A Potential Strategy for Atherosclerosis Prevention in Modernizing China - Hyperhomocysteinemia, MTHFR C677T Polymorphism and Air Pollution (PM2.5) on Atherogenesis in Chinese Adults

BACKGROUND

Atherosclerosis is one of the most important global health hazards and air pollution (AP, PM2.5) has been implicated. In addition to traditional risk factors hyperhomocysteinemia (HC) has been recognized in many parts of China related to risk of stroke.

METHODS

To evaluate the impact of HC (homocysteine >14μmol/l) and PM2.5 air pollution on atherogenesis in modernizing China, we studied 756 asymptomatic Chinese in China from 1998-2007. PM2.5 exposure, HC, folate, and methylenetetrahydrofolate reductase (MTHFR) C/T genotype were evaluated. Brachial flow-mediated dilation (FMD) and carotid intima-media thickness (IMT) were measured by ultrasound. Locations were categorized as zones 1, 2 and 3, with increasing PM2.5 exposure.

RESULTS

HC was higher (19.4±13.1 and 27.1±25.1μmol/l) in high PM2.5-polluted zones 2 and 3 than in zone 1 (9.7±4.5μmol/l, p<0.0015). The top HC tertile was characterized by lower folate and vitamin B12, but a higher proportion of the MTHFR TT genotype, Metabolic Syndrome (MS) and PM2.5 level (p=0.0018). FMD was significantly lower (7.3±2.3%) and carotid IMT thicker (0.63±0.12mm) in the top HC tertile, compared with low HC tertile (8.4±2.5%, p<0.0001; 0.57±0.1mm, p<0.0001 respectively). Similar differences in FMD and IMT were seen in zones 2 and 3, compared with zone 1 (p<0.0001). On multivariate regression, HC was related to male gender (beta=0.106, p=0.021), MTHFR-TT (beta=0.935, p<0.0001), locations (beta=0.230, p<0.0001) and folate-MTHFR interaction (beta=-0.566, p<0.0001). FMD was related to age (beta= -0.221; p<0.0001), male gender (beta= -0.194, p=0.001) PM2.5 and location (beta=-0.285 to -0.303, p<0.0001). Carotid IMT was related to PM2.5 (beta=0.173, p<0.0001), HC (0.122, p=0.006) but not to MTHFR or location, independent of age, gender, MS, and LDL-C. No significant HC-PM2.5 interaction effect on FMD and IMT was observed.

CONCLUSION

HC and PM2.5 pollution but not MTHFR genotype were both related to carotid IMT, independent of other traditional risk factors. This has potential implications in dietary and AP strategies for atherosclerosis prevention in China.

Associations of dietary macronutrient composition with cardiometabolic health: data from the National Health and Nutrition Examination Survey (NHANES) 1999–2014

Background

Human nutrition is a leading modifiable risk factor for the prevention of cardiometabolic diseases. However, most nutritional research focuses on the role of specific nutrients rather than compositional analysis of the diet.

Purpose

We aimed to assess the association of dietary macronutrient composition with various markers of cardiometabolic health.

Methods

This study was undertaken using 24-hour food recall data from the National Health and Nutrition Examination Survey from years 1999–2014 (n=36,637). Participants included both males and females ≥20 years of age (49.8±18.3 years; 53% Female). Caloric outliers for males (&lt;800 kcal/day or &gt;4200 kcal/day) and females (&lt;600 kcal/day or &gt;3500 kcal/day) were removed from the analysis (n=1844). Cardiometabolic health markers were collected via mobile examination center and included triglycerides (n=16,444), total cholesterol (n=31,155), LDL cholesterol (n=15,798), HDL cholesterol (n=33,435), blood pressure (n=34,121), body fat percentage (n=4269), body mass index (n=35,187), glucose (n=17,208), insulin (n=16,273), oral glucose tolerance test (n=8280), and HbA1c (n=27,288). Associations of dietary macronutrients with cardiometabolic health markers were assessed using 3-dimensional general additive models (Protein; Carbohydrate; Fat) with adjustment for age, sex, misreporting, ethnicity, education level, household income, physical activity, alcohol intake, and smoking. Response surfaces on right-angled mixture triangles were generated as predictions from absolute macronutrient intake at the 50th percentile of total energy intake. Macronutrient intakes were transformed to a percentage of energy to visualize and interpret associations compositionally.

Results

There was a complex 3-way interactive non-linear association of macronutrient composition with lipid profile (Figure A-D; all p&lt;0.04), blood pressure (Figure E-F; all p&lt;0.001), body fat percentage (Figure G; p&lt;0.001), body mass index (Figure H; p&lt;0.001), and all markers of glycemic control (Figure I-L; all p&lt;0.001). Diets comprised of high protein coupled with low fat were associated with higher triglycerides but generally more favorable total cholesterol, blood pressure, and body fatness. Conversely, diets composed of high protein coupled with high fat were associated with higher HDL cholesterol but worse total cholesterol, body fatness, body mass index, and glycemic control.

Conclusions

These findings display a complex relationship between dietary macronutrient composition and cardiometabolic health. Future research is needed to evaluate how dietary source and quality may modify the observed associations.

Funding Acknowledgement

Type of funding sources: Private company.

Novel insights into bicuspid aortic valve (BAV) aortopathy: Long non-coding RNAs TUG1 and MIAT are differentially expressed in BAV ascending aortas

BACKGROUND

Whilst a combination of genetically mediated vulnerability and haemodynamic insult is suspected to contribute to bicuspid aortic valve (BAV) aortopathy, the underlying pathophysiological mechanisms are poorly understood.

METHODS

Utilising RT-qPCR, we compared the expression of 28 potentially relevant long non-coding RNA (lncRNA) in aortic tissue from BAV patients undergoing aortic surgery for aortopathy, to healthy controls. Relative lncRNA expression was measured using ΔΔCT, with fold-change calculated as RQ=2^-ΔΔCT.

RESULTS

When comparing samples from BAV patients (n=29, males n=25; median age 58 years, Q1-Q3 51-65, maximum aortic dimension 50±5mm) with healthy controls (n=7; males n=4, p=0.12; median age 39 years, Q1-Q3 18-47, p=0.001), there were two differentially expressed lncRNA: TUG1 expression was significantly lower in BAV aortic tissue (RQ 0.59, 95% CI 0.50-0.69, p=0.02), whilst MIAT expression was significantly higher (RQ 2.87, 95% CI 1.96-4.20, p=0.01). Sensitivity analysis including only patients with normal BAV function showed similar trends of differential expression of TUG1 (RQ 0.69, 95% CI 0.50-0.90, p=0.29) and MIAT (RQ 2.55, 95% CI 1.21-5.36, p=0.29) compared to controls.

CONCLUSIONS

LncRNA TUG1 and MIAT are differentially expressed in BAV aortopathy compared to healthy controls, independent of BAV haemodynamics. Aberrant lncRNA expression may be involved in the pathogenesis of BAV aortopathy.

Novel pressure-regulated deployment strategy for improving the safety and efficacy of balloon-expandable transcatheter aortic valves

Background

The optimal method for balloon-expandable transcatheter heart valve (THV) deployment remains unknown. Current implantation protocols are volume-dependent and rely on ad-hoc filling of the deployment apparatus without accounting for annular wall tension during prosthesis expansion, predisposing patients to inconsistent clinical outcomes. During THV deployment, the annular wall tension exerted by the expanding prosthesis is determined by prosthesis diameter and balloon pressure (Laplace's Law).

Objective

We proposed and tested a novel method for balloon-expandable THV deployment, aimed at controlling balloon pressure and the resulting annular wall tension to allow optimal prosthesis-annulus apposition while preventing significant tissue injury.

Methods

330 consecutive patients with severe native aortic stenosis who underwent balloon-expandable THV implantation between 2015–2020 were included. 106 patients were considered high-risk for annular rupture. THVs were deployed until reaching a pre-determined balloon pressure; 4–4.5atm in earlier cases to establish experience and safety, later increasing to 5–6.5atm in most cases. Post-dilatation was performed to reduce &gt;mild angiographic regurgitation (PVR). Using a biomechanical model, annular wall stress (tension) was estimated for each case and assessed against recorded rates of post-dilatation, ≥mild paravalvular regurgitation (PVR) on TTE, new PPM or LBBB and annular rupture.

Results

Patients with wall stress &gt;3MPa (n=184) had reduced post-dilatation rate (p&lt;0.001) and final PVR (≥mild, p=0.014). Annular rupture occurred in 2/3 high-risk cases with wall stress &gt;3.5MPa; no rupture occurred in 102 high-risk cases with wall stress ≤3.5MPa. Based on these results, we defined target deployment wall stress levels (3–3.5MPa) and associated deployment pressure per THV size. Patients within this target range (n=136) had 8.1% new PPM, 12.5% new LBBB, 12.7% mild PVR with no cases of ≥moderate PVR. Importantly, there was an inconsistent relationship between deployment balloon volume and resulting annular wall stress.

Conclusion

Pressure-regulated THV deployment is a simple, easily reproducible, safe and effective method, regardless of high-risk anatomical complexities.

Funding Acknowledgement

Type of funding sources: None. Annular wall stress and PVRModel, stress vs volume and new strategy

Relative prevalence and outcomes of low gradient severe aortic stenosis in routine clinical practice

Background

The prevalence and outcomes of low-gradient severe aortic stenosis (AS), in particular low-flow low-gradient (LFLG) severe AS, have not been well characterized.

Objectives

We sought to delineate the relative prevalence and outcomes of patients with low-gradient severe AS in routine clinical cardiology practice.

Methods

Data were derived from the National Echocardiography Database of Australia (NEDA), a national multicentre clinical registry with data linkage to mortality. A total of 192,060 adults with native aortic valve profiling from 2000–2019 were identified, of whom 12,013 (6.3%) had severe AS (aged 75.3±13.1 years, 53.5% men). Severe AS subtypes were determined using standard echocardiographic criteria. All-cause and cardiovascular-related mortality were assessed on an adjusted basis (age and sex) in 8,162 patients with classifiable severe AS subtypes, during mean follow-up of 88±45 months. Additionally, rates of recorded Aortic Valve Replacement (AVR) during follow-up were compared between AS groups.

Results

5,601 patients (47%) had high-gradient and 6,412 patients (53%) had low-gradient severe AS. In the low-gradient group, Stroke Volume Index data was recorded in 2,741 patients; 1,750 (64%) had LFLG and 991 (36%) had normal-flow low-gradient (NFLG). For LFLG patients, 1,570 had LV ejection fraction recorded; 959 (61%) had paradoxical LFLG and 651 (39%) had classical LFLG. Adjusted 5-year cardiovascular mortality rates were 28% in high-gradient, 24% in NFLG, 27% in paradoxical LFLG and 50% in classical LFLG patients (p&lt;0.001). Rates of recorded AVR per mean follow-up years were 5.2% for high-gradient, 4.0% for NFLG, 3.1% for classical LFLG and 2.4% for paradoxical LFLG severe AS (p&lt;0.001).

Conclusions

Approximately half the subjects with echocardiographic features of severe AS in routine clinical practice have low-gradient haemodynamics, associated with long-term mortality comparable to or worse than high-gradient severe AS. The poorest survival was associated with classical LFLG severe AS.

Funding Acknowledgement

Type of funding sources: None. Summary illustration5 year mortality curves

Cardiac damage staging classification and prognosis in low flow low gradient severe aortic stenosis

Introduction

There are currently no established prognostic models for low-flow, low-Gradient (LFLG) severe aortic stenosis (AS). The Cardiac Damage Staging Classification, has been validated as a clinically useful prognostic tool in high-gradient severe AS, but not specifically in LFLG severe AS.

Objective

To assess and confirm the prognostic utility of the Cardiac Damage Staging Classification, in LFLG severe AS patients.

Methods

We analysed data from the National Echocardiography Database of Australia (NEDA), a national multicentre registry with individual data linkage to mortality. Of 192,060 adults (aged 62.8±17.8 years) with comprehensive ultrasound profiling of the native aortic valve studied between 2000–2019, 12,013 (6.3%) had severe AS. Based on standard echocardiographic parameters, 611 classical and 959 paradoxical LFLG patients were identified. Mean follow-up was 70±41 months. All-cause and cardiovascular-related mortality were assessed for each LFLG group on an adjusted basis (age and sex), according to cardiac damage classification staging.

Results

Paradoxical LFLG patients were younger (mean age 74.3 vs 76.2, p=0.006) and more often female (62.8% vs 36.3%, p&lt;0.001). Classical LFLG patients had greater associated cardiac damage at diagnosis (76% vs. 49%, for Stage ≥2, p&lt;0.001). Compared to Stage 0 paradoxical LFLG patients, adjusted 1- and 5-year cardiovascular-related mortality was 200% (HR 2.82, 95% CI 1.12–7.11) and 120% (HR 2.42, 95% CI 1.46–4.02) higher in Stage 2 patients and 350% (HR 4.23, 95% CI 1.68–10.63) and 175% (HR 3.18, 95% CI 1.90–5.34) higher in Stage 3/4 patients, respectively. Compared to Stage 1 classical LFLG patients, adjusted 1- and 5-year cardiovascular-related mortality was 58% (HR 1.66, 95% CI 0.95–2.90) and 24% (HR 1.35, 95% CI 0.91–1.99) higher in Stage 2 patients and 125% (HR 2.48, 95% CI 1.43–4.28) and 52% (HR 1.87, 95% CI 1.26–2.78) higher in Stage 3/4 patients, respectively.

Conclusion

In patients with LFLG severe AS identified by echocardiography, increasing severity denoted by the cardiac damage staging classification is strongly associated with increasing medium- to long-term mortality.

Funding Acknowledgement

Type of funding sources: None. Stages + Classical LFLG 5 year mortalityParadoxical LFLG 5 year mortality curves

Stroke volume index and outcomes in low gradient severe aortic stenosis

Background

Conventionally, stroke volume index (SVI) ≤35ml/m2 is considered as “low-flow” in severe aortic stenosis (AS). Recent evidence suggests a lower threshold SVI (30ml/m2) may be more prognostically informative.

Objectives

To assess the association between SVI and survival in patients with low-gradient severe AS, with either preserved (LVEF ≥50%) or reduced (LVEF&lt;50%) ejection fraction.

Methods

Data were derived from the National Echocardiography Database of Australia (NEDA). Of 192,060 adults (aged 62.8±17.8 years) with comprehensive aortic valve profiling between 2000–2019, 12,013 (6.3%) had severe AS. Based on standard echocardiographic parameters, 1,623 patients had severe low-gradient AS with preserved LVEF and 744 patients had severe low-gradient AS with reduced LVEF. All-cause and cardiovascular-related mortality were assessed for each low-gradient group on an adjusted basis (age, sex, BMI, AVA indexed and RVSP), according to SVI. Mean follow-up was 81±42 months.

Results

Compared to patients with “normal” flow (SVI &gt;35ml/m2), those with “low-flow” (SVI ≤35ml/m2) had significantly higher BMI, smaller AVA index and lower AV mean gradient and peak velocity (p≤0.001). In low-gradient with preserved LVEF patients, adjusted survival at 1- and 3-years was significantly lower only for SVI ≤30ml/m2 compared with SVI&gt;35ml/m2 (p&lt;0.001 and p&lt;0.03, respectively). In low-gradient with reduced LVEF patients, adjusted survival at 1- and 3-years was significantly lower for SVI ≤35ml/m2 compared with SVI&gt;35ml/m2 (p=0.015 and p=0.018, respectively).

Conclusions

Taken together with previous data, our results suggest that a SVI threshold of ≤30ml/m2 (rather than ≤35 ml/m2) is prognostically significant in severe low-gradient AS with preserved LVEF.

Funding Acknowledgement

Type of funding sources: None. Survival plots LGAS with preserved EFSummary of results

The impact of particulate matter air pollution (PM2.5) on atherosclerosis in modernizing China: a report from the CATHAY study

BACKGROUND

Air pollution has been associated with an increase in cardiovascular diseases incidence. To evaluate whether air pollution can accelerate atherogenic processes, we assessed the effects of air pollution on important surrogate markers of atherosclerosis [brachial flow-mediated dilation (FMD) and carotid intima-media thickness (IMT)].

METHODS

A total of 1656 Han Chinese (mean age 46.0 + 11.2 years; male 47%) in Hong Kong, Macau, Pun Yu, Yu County and the 3-Gorges Territories (Yangtze River) were studied between 1996 and 2007 [Chinese Atherosclerosis in the Aged and Young Project (the CATHAY Study)]. Cardiovascular risk profiles were evaluated. Particulate matter with an aerodynamic diameter <2.5 µm (PM2.5) parameters were computed from satellite sensors. Brachial FMD and carotid IMT were measured by ultrasound.

RESULTS

Health parameters [age, gender, body mass index, waist : hip ratio (WHR) and glucose)] were similar in lowest and highest PM2.5 exposure tertiles, systolic and diastolic blood pressures and triglycerides were higher (P < 0.001) and low-density cholesterol (LDL-C) was lower in the top PM2.5 tertile (P < 0.001). Brachial FMD [7.84 ± 1.77, 95% confidence interval (CI) 7.59-8.10%, vs 8.50 ± 2.52, 95% CI 8.23-8.77%, P < 0.0001) was significantly lower and carotid IMT (0.68 ± 0.13 mm, 95% CI 0.67-0.69 mm vs 0.63 mm ± 0.15 mm 95% CI 0.62-0.64 mm; P < 0.0001) was significantly thicker in the top PM2.5 tertile compared with the lowest tertile. On multiple regression, FMD was inversely related to PM2.5 (beta = 0.134, P = 0.015) independent of gender, age and blood pressure (model R2 = 0.156, F-value = 7.6, P < 0.0001). Carotid IMT was significantly correlated with PM2.5 exposure (beta = 0.381, P < 0.0001) independent of age, location, gender, WHR, blood pressure and LDL-C (model R2 = 0.408, F-value = 51.4, P-value <0.0001).

CONCLUSIONS

Air pollution is strongly associated with markers of early atherosclerosis, suggesting a potential target for preventive intervention.

P593Oxygen sensitive cardiac magnetic resonance in demonstrating myocardial ischaemia of the right ventricle in patients with pulmonary artery hypertension

Background

Progressive right ventricular (RV) dysfunction is a natural progression of pulmonary arterial hypertension (PAH) which is associated with adverse clinical outcomes. The main contributor to progressive RV dysfunction is RV ischemia. Oxygen-sensitive (OS) cardiovascular magnetic resonance (CMR) has been used to determine the in-vivo myocardial oxygenation of the left ventricle (LV).

Purpose

The aim of the present study was to (1) Determine the feasibility of RV targeted rest/stress OS-CMR imaging in PAH patients and normal volunteers; (2) To define the presence and extent of RV myocardial ischaemia in patients with known PAH.

Methods

We prospectively recruited 20 patients with right heart catheter proven PAH and 9 normal (NC), age matched controls with no heart disease. The CMR examination involved standard functional imaging and OS-CMR imaging. OS-CMR images were acquired using a T2* sequence at rest and adenosine-induced stress vasodilatation. The RV was divided into 3 segments - RV anterior, RV free-wall and RV inferior. An OS-CMR signal intensity (SI) index (stress/rest signal intensity) was acquired at RV anterior, RV free-wall and RV inferior segments.

Results

All the PAH patients tolerated and completed the adenosine induced stress OS-CMR without any complications or adverse effects. In NC, reliable OS signal intensity changes was only obtained from the RV inferior segment. As RV dysfunction in PAH is a global process, hence this segment was used in both patients and NC for further comparison. RV OS-CMR signal intensity change between rest and stress in the normal volunteers was 17±4% (mean ± SD). 9 out of twenty (45%) of the PAH patients had a mean BOLD signal intensity change of less than 9% (or 2SD different from the mean values in normal volunteers). Overall, RV OS SI index between the PAH patients and controls was 11±9% vs 17±5% (p-value = 0.045) in RV inferior segment.

Conclusion

Pharmacological induced OS-CMR is a feasible and safe technique to identify and study myocardial oxygenation in the RV of PAH patients.

Obesity, arterial function and arterial structure - a systematic review and meta-analysis

OBJECTIVE

Obesity is an established risk factor for cardiovascular disease. The mechanisms by which obesity affects cardiovascular risk have not been fully elucidated. This paper reports a comprehensive systematic review and meta-analysis on obesity and two key aspects of vascular health using gold-standard non-invasive measures - arterial endothelial function (brachial flow-mediated dilatation) and subclinical atherosclerosis (carotid intima-media thickness).

METHODS

Electronic searches for 'Obesity and flow-mediated dilatation' and 'Obesity and intima-media thickness' were performed using Ovid Medline and Embase databases. A meta-analysis was undertaken for brachial flow-mediated dilatation and carotid intima-media thickness to obtain pooled estimates for adults with obesity and those with healthy weight.

RESULTS

Of the 5,810 articles retrieved, 19 studies on flow-mediated dilatation and 19 studies on intima-media thickness were included. Meta-analysis demonstrated that obesity was associated with lower flow-mediated dilatation (-1.92 % [95% CI -2.92, -0.92], P = 0.0002) and greater carotid intima-media thickness (0.07 mm [95% CI 0.05, 0.08], P < 0.0001).

CONCLUSIONS

Obesity is associated with poorer arterial endothelial function and increased subclinical atherosclerosis, consistent with these aspects of vascular health at least partially contributing to the increased risk of cardiovascular events in adults with obesity. These estimated effect sizes will enable vascular health benefits in response to weight loss treatment to be put in greater perspective, both in the research setting and potentially also clinical practice.

Periodontal therapy and glycaemic control among individuals with type 2 diabetes: reflections from the PerioCardio study

OBJECTIVES

Diabetes mellitus and periodontal disease are highly prevalent among Indigenous Australian adults. Untreated periodontitis impacts glycaemic control in people with diabetes. The aim of this study was to report on the effect of periodontal therapy on glycaemic control among people with obesity.

METHODS

This subgroup analysis is limited to 62 participants with diabetes from the original 273 Aboriginal Australian adults enrolled into the PerioCardio study. Intervention participants received full-mouth non-surgical periodontal scaling during a single, untimed session while controls were untreated. Endpoints of interest included change in glycated haemoglobin (HbA1c), C-reactive protein (CRP) and periodontal status at 3 months post-intervention.

RESULTS

There were more females randomized to the treatment group (n = 17) than control (n = 10) while the control group had a higher overall body mass index (BMI) [mean (SD)] 33.1 (9.7 kg m^-2 ) versus 29.9 (6.0 kg m^-2 ). A greater proportion of males were followed up at 3 months compared to females, P = 0.05. Periodontal therapy did not significantly reduce HbA1c: ancova difference in means 0.22 mmol mol^-1 (95% CI -6.25 to 6.69), CRP: ancova difference in means 0.64 (95% CI -1.08, 2.37) or periodontal status at 3 months.

CONCLUSIONS

Non-surgical periodontal therapy did not significantly reduce glycated haemoglobin in participants with type 2 diabetes. Reasons are likely to be multifactorial and may be influenced by persistent periodontal inflammation at the follow-up appointments. Alternatively, the BMI of study participants may impact glycaemic control via alternative mechanisms involving the interplay between inflammation and adiposity meaning HbA1c may not be amenable to periodontal therapy in these individuals.

Prevalence, distribution and clinical correlates of myocardial fibrosis in systemic lupus erythematosus: a cardiac magnetic resonance study

Objectives

To assess the prevalence, distribution and clinical correlates of myocardial fibrosis, as detected by cardiac magnetic resonance (CMR), in systemic lupus erythematosus (SLE).

Methods

Forty-one subjects (average age 39 ± 12 years and 80% female) with SLE underwent CMR imaging at 1.5T, using late gadolinium enhancement (LGE) to quantify the area of myocardial fibrosis in the left ventricle (LV). Subjects also underwent transthoracic echocardiography (TTE) and exercise testing.

Results

LGE was detected in 15/41 subjects, 11 with localized LGE (<15% LV mass) and four with extensive LGE (>15% LV mass). The commonest site of LGE was the interventricular septum, with all but one case demonstrating an intramural or inflammatory pattern. The mean age of the >15% LGE group (55 ± 15 years) was significantly higher than the <15% or absent LGE subgroups. Based on both CMR and TTE measurements, subjects with LGE > 15% demonstrated a reduced E/A ratio of 0.9 ± 0.4 relative to the <15% and absent LGE subgroups. LV end-systolic volume (ESVi), end-diastolic volume (EDVi) and maximum exercise capacity were also reduced in the >15% LGE group.

Conclusions

Mid-wall myocardial fibrosis occurs frequently in SLE and is strongly associated with advancing subject age, but not with SLE duration or severity. Extensive LGE may be associated with diastolic dysfunction and impaired exercise capacity, although this may be an epiphenomenon of age. Cardiac magnetic resonance with quantitative assessment of LGE may provide a basis for cardiac risk stratification in SLE.

Late outcomes in adults with coarctation of the aorta

AIMS

Previous cohort studies of patients with coarctation of the aorta (CoA) demonstrate reduced long-term survival. Improved surgical outcomes in children and evolution of adult congenital heart disease (ACHD) services have resulted in improved survival in patients with other CHDs. We hypothesise that for young adult patients with CoA long-term outcomes have improved in the contemporary era.

METHODS

151 patients (58% men) with simple CoA followed up at a tertiary ACHD service in Sydney, Australia, from 1993 to 2013 were included. We documented mortality and major morbidity such as the need for re-intervention for re-coarctation or aneurysms.

RESULTS

140 patients (mean age 35±15 years) underwent CoA repair at median age of 5 (IQR 0-10) years. Initial surgical strategy included end-to-end repair in 43, subclavian flap aortoplasty in 28 and patch aortoplasty in 31 patients (and was not documented in 28 cases). 6 patients had endovascular repair, 4 had interposition tube grafts and 11 were unrepaired. There were a total of seven deaths at a median age of 60 years. Actuarial survival was 98% at 40, 98% at 50 and 89% at 60 years of age. Re-coarctation occurred in 34% and descending aortic aneurysms were noted in 18%. Patients with end-to-end repair had lower rates of significant re-coarctation or descending aortic aneurysms (p=0.026 and <0.001, respectively). 66% had bicuspid aortic valve and 44% were hypertensive.

CONCLUSIONS

Patients with CoA who reach adolescence demonstrate very good long-term survival up to age 60 years. Long-term morbidity is common, however, related largely to aortic complications and late hypertension.

Improving the diagnosis of LV non-compaction with cardiac magnetic resonance imaging

BACKGROUND

Current diagnostic criteria for left ventricular non-compaction (LVNC) poorly correlate with clinical outcomes. We aimed to develop a cardiac magnetic resonance (CMR) based semi-automated technique for quantification of non-compacted (NC) and compacted (C) masses and to ascertain their relationships to global and regional LV function.

METHODS

We analysed CMR data from 30 adults with isolated LVNC and 20 controls. NC and C masses were measured using relative signal intensities of myocardium and blood pool. Global and regional LVNC masses was calculated and correlated with both global and regional LV systolic function as well as occurrence of arrhythmia.

RESULTS

LVNC patients had significantly higher end-systolic (ES) and end-diastolic (ED) NC:C ratios compared to controls (ES 0.21 [SD 0.09] vs. 0.12 [SD 0.02], p<0.001; ED 0.39 [SD 0.08] vs. 0.26 [SD 0.05], p<0.001). NC:C ratios correlated inversely with global ejection fraction, with a stronger correlation in ES vs. ED (r=-0.58, p<0.001 vs. r=-0.30, p=0.03). ES basal, mid and apical NC:C ratios also showed a significant inverse correlation with global LV ejection fraction (ES basal r=-0.29, p=0.04; mid-ventricular r=-0.50, p<0.001 and apical r=-0.71, p<0.001). Upon ROC testing, an ES NC:C ratio of 0.16 had a sensitivity of 70% and a specificity of 95% for detection of significant LVNC. Patients with sustained ventricular tachycardia had a significantly higher ES NC:C ratio (0.31 [SD 0.18] vs. 0.20 [SD 0.06], p=0.02).

CONCLUSIONS

The NC:C ratio derived from relative signal intensities of myocardium and blood pool improves the ability to detect clinically relevant NC compared to previous CMR techniques.

Asymptomatic left ventricular dysfunction with long-term clozapine treatment for schizophrenia: a multicentre cross-sectional cohort study

Objectives

Patients with schizophrenia treated with clozapine are at risk of acute myocarditis and dilated cardiomyopathy. However, there are no data on the prevalence of subclinical cardiomyopathy or its associations.

Methods

100 consecutive patients with schizophrenia treated with clozapine for >1 year and without a history of cardiac pathology (group 1), 21 controls with a history of schizophrenia treated with non-clozapine antipsychotics for >1 year (group 2) and 20 controls without schizophrenia (group 3) were studied. Comprehensive evaluation by clinical examination, ECG, transthoracic echocardiography including left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) and biochemical profiles were performed.

Results

Patients with schizophrenia were of similar age, but had higher body mass index (BMI), rates of smoking and hyperlipidaemia than controls. Patients with schizophrenia had received clozapine or non-clozapine antipsychotics for a mean duration of 6.8±5.3 and 9.7±6.1 years, respectively. Patients taking clozapine demonstrated globally impaired LVEF (58.3%: group 1 vs 62.2%: group 2 vs 64.8%: group 3, p<0.001) and GLS (−16.7%: group 1 vs −18.6%: group 2 vs −20.2%: group 3, p<0.001). Moreover, LVEF was <50% in 9/100 (9%) patients receiving clozapine and in non-clozapine schizophrenia patients or healthy controls, but this was not statistically significantly different (analysis of covariance, p=0.19). Univariate analysis in patients taking clozapine found that impaired LV was not predicted by high-sensitivity troponin T, but was associated with features of the metabolic syndrome (including increased triglycerides, low high-density lipoprotein cholesterol (HDL-C), high-sensitivity C reactive protein and BMI), elevated neutrophil count, elevated heart rate, smoking and N-terminal probrain natriuretic peptide. In patients taking clozapine, multivariable analysis identified elevated neutrophil count and low HDL-C as the only independent predictors of impaired GLS.

Conclusions

Asymptomatic mild LV impairment is common in patients with schizophrenia receiving long-term clozapine treatment and is associated with neutrophilia and low HDL-C.

Congenital heart disease-associated pulmonary arterial hypertension: preliminary results from a novel registry

BACKGROUND/AIMS

Pulmonary arterial hypertension (PAH) frequently accompanies childhood congenital heart disease (CHD) and may persist into adult life. The advent of specific PAH therapies for PAH prompted formation of a national Australian and New Zealand registry in 2010 to document the incidence, demographics, presentation and outcomes for these patients.

METHODS

This multicentre, prospective, web-based registry enrols patients with CHD-associated PAH being followed in a tertiary centre. The inclusion criteria stipulated patient age ≥16 years, a measured mean pulmonary arterial pressure >25 mmHg at rest or echocardiographical evidence of PAH or a diagnosis of Eisenmenger syndrome, and followed since 1 January 2000. A single observer collected standardised data during a series of site visits.

RESULTS

Of the first 50 patients enrolled, 30 (60%) were female. The mean age (standard deviation (SD)) at the time of PAH diagnosis or confirmation in an adult centre was 27.23 (10.07) years, and 32 (64%) patients are currently aged >30 years. Fourteen (28%) patients were in World Health Organization Functional Class II and 36 (72%) in Class III at the time of diagnosis. Forty-seven of 50 (94%) had congenital systemic-pulmonary shunts, and 36 (72%) never underwent intervention. Thirteen (26%) had Down syndrome. Confirmation of PAH by recent cardiac catheterisation was available in 30 (60%) subjects. During follow up, a total of 32 (64%) patients received a PAH-specific therapy.

CONCLUSIONS

CHD associated with PAH in adult life has resulted in a new population with unique needs. This registry will allow documentation of clinical course and long-term outcomes for these patients.

Screening and treating pulmonary arterial hypertension in a tertiary hospital-based multidisciplinary clinic: the first 200 patients

BACKGROUND

Pulmonary arterial hypertension (PAH) is an increasingly recognised serious illness with insidious onset, delayed diagnosis, complex diagnostic algorithms and poor prognosis, but with recently available effective treatments.

AIMS

To efficiently diagnose and to offer treatment for PAH, we established a multidisciplinary service in 2005, where patients attend a clinic staffed by specialists in cardiology, respiratory medicine, rheumatology and immunology in a tertiary referral hospital setting.

METHODS

We studied the first 200 patients referred. Serology, echocardiography, lung function tests, high-resolution computed tomography, World Health Organisation Class determination and 6-min walk tests and/or right heart catheterisation were performed, as clinically indicated.

RESULTS

Of the 200 patients seen, 66 had confirmed pulmonary hypertension (mean pulmonary artery pressure > 25 mmHg) diagnosed on echocardiography ± right heart catheterisation. Of these patients, 58 had catheter-proven PAH (mean pulmonary artery pressure > 25 mmHg with mean wedge pressure < 15 mmHg). Underlying diagnoses for the confirmed PAH patients were idiopathic (32), scleroderma-associated (14), other connective tissue disease (4) and associated with congenital heart disease (8). Patients with confirmed PAH were commenced on PAH-specific therapy--initially bosentan in the majority but sildenafil, and iloprost were occasionally used initially for patient-specific reasons. Median time from when the patient first called the clinic to prescription of therapy was 16 days (interquartile range; 0-31 days). All surviving patients with PAH have attended for regular 6-monthly follow-up visits with a 100% retention rate up to 4 years.

CONCLUSION

A multidisciplinary clinic can provide efficient diagnosis and rapid triage to PAH-specific therapy, if appropriate. Retention rates remain high, at follow up.

Ironic case of hepatic dysfunction following the global withdrawal of sitaxentan

A patient with pulmonary arterial hypertension secondary to systemic sclerosis was successfully treated with sitaxentan prior to its worldwide withdrawal (because of hepatotoxicity concerns), but then ironically experienced acute hepatic dysfunction during substitute bosentan therapy, and was eventually stabilised on a phosphodiesterase-5 inhibitor.

Vitamin B-12 supplementation improves arterial function in vegetarians with subnormal vitamin B-12 status

OBJECTIVE

Vegetarians are more vascular-healthy but those with subnormal vitamin B-12 status have impaired arterial endothelial function and increased intima-media thickness. We aimed to study the impact of vitamin B-12 supplementation on these markers, in the vegetarians.

DESIGN

Double-blind, placebo controlled, randomised crossover study.

SETTING

Community dwelling vegetarians.

PARTICIPANTS

Fifty healthy vegetarians (vegetarian diet for at least 6 years) were recruited.

INTERVENTION

Vitamin B-12 (500 µg/day) or identical placebo were given for 12 weeks with 10 weeks of placebo-washout before crossover (n=43), and then open label vitamin B-12 for additional 24 weeks (n=41).

MEASUREMENT

Flow-mediated dilation of brachial artery (FMD) and intima-media thickness (IMT) of carotid artery were measured by ultrasound.

RESULTS

The mean age of the subjects was 45±9 years and 22 (44%) were male. Thirty-five subjects (70%) had serum B-12 levels <150 pmol/l. Vitamin B-12 supplementation significantly increased serum vitamin B-12 levels (p<0.0001) and lowered plasma homocysteine (p<0.05). After vitamin B-12 supplementation but not placebo, significant improvement of brachial FMD (6.3±1.8% to 6.9±1.9%; p<0.0001) and in carotid IMT (0.69±0.09 mm to 0.67±0.09 mm, p<0.05) were found, with further improvement in FMD (to 7.4±1.7%; p<0.0001) and IMT (to 0.65±0.09 mm; p<0.001) after 24 weeks open label vitamin B-12. There were no significant changes in blood pressures or lipid profiles. On multivariate analysis, changes in B-12 (β=0.25; p=0.02) but not homocysteine were related to changes in FMD, (R=0.32; F value=3.19; p=0.028).

CONCLUSIONS

Vitamin B-12 supplementation improved arterial function in vegetarians with subnormal vitamin B-12 levels, proposing a novel strategy for atherosclerosis prevention.

Therapeutic approaches in adults with congenital heart disease-associated pulmonary arterial hypertension

Pulmonary arterial hypertension is a major contributor to reduced functional capacity in patients with congenital heart disease. Expert care is essential. Whilst careful supportive management has traditionally been the mainstay for these patients, in recent times significant improvements in exercise capacity and even survival have been observed with the use of disease-targeted therapy, including endothelin receptor antagonists, phosphodiesterase inhibitors and prostanoids. In this review we will discuss current therapeutic options and summarise the recent literature on disease-targeted therapy.

Risk factors for cardiovascular disease do not fully explain differences in carotid intima-media thickness between Indigenous and European Australians without diabetes

OBJECTIVE

To investigate whether cardiovascular risk factors can explain the higher carotid intima-media thickness (CIMT) in Indigenous compared with European Australians.

DESIGN

Cross-sectional study in three subgroups.

PATIENTS

Non-diabetic urban European (n = 86), urban Indigenous (n = 69), and remote Indigenous (n = 60) Australians aged 25-64 years.

MEASUREMENTS

CIMT, age, sex, anthropometry, blood pressure, smoking status, fasting glucose and insulin, haemoglobin (Hb)A1c, homocysteine, C-reactive protein (CRP), lipids, urinary albumin and creatinine.

RESULTS

CIMT and levels of risk factors, except fasting glucose and total cholesterol, worsened across the three groups. Log(n) fasting insulin [beta = 0.022, 95% confidence interval (CI) 0-0.0439], age (beta = 0.006, 95% CI 0.004-0.007), gender (female beta = -0.005 vs. male, 95% CI -0.084 to -0.026), mean arterial pressure (MAP) (beta = 0.001, 95% CI 0.001-0.002) and ethnicity/location [urban Indigenous (beta = 0.027, 95% CI -0.010 to 0.064 vs. European); remote Indigenous (beta = 0.083, 95% CI 0.042-0.123 vs. European)] explained 41% of variance in CIMT. Significant interactions were seen for ethnicity/location with age (P = 0.014) and MAP (P = 0.018). Age was consistently associated with CIMT across the three populations, and was associated with larger increments in CIMT for the Indigenous subgroups (beta = 0.007, 95% CI 0.005-0.009 urban; beta = 0.007, 95% CI 0.004-0.010 remote) compared with Europeans (beta = 0.003, 95% CI 0.002-0.006) in models including age, sex and MAP. MAP was only associated with CIMT in the remote Indigenous subgroup.

CONCLUSION

After adjusting for selected risk factors, CIMT in remote Indigenous participants was still higher than in Europeans. The slope of the association between age and CIMT steepened from urban Europeans to remote Indigenous.

The "atheroprotective" mediators apolipoprotein A-I and Foxp3 are over-abundant in unstable carotid plaques

OBJECTIVE

Inflammation is important in plaque vulnerability but the role of atheroprotective mediators in unstable plaques is not defined. The apolipoproteinA-I (apoA-I) component of HDL, and CD4+/CD25+ regulatory T cells (with their major transcription factor, Foxp3), have been implicated in the suppression of vascular inflammation. Our aim was to characterise the presence of these novel "protective" markers (apoA-I and Foxp3) in carotid plaques from symptomatic and asymptomatic subjects.

METHODS AND RESULTS

Plaques from 57 patients (25 symptomatic, 32 asymptomatic) were stained immunohistochemically for macrophages (CD68), T cells (CD3), monocyte chemotactic protein-1 (MCP-1), matrix metalloproteinase-2 (MMP-2), myeloperoxidase (MPO), apoA-I and Foxp3. Twelve randomly selected plaques (6 asymptomatic, 6 symptomatic) were immunostained for interleukin-10 (IL-10) and interleukin-17 (IL-17). Staining was quantified using Image-Pro Plus software. Significantly greater areas of positive immunostaining for CD68, CD3, MCP-1, MMP-2, IL-17 and MPO were found in plaques from symptomatic patients compared with asymptomatic patients (p<0.05 for all). Furthermore, significantly greater areas of positive immunostaining for apoA-I, Foxp3 and IL-10 were found in symptomatic versus asymptomatic plaques (p<0.05 for all). The presence of apoA-I was correlated significantly and co-localised with CD3, CD68, MCP-1, MMP-2 and MPO immunostaining (R=0.70, 0.63, 0.52, 0.55 and 0.79, respectively; p<0.01 for all). Foxp3 immunostaining also correlated significantly with CD3 (R=0.42), CD68 (R=0.47), MCP-1 (R=0.55) and MMP-2 (R=0.44) immunostaining (p<0.05 for all).

CONCLUSIONS

ApoA-I and Foxp3 are over-abundant in plaques from symptomatic subjects and co-localise with key inflammatory mediators. These data suggest ineffective/insufficient protection against atherosclerosis-mediated inflammation by these "atheroprotective" moieties.

Recalibration of a Framingham risk equation for a rural population in India

BACKGROUND

Coronary heart disease (CHD) risk estimation tools are a simple means of identifying those at high risk in a community and hence a potentially cost-effective strategy for CHD prevention in resource-poor countries. Since India has few local data upon which to develop such a tool de novo, in this study a Framingham risk equation has been recalibrated to estimate CHD risks in a population from rural India and the sensitivity of the method to information resources examined. Recent surveys of this population have found high levels of cardiovascular risk factors, particularly metabolic risk factors and a high proportion of mortality due to cardiovascular diseases.

METHODS

The proportion of a rural Indian population at high risk of CHD using three risk estimation equations was estimated. The first a published version of the Framingham risk equation, the second a recalibrated equation using local mortality surveillance data and local risk factor data, and the third a recalibrated equation using national mortality data and local risk factor data.

RESULTS

The mean 10-year probability of CHD for adults >30 years was 10.4% (9.6% to 11.1%) for men and 5.3% (4.9% to 5.7%) for women using the Framingham equation; 10.7% (9.9% to 11.5%) for men and 4.2% (3.9% to 4.5%) for women using the local recalibration; and 18.9% (17.7% to 20.1%) for men and 8.2% (7.6% to 8.8%) for women using the national recalibration.

CONCLUSION

These findings indicate that in India, equations recalibrated to summary national data are unlikely to be relevant to all regions of India and demonstrate the importance of local data collection to enable development of relevant CHD risk tools.

Diastolic dysfunction and abnormalities of the microcirculation in type 2 diabetes

AIM

Diabetic cardiomyopathy is an increasingly recognized entity. The pathogenic factors that may contribute to its development, especially the earliest changes of diastolic dysfunction (DD), have not been clearly defined. Microvessel dysfunction and upregulation of profibrotic growth factors have been described as possible causes. The aim of this study was therefore to determine whether microvascular dysfunction and/or upregulation of the profibrotic connective tissue growth factor (CTGF) are associated with subclinical DD in subjects with type 2 diabetes.

METHODS

Forty subjects with type 2 diabetes and 20 age-matched non-diabetic controls, all of whom had no clinical evidence of ischaemic heart disease, cardiac failure or echo evidence of systolic ventricular dysfunction, were recruited. Microvascular function was measured by laser Doppler velocimetry, with examination of endothelium-dependent increase in blood flow following iontophoresis of acetylcholine (ACh) and endothelium-independent increase in blood flow in response to the nitric oxide donor sodium nitroprusside (SNP). CTGF levels were determined by Western immunoblotting.

RESULTS

DD determined on the basis of traditional echocardiographic criteria was similar in diabetic subjects compared with controls (28 vs. 20%, p = 0.5). Using left ventricular myocardial tissue Doppler-based indices for DD, the E/E' and the E'/A' ratios (where E is the flow related to early ventricular filling and E' and A' are early and late diastolic velocities, respectively) in diabetic subjects revealed evidence of more DD than controls (p = 0.046 and p = 0.007 respectively) . Comparing controls with no DD by conventional echocardiographic criteria (Group I), diabetes and no DD (Group II) and diabetes with DD (Group III), there was a significant trend in reduction of both endothelium-dependent (ACh fold change; p = 0.04) and endothelium-independent (SNP fold change; p = 0.0004) blood flow across the groups. The ACh and SNP responses, however, were not correlated significantly with quartiles of the E/E' ratio or the E'/A' ratio. CTGF plasma levels did not differ across the groups and CTGF did not correlate with parameters of microvascular function.

CONCLUSIONS

This study indicates that while there is a significant association between DD and measures of microvascular function, the relationship between endothelial dysfunction, CTGF and subtle measures of DD is not strong. Other factors are therefore likely to play an important role in the early pathogenesis of subclinical cardiac DD in type 2 diabetes.

The effects of obesity and non-pharmacological weight loss on vascular and ventricular function and structure

AIMS

The mechanisms by which obesity confers increased cardiovascular risk and the effects of moderate weight loss on cardiovascular health are incompletely understood. We sought to characterize the preclinical changes in cardiac and vascular health that accompany obesity and the influence of lifestyle modification on these parameters.

METHODS

Preclinical markers of vasculopathy in resistance vessels and conduit arteries and left ventricular structure and function were assessed in 39 obese subjects (BMI > 30 kg/m(2)) and 11 healthy weight controls. The influence of serum on cellular adhesion molecule (CAM) expression on human endothelial cells was studied ex vivo in a subgroup of 13 obese and nine healthy weight subjects. These analyses were repeated in all 17 of the obese subjects who complied with 4-9 months of lifestyle modification treatment (six with weight loss >5% and 11 with weight loss <5%).

RESULTS

Compared with healthy weight controls, obese subjects had decreased peak hyperaemic forearm blood flow (p = 0.015), increased carotid intima-media thickness (p = 0.009), increased left ventricular wall thickness and volume and evidence of systolic and diastolic dysfunction as assessed using tissue Doppler imaging (S', p = 0.09; E'/A', p = 0.02), and serum from obese subjects increased the intercellular CAM-1 expression on human endothelial cells (p = 0.009). However, arterial endothelial function assessed by flow-mediated dilatation was not altered (p = 0.99). Lifestyle modification treatment resulted in potentially beneficial changes in fibrinogen (p = 0.003), HDL cholesterol (p = 0.05) and soluble vascular CAM-1 (p = 0.06). In subjects with weight loss greater than 5% of body weight, there was also a decrease in low-level inflammation (high-sensitivity C-reactive protein, p = 0.05), lipid peroxidation (thiobarbituric acid-reactive substances, p = 0.05) and triglycerides (p = 0.07).

CONCLUSIONS

Obesity is associated with widespread alterations in cardiac and vascular structure and function. Moderate short-term weight loss by lifestyle modification results in some beneficial changes in serum profile; however, these are not accompanied by significant alterations to either cardiac or vascular structure and function.

Increased carotid intima-media thickness in remote and urban Indigenous Australians: impact of diabetes and components of the metabolic syndrome

OBJECTIVE

Indigenous Australians have rates of cardiovascular (CVD) mortality some seven to 10-fold higher than non-Indigenous Australians aged 25-64 years. We aimed to evaluate the impact of type 2 diabetes and components of the metabolic syndrome on carotid intima-media thickness (CIMT) as a marker of cardiovascular risk in Indigenous Australians living in remote and urban environments and in Australians of European ancestry.

DESIGN, PATIENTS AND MEASUREMENTS

CIMT was measured by high-resolution B-mode ultrasound imaging of the common carotid artery in 119 remote Indigenous, 144 urban Indigenous and 122 urban European Australians with and without diabetes.

RESULTS

In nondiabetic participants, CIMT was lowest in Europeans (mean (SD) 0.64 mm (0.10)), higher in urban Indigenous Australians (0.67 mm (0.12)) and highest in remote Indigenous Australians (0.73 mm (0.15), P < 0.001). CIMT was higher with diabetes with the same pattern observed between populations: 0.73 mm, 0.79 mm and 0.82 mm, respectively (P < 0.001). Traditional risk factors (age, male gender, blood pressure and HbA1c) explained 35-45% of the variance of CIMT within each population group. However, differences in CIMT between population groups were maintained after adjustment for these cardiovascular risks plus cholesterol and smoking (P < 0.001). Factor analysis revealed that variables of the metabolic syndrome, together with smoking and elevated C-reactive protein (CRP) and urinary albumin-creatinine ratio (ACR), are likely to explain the higher CIMT in Indigenous Australians (and the urban-remote gradient). Unmeasured variables (genetic, psychosocial and socioeconomic) may also contribute to higher CIMT in these populations.

CONCLUSION

Glycaemic control and metabolic syndrome components contribute significantly to premature atherogenesis in Indigenous Australians and we recommend that therapy should be targeted accordingly.

Endothelial dysfunction and arterial abnormalities in childhood obesity

Rates of overweight and obesity in both adults and children have risen sharply during the past 20 years. The reasons for this escalation in obesity are not fully determined, however, sedentary lifestyle and dietary changes in combination with genetic predisposition are probably involved. Clinical cardiovascular disease, including myocardial infarction and stroke, are usually only manifest in the fifth decade of life or beyond. However, the earliest physical signs of atherosclerosis, the underlying disease process that leads to these events, may be present from early childhood. There are now a variety of noninvasive tests used to assess both the structural and functional properties of the vasculature and in vivo changes suggestive of 'early atherosclerosis' have now been characterised. These have allowed not only an increased understanding of the atherosclerotic changes to the vasculature that accompany overweight and obesity in children, but have also allowed serial study of the effects of diet and exercise interventions on early atherosclerosis changes, in childhood obesity.

Treatment of obstructive sleep apnoea leads to improved microvascular endothelial function in the systemic circulation

BACKGROUND

Obstructive sleep apnoea (OSA) is a common and potentially reversible cause of systemic hypertension. The mechanisms whereby OSA leads to hypertension and the effects of treatment on arterial function, however, are not well established. Microvascular arterial endothelial and smooth muscle function was assessed in subjects with OSA before and after treatment with continuous positive airways pressure (CPAP).

METHODS

Ten subjects of mean (SE) age 49 (8) years with at least moderately severe OSA had detailed forearm vascular reactivity studies before and after 3 months of CPAP treatment. The systemic circulation was assessed by measuring brachial artery pressure, flow and resistance responses to intra-arterial infusions of acetylcholine (ACh; an endothelium dependent vasodilator), sodium nitroprusside (SNP; an endothelium independent vasodilator), L-NMMA (a nitric oxide (NO) antagonist), and L-arginine (the substrate for NO).

RESULTS

Before CPAP, ACh and SNP infusions increased forearm blood flow in a dose dependent manner (p<0.01). After CPAP, endothelium dependent dilation to ACh was significantly increased (434 (23)% of baseline after CPAP v 278 (20)% before CPAP, p<0.001), whereas SNP induced dilation was unchanged. Resting NO production was higher after CPAP, evidenced by a significantly greater reduction in basal flow by L-NMMA (p=0.05). L-Arginine reversed the effect of L-NMMA in all cases.

CONCLUSION

In patients with OSA, treatment with CPAP improves baseline endothelial NO release and stimulates endothelium dependent vasorelaxation in the systemic circulation. This is a potential mechanism for improving systemic and vascular function in patients with OSA treated with CPAP.