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Ruediger CD, John B, Kumar S, Lim HS, Rangnekar G, Roberts-Thomson KC, Young GD, Chase D, Sanders P, Willoughby SR. Influence of ethnic background on left atrial markers of inflammation, endothelial function and tissue remodelling. Indian Pacing Electrophysiol J 2018; 18:1-5. [PMID: 29477215 PMCID: PMC5840760 DOI: 10.1016/j.ipej.2017.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 08/21/2017] [Accepted: 08/28/2017] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND It has been suggested that ethnicity can make a significant difference to the likelihood of thromboembolic stroke related to atrial fibrillation. Ethnic differences have been shown to alter inflammatory and haemostatic factors; however, this may all be confounded by differences in cardiovascular risk factors between different ethnicity. The impact of different ethnicities on the thrombogenic profile is not known. The aim of this study was to investigate differences in markers of inflammation, endothelial function and tissue remodelling between Caucasian and Indian populations with supraventricular tachycardia (SVT). METHODS Patients with structurally normal hearts undergoing catheter ablation for SVT were studied. This study included 23 Australian (Caucasian) patients from the Royal Adelaide Hospital, Adelaide, Australia and 24 Indian (Indian) patients from the Christian Medical College, Vellore, India. Blood samples were collected from the femoral vein, and right and left atria. Blood samples were analysed for the markers of endothelial function (ADMA, ET-1), inflammation (CD40L, VCAM-1, ICAM-1), and tissue remodelling (MMP-9, TIMP-1) using ELISA. RESULTS The study populations were well matched for cardiovascular risk factors and the absence of structural heart disease. No difference in the echocardiographic measurements between the two ethnicities was found. In this context, there was no difference in markers of inflammation, endothelial function or tissue remodelling between the two SVT populations. CONCLUSION Caucasian and Indian populations demonstrate similar inflammatory, endothelial function or tissue remodelling profiles. This study suggests a lack of an impact of different ethnicity in these populations in terms of thrombogenic risk.
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Affiliation(s)
- Carlee D Ruediger
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Bobby John
- Department of Cardiology, Christian Medical College, Vellore, India
| | - Sathesh Kumar
- Department of Cardiology, Christian Medical College, Vellore, India
| | - Han S Lim
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Geetanjali Rangnekar
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Kurt C Roberts-Thomson
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Glenn D Young
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - David Chase
- Department of Cardiology, Christian Medical College, Vellore, India
| | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Scott R Willoughby
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
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Lim HS, Willoughby SR, Schultz C, Alasady M, Rangnekar G, Dang J, Gan C, Lau DH, Roberts-Thomson KC, Young GD, Worthley MI, Sanders P. Thrombogenic Risk in Patients With Atrial Fibrillation. JACC Clin Electrophysiol 2015; 1:210-217. [DOI: 10.1016/j.jacep.2015.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 02/17/2015] [Accepted: 03/26/2015] [Indexed: 10/23/2022]
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Schultz CD, Rangneker G, Lim HS, Fraudeau A, Young G, Roberts-Thomson K, John B, Worthley M, Sanders P, Willoughby SR. Characterization of thrombogenic, endothelial and inflammatory markers in supraventricular tachycardia: a study in patients with structurally normal hearts. Clin Exp Pharmacol Physiol 2015; 41:551-7. [PMID: 24827644 DOI: 10.1111/1440-1681.12256] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 05/01/2014] [Accepted: 05/05/2014] [Indexed: 11/28/2022]
Abstract
Patients with atrial fibrillation (AF) are at an increased risk of thromboembolism and stroke primarily from the development of thrombi within the left atrium. Pathological changes in blood constituents and atrial endothelial damage promote left atrial thrombus formation. It is not known whether factors predisposing to left atrial thrombus formation in AF are disease specific or also evident within the normal heart. The present study examined whether there are differences in platelet reactivity, endothelial function and inflammation in blood samples obtained from intracardiac and peripheral sites in subjects within structurally normal hearts. Sixteen patients with diagnosed left-sided supraventricular tachycardia (SVT) undergoing a routine elective electrophysiological study and ablation were investigated. Blood samples were taken simultaneously from the femoral vein, right atrium and left atrium, immediately following trans-septal puncture and prior to heparin bolus administration. Between peripheral and atrial sample sites, patients with SVT showed no change in platelet reactivity or aggregation (P-selectin (CD62P) P = 0.91; platelet-derived soluble CD40 ligand P = 0.9), thrombus formation (thrombin-antithrombin complex; P = 0.55), endothelial function (von Willebrand factor P = 0.75; asymmetric dimethylarginine (ADMA) P = 0.97; nitric oxide P = 0.61), or inflammation (vascular cell adhesion molecule-1 P = 0.59; intercellular adhesion molecule-1 (ICAM-1) P = 0.69). However, SVT patients had lower ADMA and ICAM-1 levels than AF patients. The present study demonstrates, for the first time, that SVT subjects with structurally normal hearts have consistent haemostatic function between atrial and peripheral sites. These results suggest that the atria of SVT patients do not contain predisposing thrombogenic, endothelial or inflammatory factors that promote and/or initiate thrombus formation.
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Affiliation(s)
- Carlee D Schultz
- Centre for Heart Rhythm Disorders, University of Adelaide and Cardiovascular Investigation Unit, Royal Adelaide Hospital, Adelaide, SA, Australia
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Reddi BA, Iannella SM, O'Connor SN, Deane AM, Willoughby SR, Wilson DP. Attenuated platelet aggregation in patients with septic shock is independent from the activity state of myosin light chain phosphorylation or a reduction in Rho kinase-dependent inhibition of myosin light chain phosphatase. Intensive Care Med Exp 2015. [PMID: 26215804 PMCID: PMC4512995 DOI: 10.1186/s40635-014-0037-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Background Impaired coagulation contributes to the morbidity and mortality associated with septic shock. Whether abnormal platelet contraction adds to the bleeding tendency is unknown. Platelets contract when Ca2+-dependent myosin light chain kinase (MLCK) phosphorylates Ser19 of myosin light chain (MLC20), promoting actin-myosin cross-bridge cycling. Contraction is opposed when myosin light chain phosphatase (MLCP) dephosphorylates MLC20. It is thought that Rho kinase (ROK) inhibits MLCP by phosphorylating Thr855 of the regulatory subunit MYPT, favouring platelet contraction. This study tested the hypotheses that in septic shock, (i) platelet function is inversely correlated with illness severity and (ii) ROK-dependent MLCP inhibition and myosin light chain phosphorylation are reduced. Methods Blood was sampled from non-septic shock patients and patients in the first 24 h of septic shock. Platelet function was assessed using whole blood impedance aggregation induced by 1) ADP (1.6 and 6.5 μM), 2) thrombin receptor-activating protein (TRAP; 32 μM), 3) arachidonic acid (500 μM) and 4) collagen (3.2 μg/ml). Arachidonic acid-induced aggregation was measured in the presence of the ROK inhibitor Y27632. Illness severity was evaluated using sequential organ failure assessment (SOFA) and acute physiology and chronic health evaluation (APACHE) II scores. Western blot analysis of [Ser19]MLC20 and [Thr855]MYPT phosphorylation quantified activation and inhibition of platelet MLC20 and MLCP, respectively. Data were analysed using Spearman's rank correlation coefficient, Student's t-test and Mann-Whitney test; p < 0.05 was considered significant. Results Agonist-induced aggregation was attenuated in septic shock patients (n = 22 to 34; p < 0.05). Aggregation correlated inversely with SOFA and APACHE II scores (n = 34; p < 0.05). Thr855 phosphorylation of MYPT from unstimulated platelets was not decreased in patients with septic shock (n = 22 to 24). Both septic shock and ROK inhibition attenuated arachidonic acid-induced platelet aggregation independent of changes in [Ser19]MLC20 and [Thr855]MYPT phosphorylation (n = 14). Conclusions Impairment of whole blood aggregation in patients within the first 24 h of septic shock was correlated with SOFA and APACHE II scores. Attenuated aggregation was independent of molecular evidence of diminished platelet contraction or reduced ROK inhibition of MLCP. Efforts to restore platelet function in septic shock should therefore focus on platelet adhesion and degranulation.
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Affiliation(s)
- Benjamin Aj Reddi
- Intensive Care Unit, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, 5000, Australia,
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Blanch N, Clifton PM, Petersen KS, Willoughby SR, Keogh JB. Effect of high potassium diet on endothelial function. Nutr Metab Cardiovasc Dis 2014; 24:983-989. [PMID: 24875671 DOI: 10.1016/j.numecd.2014.04.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/09/2014] [Accepted: 04/24/2014] [Indexed: 11/17/2022]
Abstract
BACKGROUND AND AIMS Increased potassium intake is related to reduced blood pressure (BP) and reduced stroke rate. The effect of increased dietary potassium on endothelial function remains unknown. The aim was to determine the effect of increased dietary potassium from fruit and vegetables on endothelial function. METHODS AND RESULTS Thirty five healthy men and women (age 32 ± 12 y) successfully completed a randomised cross-over study of 2 × 6 day diets either high or low in potassium. Flow mediated dilatation (FMD), BP, pulse wave velocity (PWV), augmentation index (AI) and a fasting blood sample for analysis of Intercellular Adhesion Molecule-1 (ICAM-1), E-selectin, asymmetric dimethylarginine (ADMA) and endothelin-1 were taken on completion of each intervention. Dietary change was achieved by including bananas and potatoes in the high potassium and apples and rice/pasta in the low potassium diet. Dietary adherence was assessed using 6 day weighed food diaries and a 24 h urine sample. The difference in potassium excretion between the two diets was 48 ± 32 mmol/d (P = 0.000). Fasting FMD was significantly improved by 0.6% ± 1.5% following the high compared to the low potassium diet (P = 0.03). There were no significant differences in BP, PWV, AI, ICAM-1, ADMA or endothelin-1 between the interventions. There was a significant reduction in E-selectin following the high (Median = 5.96 ng/ml) vs the low potassium diet (Median = 6.24 ng/ml), z = -2.49, P = 0.013. CONCLUSION Increased dietary potassium from fruit and vegetables improves FMD within 1 week in healthy men and women but the mechanisms for this effect remain unclear. CLINICAL TRIAL REGISTRY ACTRN12612000822886.
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Affiliation(s)
- N Blanch
- School of Pharmacy and Medical Science, University of South Australia, Australia
| | - P M Clifton
- School of Pharmacy and Medical Science, University of South Australia, Australia
| | - K S Petersen
- School of Pharmacy and Medical Science, University of South Australia, Australia
| | - S R Willoughby
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - J B Keogh
- School of Pharmacy and Medical Science, University of South Australia, Australia.
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Lim HS, Willoughby SR, Schultz C, Chakrabarty A, Alasady M, Lau DH, Roberts-Thomson KC, Worthley MI, Young GD, Sanders P. Successful catheter ablation decreases platelet activation and improves endothelial function in patients with atrial fibrillation. Heart Rhythm 2014; 11:1912-8. [PMID: 25068571 DOI: 10.1016/j.hrthm.2014.07.030] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Nonvalvular atrial fibrillation (AF) confers a five-fold increased risk of stroke. Whether catheter ablation (CA) subsequently decreases prothrombotic risk is unknown. OBJECTIVE The purpose of this study was to assess the long-term effects of CA for AF on prothrombotic risk. METHODS Fifty-seven patients undergoing CA for AF were prospectively studied. Platelet activation (CD62P [platelet P-selectin] and PAC-1 [glycoprotein IIb/IIIa] expression) and endothelial function (asymmetric dimethylarginine [ADMA] levels) were measured at baseline and 6-months postablation. RESULTS Thirty-seven (65%) patients remained in sinus rhythm (SR group) and 20 (35%) sustained AF recurrence (AF recurrence group) at 6-months. Patients with AF-recurrence were older, had a higher proportion of hypertension and long-standing persistent AF. There were no significant differences in CD62P (P = .3), PAC-1 (P = .1) and ADMA (P = .7) levels at baseline between the two groups. In the SR group, markers of platelet activation decreased significantly at 6-month follow-up compared to baseline; log CD62P % 0.79 ± 0.28 vs 1.03 ± 0.27 (P <.05) and log PAC-1 % 0.22 ± 0.58 vs 0.89 ± 0.31 (P <.01). This was not significant in the AF-recurrence group (P = .8, log CD62P; P = .1, log PAC-1). For endothelial function, ADMA levels decreased significantly at 6-months compared to baseline in the SR group (log ADMA μM/L 0.15 ± 0.02 vs 0.17 ± 0.04; P <.05), but did not alter significantly in the AF-recurrence group (P = .4, log ADMA). CONCLUSION Catheter ablation and successful maintenance of SR leads to a decrease in platelet activation and improvement in endothelial function in patients with AF. These findings suggest that AF is an important determinant of the prothrombotic state and that this may be reduced by successful catheter ablation.
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Affiliation(s)
- Han S Lim
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), and University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Scott R Willoughby
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), and University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Carlee Schultz
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), and University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Adhiraj Chakrabarty
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), and University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Muayad Alasady
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), and University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Dennis H Lau
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), and University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Kurt C Roberts-Thomson
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), and University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Matthew I Worthley
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), and University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Glenn D Young
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), and University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders (CHRD), South Australian Health and Medical Research Institute (SAHMRI), and University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
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Willoughby SR, Luu LJ, Cameron JD, Nelson AJ, Schultz CD, Worthley SG, Worthley MI. Clopidogrel improves microvascular endothelial function in subjects with stable coronary artery disease. Heart Lung Circ 2014; 23:534-41. [PMID: 24529502 DOI: 10.1016/j.hlc.2014.01.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 10/27/2013] [Accepted: 01/10/2014] [Indexed: 01/22/2023]
Abstract
BACKGROUND Clopidogrel therapy has recently been shown to reduce cardiovascular events in patients with stable vascular disease. This benefit may be due to effects not exclusively related to platelet aggregation. The aim of this study was to evaluate the effect of clopidogrel therapy on microvascular endothelial function in subjects with stable coronary artery disease (CAD). METHODS AND RESULTS Forty subjects with stable CAD were randomised to clopidogrel therapy (75mg/day) or control. Blood and endothelial function testing occurred at baseline, one week and three months following randomisation. Microvascular endothelial function was assessed via reactive hyperaemic index (RHI). Platelet function was assessed by adenosine diphosphate (ADP)-induced whole blood aggregation and the VerifyNow™ system. Plasma markers of endothelial function (asymmetric dimethylarginine, ADMA) and oxidative stress (myeloperoxidase, MPO) were also tested. The primary endpoint was endothelial function assessment (RHI) at three months. At one week RHI increased by 20±10% in the clopidogrel group; this effect was maintained at three months (21±9% increase from baseline; P<0.01). A significant decrease in ADP-induced platelet aggregation and P2Y12 reaction units was observed in the clopidogrel therapy group (P<0.01). There was no correlation between endothelial function and platelet function testing in the clopidogrel therapy group. CONCLUSION Clopidogrel therapy is associated with improved microvascular endothelial function in patients with stable CAD. This effect is independent of its effects on ADP-induced platelet reactivity.
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Affiliation(s)
- Scott R Willoughby
- Centre for Heart Rhythm Disorders, University of Adelaide, Adelaide, Australia
| | - Lee-Jen Luu
- Monash Cardiovascular Research Centre, MonashHeart and Monash University, Melbourne, Australia; Cardiovascular Research Centre, Royal Adelaide Hospital, University of Adelaide, Australia
| | - James D Cameron
- Monash Cardiovascular Research Centre, MonashHeart and Monash University, Melbourne, Australia
| | - Adam J Nelson
- Cardiovascular Research Centre, Royal Adelaide Hospital, University of Adelaide, Australia
| | - Carlee D Schultz
- Centre for Heart Rhythm Disorders, University of Adelaide, Adelaide, Australia
| | - Stephen G Worthley
- Cardiovascular Research Centre, Royal Adelaide Hospital, University of Adelaide, Australia
| | - Matthew I Worthley
- Cardiovascular Research Centre, Royal Adelaide Hospital, University of Adelaide, Australia.
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Lim HS, Schultz C, Dang J, Alasady M, Lau DH, Brooks AG, Wong CX, Roberts-Thomson KC, Young GD, Worthley MI, Sanders P, Willoughby SR. Time course of inflammation, myocardial injury, and prothrombotic response after radiofrequency catheter ablation for atrial fibrillation. Circ Arrhythm Electrophysiol 2014; 7:83-9. [PMID: 24446024 DOI: 10.1161/circep.113.000876] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Inflammation has been linked to the genesis of stroke in atrial fibrillation (AF) and is implicated in early recurrent arrhythmia after AF ablation. We aimed to define the time course of inflammation, myocardial injury, and prothrombotic markers after radiofrequency ablation for AF and its relation to AF recurrence. METHODS AND RESULTS Ninety consecutive AF patients (53% paroxysmal) undergoing radiofrequency ablation were recruited. High-sensitivity C-reactive protein (hs-CRP), Troponin-T, creatine kinase-MB, fibrinogen, and D-Dimer concentrations were measured at baseline, at 1, 2, 3, 7 days, and at 1 month after ablation. AF recurrence was documented at 3 days and at 1, 3, and 6 months follow-up. Troponin-T and creatine kinase-MB peaked at day 1 after procedure (both P<0.05). Hs-CRP peaked at day 3 after procedure (P<0.05). Fibrinogen (P<0.05) and D-Dimer (P<0.05) concentrations were significantly elevated at 1 week after procedure. Ln hs-CRP elevation correlated with Ln Troponin-T and fibrinogen elevation. The extent of Ln hs-CRP, Ln Troponin-T, and fibrinogen elevation predicted early AF recurrence within 3 days after procedure (P<0.05, respectively), but not at 3 and 6 months. CONCLUSIONS Patients undergoing radiofrequency ablation for AF exhibit an inflammatory response within 3 days. The extent of inflammatory response predicts early AF recurrence but not late recurrence. Prothrombotic markers are elevated at 1 week after ablation and may contribute to increased risk of early thrombotic events after AF ablation.
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Affiliation(s)
- Han S Lim
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide & Royal Adelaide Hospital, Adelaide, Australia
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Lau DH, Middeldorp ME, Brooks AG, Ganesan AN, Roberts-Thomson KC, Stiles MK, Leong DP, Abed HS, Lim HS, Wong CX, Willoughby SR, Young GD, Kalman JM, Abhayaratna WP, Sanders P. Aortic stiffness in lone atrial fibrillation: a novel risk factor for arrhythmia recurrence. PLoS One 2013; 8:e76776. [PMID: 24098560 PMCID: PMC3789695 DOI: 10.1371/journal.pone.0076776] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 09/02/2013] [Indexed: 01/05/2023] Open
Abstract
Background Recent community-based research has linked aortic stiffness to the development of atrial fibrillation. We posit that aortic stiffness contributes to adverse atrial remodeling leading to the persistence of atrial fibrillation following catheter ablation in lone atrial fibrillation patients, despite the absence of apparent structural heart disease. Here, we aim to evaluate aortic stiffness in lone atrial fibrillation patients and determine its association with arrhythmia recurrence following radio-frequency catheter ablation. Methods We studied 68 consecutive lone atrial fibrillation patients who underwent catheter ablation procedure for atrial fibrillation and 50 healthy age- and sex-matched community controls. We performed radial artery applanation tonometry to obtain central measures of aortic stiffness: pulse pressure, augmentation pressure and augmentation index. Following ablation, arrhythmia recurrence was monitored at months 3, 6, 9, 12 and 6 monthly thereafter. Results Compared to healthy controls, lone atrial fibrillation patients had significantly elevated peripheral pulse pressure, central pulse pressure, augmentation pressure and larger left atrial dimensions (all P<0.05). During a mean follow-up of 2.9±1.4 years, 38 of the 68 lone atrial fibrillation patients had atrial fibrillation recurrence after initial catheter ablation procedure. Neither blood pressure nor aortic stiffness indices differed between patients with and without atrial fibrillation recurrence. However, patients with highest levels (≥75th percentile) of peripheral pulse pressure, central pulse pressure and augmentation pressure had higher atrial fibrillation recurrence rates (all P<0.05). Only central aortic stiffness indices were associated with lower survival free from atrial fibrillation using Kaplan-Meier analysis. Conclusion Aortic stiffness is an important risk factor in patients with lone atrial fibrillation and contributes to higher atrial fibrillation recurrence following catheter ablation procedure.
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Affiliation(s)
- Dennis H. Lau
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Melissa E. Middeldorp
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Anthony G. Brooks
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Anand N. Ganesan
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Kurt C. Roberts-Thomson
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Martin K. Stiles
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Darryl P. Leong
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Hany S. Abed
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Han S. Lim
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Christopher X. Wong
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Scott R. Willoughby
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Glenn D. Young
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Jonathan M. Kalman
- Department of Cardiology, Royal Melbourne Hospital and the Department of Medicine, University of Melbourne, Victoria, Australia
| | | | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
- * E-mail:
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Lim HS, Willoughby SR, Sanders P. Reply. J Am Coll Cardiol 2013; 62:167-168. [DOI: 10.1016/j.jacc.2013.03.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 03/12/2013] [Indexed: 10/26/2022]
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Willoughby SR, Schultz C, Kumar S, Nair S, Srivastava A, Joseph G, Chandy S, John B, Sanders P. Abstract 180: Differential Role of Endothelin-1 in Mitral Stenosis and Atrial Fibrillation. Arterioscler Thromb Vasc Biol 2013. [DOI: 10.1161/atvb.33.suppl_1.a180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background
Chronic atrial stretch due to mitral stenosis is a major substrate for the development of atrial fibrillation (AF). It is well established that rhuematic mitral stenosis and AF are associated with an increased risk of thromboembolic events. Endothelin-1 (ET-1) is a potent vasoconstrictor and modulator of vascular function, and is known to play a role in thrombus formation. We therefore sought to compare ET-1 levels between patients with rheumatic mitral stenosis and AF.
Methods
We measured plasma levels of ET-1 in blood samples from the femoral vein (FV), right atria (RA) and left atria (LA) obtained from 19 patients with rheumatic mitral stenosis, 12 patients with lone AF and 10 subjects with supraventricular tachycardia (reference subjects [REF]). Plasma ET-1 levels were measured by conventional ELISA techniques.
Results
The FV concentrations of ET-1 were significantly higher in rheumatic mitral stenosis patients than in AF patients or REF subjects (Figure). However, there was no significant difference in the concentrations of ET-1 between AF patients and REF subjects. In rheumatic mitral stenosis patients and REF subjects there were no differences in concentrations of ET-1 between the FV, RA and LA. In contrast, ET-1 levels were highest in the femoral vein of AF patients (FV vs RA p<0.03 and FV vs LA p<0.06).
Conclusion
Patients with rheumatic mitral stenosis have significantly higher ET-1 levels than AF patients. These data suggest that ET-1 plays a differential role in the pathophysiology of thrombus formation in mitral stenosis and AF. It highlights the importance of the underlying substrate to the risk of developing thrombus within the atria.
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Affiliation(s)
| | | | | | - Sukesh Nair
- Hematology, Christian Med College, Vellore, India
| | | | | | - Sunil Chandy
- Cardiology, Christian Med College, Vellore, India
| | - Bobby John
- Cardiology, Christian Med College, Vellore, India
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Willoughby SR, Dickinson K, Schultz C, Sanders P, Clifton P, Keogh J. Abstract 168: Impact of Obesity and Atrial Fibrillation on Arterial Stiffness. Arterioscler Thromb Vasc Biol 2013. [DOI: 10.1161/atvb.33.suppl_1.a168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Introduction
Turbulent blood flow which occurs in atrial fibrillation patients due to an irregular heart rate may lead to vascular abnormalities and increased thrombotic risk. Obesity is an important emerging substrate for the development of atrial fibrillation. Obesity is also associated with endothelial dysfunction and increased arterial stiffness. We sought to determine the impact of obesity on arterial stiffness in patients with atrial fibrillation.
Methods
34 patients with atrial fibrillation (age 59±12 years,) were evaluated in lean (n=21) and obese (n=13) subgroups, and compared to age-matched lean (n=15) and obese (n=14) control subjects. Arterial stiffness was assessed using radial applanation tonometry (SphygmoCor). Heart rate adjusted aortic augmentation index (AIx: a measure of arterial stiffness) was calculated from the corresponding waveforms utilizing validated transfer functions.
Results
Obese controls and obese atrial fibrillation patients had significantly higher AIx (arterial stiffness) than lean controls and lean atrial fibrillation patients (p=0.003 and p=0.03, respectively: Figure). There was no difference in AIx scores between obese atrial fibrillation patients and obese control subjects (p=0.3) and between lean atrial fibrillation and lean control subjects (p=0.8).
Conclusion
We conclude that obesity is associated with arterial stiffness and atrial fibrillation does not add additional burden. These results suggest the interaction between obesity and atrial fibrillation may contribute to the observed increase in thromboembolic risk, in part, through vascular abnormalities other than increased arterial stiffness.
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Affiliation(s)
| | | | | | | | - Peter Clifton
- Preventative Medicine, Baker IDI Heart & Diabetes Institute, Adelaide, Australia
| | - Jennifer Keogh
- Health Sciences, Univ of South Australia, Adelaide, Australia
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Mahajan R, Pathak R, Lim HS, Willoughby SR, Sanders P. Does catheter ablation of atrial fibrillation eliminate the need for anticoagulation? Interv Cardiol 2013. [DOI: 10.2217/ica.13.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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14
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Lim HS, Willoughby SR, Schultz C, Gan C, Alasady M, Lau DH, Leong DP, Brooks AG, Young GD, Kistler PM, Kalman JM, Worthley MI, Sanders P. Effect of atrial fibrillation on atrial thrombogenesis in humans: impact of rate and rhythm. J Am Coll Cardiol 2013; 61:852-60. [PMID: 23333141 DOI: 10.1016/j.jacc.2012.11.046] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 11/18/2012] [Accepted: 11/20/2012] [Indexed: 11/18/2022]
Abstract
OBJECTIVES We sought to assess the effect of atrial fibrillation (AF) on atrial thrombogenesis in humans by determining the impact of rate and rhythm. BACKGROUND Although AF is known to increase the risk of thromboembolic stroke from the left atrium (LA), the exact mechanisms remain poorly understood. METHODS We studied 55 patients with AF who underwent catheter ablation while in sinus rhythm; 20 patients were induced into AF, 20 patients were atrial paced at 150 beats/min, and 15 were control patients. Blood samples were taken from the LA, right atrium, and femoral vein at baseline and at 15 min in all 3 groups. Platelet activation (P-selectin) was measured by flow cytometry. Thrombin generation (thrombin-antithrombin [TAT] complex), endothelial dysfunction (asymmetric dimethylarginine [ADMA]), and platelet-derived inflammation (soluble CD40 ligand [sCD40L]) were measured using enzyme-linked immunosorbent assay. RESULTS Platelet activation increased significantly in both the AF (p < 0.001) and pacing (p < 0.05) groups, but decreased in control patients (p < 0.001). Thrombin generation increased specifically in the LA compared with the periphery in both the AF (p < 0.01) and pacing (p < 0.01) groups, but decreased in control patients (p < 0.001). With AF, ADMA (p < 0.01) and sCD40L (p < 0.001) levels increased significantly at all sites, but were unchanged with pacing (ADMA, p = 0.5; sCD40L, p = 0.8) or in control patients (ADMA, p = 0.6; sCD40L, p = 0.9). CONCLUSIONS Rapid atrial rates and AF in humans both result in increased platelet activation and thrombin generation. Prothrombotic activation occurs to a greater extent in the human LA compared with systemic circulation. AF additionally induces endothelial dysfunction and inflammation. These findings suggest that although rapid atrial rates increase the thrombogenic risk, AF may further potentiate this risk.
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Affiliation(s)
- Han S Lim
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
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15
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Tayeb HM, Nelson AJ, Willoughby SR, Worthley MI. Antiplatelet therapy in acute coronary syndromes: current agents and impact on patient outcomes. Patient Relat Outcome Meas 2012; 2:7-19. [PMID: 22915965 PMCID: PMC3417919 DOI: 10.2147/prom.s9834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Indexed: 02/02/2023]
Abstract
Platelets play a central role in atherothrombosis and subsequent development of acute coronary syndromes (ACS). The understanding of this process has driven a large body of evidence demonstrating the mortality and morbidity benefits of antiplatelet agents in the ACS population. As expected, however, these agents come with an intrinsically increased risk of bleeding which underlies the vast majority of their complications and adverse effects. In today’s setting of compounding comorbidities and broadening indications, finding the balance between thrombosis prevention and bleeding risk remains the challenge for all clinicians considering these medications. This article reviews the current main antiplatelet agents that are available for clinical use and outlines their impact on ACS outcome. We also outline factors which affect the response to these agents and discuss strategies to optimize clinical outcomes.
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Affiliation(s)
- Hussam M Tayeb
- Cardiovascular Research Centre, Royal Adelaide Hospital and Discipline of Medicine, University of Adelaide, Adelaide, South Australia, Australia
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16
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Willoughby SR, Rajendran S, Chan WP, Procter N, Leslie S, Liberts EA, Heresztyn T, Chirkov YY, Horowitz JD. Ramipril sensitizes platelets to nitric oxide: implications for therapy in high-risk patients. J Am Coll Cardiol 2012; 60:887-94. [PMID: 22682555 DOI: 10.1016/j.jacc.2012.01.066] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 01/20/2012] [Accepted: 01/23/2012] [Indexed: 01/25/2023]
Abstract
OBJECTIVES Using 2 sequential studies in HOPE (Heart Outcomes Prevention Evaluation) study-type patients, the aims of this study were: 1) to test the hypothesis that ramipril improves platelet nitric oxide (NO) responsiveness: and 2) to explore biochemical and physiological effects of ramipril in a cohort selected on the basis of platelet NO resistance. BACKGROUND Ramipril prevents cardiovascular events, but the bases for these effects remain uncertain. NO resistance at both the platelet and vascular levels is present in a substantial proportion of patients with diabetes or ischemic heart disease and is an independent risk factor for cardiovascular events. METHODS Study 1 was a double-blind, randomized comparison of ramipril (10 mg) with placebo in a cohort of patients (n = 119) with ischemic heart disease or diabetes plus additional coronary risk factor(s), in which effects on platelet responsiveness to NO were compared. Study 2 was a subsequent short-term evaluation of the effects of ramipril in a cohort of subjects (n = 19) with impaired platelet NO responsiveness in whom additional mechanistic data were sought. RESULTS In study 1, ramipril therapy increased platelet responsiveness to NO relative to the extent of aggregation (p < 0.001), but this effect occurred primarily in patients with severely impaired baseline NO responsiveness (n = 41). In study 2, ramipril also improved platelet NO responsiveness (p < 0.01), and this improvement was correlated directly with increased NO-stimulated platelet generation of cyclic guanosine monophosphate (p < 0.02) but not with changes in plasma thrombospondin-1 levels. CONCLUSIONS Ramipril ameliorates platelet NO resistance in HOPE study-type patients, with associated increases in soluble guanylate cyclase responsiveness to NO. This effect is likely to contribute to treatment benefit and define patients in whom ramipril therapy is particularly effective.
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Affiliation(s)
- Scott R Willoughby
- Cardiology Unit, The Basil Hetzel Institute, The Queen Elizabeth Hospital, Discipline of Medicine, University of Adelaide, Adelaide, Australia
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17
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Wong CX, Lim HS, Schultz CD, Sanders P, Worthley MI, Willoughby SR. Assessment of endothelial function in atrial fibrillation: utility of peripheral arterial tonometry. Clin Exp Pharmacol Physiol 2012; 39:141-4. [DOI: 10.1111/j.1440-1681.2011.05647.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Kopetz V, Kennedy J, Heresztyn T, Stafford I, Willoughby SR, Beltrame JF. Endothelial Function, Oxidative Stress and Inflammatory Studies in Chronic Coronary Slow Flow Phenomenon Patients. Cardiology 2012; 121:197-203. [DOI: 10.1159/000336948] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2011] [Accepted: 01/16/2012] [Indexed: 11/19/2022]
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19
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S. Lim H, R. Willoughby S, Schultz C, Alasady M, H. Lau D, C. Roberts-Thomson K, D. Young G, Sanders P. The Effect of Acute Onset Atrial Fibrillation and Rapid Atrial Rates on Markers of Thrombogenesis in the Human Left Atrium. J Arrhythm 2011. [DOI: 10.4020/jhrs.27.op19_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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20
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S. Lim H, R. Willoughby S, Schultz C, Alasady M, Worthley M, D. Young G, Sanders P. Inflammation, Myocardial Injury and Prothrombotic Response Following Catheter Ablation for Atrial Fibrillation. J Arrhythm 2011. [DOI: 10.4020/jhrs.27.op28_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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21
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Worthley MI, Prabhu A, De Sciscio P, Schultz C, Sanders P, Willoughby SR. Detrimental effects of energy drink consumption on platelet and endothelial function. Am J Med 2010; 123:184-7. [PMID: 20103032 DOI: 10.1016/j.amjmed.2009.09.013] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 09/09/2009] [Accepted: 09/10/2009] [Indexed: 12/11/2022]
Abstract
BACKGROUND Energy drink consumption has been anecdotally linked with sudden cardiac death and, more recently, myocardial infarction. As myocardial infarction is strongly associated with both platelet and endothelial dysfunction, we tested the hypothesis that energy drink consumption alters platelet and endothelial function. METHODS Fifty healthy volunteers (34 male, aged 22+/-2 years) participated in the study. Platelet aggregation and endothelial function were tested before, and 1 hour after, the consumption of 250 mL (1 can) of a sugar-free energy drink. Platelet function was assessed by adenosine diphosphate-induced (1 micromol/L) optical aggregometry in platelet-rich plasma. Endothelial function was assessed via changes in peripheral arterial tonometry and expressed as the reactive hyperemia index (RHI). RESULTS Compared with baseline values, there was a significant increase in platelet aggregation following energy drink consumption, while no change was observed with control (13.7+/-3.7% vs 0.3+/-0.8% aggregation, respectively, P <.01). Similarly, RHI decreased following energy drink consumption (-0.33+/-0.13 vs 0.07+/-0.12 RHI [control], P <.05). Mean arterial pressure significantly increased following energy drink consumption, compared with control (P <.05). Heart rate was unaffected by energy drink consumption. CONCLUSION Energy drink consumption acutely increases platelet aggregation and decreases endothelial function in healthy young adults.
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Affiliation(s)
- Matthew I Worthley
- Department of Cardiology, Cardiovascular Research Centre, Royal Adelaide Hospital, and Disciplines of Physiology and Medicine, University of Adelaide, Adelaide, Australia
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22
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Ngo DT, Sverdlov AL, Willoughby SR, Nightingale AK, Chirkov YY, McNeil JJ, Horowitz JD. Determinants of Occurrence of Aortic Sclerosis in an Aging Population. JACC Cardiovasc Imaging 2009; 2:919-27. [DOI: 10.1016/j.jcmg.2009.03.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 03/09/2009] [Accepted: 03/25/2009] [Indexed: 10/20/2022]
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23
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Leong DP, Willoughby SR, Chakrabarty A, Shirazi M, Penhall A, Perry R, Young GD, Worthley MI, Selvanayagam JB, Sanders P. The Role of Endothelial Dysfunction in the Development of Myocardial Fibrosis in Dilated Cardiomyopathy. Heart Lung Circ 2009. [DOI: 10.1016/j.hlc.2009.05.434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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24
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Willoughby SR, De Sciscio P, Prabhu A, Roberts-Thomson R, Schultz C, Sanders P, Worthley M. Energy drink effects platelet aggregation and endothelial function: A possible link to increased cardiovascular risk. Heart Lung Circ 2009. [DOI: 10.1016/j.hlc.2009.05.653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Rajendran S, Willoughby SR, Chan WPA, Liberts EA, Heresztyn T, Saha M, Marber MS, Norman RJ, Horowitz JD. Polycystic ovary syndrome is associated with severe platelet and endothelial dysfunction in both obese and lean subjects. Atherosclerosis 2008; 204:509-14. [PMID: 19027116 DOI: 10.1016/j.atherosclerosis.2008.09.010] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 09/01/2008] [Accepted: 09/09/2008] [Indexed: 12/31/2022]
Abstract
Platelet hyporesponsiveness to the anti-aggregatory effects of nitric oxide (NO) occurs commonly in association with myocardial ischemia and coronary risk factors, often co-exists with endothelial dysfunction and represents an independent marker of long-term cardiovascular risk. We sought to determine whether polycystic ovary syndrome (PCOS), which has been postulated as a cardiovascular risk factor in women, is independently associated with this phenomenon. Twenty-four young women with PCOS (mean age 32.1+/-1.3) were evaluated in lean (n=12) and obese (n=12) subgroups, and compared with age-matched lean normals (n=12). Platelet aggregation and its inhibition by the nitric oxide donor sodium nitroprusside (SNP) were assessed and compared with vascular endothelial function. Plasma concentrations of malondialdehyde (MDA), N(G),N(G)-dimethyl-L-arginine (ADMA) and hs-CRP were measured as markers of oxidative stress, endothelial dysfunction and inflammation, respectively. Circulating endothelial progenitor cell (EPC) counts were also documented. In both PCOS subgroups, which demonstrated hyperaggregability to ADP, responses to SNP inhibition of aggregation (the principal end-point of the study) were significantly impaired (P<0.01 for both), as were their endothelium-dependent vascular responses to salbutamol (P<0.05 for both). However, vasomotor responses to nitroglycerin and circulating EPC counts did not vary between groups. PCOS subjects also had significantly elevated ADMA, MDA and hs-CRP levels relative to normals (all P<0.05). Impairment of SNP response remained unaltered after mean 30+/-2.4 months follow-up in PCOS subjects. We conclude that in PCOS subjects, independent of obesity and associated insulin resistance, profound and reproducible impairment of platelet responsiveness to NO is an additional component of cardiovascular homeostatic disturbance.
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Affiliation(s)
- Sharmalar Rajendran
- Cardiology Unit, The Basil Hetzel Institute, The Queen Elizabeth Hospital, Department of Medicine, The University of Adelaide, Australia
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Wong CX, Brooks AG, Stiles MK, John B, Dimitri H, Roberts-Thomson RL, Kuklik P, Willoughby SR, Mackenzie L, Young GD, Sanders P. Atrial Activation Rates During Atrial Fibrillation and Left Atrial Diameter are the Strongest Predictors of Cardioversion Success. Heart Lung Circ 2008. [DOI: 10.1016/j.hlc.2008.05.395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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27
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Wong CX, Stiles MK, John B, Brooks AG, Kuklik P, Lau DH, Dimitri H, Roberts-Thomson RL, Willoughby SR, Mackenzie L, Young GD, Sanders P. Characterisation of Direction-dependent Conduction Abnormalities Predisposing to Atrial Arrhythmias. Heart Lung Circ 2008. [DOI: 10.1016/j.hlc.2008.05.283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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28
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Liberts EA, Willoughby SR, Kennedy JA, Horowitz JD. Effects of perhexiline and nitroglycerin on vascular, neutrophil and platelet function in patients with stable angina pectoris. Eur J Pharmacol 2007; 560:49-55. [PMID: 17292880 DOI: 10.1016/j.ejphar.2007.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2006] [Revised: 01/08/2007] [Accepted: 01/10/2007] [Indexed: 10/23/2022]
Abstract
Perhexiline, a "metabolic" anti-anginal agent currently under investigation in management of congestive heart failure and acute coronary syndromes improves platelet nitric oxide responsiveness in patients with impaired responsiveness. The current study investigated possible interactions between perhexiline and the nitric oxide donor nitroglycerin on arterial stiffness, neutrophil superoxide release and on platelet nitric oxide responsiveness. Patients (n=39) with stable angina pectoris, awaiting cardiac catheterization were randomized to additional perhexiline or unchanged drug therapy; all patients received nitroglycerin infusion for 2 h. Vasomotor responses to perhexiline and combined perhexiline/nitroglycerin were examined using changes in augmentation index, measured via applanation tonometry. Neutrophil superoxide release was measured ex vivo utilizing lucigenin mediated chemiluminescence and effect of perhexiline on inhibition of platelet aggregation by sodium nitroprusside was also measured. Perhexiline alone did not affect augmentation index, neutrophil superoxide release, or ex vivo platelet sodium nitroprusside response. Nitroglycerin decreased augmentation index (P<0.01) and superoxide release (P<0.05). Magnitude of inhibition of superoxide release was significantly enhanced by perhexiline pre-treatment (P<0.05); however perhexiline had no effect on magnitude of vasomotor response to nitroglycerin. In conclusion, perhexiline exerts no effects on arterial stiffness and does not potentiate nitroglycerin induced dilatation. In patients with normal platelet function perhexiline does not affect platelet nitric oxide responsiveness. In vivo low dose nitroglycerin inhibits neutrophil superoxide release; this effect is potentiated by pre-treatment with perhexiline. These "anti-inflammatory" effects of nitroglycerin may contribute to utility in acute coronary syndromes and congestive heart failure.
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Affiliation(s)
- Elizabeth A Liberts
- Cardiology Unit, The Queen Elizabeth Hospital, Department of Medicine, University of Adelaide, South Australia, Australia
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29
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Worthley MI, Holmes AS, Willoughby SR, Kucia AM, Heresztyn T, Stewart S, Chirkov YY, Zeitz CJ, Horowitz JD. The deleterious effects of hyperglycemia on platelet function in diabetic patients with acute coronary syndromes mediation by superoxide production, resolution with intensive insulin administration. J Am Coll Cardiol 2007; 49:304-10. [PMID: 17239711 DOI: 10.1016/j.jacc.2006.08.053] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 08/14/2006] [Accepted: 08/30/2006] [Indexed: 01/12/2023]
Abstract
OBJECTIVES This study sought to assess the determinants of platelet nitric oxide (NO) responsiveness in diabetic patients admitted with acute coronary syndromes (ACS) and the short-term effects of aggressive glycemic control on these factors. BACKGROUND Hyperglycemia is an independent risk factor for mortality in both diabetic patients and nondiabetic patients with ACS. The mechanism(s) underlying this observation and potential benefit from its correction remain uncertain. Although a reduction in NO bioavailability has been proposed, this remains untested in the ACS setting. METHODS A total of 76 diabetic patients with ACS were studied. Putative correlations between admission blood sugar level (BSL), inhibition of platelet aggregation by the NO donor sodium nitroprusside (SNP), and superoxide (O2-) were assessed. Hyperglycemic patients (n = 60) were randomized to acute glycemic control with intravenous versus subcutaneous insulin, and changes in the aforementioned parameters were compared. Plasma levels of the endogenous inhibitor of NO synthase asymmetric dimethylarginine (ADMA) were also monitored. RESULTS There was an inverse correlation between admission BSL and both platelet SNP response (p = 0.007) and ADMA levels (p = 0.045), and a positive correlation with O2- generation (p < 0.001). Intravenous insulin infusion resulted in a greater reduction (p < 0.001) in BSL, differentially improved platelet responsiveness to SNP (p = 0.049), and decreased O2- (p < 0.001) and ADMA levels (p = 0.049). CONCLUSIONS A component of platelet dysfunction in diabetic patients with ACS is impaired responsiveness to the anti-aggregatory effects of NO, probably reflecting increased NO clearance by O2-. This phenomenon is reversed by acute aggressive glycemic control. These findings provide a further rationale for use of insulin therapy in acute myocardial infarction and suggest its extension to ACS patients.
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Affiliation(s)
- Matthew I Worthley
- Cardiology Unit, Basil Hetzel Research Institute, The Queen Elizabeth Hospital, University of Adelaide, South Australia, Australia
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30
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Ngo DT, Sverdlov AL, Willoughby SR, Nightingale AK, Chirkov YY, McNeil JJ, Horowitz JD. Aortic Valve Sclerosis is Associated with Impairment of Platelet Responsiveness to Nitric Oxide. Heart Lung Circ 2007. [DOI: 10.1016/j.hlc.2007.06.177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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31
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Sverdlov AL, Ngo DT, Willoughby SR, Nightingale AK, Chirkov YY, McNeil JJ, Horowitz JD. Predictors of Elevated Augmentation Index in an Ageing Population: Beyond Hypertension. Heart Lung Circ 2007. [DOI: 10.1016/j.hlc.2007.06.178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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32
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Holmes AS, Chirkov YY, Willoughby SR, Poropat S, Pereira J, Horowitz JD. Preservation of platelet responsiveness to nitroglycerine despite development of vascular nitrate tolerance. Br J Clin Pharmacol 2006; 60:355-63. [PMID: 16187967 PMCID: PMC1884829 DOI: 10.1111/j.1365-2125.2005.02437.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
AIMS Organic nitrates, via nitric oxide (NO) release, induce vasodilatation and inhibit platelet aggregation. Development of nitrate tolerance in some vascular preparations may be associated with diminished responsiveness to NO. To date it is not known to what extent vascular tolerance to organic nitrates is associated with acquired platelet hypo-responsiveness to NO. In the current study we compared the acute and chronic effects of sustained release (SR) isosorbide 5' mono-nitrate (ISMN) and transdermal nitroglycerine (TD-NTG) on blood vessels (effects on apparent arterial stiffness) and platelets (effects on responsiveness to NO donors) in patients with stable angina pectoris (SAP). METHODS Patients (n = 34) with SAP entered a blinded randomized crossover study of ISMN (120 mg) vs. intermittent TD-NTG (15 mg 24 h(-1)). Effects of each nitrate on pulse wave reflection (augmentation index (AIx)), platelet response to adenosine di-phosphate (ADP 1 micromol l(-1)), nitroglycerine (NTG 100 micromol l(-1)) and the non-nitrate NO donor sodium nitroprusside (SNP 10 micromol l(-1)), were measured pre-dose, 4 and 8 h post dose, on three occasions: 1) at the end of a pre-nitrate phase, 2) after dosing for 7 days and 3) following 14 days of full dose therapy with either nitrate. RESULTS Acutely, both ISMN and TD-NTG markedly reduced AIx. After 14 days, these effects were significantly attenuated (ANOVA, P = 0.018) but not abolished, indicating development of nitrate tolerance. Neither nitrate preparation affected ADP (1 micromol l(-1))-induced platelet aggregation. Platelet responsiveness to NTG (100 micromol l(-1)) and SNP (10 micromol l(-1)) was not diminished during chronic nitrate therapy, and there was no evidence of 'rebound' hyper-aggregability during 'nitrate-free' periods. CONCLUSIONS Chronic therapy with either ISMN or TD-NTG is associated with development of vascular tolerance. Despite the induction of vascular tolerance, platelet responsiveness to NTG and SNP remains unaffected. Therefore, development of vascular tolerance is unlikely to compromise the anti-aggregatory effects of organic nitrates, or those of endogenous NO.
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Affiliation(s)
- Andrew S Holmes
- The Cardiology Unit, The Basil Hetzel Institute, The Queen Elizabeth Hospital, Department of Medicine, The University of Adelaide, Australia
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33
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Willoughby SR, Stewart S, Holmes AS, Chirkov YY, Horowitz JD. Platelet nitric oxide responsiveness: a novel prognostic marker in acute coronary syndromes. Arterioscler Thromb Vasc Biol 2005; 25:2661-6. [PMID: 16254202 DOI: 10.1161/01.atv.0000193622.77294.57] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Nitric oxide (NO) is critically important in the regulation of vascular tone and the inhibition of platelet aggregation. We have shown previously that patients with acute coronary syndromes (ACS) or stable angina pectoris have impaired platelet responses to NO donors when compared with normal subjects. We tested the hypotheses that platelet hyporesponsiveness to NO is a predictor of (1) cardiovascular readmission and/or death and (2) all-cause mortality in patients with ACS (unstable angina pectoris or non-Q-wave myocardial infarction). METHODS AND RESULTS Patients (n=51) with ACS had evaluation of platelet aggregation within 24 hours of coronary care unit admission using impedance aggregometry. Patients were categorized as having "normal" (> or =32% inhibition of ADP-induced aggregation with the NO donor sodium nitroprusside; 10 micromol/L; n=18) or "impaired" (<32% inhibition of ADP-induced aggregation; n=33) NO responses. We then compared the incidence of cardiovascular readmission and death during a median of 7 years of follow-up in these 2 groups. Using a Cox proportional hazards model adjusting for age, sex, index event, postdischarge medical treatment, revascularization status, left ventricular systolic dysfunction, concurrent disease states, and cardiac risk factors, impaired NO responsiveness was associated with an increased risk of the combination of cardiovascular readmission and/or death (relative risk, 2.7; 95% CI, 1.03 to 7.10; P=0.041) and all-cause mortality (relative risk, 6.3; 95% CI, 1.09 to 36.7; P=0.033). CONCLUSIONS Impaired platelet NO responsiveness is a novel, independent predictor of increased mortality and cardiovascular morbidity in patients with high-risk ACS.
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Affiliation(s)
- Scott R Willoughby
- Basil Hetzel Institute, Queen Elizabeth Hospital, Department of Medicine, University of Adelaide, Adelaide, Australia
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Stepien JM, Prideaux RM, Willoughby SR, Chirkov YY, Horowitz JD. Pilot study examining the effect of cholesterol lowering on platelet nitric oxide responsiveness and arterial stiffness in subjects with isolated mild hypercholesterolaemia. Clin Exp Pharmacol Physiol 2003; 30:507-12. [PMID: 12823268 DOI: 10.1046/j.1440-1681.2003.03859.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. Hypercholesterolaemia has been associated with impaired endothelial function. However, there are no available data as to whether hypercholesterolaemia is also associated with platelet dysfunction. 2. In a group of asymptomatic adults with (n = 16) and without (n = 13) mild hypercholesterolaemia, we evaluated inhibition of platelet aggregation in response to the nitric oxide (NO) donor sodium nitroprusside (SNP), as well as the augmentation index (AIx), a parameter of arterial stiffness that is impaired in the presence of endothelial dysfunction. 3. Neither SNP response nor AIx varied significantly between normocholesterolaemic (NC) and hypercholesterolaemic (HC) subjects. 4. Three months treatment with pravastatin (40 mg/day) in HC subjects lowered mean (+/-SEM) total cholesterol levels from 6.6 +/- 0.2 to 5.5 +/- 0.2 mmol/L. Platelet response to SNP increased in platelet-rich plasma and tended to increase in whole blood. The AIx did not change significantly. However, falls in low-density lipoprotein (P = 0.03) and total cholesterol (P = 0.08) correlated with reductions in AIx in individual subjects. 5. These data provide evidence that moderate reduction of cholesterol levels may improve platelet responses to NO, whereas improvement in arterial stiffness may be detectable only with more extensive and/or a prolonged reduction in cholesterol levels.
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Affiliation(s)
- Jacqueline M Stepien
- Cardiology Unit, The Queen Elizabeth Hospital, Department of Medicine, The University of Adelaide, Adelaide, South Australia, Australia
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Willoughby SR, Cap AP, Horowitz JD, Loscalzo J. Inhibition of human platelet aggregation by nitric oxide species: Differential effects of L-cysteine. Heart Lung Circ 2003. [DOI: 10.1046/j.1443-9506.2003.02307.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Chirkov YY, Holmes AS, Willoughby SR, Stewart S, Horowitz JD. Aortic stenosis is associated with platelet hyperaggregability and impaired responsiveness to nitric oxide. Heart Lung Circ 2003. [DOI: 10.1046/j.1443-9506.2003.0271x.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Willoughby SR, Stewart S, Chirkov YY, Kennedy JA, Holmes AS, Horowitz JD. Beneficial clinical effects of perhexiline in patients with stable angina pectoris and acute coronary syndromes are associated with potentiation of platelet responsiveness to nitric oxide. Eur Heart J 2002; 23:1946-54. [PMID: 12473257 DOI: 10.1053/euhj.2002.3296] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIMS To examine whether the prophylactic antianginal agent perhexiline potentiates platelet responsiveness to nitric oxide (NO) in patients with stable angina pectoris (SAP) and acute coronary syndromes (ACS: unstable angina pectoris or non-Q-wave myocardial infarction). METHODS AND RESULTS Blood samples were obtained from patients before and after initiation of treatment with perhexiline. ADP-induced platelet aggregation and its inhibition by the NO donor sodium nitroprusside (SNP) were determined via impedance aggregometry in whole blood (WB) and platelet-rich plasma (PRP). Intraplatelet cGMP content was assayed by RIA, and superoxide (O(2)(-)) level by lucigenin-derived chemiluminescence. In patients with ACS not receiving perhexiline (n=12), platelet responsiveness to SNP did not vary significantly over the first 3 days post admission to hospital. Therapy with perhexiline for 3 days was associated with increases in SNP-induced inhibition of aggregation from 29+/-2% to 43+/-4% (n=50,P <0.001) in WB and from 20+/-5% to 42+/-7% (n=12, P<0.01) in PRP. Resolution of symptomatic ischaemia (n=39) was associated with significantly greater (P<0.01) increases than non-resolution (n=11). Similar increases in SNP responsiveness (P<0.001) occurred following institution of perhexiline therapy in patients with SAP (n=30), associated with a 85% decrease in anginal frequency. Treatment with perhexiline potentiated the cGMP-elevating effects of SNP in platelets (n=9,P =0.03). Although perhexiline did not alter whole blood O(2)(-) concentration ex vivo, it inhibited (P<0.01) O(2)(-) release from neutrophils in vitro. CONCLUSION Perhexiline potentiates platelet responsiveness to NO both in SAP and ACS patients; in the latter group this improvement was predictive of resolution of ischaemic symptoms. The predominant mechanism of perhexiline effect is an increase in platelet cGMP responsiveness. Perhexiline also may reduce the potential for NO clearance by neutrophil-derived O(2)(-).
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Affiliation(s)
- S R Willoughby
- Cardiology Unit, The Queen Elizabeth Hospital, Department of Medicine, The University of Adelaide, Adelaide, Australia
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Chirkov YY, Holmes AS, Willoughby SR, Stewart S, Horowitz JD. Association of aortic stenosis with platelet hyperaggregability and impaired responsiveness to nitric oxide. Am J Cardiol 2002; 90:551-4. [PMID: 12208424 DOI: 10.1016/s0002-9149(02)02536-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yuliy Y Chirkov
- Cardiology Unit, The Queen Elizabeth Hospital, Department of Medicine, The University of Adelaide, Adelaide, Australia
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Battinelli E, Willoughby SR, Foxall T, Valeri CR, Loscalzo J. Induction of platelet formation from megakaryocytoid cells by nitric oxide. Proc Natl Acad Sci U S A 2001; 98:14458-63. [PMID: 11734646 PMCID: PMC64703 DOI: 10.1073/pnas.241427398] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Although the growth factors that regulate megakaryocytopoiesis are well known, the molecular determinants of platelet formation from mature megakaryocytes remain poorly understood. Morphological changes in megakaryocytes associated with platelet formation and removal of senescent megakaryocytes are suggestive of an apoptotic process. Previously, we have established that nitric oxide (NO) can induce apoptosis in megakaryocytoid cell lines. To determine whether there is an association between NO-induced apoptosis and platelet production, we exposed Meg-01 cells to S-nitrosoglutathione (GSNO) with or without thrombopoeitin (TPO) pretreatment and used flow cytometry and electron microscopy to assess platelet-sized particle formation. Meg-01 cells treated with TPO alone produced few platelet-sized particles (<3% of total counts), whereas treatment with GSNO alone produced a significant percentage of platelet-sized particles (22 +/- 4% of total counts); when combined with TPO pretreatment, however, GSNO led to a marked increase in platelet-sized particle production (48 +/- 3% of total counts). Electron microscopy confirmed that Meg-01 cells treated with TPO and GSNO yielded platelet-sized particles with morphological features specific for platelet forms. The platelet-sized particle population appears to be functional, because addition of calcium, fibrinogen, and thrombin receptor-activating peptide led to aggregation. These results demonstrate that NO facilitates platelet production, thereby establishing the essential role of NO in megakaryocyte development and thrombopoiesis.
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Affiliation(s)
- E Battinelli
- Whitaker Cardiovascular Institute and Evans Department of Medicine, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
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Chirkov YY, Holmes AS, Willoughby SR, Stewart S, Wuttke RD, Sage PR, Horowitz JD. Stable angina and acute coronary syndromes are associated with nitric oxide resistance in platelets. J Am Coll Cardiol 2001; 37:1851-7. [PMID: 11401122 DOI: 10.1016/s0735-1097(01)01238-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVES The study examined possible clinical determinants of platelet resistance to nitric oxide (NO) donors in patients with stable angina pectoris (SAP) and acute coronary syndromes (ACS), relative to nonischemic patients and normal subjects. BACKGROUND We have shown previously that platelets from patients with SAP are resistant to the antiaggregating effects of nitroglycerin (NTG) and sodium nitroprusside (SNP). METHODS Extent of adenosine diphosphate (1 micromol/liter)-induced platelet aggregation (impedance aggregometry in whole blood) and inhibition of aggregation by NTG (100 micromol/liter) and SNP (10 micromol/liter) were compared in normal subjects (n = 43), nonischemic patients (those with chest pain but no fixed coronary disease, (n = 35) and patients with SAP (n = 82) or ACS (n = 153). Association of NO resistance with coronary risk factors, coronary artery disease (CAD), intensity of angina and current medication was examined by univariate and multivariate analyses. RESULTS In patients with SAP and ACS as distinct from nonischemic patients and normal subjects, platelet aggregability was increased (both p < 0.01), and inhibition of aggregation by NTG and SNP was decreased (both p < 0.01). Multivariate analysis revealed that NO resistance occurred significantly more frequently with ACS than with SAP (odds ratio [OR] 2.3:1), and was less common among patients treated with perhexiline (OR 0.3:1) or statins (OR 0.45:1). Therapy with other antianginal drugs, extent of CAD, intensity of angina and coronary risk factors were not associated with variability in platelet responsiveness to NO donor. CONCLUSIONS Patients with symptomatic ischemic heart disease, especially ACS, exhibit increased platelet aggregability and decreased platelet responsiveness to the antiaggregatory effects of NO donors. The extent of NO resistance in platelets is not correlated with coronary risk factors. Pharmacotherapy with perhexiline and/or statins may improve platelet responsiveness to NO.
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Affiliation(s)
- Y Y Chirkov
- Department of Cardiology, The Queen Elizabeth Hospital, University of Adelaide, Australia
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Abstract
Although heparin is a well-known anticoagulant, in some cases it promotes a prothrombotic state and does so through both antibody-dependent and antibody-independent platelet activation. In this study, heparin was found to reverse the antiplatelet effect of an NO donor. S-nitroso-glutathione (SNO-Glu), with an EC(50) of 1.8 U/mL. Ultraviolet/visible spectral analysis and the Griess assay showed that increasing heparin concentrations on a dose-dependent basis eliminated acidified NO(x) species. Since heparin is a heterogeneous mixture of glycosaminoglycans, the effects of six different heparin disaccharides were compared with various substitutions on the hexose rings to determine which functional group(s) of the polysaccharide interact with acidified NO(x). Among the six disaccharides tested, only types I-S and II-S had the effect, suggesting that the sulfamino-group at the C2 position of the glucosamine moiety was critical for the elimination of acidified NO(x) species. Mass spectrometry experiments gave results consistent with these observations, indicating that only the I-S and II-S heparin disaccharides were modified upon treatment with NaNO(2)/HCl. Negative-ion electro-spray ionization MS and tandem MS analyses of the native compounds and their deuterium-labeled analogs confirmed that the reaction products from nitrosation of these N-sulfated disaccharides had eliminated the C2-sulfamino-moiety and replaced it with methoxide derived from the solvent. Participation of the 6-sulfato-substituent appears to facilitate the elimination reaction. These data show that heparin can impair the antiplatelet properties of nitric oxide by interacting with the nitrosating species, and suggest that heparin-like glycosamino-glycans may interact with endothelium-derived nitric oxide in vivo to regulate the bioactivity of this important antiplatelet and vasorelaxant substance.
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Affiliation(s)
- G R Upchurch
- Whitaker Cardiovascular Institute, Evans Department of Medicine, Boston University School of Medicine, MA 02118, USA
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Willoughby SR, Chirkov YY, Kennedy JA, Murphy GA, Chirkova LP, Horowitz JD. Inhibition of long-chain fatty acid metabolism does not affect platelet aggregation responses. Eur J Pharmacol 1998; 356:207-13. [PMID: 9774251 DOI: 10.1016/s0014-2999(98)00527-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
A number of anti-anginal agents (perhexiline, amiodarone, trimetazidine) have been shown to inhibit myocardial carnitine palmitoyltransferase-1, which controls access of long-chain fatty acids to mitochondrial sites of beta-oxidation. In view of clinical data suggesting that perhexiline improves symptomatic status in unstable angina pectoris, and the known role of mitochondrial beta-oxidation in platelet metabolism, we compared the platelet carnitine palmitoyltransferase-1 inhibitory and putative anti-aggregatory effects of perhexiline, amiodarone and trimetazidine with those of specific carnitine palmitoyltransferase-1 inhibitors: etomoxir and hydroxyphenylglyoxylate in both normal subjects and patients with stable angina. All of the compounds examined inhibited platelet carnitine palmitoyltransferase-1 activity; rank order of potency etomoxir > malonyl-CoA > hydroxyphenylglyoxylate > amiodarone > or = perhexiline > trimetazidine. However, only perhexiline, amiodarone and trimetazidine inhibited platelet aggregation. We conclude that (a) the carnitine palmitoyltransferase-1 inhibitors perhexiline, amiodarone and trimetazidine exert significant anti-aggregatory effects which may be therapeutically relevant and, (b) these effects are independent of carnitine palmitoyltransferase-1 inhibition.
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Affiliation(s)
- S R Willoughby
- Department of Physiology, The University of Adelaide, SA, Australia
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