© 2013, Wiley Periodicals, Inc. DOI: 10.1111/echo.12498
Echocardiography
Epicardial Adipose Tissue Thickness in Hemodialysis Patients lu, M.D.,§ Burak Altun, M.D.,* Hakan Tasolar, M.D.,† Necmi Eren, M.D.,‡ Emine Binnetog Mehzat Altun, B.S.,¶ Ahmet Temiz, M.D.,* Emine Gazi, M.D.,* Ahmet Barutcu, M.D.,* Orcun Altunoren, M.D.,‡ Yucel Colkesen, M.D.,* and Fatma Uysal, M.D.** *Department of Cardiology, Canakkale Onsekiz Mart University, Canakkale, Turkey; †Department of Cardiology, Adiyaman University Training and Research Hospital, Adiyaman, Turkey; ‡Department of Nephrology, Adiyaman University Training and Research Hospital, Adiyaman, Turkey; §Department of Internal Medicine, Canakkale Onsekiz Mart University, Canakkale, Turkey; ¶Vocational Health College, Canakkale Onsekiz Mart University, Canakkale, Turkey; and **Department of Radiology, Canakkale Onsekiz Mart University, Canakkale, Turkey
Aim: Hemodialysis (HD) patients had higher cardiovascular mortality and it is related to atherosclerosis. Epicardial adipose tissue (EAT) thickness is a marker of atherosclerosis and independent predictor of coronary artery disease. The aim of our study was to evaluate the relationship between EAT and carotid intima-media thickness (CIMT) predictors of early atherosclerosis in HD patients. Methods: The study included 62 HD patients and 40 healthy controls. EAT thickness and CIMT were measured by echocardiography in all subjects. Results: Epicardial adipose tissue thickness and CIMT were higher (6.98 1.67 vs. 3.84 0.73 mm, P < 0.001, 0.94 0.17 vs. 0.63 0.11 mm, P < 0.001, respectively) in HD patients than in control subjects. EAT thickness were correlated with CIMT, HD duration, age, and calcium. In addition, HD duration, CIMT, and age were independent predictors of EAT thickness on HD patients in regression analysis. Conclusion: Epicardial adipose tissue thickness may be a useful indicator of early atherosclerosis in HD patients. (Echocardiography 2014;31:941–946) Key words: epicardial adipose tissue, hemodialysis, atherosclerosis The association between chronic renal impairment and atherosclerotic vascular disease has been shown previously.1,2 It has been reported that dialysis patients had increased risk for adverse cardiac events.3 Epicardial adipose tissue (EAT) is located around the heart, especially subepicardial coronary vessels. EAT has been associated with development of coronary atherosclerosis.4 Many studies have showed conflicting results about association between EAT thickness and severity of coronary artery disease (CAD).5–7 Turkmen et al.8 reported that EAT volume were higher in peritoneal dialysis (PD) patients. EAT is shown to be correlated with atherosclerosis, arterial stiffness and presence of coronary artery calcification in hemodialysis (HD) patients, by multislice computerized tomography (MSCT) in another study.9 Previous studies have revealed that carotid intima-media thickness (CIMT) is a good predictor of cardiovascular events,10–12 and relationship Address for correspondence and reprint requests: Burak Altun, M.D., Department of Cardiology, Canakkale Onsekiz Mart University, Canakkale, Turkey. Fax: 90-2862635959; E-mail: [email protected]
between CIMT and major cardiovascular risk factors has also been proved.13 Furthermore, CIMT was positively correlated with EAT thickness in several diseases.14–16 By referencing these studies, EAT thickness may demonstrate early atherosclerosis, similar to CIMT. However, there are no reports on the relationship between EAT and CIMT in HD patients. Therefore, the aim of our study was to assess the relationship between echocardiographic EAT thickness and CIMT, predictors of early atherosclerosis, in HD patients. Materials and Methods: Study Population: Seventy-four patients received HD therapy for at least 6 months at 4 hours and 3 days a week with a mean age 48.0 13.8 years and 40 healthy subjects with a mean age of 51.3 7.1 years were enrolled in our study. Patients were excluded if they had abnormal images on transthoracic echocardiography (Vivid 7, General Electric, Horten, Norway), a history of coronary artery bypass graft surgery, and severe valvular disease. For those reasons, 12 HD patients were excluded because of inadequate echocardiographic views in 6, and a history of 941
Altun, et al.
coronary artery bypass graft surgery in 6. Each participant signed an informed consent form in accordance with the declaration of Helsinki, and this study was approved by the local ethical committee of Canakkale Onsekiz Mart University. Systolic and diastolic blood pressures were measured after 5 minutes of rest. Blood samples were obtained before HD session in a fasting state and levels of plasma glucose, creatinin, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, and triglycerides were measured. EAT and CIMT Measurements: Echocardiograms were performed with a VIVID 7 instrument according to standard techniques, with subjects in the left lateral decubitus position. Echocardiographic images were recorded onto a computerized database and videotape. We measured EAT thickness on the free wall of right ventricle from the parasternal long-axis views. EAT was identified as an echo free space in the pericardial layers on the two-dimensional echocardiography, and its thickness was measured perpendicularly on the free wall of the right ventricle at end-diastole for 3 cardiac cycles15,17 (Fig. 1). The same machine with a linear-array imaging probe was employed to evaluate the CIMT of the right common carotid artery. The probe was manipulated manually so as to run parallel to the common carotid artery. A region 10 mm proximal to the carotid bifurcation was identified, and the intima-media thickness of the far wall was calculated as the distance between the lumen– intima and media–adventitia interfaces. CIMT was measured on this image at 3 adjacent sites 1 mm apart (Fig. 2). The average value of the 3
Figure 1. Echocardiographic measurement of epicardial adipose tissue (EAT). Anterior echolucent space between the linear echo dense parietal pericardium and the epicardium was considered to be EAT.
942
Figure 2. Echocardiographic measurement of carotid intimamedia thickness (CIMT).
measurements was used for analyses. The offline measurement of EAT thickness and CIMT was performed by the same cardiologist who was unaware of the clinical data. Statistical Analysis: SPSS 17.0 statistical program (SPSS Inc, Chicago, IL, USA) was used for statistical analysis. All values are given as mean standard deviation. Kolmogorov–Smirnov test was used normality of the variances. Descriptive statistics were used for definition of clinical and social demographic variables. Correlation of numerical variables was examined by Pearson correlation. The determinants of the dependent EAT thickness variable were assessed with multiple regression analyses using the following independent variables: age, HD duration, creatinine, HDL cholesterol, calcium and CIMT in patients group. Regression analysis was performed with a stepwise method. Receiver operating characteristics (ROC) curve analysis was performed to identify the optimal cutoff value at EAT thickness (at which sensitivity and specificity would be maximal), by referencing CIMT, for the prediction of early atherosclerosis. P values of
Echocardiography
Epicardial Adipose Tissue Thickness in Hemodialysis Patients lu, M.D.,§ Burak Altun, M.D.,* Hakan Tasolar, M.D.,† Necmi Eren, M.D.,‡ Emine Binnetog Mehzat Altun, B.S.,¶ Ahmet Temiz, M.D.,* Emine Gazi, M.D.,* Ahmet Barutcu, M.D.,* Orcun Altunoren, M.D.,‡ Yucel Colkesen, M.D.,* and Fatma Uysal, M.D.** *Department of Cardiology, Canakkale Onsekiz Mart University, Canakkale, Turkey; †Department of Cardiology, Adiyaman University Training and Research Hospital, Adiyaman, Turkey; ‡Department of Nephrology, Adiyaman University Training and Research Hospital, Adiyaman, Turkey; §Department of Internal Medicine, Canakkale Onsekiz Mart University, Canakkale, Turkey; ¶Vocational Health College, Canakkale Onsekiz Mart University, Canakkale, Turkey; and **Department of Radiology, Canakkale Onsekiz Mart University, Canakkale, Turkey
Aim: Hemodialysis (HD) patients had higher cardiovascular mortality and it is related to atherosclerosis. Epicardial adipose tissue (EAT) thickness is a marker of atherosclerosis and independent predictor of coronary artery disease. The aim of our study was to evaluate the relationship between EAT and carotid intima-media thickness (CIMT) predictors of early atherosclerosis in HD patients. Methods: The study included 62 HD patients and 40 healthy controls. EAT thickness and CIMT were measured by echocardiography in all subjects. Results: Epicardial adipose tissue thickness and CIMT were higher (6.98 1.67 vs. 3.84 0.73 mm, P < 0.001, 0.94 0.17 vs. 0.63 0.11 mm, P < 0.001, respectively) in HD patients than in control subjects. EAT thickness were correlated with CIMT, HD duration, age, and calcium. In addition, HD duration, CIMT, and age were independent predictors of EAT thickness on HD patients in regression analysis. Conclusion: Epicardial adipose tissue thickness may be a useful indicator of early atherosclerosis in HD patients. (Echocardiography 2014;31:941–946) Key words: epicardial adipose tissue, hemodialysis, atherosclerosis The association between chronic renal impairment and atherosclerotic vascular disease has been shown previously.1,2 It has been reported that dialysis patients had increased risk for adverse cardiac events.3 Epicardial adipose tissue (EAT) is located around the heart, especially subepicardial coronary vessels. EAT has been associated with development of coronary atherosclerosis.4 Many studies have showed conflicting results about association between EAT thickness and severity of coronary artery disease (CAD).5–7 Turkmen et al.8 reported that EAT volume were higher in peritoneal dialysis (PD) patients. EAT is shown to be correlated with atherosclerosis, arterial stiffness and presence of coronary artery calcification in hemodialysis (HD) patients, by multislice computerized tomography (MSCT) in another study.9 Previous studies have revealed that carotid intima-media thickness (CIMT) is a good predictor of cardiovascular events,10–12 and relationship Address for correspondence and reprint requests: Burak Altun, M.D., Department of Cardiology, Canakkale Onsekiz Mart University, Canakkale, Turkey. Fax: 90-2862635959; E-mail: [email protected]
between CIMT and major cardiovascular risk factors has also been proved.13 Furthermore, CIMT was positively correlated with EAT thickness in several diseases.14–16 By referencing these studies, EAT thickness may demonstrate early atherosclerosis, similar to CIMT. However, there are no reports on the relationship between EAT and CIMT in HD patients. Therefore, the aim of our study was to assess the relationship between echocardiographic EAT thickness and CIMT, predictors of early atherosclerosis, in HD patients. Materials and Methods: Study Population: Seventy-four patients received HD therapy for at least 6 months at 4 hours and 3 days a week with a mean age 48.0 13.8 years and 40 healthy subjects with a mean age of 51.3 7.1 years were enrolled in our study. Patients were excluded if they had abnormal images on transthoracic echocardiography (Vivid 7, General Electric, Horten, Norway), a history of coronary artery bypass graft surgery, and severe valvular disease. For those reasons, 12 HD patients were excluded because of inadequate echocardiographic views in 6, and a history of 941
Altun, et al.
coronary artery bypass graft surgery in 6. Each participant signed an informed consent form in accordance with the declaration of Helsinki, and this study was approved by the local ethical committee of Canakkale Onsekiz Mart University. Systolic and diastolic blood pressures were measured after 5 minutes of rest. Blood samples were obtained before HD session in a fasting state and levels of plasma glucose, creatinin, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, and triglycerides were measured. EAT and CIMT Measurements: Echocardiograms were performed with a VIVID 7 instrument according to standard techniques, with subjects in the left lateral decubitus position. Echocardiographic images were recorded onto a computerized database and videotape. We measured EAT thickness on the free wall of right ventricle from the parasternal long-axis views. EAT was identified as an echo free space in the pericardial layers on the two-dimensional echocardiography, and its thickness was measured perpendicularly on the free wall of the right ventricle at end-diastole for 3 cardiac cycles15,17 (Fig. 1). The same machine with a linear-array imaging probe was employed to evaluate the CIMT of the right common carotid artery. The probe was manipulated manually so as to run parallel to the common carotid artery. A region 10 mm proximal to the carotid bifurcation was identified, and the intima-media thickness of the far wall was calculated as the distance between the lumen– intima and media–adventitia interfaces. CIMT was measured on this image at 3 adjacent sites 1 mm apart (Fig. 2). The average value of the 3
Figure 1. Echocardiographic measurement of epicardial adipose tissue (EAT). Anterior echolucent space between the linear echo dense parietal pericardium and the epicardium was considered to be EAT.
942
Figure 2. Echocardiographic measurement of carotid intimamedia thickness (CIMT).
measurements was used for analyses. The offline measurement of EAT thickness and CIMT was performed by the same cardiologist who was unaware of the clinical data. Statistical Analysis: SPSS 17.0 statistical program (SPSS Inc, Chicago, IL, USA) was used for statistical analysis. All values are given as mean standard deviation. Kolmogorov–Smirnov test was used normality of the variances. Descriptive statistics were used for definition of clinical and social demographic variables. Correlation of numerical variables was examined by Pearson correlation. The determinants of the dependent EAT thickness variable were assessed with multiple regression analyses using the following independent variables: age, HD duration, creatinine, HDL cholesterol, calcium and CIMT in patients group. Regression analysis was performed with a stepwise method. Receiver operating characteristics (ROC) curve analysis was performed to identify the optimal cutoff value at EAT thickness (at which sensitivity and specificity would be maximal), by referencing CIMT, for the prediction of early atherosclerosis. P values of
