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Wernz MM, Voskrebenzev A, Müller RA, Zubke M, Klimeš F, Glandorf J, Czerner C, Wacker F, Olsson KM, Hoeper MM, Hohlfeld JM, Vogel-Claussen J. Feasibility, Repeatability, and Correlation to Lung Function of Phase-Resolved Functional Lung (PREFUL) MRI-derived Pulmonary Artery Pulse Wave Velocity Measurements. J Magn Reson Imaging 2024; 60:2216-2228. [PMID: 38460124 DOI: 10.1002/jmri.29337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/22/2024] [Accepted: 02/22/2024] [Indexed: 03/11/2024] Open
Abstract
BACKGROUND Pulse wave velocity (PWV) in the pulmonary arteries (PA) is a marker of vascular stiffening. Currently, only phase-contrast (PC) MRI-based options exist to measure PA-PWV. PURPOSE To test feasibility, repeatability, and correlation to clinical data of Phase-Resolved Functional Lung (PREFUL) MRI-based calculation of PA-PWV. STUDY TYPE Retrospective. SUBJECTS 79 (26 female) healthy subjects (age range 19-78), 58 (24 female) patients with chronic obstructive pulmonary disease (COPD, age range 40-77), 60 (33 female) patients with suspected pulmonary hypertension (PH, age range 28-85). SEQUENCE 2D spoiled gradient echo, 1.5T. ASSESSMENT PA-PWV was measured from PREFUL-derived cardiac cycles based on the determination of temporal and spatial distance between lung vasculature voxels using a simplified (sPWV) method and a more comprehensive (cPWV) method including more elaborate distance calculation. For 135 individuals, PC MRI-based PWV (PWV-QA) was measured. STATISTICAL TESTS Intraclass-correlation-coefficient (ICC) and coefficient of variation (CoV) were used to test repeatability. Nonparametric tests were used to compare cohorts. Correlation of sPWV/cPWV, PWV-QA, forced expiratory volume in 1 sec (FEV1) %predicted, residual volume (RV) %predicted, age, and right heart catheterization (RHC) data were tested. Significance level α = 0.05 was used. RESULTS sPWV and cPWV showed no significant differences between repeated measurements (P-range 0.10-0.92). CoV was generally lower than 15%. COPD and PH patients had significantly higher sPWV and cPWV than healthy subjects. Significant correlation was found between sPWV or cPWV and FEV1%pred. (R = -0.36 and R = -0.44), but not with RHC (P-range -0.11 - 0.91) or age (P-range 0.23-0.89). Correlation to RV%pred. was significant for cPWV (R = 0.42) but not for sPWV (R = 0.34, P = 0.055). For all cohorts, sPWV and cPWV were significantly correlated with PWV-QA (R = -0.41 and R = 0.48). DATA CONCLUSION PREFUL-derived PWV is feasible and repeatable. PWV is increased in COPD and PH patients and correlates to airway obstruction and hyperinflation. LEVEL OF EVIDENCE 3 TECHNICAL EFFICACY: Stage 2.
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Affiliation(s)
- Marius M Wernz
- Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
| | - Andreas Voskrebenzev
- Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
| | - Robin A Müller
- Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
| | - Maximilian Zubke
- Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
| | - Filip Klimeš
- Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
| | - Julian Glandorf
- Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
| | - Christoph Czerner
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - Frank Wacker
- Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
| | - Karen M Olsson
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
- Department of Respiratory Medicine and Infectious Diseases, Hannover Medical School, Hannover, Germany
| | - Marius M Hoeper
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
- Department of Respiratory Medicine and Infectious Diseases, Hannover Medical School, Hannover, Germany
| | - Jens M Hohlfeld
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
- Department of Respiratory Medicine and Infectious Diseases, Hannover Medical School, Hannover, Germany
- Fraunhofer Institute for Toxicology and Experimental Medicine, Hannover, Germany
| | - Jens Vogel-Claussen
- Institute of Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), Hannover, Germany
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Bajpai J, Pradhan A, Bajaj DK, Verma AK, Kant S, Sethi R. Comparative analysis of central aortic blood pressure, pulse wave velocity & arterial stiffness in patients with obstructive airway disease. Physiol Rep 2024; 12:e16109. [PMID: 39225167 PMCID: PMC11369788 DOI: 10.14814/phy2.16109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 05/29/2024] [Accepted: 05/31/2024] [Indexed: 09/04/2024] Open
Abstract
BACKGROUND As the pulmonary system and cardiovascular system are intimately linked, patients with chronic obstructive pulmonary disease (COPD) and asthma have high risk for developing cardiovascular diseases (CVDs) and altered central hemodynamic. OBJECTIVE We aim to assess the central aortic blood pressure (CABP) indices, pulse wave velocity (PWV) and other indicators of arterial stiffness in Indian patients with COPD and bronchial asthma. METHODS This is a single-center, cross-sectional study conducted in outpatients diagnosed with either chronic stable phase of COPD or bronchial asthma. CABP indices, vascular age, arterial stiffness and central hemodynamics were measured in patients. RESULTS Of 193 patients with obstructive airway disease who were enrolled, (n = 81 had COPD and n = 112 had partially-controlled bronchial asthma) the proportion of male patients was higher in both groups. The PWV, augmentation index (AI) and vascular age (VA) were significantly higher in patients with COPD compared to those with bronchial asthma (all, p < 0.05). CONCLUSION The study showed that PWV, AI and VA were higher in patients with stable COPD without any cardiac comorbidities compared to bronchial asthma.
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Affiliation(s)
- Jyoti Bajpai
- Department of Respiratory MedicineKing George's Medical UniversityLucknowUttar PradeshIndia
| | - Akshyaya Pradhan
- Department of CardiologyKing George's Medical UniversityLucknowIndia
| | - Darshan Kumar Bajaj
- Department of Respiratory MedicineKing George's Medical UniversityLucknowUttar PradeshIndia
| | - Ajay Kumar Verma
- Department of Respiratory MedicineKing George's Medical UniversityLucknowUttar PradeshIndia
| | - Surya Kant
- Department of Respiratory MedicineKing George's Medical UniversityLucknowUttar PradeshIndia
| | - Rishi Sethi
- Department of CardiologyKing George's Medical UniversityLucknowIndia
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Xu M, Lu ZY. Early diagnostic value of carotid artery ultrasound parameters combined with epicardial adipose layer thickness in coronary heart disease. World J Clin Cases 2024; 12:3004-3011. [PMID: 38898833 PMCID: PMC11185360 DOI: 10.12998/wjcc.v12.i17.3004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 04/12/2024] [Accepted: 04/23/2024] [Indexed: 06/04/2024] Open
Abstract
BACKGROUND Coronary heart disease is associated with coronary atherosclerosis indicated by carotid intima-media thickness (CIMT) thickening and altered vascular elasticity. The epicardial adipose layer can secrete proinflammatory factors that promote the formation of coronary atherosclerosis. Thus, the epicardial fat layer thickness (EAT) may also predict coronary heart disease. AIM To determine the role of common carotid artery ultrasound parameters and EAT in the early diagnosis of coronary artery disease. METHODS Based on coronary angiography, patients with newly suspected coronary heart disease were divided into case (n = 107) and control (n = 41) groups. The carotid ultrasound parameters, including vascular stiffness (β), elastic coefficient (EP), pulse wave conduction velocity (PWV-β), CIMT, and EAT were compared between the case and control groups and among patients with different lesion numbers in the case group. Pearson correlation was used to evaluate the early diagnostic value of EAT, common carotid artery elasticity, and CIMT for coronary heart disease. RESULTS EP, β, PWV-β, CIMT, and EAT were significantly higher in the case group compared with the levels in the control group (all P < 0.001). In the case group, lesions were detected in one vessel in 34 patients, two vessels in 38 patients, and three vessels in 35 patients. Within the case group, β, EP, PWV-β, CIMT, and EAT levels significantly increased with an increased number of lesions (all P < 0.001). EAT positively correlated with β, EP, PWV-β, and CIMT (all P < 0.01). The area under the curve for diagnosing coronary heart disease using EAT combined with CIMT and carotid elasticity was 0.893, and the sensitivity and specificity were 0.890 and 0.837. CONCLUSION EAT correlated well with changes in carotid artery elasticity and CIMT in patients with coronary heart disease. The combination of EAT, carotid artery elasticity, and CIMT facilitates the early diagnosis of coronary heart disease.
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Affiliation(s)
- Min Xu
- Department of Ultrasound, Suzhou Ninth People's Hospital, Suzhou 215200, Jiangsu Province, China
| | - Zhao-Yang Lu
- Department of Ultrasound, Suzhou Ninth People's Hospital, Suzhou 215200, Jiangsu Province, China
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Czerwaty K, Dżaman K, Sobczyk KM, Sikorska KI. The Overlap Syndrome of Obstructive Sleep Apnea and Chronic Obstructive Pulmonary Disease: A Systematic Review. Biomedicines 2022; 11:biomedicines11010016. [PMID: 36672523 PMCID: PMC9856172 DOI: 10.3390/biomedicines11010016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/08/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) are common diseases that strongly impact the quality and length of life. Their coexistence is determined by overlap syndrome (OS). This systematic review aims to define the significance of these comorbidities according to the current state of knowledge. For this systematic review, we searched PubMed, Scopus, and Cochrane for studies published between 2018 and 26 October 2022, to find original, observational, human studies published in English, where the diagnosis of COPD was according to the Global Initiative for Obstructive Lung Disease guidelines and the diagnosis of OSA was based on polysomnography. The quality of studies was assessed using the Newcastle-Ottawa quality assessment tool for cohort and case-control studies, as well as its modification for cross-sectional studies. Of the 1548 records identified, 38 were eligible and included in this systematic review. The included studies covered a total population of 27,064 participants. This paper summarizes the most important, up-to-date information regarding OS, including the prevalence, meaning of age/gender/body mass index, polysomnography findings, pulmonary function, comorbidities, predicting OSA among COPD patients, and treatment of this syndrome.
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Clímaco DCS, Lustosa TC, de F P MV, Lins-Filho OL, Rodrigues VK, de Oliveira Neto LDAP, Feitosa ADM, Queiroga Júnior FJP, Cabral MM, Pedrosa RP. Is obstructive sleep apnea associated with increased arterial stiffness in patients with COPD? Sleep Breath 2022; 27:765-770. [PMID: 35538181 DOI: 10.1007/s11325-022-02635-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 04/12/2022] [Accepted: 05/03/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE To evaluate arterial stiffness, a predictor of vascular damage was assessed by means of pulse wave velocity (PWV) in patients with chronic obstructive pulmonary disease (COPD) and comorbid obstructive sleep apnea (OSA), namely overlap syndrome (OS). METHODS Consecutive stable patients with COPD were evaluated for OSA by means of overnight polysomnography in the laboratory. A clinical assessment was performed according to a strict protocol, including two COPD questionnaires: the COPD assessment test and the modified Medical Research Council scale. COPD severity was graded according to the guidelines of the Global Initiative for Chronic Obstructive Lung Disease. Arterial stiffness was assessed by means of PWV, using a standard technique. RESULTS Of 102 patients with COPD, 51 had associated OSA. The OS group had more men than the COPD group (73% vs. 47%, respectively; p < 0.01). Both groups had similar ages (66.2 ± 9.2 years vs. 69.6 ± 10.7, p = 0.09) and airflow limitation (p = 0.37). Hypertension was found in 22% of COPD patients, as opposed to 17% patients in the OS group (p = 0.29). High PWV values were present in 42% of the patients. Patients with COPD and OS had the same PWV values (9.8 vs. 10.5 m/s, p = 0.34). There were no differences in central blood pressure, peripheral blood pressure, and augmentation index between the two groups (p > 0.05). CONCLUSION High PWV values were frequently observed in patients with COPD. However, there was no difference in PWV between patients with OS and those with COPD alone.
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Affiliation(s)
- Danielle Cristina Silva Clímaco
- Pulmonology Clinic, Hospital Otávio de Freitas, Rua Aprígio Guimarães s/n, Pernambuco, Tejipió, Recife, Brazil.
- Laboratório Do Sono E Coração, Pronto Socorro Cardiológico de Pernambuco, (PROCAPE) da Universidade de Pernambuco, Rua dos Palmares, s/n, Santo Amaro, Recife, Brazil.
| | - Thais C Lustosa
- Laboratório Do Sono E Coração, Pronto Socorro Cardiológico de Pernambuco, (PROCAPE) da Universidade de Pernambuco, Rua dos Palmares, s/n, Santo Amaro, Recife, Brazil
| | - Marcus Vinícius de F P
- Laboratório Do Sono E Coração, Pronto Socorro Cardiológico de Pernambuco, (PROCAPE) da Universidade de Pernambuco, Rua dos Palmares, s/n, Santo Amaro, Recife, Brazil
| | - Ozeas L Lins-Filho
- Laboratório Do Sono E Coração, Pronto Socorro Cardiológico de Pernambuco, (PROCAPE) da Universidade de Pernambuco, Rua dos Palmares, s/n, Santo Amaro, Recife, Brazil
| | - Valesca Kehrle Rodrigues
- Hospital Universitário Oswaldo Cruz, Rua Arnóbio Marques, s/n, Pernambuco, Santo Amaro, Recife, Brazil
| | | | - Audes Diógenes Magalhães Feitosa
- Pronto Socorro Cardiológico de Pernambuco (PROCAPE) da Universidade de Pernambuco, Rua dos Palmares, s/n, Santo Amaro, Recife, Brazil
| | | | - Marília Montenegro Cabral
- Laboratório Do Sono E Coração, Pronto Socorro Cardiológico de Pernambuco, (PROCAPE) da Universidade de Pernambuco, Rua dos Palmares, s/n, Santo Amaro, Recife, Brazil
| | - Rodrigo P Pedrosa
- Laboratório Do Sono E Coração, Pronto Socorro Cardiológico de Pernambuco, (PROCAPE) da Universidade de Pernambuco, Rua dos Palmares, s/n, Santo Amaro, Recife, Brazil
- Pronto Socorro Cardiológico de Pernambuco (PROCAPE) da Universidade de Pernambuco, Rua dos Palmares, s/n, Santo Amaro, Recife, Brazil
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Zhang X, Zhang S, Huang Q, Liu Y, Chang J, Liu P. Comparison of arterial stiffness and ultrasound indices in patients with and without chronic obstructive pulmonary disease. Rev Assoc Med Bras (1992) 2022; 68:605-609. [PMID: 35584482 DOI: 10.1590/1806-9282.2021203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 11/22/2022] Open
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Waeijen-Smit K, Reynaert NL, Beijers RJHCG, Houben-Wilke S, Simons SO, Spruit MA, Franssen FME. Alterations in plasma hyaluronic acid in patients with clinically stable COPD versus (non)smoking controls. Sci Rep 2021; 11:15883. [PMID: 34354097 PMCID: PMC8342478 DOI: 10.1038/s41598-021-95030-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 07/20/2021] [Indexed: 12/02/2022] Open
Abstract
Hyaluronic acid (HA) is a key component of the extracellular matrix. HA and its metabolism are suggested to be altered in the lungs of patients with chronic obstructive pulmonary disease (COPD). The present study explored systemic HA, and its metabolic regulators, in patients with clinically stable COPD and smoking and non-smoking controls. Furthermore, associations of HA with acute exacerbations (AECOPD), airway-related hospitalizations, systemic inflammation and cardiovascular risk were studied. In total, 192 patients with moderate to very severe COPD [aged 62.3 y (± SD 7.0)], 84 smoking controls [aged 61.8 y (± 5.7)], and 107 non-smoking controls [aged 60.1 y (± 7.0)] were included. Plasma HA was reduced in patients with COPD compared to non-smoking controls (p = 0.033), but was comparable after adjusting for age and sex. Expression of HAS-3 did not differ between groups, but was substantially less detectable in more patients with COPD than (non)smoking controls (p < 0.001). Expression of HYAL-2 was enhanced in patients with COPD versus smoking (p = 0.019) and non-smoking (p < 0.001) controls, also in the age- and sex- adjusted model (p < 0.001). Plasma HA was not associated with AECOPD, airway-related hospitalizations in the previous year, or systemic inflammation in COPD. Arterial pulse wave velocity explained some of the variance (< 10%) in plasma HA (p = 0.006). Overall, these results indicate that expression of HYAL-2, but not plasma HA nor HAS-3, is enhanced in patients with COPD compared to (non)smoking controls. Furthermore, HA was not associated with clinical outcomes, yet, cardiovascular risk might play a role in its systemic regulation in stable COPD.
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Affiliation(s)
- Kiki Waeijen-Smit
- Department of Research and Education, Ciro, Horn, The Netherlands. .,Department of Respiratory Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands.
| | - Niki L Reynaert
- Department of Respiratory Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Rosanne J H C G Beijers
- Department of Respiratory Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | | | - Sami O Simons
- Department of Respiratory Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Martijn A Spruit
- Department of Research and Education, Ciro, Horn, The Netherlands.,Department of Respiratory Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Frits M E Franssen
- Department of Research and Education, Ciro, Horn, The Netherlands.,Department of Respiratory Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
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Roeder M, Sievi NA, Kohlbrenner D, Clarenbach CF, Kohler M. Arterial Stiffness Increases Over Time in Relation to Lung Diffusion Capacity: A Longitudinal Observation Study in COPD. Int J Chron Obstruct Pulmon Dis 2020; 15:177-187. [PMID: 32158204 PMCID: PMC6986246 DOI: 10.2147/copd.s234882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 12/17/2019] [Indexed: 12/24/2022] Open
Abstract
Background Cardiovascular events are, after cancer, the most common cause of death in COPD patients. Arterial stiffness is an independent predictor of all-cause mortality and cardiovascular events. Several cross-sectional studies have confirmed increased arterial stiffness in patients with COPD. Various mechanisms in the development of arterial stiffness in COPD such as reduced lung function or systemic inflammation have been proposed. However, clinical predictors of arterial stiffness that had been reported in cross-sectional studies have not yet been confirmed in a longitudinal setting. We have assessed the course of augmentation index (AIx) - a measure of systemic arterial stiffness - and possible predictors in a cohort of COPD patients over a period of up to 7 years. Methods COPD patients underwent annual AIx measurement by applanation tonometry for a maximum duration of 7 years. Additionally, we performed annual assessments of lung function, blood gases, systemic inflammation, serum lipids and blood pressure. Associations between the course of AIx and potential predictors were investigated through a mixed effect model. Results Seventy-six patients (mean (SD) age 62.4 (7.1), male 67%) were included. The AIx showed a significant annual increase of 0.91% (95% CI 0.21/1.60) adjusted for baseline. The change in diffusion capacity (DLco), low-density lipoprotein (LDL), and high-sensitivity c-reactive protein (hsCRP) was independently associated with the increasing evolution of AIx (Coef. - 0.10, p<0.001, Coef. 1.37, p=0.003, and Coef. 0.07, p=0.033, respectively). Conclusion This study demonstrated a meaningful increase in arterial stiffness in COPD over time. A greater annual increase in arterial stiffness was associated with the severity of emphysema (measured by DLco), systemic inflammation, and dyslipidaemia. Clinical Trial Registration www.ClinicalTrials.gov, NCT01527773.
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Affiliation(s)
- Maurice Roeder
- Pulmonary Division, University Hospital of Zurich, Zurich, Switzerland
| | - Noriane A Sievi
- Pulmonary Division, University Hospital of Zurich, Zurich, Switzerland
| | - Dario Kohlbrenner
- Pulmonary Division, University Hospital of Zurich, Zurich, Switzerland
| | | | - Malcolm Kohler
- Pulmonary Division, University Hospital of Zurich, Zurich, Switzerland.,Centre for Interdisciplinary Sleep Research, University of Zurich, Zurich, Switzerland
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