© 2013, Wiley Periodicals, Inc. DOI: 10.1111/echo.12392
Echocardiography
ORIGINAL INVESTIGATIONS
Gender-Related Changes of the Epicardial Fat Thickness and Leptin in Obstructive Sleep Apnea Hakan Akilli, M.D.,* Mehmet Kayrak, M.D.,* Taha Tahir Bekci, M.D.,† Halil _Ibrahim Erdogan, M.D.,* Alpay Aribas, M.D.,* Oguzhan Yildirim, M.D.,* Alpaslan Taner, M.D.,‡ Murat Erer, M.D.,* and Ali Unlu, M.D.§ *Department of Cardiology, Meram Faculty of Medicine, Necmettin Erbakan University, Konya, Turkey; †Department of Pulmonary Medicine, Konya Education and Research Hospital, Konya, Turkey; ‡Department € kan Maternity and Children Hospital, Konya, Turkey; and §Department of of Biochemistry, Dr Faruk Su Biochemistry, Selcuklu School of Medicine, Selcuk University, Konya, Turkey
Background: Epicardial fat thickness (EFT), an indicator of visceral obesity, and leptin are 2 novel markers for studying the obstructive sleep apnea (OSA) population. This study aimed to investigate the effects of gender on leptin levels and EFT, and the relation with OSA severity. Methods: A total of 149 patients with OSA (female/male 55/94 and mean age 50.8 9.2 years) and 50 control patients (female/male 24/26 and mean age 48.9 8.8 years) were included in the study. The study population was divided into 4 groups according to apnea/hypopnea index (AHI) as control (AHI 0.05). EFT was thicker in the severe OSA group than in the control and mild OSA groups among women, whereas EFT was not changed according to OSA severity among males (P > 0.05). Conclusion: Leptin and EFT may be a valuable parameter in the evaluation of OSA severity in women than in men. (Echocardiography 2014;31:411–419) Key words: epicardial fat, gender, leptin, obstructive sleep apnea Obstructive sleep apnea (OSA) is a sleep disorder characterized by repetitive episodes of upper airway obstruction during sleep, resulting in decreased oxygen saturation, disruption of sleep, and daytime somnolence.1 OSA has become an important community health problem2 due to its association with increased risk of cardiovascular disease3–6 and impaired quality of life.7 Epidemiological studies show that OSA is 2 to 3 times more common among males compared with females.8 The mechanism explaining gender distribution OSA incidence is not understood. However, several factors such as the obesity, fat distribution, upper airway anatomy and function, control of breathing, and hormonal status have been reported to be effective.9 Activation of sympathetic, hormonal, thrombotic, and metabolic factors in patients with OSA is related to the presence of repetitive nocturnal Address for correspondence and reprint requests: Hakan Akilli, M.D., Necmettin Erbakan Universitesi Meram Tip Fakultesi Kardiyoloji Sekreterligi, Meram, Konya 42090, Turkey. Fax: 0090-332-2236181; E-mail: [email protected]
hypoxemia, negative intrathoracic pressure, and arousal state.10 Leptin has many metabolic effects, in particular, the regulation of body fat.11 Several studies have investigated the role of leptin levels in OSA populations.12–22 In some, but not all of these studies, leptin levels are linked to OSA.12–18 Women have been underrepresented in many of these studies. Hence, the role of leptin in female patients with OSA remains unclear. Visceral fat is increased in most patients with OSA.23 Body mass index (BMI) is a broad measurement of body fat,24 which fails to reflect the mass of the visceral fat.25 Epicardial fat thickness (EFT) is a novel parameter of visceral fat and is related to cardiovascular disease.26,27 Two recent studies have investigated the relationship between EFT and the OSA severity,28,29 although no genderspecific subgroup analysis was performed. To our knowledge, there have been no previous studies investigating the relationship between leptin levels and EFT. In this study, we aimed to investigate the relationship among EFT, leptin, and OSA severity, and the gender-related differences in leptin levels and EFT in patients with OSA. 411
Akilli, et al.
Methods: Study Population: For this study, 265 suspected OSA patients were evaluated prospectively. The study was approved by the ethics committee, and informed consent was obtained from each patient. Exclusion criteria: The patients with the following diseases were excluded from the study: the presence of chronic obstructive/restrictive pulmonary disease, heart failure, chronic renal disease, psychiatric disorders, cancer, respiratory infection, uncontrolled hypertension (blood pressure [BP]>160/90 mmHg), and refusal to sign informed consent. Known thyroid diseases such as hypo- and hyperthyroidism were excluded because of relationship between EFT and thyroid functions.30 In addition, poor echocardiographic image quality was accepted as criteria for exclusion. Study protocol: After initial screening for exclusion criteria, all-night polysomnography was performed in the sleep laboratory. On the morning of the subsequent day following the polysomnography test, a fasting blood sample was obtained for biochemical analysis. The demographic and anthropometric characteristics of all patients were recorded. BP were measured and BMIs were calculated as weight (kg)/height (m)2.
After polysomnography, patients were referred to the echocardiography laboratory. Echocardiography was performed on 213 patients (126 males, 87 females). Six male and 8 female patients were excluded from the study due to insufficient echocardiographic images. The study was completed with 149 OSA patients (94 males, 55 females) and 50 control patients (26 males, 24 females). A study flow chart is provided in Figure 1. Polysomnography: All-night polysomnography was performed using Compumedics E-series Sleep System (Compumedics, Melbourne, Australia). The polysomnography records included the following parameters: electroencephalography, electromyography, electrooculography, electrocardiography, nasal thermistor for airflow, pulse oxymeter for oxygen saturation, and chest and abdominal respiratory movements. An apnea was defined as complete cessation of breathing for at least 10 seconds. Hypopnea was defined as a decrease in oxygen saturation to ≤4 or at least a 50% decrease in the airflow for a minimum of 10 seconds. Individuals with an apnea/hypopnea index (AHI) of ≥5 were diagnosed as OSA. The study population was divided into 4 groups according to AHI: control (AHI
Echocardiography
ORIGINAL INVESTIGATIONS
Gender-Related Changes of the Epicardial Fat Thickness and Leptin in Obstructive Sleep Apnea Hakan Akilli, M.D.,* Mehmet Kayrak, M.D.,* Taha Tahir Bekci, M.D.,† Halil _Ibrahim Erdogan, M.D.,* Alpay Aribas, M.D.,* Oguzhan Yildirim, M.D.,* Alpaslan Taner, M.D.,‡ Murat Erer, M.D.,* and Ali Unlu, M.D.§ *Department of Cardiology, Meram Faculty of Medicine, Necmettin Erbakan University, Konya, Turkey; †Department of Pulmonary Medicine, Konya Education and Research Hospital, Konya, Turkey; ‡Department € kan Maternity and Children Hospital, Konya, Turkey; and §Department of of Biochemistry, Dr Faruk Su Biochemistry, Selcuklu School of Medicine, Selcuk University, Konya, Turkey
Background: Epicardial fat thickness (EFT), an indicator of visceral obesity, and leptin are 2 novel markers for studying the obstructive sleep apnea (OSA) population. This study aimed to investigate the effects of gender on leptin levels and EFT, and the relation with OSA severity. Methods: A total of 149 patients with OSA (female/male 55/94 and mean age 50.8 9.2 years) and 50 control patients (female/male 24/26 and mean age 48.9 8.8 years) were included in the study. The study population was divided into 4 groups according to apnea/hypopnea index (AHI) as control (AHI 0.05). EFT was thicker in the severe OSA group than in the control and mild OSA groups among women, whereas EFT was not changed according to OSA severity among males (P > 0.05). Conclusion: Leptin and EFT may be a valuable parameter in the evaluation of OSA severity in women than in men. (Echocardiography 2014;31:411–419) Key words: epicardial fat, gender, leptin, obstructive sleep apnea Obstructive sleep apnea (OSA) is a sleep disorder characterized by repetitive episodes of upper airway obstruction during sleep, resulting in decreased oxygen saturation, disruption of sleep, and daytime somnolence.1 OSA has become an important community health problem2 due to its association with increased risk of cardiovascular disease3–6 and impaired quality of life.7 Epidemiological studies show that OSA is 2 to 3 times more common among males compared with females.8 The mechanism explaining gender distribution OSA incidence is not understood. However, several factors such as the obesity, fat distribution, upper airway anatomy and function, control of breathing, and hormonal status have been reported to be effective.9 Activation of sympathetic, hormonal, thrombotic, and metabolic factors in patients with OSA is related to the presence of repetitive nocturnal Address for correspondence and reprint requests: Hakan Akilli, M.D., Necmettin Erbakan Universitesi Meram Tip Fakultesi Kardiyoloji Sekreterligi, Meram, Konya 42090, Turkey. Fax: 0090-332-2236181; E-mail: [email protected]
hypoxemia, negative intrathoracic pressure, and arousal state.10 Leptin has many metabolic effects, in particular, the regulation of body fat.11 Several studies have investigated the role of leptin levels in OSA populations.12–22 In some, but not all of these studies, leptin levels are linked to OSA.12–18 Women have been underrepresented in many of these studies. Hence, the role of leptin in female patients with OSA remains unclear. Visceral fat is increased in most patients with OSA.23 Body mass index (BMI) is a broad measurement of body fat,24 which fails to reflect the mass of the visceral fat.25 Epicardial fat thickness (EFT) is a novel parameter of visceral fat and is related to cardiovascular disease.26,27 Two recent studies have investigated the relationship between EFT and the OSA severity,28,29 although no genderspecific subgroup analysis was performed. To our knowledge, there have been no previous studies investigating the relationship between leptin levels and EFT. In this study, we aimed to investigate the relationship among EFT, leptin, and OSA severity, and the gender-related differences in leptin levels and EFT in patients with OSA. 411
Akilli, et al.
Methods: Study Population: For this study, 265 suspected OSA patients were evaluated prospectively. The study was approved by the ethics committee, and informed consent was obtained from each patient. Exclusion criteria: The patients with the following diseases were excluded from the study: the presence of chronic obstructive/restrictive pulmonary disease, heart failure, chronic renal disease, psychiatric disorders, cancer, respiratory infection, uncontrolled hypertension (blood pressure [BP]>160/90 mmHg), and refusal to sign informed consent. Known thyroid diseases such as hypo- and hyperthyroidism were excluded because of relationship between EFT and thyroid functions.30 In addition, poor echocardiographic image quality was accepted as criteria for exclusion. Study protocol: After initial screening for exclusion criteria, all-night polysomnography was performed in the sleep laboratory. On the morning of the subsequent day following the polysomnography test, a fasting blood sample was obtained for biochemical analysis. The demographic and anthropometric characteristics of all patients were recorded. BP were measured and BMIs were calculated as weight (kg)/height (m)2.
After polysomnography, patients were referred to the echocardiography laboratory. Echocardiography was performed on 213 patients (126 males, 87 females). Six male and 8 female patients were excluded from the study due to insufficient echocardiographic images. The study was completed with 149 OSA patients (94 males, 55 females) and 50 control patients (26 males, 24 females). A study flow chart is provided in Figure 1. Polysomnography: All-night polysomnography was performed using Compumedics E-series Sleep System (Compumedics, Melbourne, Australia). The polysomnography records included the following parameters: electroencephalography, electromyography, electrooculography, electrocardiography, nasal thermistor for airflow, pulse oxymeter for oxygen saturation, and chest and abdominal respiratory movements. An apnea was defined as complete cessation of breathing for at least 10 seconds. Hypopnea was defined as a decrease in oxygen saturation to ≤4 or at least a 50% decrease in the airflow for a minimum of 10 seconds. Individuals with an apnea/hypopnea index (AHI) of ≥5 were diagnosed as OSA. The study population was divided into 4 groups according to AHI: control (AHI
