, Chicago, IL, USA) was used for analysis. Descriptive parameters were shown as mean ± standard deviation or in percentages. Twosided t-tests and Pearson s chi-square tests were used to analyze the differences in means and proportions between groups. Abnormally distributed variables were compared using Mann-Whitney U test. Spearman s correlation analysis was applied to examine the relationship between CIMT and other

3 Predictors of subclinical atherosclerosis in premenopausal women 943 clinical parameters. Multiple logistic regression analysis was applied to identify independent predictors of subclinical atherosclerosis. A p value of < 0.05 was considered significant Results Mean CIMT of the whole cohort was 0.61 ± 0.19 mm. The final cohort included 783 premenopausal women (with a mean age of 39 ± 11). Characteristics and demographic findings of the study population were shown in Table 1. Variable Beta value P value Age (years) 0.59 <0.001 Systolic blood pressure (mmhg) Diastolic blood pressure (mmhg) Glucose (mmhg) Triglyceride (mmhg) Total Cholesterol General population Normal (n=751) Subclinical atherosclerosis (n=32) P value LDL cholesterol Variables Median Mean ± Mean ± SD/% (percentile 25-75) SD/% Mean ± SD/% HDL cholesterol Age (year) 38 (30-46) 39±11 38±10 46±4 <0.001 Body mass index 29 (25-33) 29±6 29±6 31± HOMA Carotid intima media thickness (mm) Systolic blood pressure (mmhg) Diastolic blood pressure (mmhg) Total cholesterol HDL cholesterol LDL cholesterol Triglyceride 0.48 ( ) 0.51 ± ± ± 0.15 < ( ) 119±22 118±21 132± (70 80) 76±13 76±12 82± ( ) 172 ± ± ± ( ± ± ± (74-112) 96 ± ± ± (89-190) 156 ± ± ± HDL: high-density lipoprotein, HOMA: Homeostasis model assessment, LDL: low-density lipoprotein Table 2: Independent covariates of carotid intima media thickness in linear regression analysis. Variables Odds Ratio 95%CI P value Age <0.001 HOMA 2.3 ( ) 3.8 ± ± ± Active smoker (n, %) NA 142, (18%) 137 (18%) 5 (16%) Smoker Waist circumference (cm) 90 (80-101) 91 ± ± ± 14 <0.001 HDL: high-density lipoprotein, HOMA: Homeostasis model assessment, LDL: low-density lipoprotein Table 1: Basic characteristics of the study population. Hypertension LDL/HDL ratio The participants with subclinical atherosclerosis were older, had significantly higher levels of LDL and total cholesterol, systolic and diastolic blood pressure, carotid artery thickness and waist circumference (Table 1). Mean CIMT was 0.51 ± 0.14 mm. Age- adjusted correlates of CIMT was SBP (r = 0.138; p=<0.001), DBP (r=0.095; p=0.012) and LDL/HDL (r =0.077; p=0.041) ratio. Linear regression analysis was done in order to find independent covariates of carotid intima media thickness. Only age and systolic blood pressure were independently associated with CIMT (Table 2). Logistic regression analysis revealed that only age was an independent predictor of subclinical atherosclerosis. Hypertension had the highest Odds ratio with borderline significance (Table 3). Discussion DM DM: Diabetes mellitus, HDL: high-density lipoprotein, LDL: low density lipoprotein Table 3: Multiple logistic regression analysis showing independent predictors of thickened carotid intima media. In this study, we demonstrated that the age and systolic blood pressure were independently associated with CIMT in premenopausal healthy women. Additionally, age was an independent predictor of subclinical atherosclerosis.

4 944 Mesut Aydin, Recai Alemdar et Al Age, smoking, hypertension, dyslipidemia, and diabetes have been shown to be associated with subclinical atherosclerosis. However, it is well known that in younger populations some of the conventional risk associates loss their independent effect. When age was taken into account as the most important and un-modifiable risk factor for atherosclerosis, hypertension becomes the most single modifiable risk of atherosclerosis at the very early phase in premenopausal women. Mean CIMT was relatively lower than previous epidemiologic studies. This may be related to the differences in population characteristic and calculation method of CIMT. We calculated the mean CIMT with subsequent three measurements on far walls of left and right common carotid arteries without application of software analysis. In some of the previously published studies, mean CIMT was calculated from bulbus and internal carotid arteries (1, 9-12). However, some of the investigators calculated the mean CIMT by using similar method with us (1, 13). Agnieszka et al. have determined mean CIMT in premenopausal normotensive group similar to the results of our study (0.54±0.14 and 0.51 ± 0.14 respectively) (13). The effect of various risk factors on CIMT was investigated in several specific populations such as healthy young adults, women at midlife, women suspected coronary artery disease and healthy menopausal women (1,9-11). But the predictors of subclinical atherosclerosis in premenopausal women have not been evaluated before. Tyrell and colleagues have reported that the mean CIMT was 0.69 mm in premenopausal women and it was independently associated to higher BMI and systolic blood pressure (4). The cohort of this study was older and had higher BMI compared with our study population (47 ± 2 vs. 39 ± 11 and 29 ± 6 vs. 25 ± 3, respectively). Moreover, the method of mean CIMT calculation was different. They measured the mean CIMT 1.0 cm segment of the near and far wall of the distal common carotid artery and the far wall of the carotid bulb and the internal carotid artery on both right and left sides. Measures from each location were then averaged to produce an overall measure of CIMT. Finally, their study population was smaller compared with the size of our study. The predictors of CIMT have been investigated in children and young adults in the Bogalusa Heart Study, a long-term epidemiologic study of the natural history of atherosclerosis (1). Systolic blood pressure (major contributor), black race, age, LDL cholesterol and HDL cholesterol (inverse association) were found as predictor variables of mean CIMT. This findings were concordant with our results, although there are several differences in demographic features of Bogalusa cohort and our study population such as mean age (32±3 vs. 39±11), mean CIMT (0,65 ±0,08 vs. 0,51±0,14) mean systolic blood pressure (108 ±11 vs. 119±22) and mean BMI (27±7 vs. 29±6). Schott et al investigated the predictors of CIMT in midlife women (9). Higher weight (the largest contributor), systolic blood pressure, age, and current smoking were found as predictors of greater mean CIMT. The study population was consisting of women with premenopausal dominance (83.6%), aged 44 to 50 years (mean 46.9±1.9), mean DBP 68.2±8.2, BMI between 10 and 34 (mean 25.1±3.3). Body mass index and smoking status were not independent associates of CIMT in our study. The methodology of CIMT measurement again was different from our study. They examined common carotid artery (CCA) 2 cm proximal to the bifurcation (bulb) and internal carotid artery (ICA). In conclusion, the present study suggests that the high blood pressure is the most important and independent modifiable risk factor for CIMT in premenopausal women. Hypertension might be the best target for a modifiable risk factor for CIMT and future cardiovascular risk in this population. These results may guide national risk modification strategies for early atherosclerosis. Epidemiological studies in different countries will provide additional findings and help guiding approaches for risk modification in different populations. References 1) Urbina EM, Srinivasan SR, Tang R, Bond MG, Kieltyka L, Berenson GS. Impact of multiple coronary risk factors on the intima-media thickness of different segments of carotid artery in healthy young adults (the Bogalusa Heart Study). Am J Cardiol 2002; 90: ) Lieberman EH, Gerhard MD, Uehata A, Walsh BW, Selwyn AP, Ganz P, Yeung AC, Creager MA. Estrogen improves endothelium- dependent fl ow mediated vasodilation in postmenopausal women. Ann Intern Med 1994; 121: ) Kablak-Ziembicka A, Przewlocki T, Tracz W, Pieniazek P, Musialek P, Sokolowski A, Drwila R, Rzeznik D. Carotid intima-media thickness in pre- and postmenopausal women with suspected coronary artery disease. Heart Vessels 2008; 23:

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