Sex associations and computed tomography coronary angiography-guided management in patients with stable chest pain

AIMS

The relative benefits of computed tomography coronary angiography (CTCA)-guided management in women and men with suspected angina due to coronary heart disease (CHD) are uncertain.

METHODS AND RESULTS

In this post hoc analysis of an open-label parallel-group multicentre trial, we recruited 4146 patients referred for assessment of suspected angina from 12 cardiology clinics across the UK. We randomly assigned (1:1) participants to standard care alone or standard care plus CTCA. Fewer women had typical chest pain symptoms (n = 582, 32.0%) when compared with men (n = 880, 37.9%; P < 0.001). Amongst the CTCA-guided group, more women had normal coronary arteries [386 (49.6%) vs. 263 (26.2%)] and less obstructive CHD [105 (11.5%) vs. 347 (29.8%)]. A CTCA-guided strategy resulted in more women than men being reclassified as not having CHD {19.2% vs. 13.1%; absolute risk difference, 5.7 [95% confidence interval (CI): 2.7-8.7, P < 0.001]} or having angina due to CHD [15.0% vs. 9.0%; absolute risk difference, 5.6 (2.3-8.9, P = 0.001)]. After a median of 4.8 years follow-up, CTCA-guided management was associated with similar reductions in the risk of CHD death or non-fatal myocardial infarction in women [hazard ratio (HR) 0.50, 95% CI 0.24-1.04], and men (HR 0.63, 95% CI 0.42-0.95; Pinteraction = 0.572).

CONCLUSION

Following the addition of CTCA, women were more likely to be found to have normal coronary arteries than men. This led to more women being reclassified as not having CHD, resulting in more downstream tests and treatments being cancelled. There were similar prognostic benefits of CTCA for women and men.

Guiding Therapy by Coronary CT Angiography Improves Outcomes in Patients With Stable Chest Pain

BACKGROUND

Within the SCOT-HEART (Scottish COmputed Tomography of the HEART Trial) trial of patients with stable chest pain, the use of coronary computed tomography angiography (CTA) reduced the rate of death from coronary heart disease or nonfatal myocardial infarction (primary endpoint).

OBJECTIVES

This study sought to assess the consistency and mechanisms of the 5-year reduction in this endpoint.

METHODS

In this open-label trial, 4,146 participants were randomized to standard care alone or standard care plus coronary CTA. This study explored the primary endpoint by symptoms, diagnosis, coronary revascularizations, and preventative therapies.

RESULTS

Event reductions were consistent across symptom and risk categories (p = NS for interactions). In patients who were not diagnosed with angina due to coronary heart disease, coronary CTA was associated with a lower primary endpoint incidence rate (0.23; 95% confidence interval [CI]: 0.13 to 0.35 vs. 0.59; 95% CI: 0.42 to 0.80 per 100 patient-years; p < 0.001). In those who had undergone coronary CTA, rates of coronary revascularization were higher in the first year (hazard ratio [HR]: 1.21; 95% CI: 1.01 to 1.46; p = 0.042) but lower beyond 1 year (HR: 0.59; 95% CI: 0.38 to 0.90; p = 0.015). Patients assigned to coronary CTA had higher rates of preventative therapies throughout follow-up (p < 0.001 for all), with rates highest in those with CT-defined coronary artery disease. Modeling studies demonstrated the plausibility of the observed effect size.

CONCLUSIONS

The beneficial effect of coronary CTA on outcomes is consistent across subgroups with plausible underlying mechanisms. Coronary CTA improves coronary heart disease outcomes by enabling better targeting of preventative treatments to those with coronary artery disease. (Scottish COmputed Tomography of the HEART Trial [SCOT-HEART]; NCT01149590).

Coronary CT Angiography and 5-Year Risk of Myocardial Infarction

BACKGROUND

Although coronary computed tomographic angiography (CTA) improves diagnostic certainty in the assessment of patients with stable chest pain, its effect on 5-year clinical outcomes is unknown.

METHODS

In an open-label, multicenter, parallel-group trial, we randomly assigned 4146 patients with stable chest pain who had been referred to a cardiology clinic for evaluation to standard care plus CTA (2073 patients) or to standard care alone (2073 patients). Investigations, treatments, and clinical outcomes were assessed over 3 to 7 years of follow-up. The primary end point was death from coronary heart disease or nonfatal myocardial infarction at 5 years.

RESULTS

The median duration of follow-up was 4.8 years, which yielded 20,254 patient-years of follow-up. The 5-year rate of the primary end point was lower in the CTA group than in the standard-care group (2.3% [48 patients] vs. 3.9% [81 patients]; hazard ratio, 0.59; 95% confidence interval [CI], 0.41 to 0.84; P=0.004). Although the rates of invasive coronary angiography and coronary revascularization were higher in the CTA group than in the standard-care group in the first few months of follow-up, overall rates were similar at 5 years: invasive coronary angiography was performed in 491 patients in the CTA group and in 502 patients in the standard-care group (hazard ratio, 1.00; 95% CI, 0.88 to 1.13), and coronary revascularization was performed in 279 patients in the CTA group and in 267 in the standard-care group (hazard ratio, 1.07; 95% CI, 0.91 to 1.27). However, more preventive therapies were initiated in patients in the CTA group (odds ratio, 1.40; 95% CI, 1.19 to 1.65), as were more antianginal therapies (odds ratio, 1.27; 95% CI, 1.05 to 1.54). There were no significant between-group differences in the rates of cardiovascular or noncardiovascular deaths or deaths from any cause.

CONCLUSIONS

In this trial, the use of CTA in addition to standard care in patients with stable chest pain resulted in a significantly lower rate of death from coronary heart disease or nonfatal myocardial infarction at 5 years than standard care alone, without resulting in a significantly higher rate of coronary angiography or coronary revascularization. (Funded by the Scottish Government Chief Scientist Office and others; SCOT-HEART ClinicalTrials.gov number, NCT01149590 .).

An in vivo Model for the Assessment of Acute Fibrinolytic Capacity of the Endothelium

The effects on blood flow and plasma fibrinolytic and coagulation parameters of intraarterial substance P, an endothelium dependent vasodilator, and sodium nitroprusside, a control endothelium independent vasodilator, were studied in the human forearm circulation. At subsystemic locally active doses, both substance P (2-8 pmol/min) and sodium nitroprusside (2-8 μg/min) caused dose-dependent vasodilatation (p <0.001 for both) without affecting plasma concentrations of PAI-1, von Willebrand factor antigen or factor VIII:C activity. Substance P caused local increases in t-PA antigen and activity (p <0.001) in the infused arm while sodium nitroprusside did not. At higher doses, substance P increased blood flow and t-PA concentrations in the noninfused arm. We conclude that brief, locally active and subsystemic infusions of intraarterial substance P cause a rapid and substantial local release of t-PA which appear to act via a flow and nitric oxide independent mechanism. This model should provide a useful and selective method of assessing the in vivo capacity of the forearm endothelium to release t-PA acutely.

High-Sensitivity Cardiac Troponin I and the Diagnosis of Coronary Artery Disease in Patients With Suspected Angina Pectoris

BACKGROUND

We determined whether high-sensitivity cardiac troponin I can improve the estimation of the pretest probability for obstructive coronary artery disease (CAD) in patients with suspected stable angina.

METHODS AND RESULTS

In a prespecified substudy of the SCOT-HEART trial (Scottish Computed Tomography of the Heart), plasma cardiac troponin was measured using a high-sensitivity single-molecule counting assay in 943 adults with suspected stable angina who had undergone coronary computed tomographic angiography. Rates of obstructive CAD were compared with the pretest probability determined by the CAD Consortium risk model with and without cardiac troponin concentrations. External validation was undertaken in an independent study population from Denmark comprising 487 patients with suspected stable angina. Higher cardiac troponin concentrations were associated with obstructive CAD with a 5-fold increase across quintiles (9%-48%; P<0.001) independent of known cardiovascular risk factors (odds ratio, 1.35; 95% confidence interval, 1.25-1.46 per doubling of troponin). Cardiac troponin concentrations improved the discrimination and calibration of the CAD Consortium model for identifying obstructive CAD (C statistic, 0.788-0.800; P=0.004; χ2=16.8 [P=0.032] to 14.3 [P=0.074]). The updated model also improved classification of the American College of Cardiology/American Heart Association pretest probability risk categories (net reclassification improvement, 0.062; 95% confidence interval, 0.035-0.089). The revised model achieved similar improvements in discrimination and calibration when applied in the external validation cohort.

CONCLUSIONS

High-sensitivity cardiac troponin I concentration is an independent predictor of obstructive CAD in patients with suspected stable angina. Use of this test may improve the selection of patients for further investigation and treatment.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01149590.

Diagnostic and prognostic benefits of computed tomography coronary angiography using the 2016 National Institute for Health and Care Excellence guidance within a randomised trial

Objectives

To evaluate the diagnostic and prognostic benefits of CT coronary angiography (CTCA) using the 2016 National Institute for Health and Care Excellence (NICE) guidelines for the assessment of suspected stable angina.

Methods

Post hoc analysis of the Scottish COmputed Tomography of the HEART (SCOT-HEART) trial of 4146 participants with suspected angina randomised to CTCA. Patients were dichotomised into NICE guideline-defined possible angina and non-anginal presentations. Primary (diagnostic) endpoint was diagnostic certainty of angina at 6 weeks and prognostic endpoint comprised fatal and non-fatal myocardial infarction (MI).

Results

In 3770 eligible participants, CTCA increased diagnostic certainty more in those with possible angina (relative risk (RR) 2.22 (95% CI 1.91 to 2.60), p<0.001) than those with non-anginal symptoms (RR 1.30 (1.11 to 1.53), p=0.002; p_interaction <0.001). In the possible angina cohort, CTCA did not change rates of invasive angiography (p=0.481) but markedly reduced rates of normal coronary angiography (HR 0.32 (0.19 to 0.52), p<0.001). In the non-anginal cohort, rates of invasive angiography increased (HR 1.82 (1.13 to 2.92), p=0.014) without reducing rates of normal coronary angiography (HR 0.78 (0.30 to 2.05), p=0.622). At 3.2 years of follow-up, fatal or non-fatal MI was reduced in patients with possible angina (3.2% to 1.9%%; HR 0.58 (0.34 to 0.99), p=0.045) but not in those with non-anginal symptoms (HR 0.65 (0.25 to 1.69), p=0.379).

Conclusions

NICE-guided patient selection maximises the benefits of CTCA on diagnostic certainty, use of invasive coronary angiography and reductions in fatal and non-fatal myocardial infarction. Patients with non-anginal chest pain derive minimal benefit from CTCA and increase the rates of invasive investigation.

Trial registration number

ClinicalTrials.gov: NCT01149590;post results.

Symptoms and quality of life in patients with suspected angina undergoing CT coronary angiography: a randomised controlled trial

BACKGROUND

In patients with suspected angina pectoris, CT coronary angiography (CTCA) clarifies the diagnosis, directs appropriate investigations and therapies, and reduces clinical events. The effect on patient symptoms is currently unknown.

METHODS

In a prospective open-label parallel group multicentre randomised controlled trial, 4146 patients with suspected angina due to coronary heart disease were randomised 1:1 to receive standard care or standard care plus CTCA. Symptoms and quality of life were assessed over 6 months using the Seattle Angina Questionnaire and Short Form 12.

RESULTS

Baseline scores indicated mild physical limitation (74±0.4), moderate angina stability (44±0.4), modest angina frequency (68±0.4), excellent treatment satisfaction (92±0.2) and moderate impairment of quality of life (55±0.3). Compared with standard care alone, CTCA was associated with less marked improvements in physical limitation (difference -1.74 (95% CIs, -3.34 to -0.14), p=0.0329), angina frequency (difference -1.55 (-2.85 to -0.25), p=0.0198) and quality of life (difference -3.48 (-4.95 to -2.01), p<0.0001) at 6 months. For patients undergoing CTCA, improvements in symptoms were greatest in those diagnosed with normal coronary arteries or who had their preventative therapy discontinued, and least in those with moderate non-obstructive disease or had a new prescription of preventative therapy (p<0.001 for all).

CONCLUSIONS

While improving diagnosis, treatment and outcome, CTCA is associated with a small attenuation of the improvements in symptoms and quality of life due to the detection of moderate non-obstructive coronary artery disease.

TRIAL REGISTRATION NUMBER

NCT01149590.

Use of Coronary Computed Tomographic Angiography to Guide Management of Patients With Coronary Disease

BACKGROUND

In a prospective, multicenter, randomized controlled trial, 4,146 patients were randomized to receive standard care or standard care plus coronary computed tomography angiography (CCTA).

OBJECTIVES

The purpose of this study was to explore the consequences of CCTA-assisted diagnosis on invasive coronary angiography, preventive treatments, and clinical outcomes.

METHODS

In post hoc analyses, we assessed changes in invasive coronary angiography, preventive treatments, and clinical outcomes using national electronic health records.

RESULTS

Despite similar overall rates (409 vs. 401; p = 0.451), invasive angiography was less likely to demonstrate normal coronary arteries (20 vs. 56; hazard ratios [HRs]: 0.39 [95% confidence interval (CI): 0.23 to 0.68]; p < 0.001) but more likely to show obstructive coronary artery disease (283 vs. 230; HR: 1.29 [95% CI: 1.08 to 1.55]; p = 0.005) in those allocated to CCTA. More preventive therapies (283 vs. 74; HR: 4.03 [95% CI: 3.12 to 5.20]; p < 0.001) were initiated after CCTA, with each drug commencing at a median of 48 to 52 days after clinic attendance. From the median time for preventive therapy initiation (50 days), fatal and nonfatal myocardial infarction was halved in patients allocated to CCTA compared with those assigned to standard care (17 vs. 34; HR: 0.50 [95% CI: 0.28 to 0.88]; p = 0.020). Cumulative 6-month costs were slightly higher with CCTA: difference $462 (95% CI: $303 to $621).

CONCLUSIONS

In patients with suspected angina due to coronary heart disease, CCTA leads to more appropriate use of invasive angiography and alterations in preventive therapies that were associated with a halving of fatal and non-fatal myocardial infarction. (Scottish COmputed Tomography of the HEART Trial [SCOT-HEART]; NCT01149590).

Left ventricular hypertrophy with strain and aortic stenosis

BACKGROUND

ECG left ventricular hypertrophy with strain is associated with an adverse prognosis in aortic stenosis. We investigated the mechanisms and outcomes associated with ECG strain.

METHODS AND RESULTS

One hundred and two patients (age, 70 years [range, 63-75 years]; male, 66%; aortic valve area, 0.9 cm(2) [range, 0.7-1.2 cm(2)]) underwent ECG, echocardiography, and cardiovascular magnetic resonance. They made up the mechanism cohort. Myocardial fibrosis was determined with late gadolinium enhancement (replacement fibrosis) and T1 mapping (diffuse fibrosis). The relationship between ECG strain and cardiovascular magnetic resonance was then assessed in an external validation cohort (n=64). The outcome cohort was made up of 140 patients from the Scottish Aortic Stenosis and Lipid Lowering Trial Impact on Regression (SALTIRE) study and was followed up for 10.6 years (1254 patient-years). Compared with those without left ventricular hypertrophy (n=51) and left ventricular hypertrophy without ECG strain (n=30), patients with ECG strain (n=21) had more severe aortic stenosis, increased left ventricular mass index, more myocardial injury (high-sensitivity plasma cardiac troponin I concentration, 4.3 ng/L [interquartile range, 2.5-7.3 ng/L] versus 7.3 ng/L [interquartile range, 3.2-20.8 ng/L] versus 18.6 ng/L [interquartile range, 9.0-45.2 ng/L], respectively; P<0.001) and increased diffuse fibrosis (extracellular volume fraction, 27.4±2.2% versus 27.2±2.9% versus 30.9±1.9%, respectively; P<0.001). All patients with ECG strain had midwall late gadolinium enhancement (positive and negative predictive values of 100% and 86%, respectively). Indeed, late gadolinium enhancement was independently associated with ECG strain (odds ratio, 1.73; 95% confidence interval, 1.08-2.77; P=0.02), a finding confirmed in the validation cohort. In the outcome cohort, ECG strain was an independent predictor of aortic valve replacement or cardiovascular death (hazard ratio, 2.67; 95% confidence interval, 1.35-5.27; P<0.01).

CONCLUSION

ECG strain is a specific marker of midwall myocardial fibrosis and predicts adverse clinical outcomes in aortic stenosis.

High-sensitivity troponin I concentrations are a marker of an advanced hypertrophic response and adverse outcomes in patients with aortic stenosis

Aims

High-sensitivity cardiac troponin I (cTnI) assays hold promise in detecting the transition from hypertrophy to heart failure in aortic stenosis. We sought to investigate the mechanism for troponin release in patients with aortic stenosis and whether plasma cTnI concentrations are associated with long-term outcome.

Methods and results

Plasma cTnI concentrations were measured in two patient cohorts using a high-sensitivity assay. First, in the Mechanism Cohort, 122 patients with aortic stenosis (median age 71, 67% male, aortic valve area 1.0 ± 0.4 cm²) underwent cardiovascular magnetic resonance and echocardiography to assess left ventricular (LV) myocardial mass, function, and fibrosis. The indexed LV mass and measures of replacement fibrosis (late gadolinium enhancement) were associated with cTnI concentrations independent of age, sex, coronary artery disease, aortic stenosis severity, and diastolic function. In the separate Outcome Cohort, 131 patients originally recruited into the Scottish Aortic Stenosis and Lipid Lowering Trial, Impact of REgression (SALTIRE) study, had long-term follow-up for the occurrence of aortic valve replacement (AVR) and cardiovascular deaths. Over a median follow-up of 10.6 years (1178 patient-years), 24 patients died from a cardiovascular cause and 60 patients had an AVR. Plasma cTnI concentrations were associated with AVR or cardiovascular death HR 1.77 (95% CI, 1.22 to 2.55) independent of age, sex, systolic ejection fraction, and aortic stenosis severity.

Conclusions

In patients with aortic stenosis, plasma cTnI concentration is associated with advanced hypertrophy and replacement myocardial fibrosis as well as AVR or cardiovascular death.

18F-sodium fluoride uptake is a marker of active calcification and disease progression in patients with aortic stenosis

BACKGROUND

18F-Sodium fluoride (18F-NaF) and 18F-fluorodeoxyglucose (18F-FDG) are promising novel biomarkers of disease activity in aortic stenosis. We compared 18F-NaF and 18F-FDG uptake with histological characterization of the aortic valve and assessed whether they predicted disease progression.

METHODS AND RESULTS

Thirty patients with aortic stenosis underwent combined positron emission and computed tomography using 18F-NaF and 18F-FDG radiotracers. In 12 patients undergoing aortic valve replacement surgery (10 for each tracer), radiotracer uptake (mean tissue/

BACKGROUND

=0.65; P=0.04) and osteocalcin (r=0.68; P=0.03) immunohistochemistry. There was no significant correlation between 18F-FDG uptake and CD68 staining (r=-0.43; P=0.22). After 1 year, aortic valve calcification increased from 314 (193-540) to 365 (207-934) AU (P<0.01). Baseline 18F-NaF uptake correlated closely with the change in calcium score (r=0.66; P<0.01), and this improved further (r=0.75; P<0.01) when 18F-NaF uptake overlying computed tomography-defined macrocalcification was excluded. No significant correlation was noted between valvular 18F-FDG uptake and change in calcium score (r=-0.11; P=0.66).

CONCLUSIONS

18F-NaF uptake identifies active tissue calcification and predicts disease progression in patients with calcific aortic stenosis.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01358513.

Endogenous tissue plasminogen activator enhances fibrinolysis and limits thrombus formation in a clinical model of thrombosis

OBJECTIVE

Using a clinical model of deep arterial injury, we assessed the ability of exogenous and endogenous tissue plasminogen activator (t-PA) to limit acute in situ thrombus formation.

APPROACH AND RESULTS

Ex vivo thrombus formation was assessed in the Badimon chamber at low and high shear rates in 2 double-blind randomized cross-over studies of 20 healthy volunteers during extracorporeal administration of recombinant t-PA (0, 40, 200, and 1000 ng/mL) or during endogenous t-PA release stimulated by intra-arterial bradykinin infusion in the presence or absence of oral enalapril. Recombinant t-PA caused a dose-dependent reduction in thrombus area under low and high shear conditions (P<0.001 for all). Intra-arterial bradykinin increased plasma t-PA concentrations in the chamber effluent (P<0.01 for all versus saline) that was quadrupled in the presence of enalapril (P<0.0001 versus placebo). These increases were accompanied by an increase in plasma D-dimer concentration (P<0.005 for all versus saline) and, in the presence of enalapril, a reduction in thrombus area in the low shear (16±5; P=0.03) and a trend toward a reduction in the high shear chamber (13±7%; P=0.07).

CONCLUSIONS

Using a well-characterized clinical model of coronary arterial injury, we demonstrate that endogenous t-PA released from the vascular endothelium enhances fibrinolysis and limits in situ thrombus propagation. These data support a crucial role for the endogenous fibrinolytic system in vivo and suggest that continued exploration and manipulation of its therapeutic potential are warranted.

Role of multidetector computed tomography in the diagnosis and management of patients attending the rapid access chest pain clinic, The Scottish computed tomography of the heart (SCOT-HEART) trial: study protocol for randomized controlled trial

Background

Rapid access chest pain clinics have facilitated the early diagnosis and treatment of patients with coronary heart disease and angina. Despite this important service provision, coronary heart disease continues to be under-diagnosed and many patients are left untreated and at risk. Recent advances in imaging technology have now led to the widespread use of noninvasive computed tomography, which can be used to measure coronary artery calcium scores and perform coronary angiography in one examination. However, this technology has not been robustly evaluated in its application to the clinic.

Methods/design

The SCOT-HEART study is an open parallel group prospective multicentre randomized controlled trial of 4,138 patients attending the rapid access chest pain clinic for evaluation of suspected cardiac chest pain. Following clinical consultation, participants will be approached and randomized 1:1 to receive standard care or standard care plus ≥64-multidetector computed tomography coronary angiography and coronary calcium score. Randomization will be conducted using a web-based system to ensure allocation concealment and will incorporate minimization. The primary endpoint of the study will be the proportion of patients diagnosed with angina pectoris secondary to coronary heart disease at 6 weeks. Secondary endpoints will include the assessment of subsequent symptoms, diagnosis, investigation and treatment. In addition, long-term health outcomes, safety endpoints, such as radiation dose, and health economic endpoints will be assessed. Assuming a clinic rate of 27.0% for the diagnosis of angina pectoris due to coronary heart disease, we will need to recruit 2,069 patients per group to detect an absolute increase of 4.0% in the rate of diagnosis at 80% power and a two-sided P value of 0.05. The SCOT-HEART study is currently recruiting participants and expects to report in 2014.

Discussion

This is the first study to look at the implementation of computed tomography in the patient care pathway that is outcome focused. This study will have major implications for the management of patients with cardiovascular disease.

Trial registration

ClinicalTrials.gov Identifier: NCT01149590

Left ventricular remodeling and hypertrophy in patients with aortic stenosis: insights from cardiovascular magnetic resonance

BACKGROUND

Cardiovascular magnetic resonance (CMR) is the gold standard non-invasive method for determining left ventricular (LV) mass and volume but has not been used previously to characterise the LV remodeling response in aortic stenosis. We sought to investigate the degree and patterns of hypertrophy in aortic stenosis using CMR.

METHODS

Patients with moderate or severe aortic stenosis, normal coronary arteries and no other significant valve lesions or cardiomyopathy were scanned by CMR with valve severity assessed by planimetry and velocity mapping. The extent and patterns of hypertrophy were investigated using measurements of the LV mass index, indexed LV volumes and the LV mass/volume ratio. Asymmetric forms of remodeling and hypertrophy were defined by a regional wall thickening ≥ 13 mm and >1.5-fold the thickness of the opposing myocardial segment.

RESULTS

Ninety-one patients (61 ± 21 years; 57 male) with aortic stenosis (aortic valve area 0.93 ± 0.32 cm2) were recruited. The severity of aortic stenosis was unrelated to the degree (r2=0.012, P=0.43) and pattern (P=0.22) of hypertrophy. By univariate analysis, only male sex demonstrated an association with LV mass index (P=0.02). Six patterns of LV adaption were observed: normal ventricular geometry (n=11), concentric remodeling (n=11), asymmetric remodeling (n=11), concentric hypertrophy (n=34), asymmetric hypertrophy (n=14) and LV decompensation (n=10). Asymmetric patterns displayed considerable overlap in appearances (wall thickness 17 ± 2mm) with hypertrophic cardiomyopathy.

CONCLUSIONS

We have demonstrated that in patients with moderate and severe aortic stenosis, the pattern of LV adaption and degree of hypertrophy do not closely correlate with the severity of valve narrowing and that asymmetric patterns of wall thickening are common.

Coronary arterial 18F-sodium fluoride uptake: a novel marker of plaque biology

OBJECTIVES

With combined positron emission tomography and computed tomography (CT), we investigated coronary arterial uptake of 18F-sodium fluoride (18F-NaF) and 18F-fluorodeoxyglucose (18F-FDG) as markers of active plaque calcification and inflammation, respectively.

BACKGROUND

The noninvasive assessment of coronary artery plaque biology would be a major advance particularly in the identification of vulnerable plaques, which are associated with specific pathological characteristics, including micro-calcification and inflammation.

METHODS

We prospectively recruited 119 volunteers (72 ± 8 years of age, 68% men) with and without aortic valve disease and measured their coronary calcium score and 18F-NaF and 18F-FDG uptake. Patients with a calcium score of 0 were used as control subjects and compared with those with calcific atherosclerosis (calcium score >0).

RESULTS

Inter-observer repeatability of coronary 18F-NaF uptake measurements (maximum tissue/background ratio) was excellent (intra-class coefficient 0.99). Activity was higher in patients with coronary atherosclerosis (n = 106) versus control subjects (1.64 ± 0.49 vs. 1.23 ± 0.24; p = 0.003) and correlated with the calcium score (r = 0.652, p < 0.001), although 40% of those with scores >1,000 displayed normal uptake. Patients with increased coronary 18F-NaF activity (n = 40) had higher rates of prior cardiovascular events (p = 0.016) and angina (p = 0.023) and higher Framingham risk scores (p = 0.011). Quantification of coronary 18F-FDG uptake was hampered by myocardial activity and was not increased in patients with atherosclerosis versus control subjects (p = 0.498).

CONCLUSIONS

18F-NaF is a promising new approach for the assessment of coronary artery plaque biology. Prospective studies with clinical outcomes are now needed to assess whether coronary 18F-NaF uptake represents a novel marker of plaque vulnerability, recent plaque rupture, and future cardiovascular risk. (An Observational PET/CT Study Examining the Role of Active Valvular Calcification and Inflammation in Patients With Aortic Stenosis; NCT01358513).

Reducing personal exposure to particulate air pollution improves cardiovascular health in patients with coronary heart disease

BACKGROUND

Air pollution exposure increases cardiovascular morbidity and mortality and is a major global public health concern.

OBJECTIVES

We investigated the benefits of reducing personal exposure to urban air pollution in patients with coronary heart disease.

METHODS

In an open randomized crossover trial, 98 patients with coronary heart disease walked on a predefined route in central Beijing, China, under different conditions: once while using a highly efficient face mask, and once while not using the mask. Symptoms, exercise, personal air pollution exposure, blood pressure, heart rate, and 12-lead electrocardiography were monitored throughout the 24-hr study period.

RESULTS

Ambient air pollutants were dominated by fine and ultrafine particulate matter (PM) that was present at high levels [74 μg/m³ for PM(2.5) (PM with aerodynamic diamater <2.5 µm)]. Consistent with traffic-derived sources, this PM contained organic carbon and polycyclic aromatic hydrocarbons and was highly oxidizing, generating large amounts of free radicals. The face mask was well tolerated, and its use was associated with decreased self-reported symptoms and reduced maximal ST segment depression (-142 vs. -156 μV, p = 0.046) over the 24-hr period. When the face mask was used during the prescribed walk, mean arterial pressure was lower (93 ± 10 vs. 96 ± 10 mmHg, p = 0.025) and heart rate variability increased (high-frequency power: 54 vs. 40 msec², p = 0.005; high-frequency normalized power: 23.5 vs. 20.5 msec, p = 0.001; root mean square successive differences: 16.7 vs. 14.8 msec, p = 0.007). However, mask use did not appear to influence heart rate or energy expenditure.

CONCLUSIONS

Reducing personal exposure to air pollution using a highly efficient face mask appeared to reduce symptoms and improve a range of cardiovascular health measures in patients with coronary heart disease. Such interventions to reduce personal exposure to PM air pollution have the potential to reduce the incidence of cardiovascular events in this highly susceptible population.

Assessment of valvular calcification and inflammation by positron emission tomography in patients with aortic stenosis

BACKGROUND

The pathophysiology of aortic stenosis is incompletely understood, and the relative contributions of valvular calcification and inflammation to disease progression are unknown.

METHODS AND RESULTS

Patients with aortic sclerosis and mild, moderate, and severe stenosis were compared prospectively with age- and sex-matched control subjects. Aortic valve severity was determined by echocardiography. Calcification and inflammation in the aortic valve were assessed by 18F-sodium fluoride (18F-NaF) and 18F-fluorodeoxyglucose (18F-FDG) uptake with the use of positron emission tomography. One hundred twenty-one subjects (20 controls; 20 aortic sclerosis; 25 mild, 33 moderate, and 23 severe aortic stenosis) were administered both 18F-NaF and 18F-FDG. Quantification of tracer uptake within the valve demonstrated excellent interobserver repeatability with no fixed or proportional biases and limits of agreement of ±0.21 (18F-NaF) and ±0.13 (18F-FDG) for maximum tissue-to-background ratios. Activity of both tracers was higher in patients with aortic stenosis than in control subjects (18F-NaF: 2.87±0.82 versus 1.55±0.17; 18F-FDG: 1.58±0.21 versus 1.30±0.13; both P<0.001). 18F-NaF uptake displayed a progressive rise with valve severity (r(2)=0.540, P<0.001), with a more modest increase observed for 18F-FDG (r(2)=0.218, P<0.001). Among patients with aortic stenosis, 91% had increased 18F-NaF uptake (>1.97), and 35% had increased 18F-FDG uptake (>1.63). A weak correlation between the activities of these tracers was observed (r(2)=0.174, P<0.001).

CONCLUSIONS

Positron emission tomography is a novel, feasible, and repeatable approach to the evaluation of valvular calcification and inflammation in patients with aortic stenosis. The frequency and magnitude of increased tracer activity correlate with disease severity and are strongest for 18F-NaF.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov. Unique identifier: NCT01358513.

Combustion-derived nanoparticulate induces the adverse vascular effects of diesel exhaust inhalation

Aim

Exposure to road traffic and air pollution may be a trigger of acute myocardial infarction, but the individual pollutants responsible for this effect have not been established. We assess the role of combustion-derived-nanoparticles in mediating the adverse cardiovascular effects of air pollution.

Methods and results

To determine the in vivo effects of inhalation of diesel exhaust components, 16 healthy volunteers were exposed to (i) dilute diesel exhaust, (ii) pure carbon nanoparticulate, (iii) filtered diesel exhaust, or (iv) filtered air, in a randomized double blind cross-over study. Following each exposure, forearm blood flow was measured during intra-brachial bradykinin, acetylcholine, sodium nitroprusside, and verapamil infusions. Compared with filtered air, inhalation of diesel exhaust increased systolic blood pressure (145 ± 4 vs. 133 ± 3 mmHg, P< 0.05) and attenuated vasodilatation to bradykinin (P= 0.005), acetylcholine (P= 0.008), and sodium nitroprusside (P< 0.001). Exposure to pure carbon nanoparticulate or filtered exhaust had no effect on endothelium-dependent or -independent vasodilatation. To determine the direct vascular effects of nanoparticulate, isolated rat aortic rings (n= 6–9 per group) were assessed in vitro by wire myography and exposed to diesel exhaust particulate, pure carbon nanoparticulate and vehicle. Compared with vehicle, diesel exhaust particulate (but not pure carbon nanoparticulate) attenuated both acetylcholine (P< 0.001) and sodium-nitroprusside (P= 0.019)-induced vasorelaxation. These effects were partially attributable to both soluble and insoluble components of the particulate.

Conclusion

Combustion-derived nanoparticulate appears to predominately mediate the adverse vascular effects of diesel exhaust inhalation. This provides a rationale for testing environmental health interventions targeted at reducing traffic-derived particulate emissions.

Diesel exhaust inhalation does not affect heart rhythm or heart rate variability

OBJECTIVE

Exposure to air pollution is associated with increases in cardiovascular morbidity and mortality. This study was undertaken to determine the effect of diesel exhaust inhalation on heart rhythm and heart rate variability in healthy volunteers and patients with coronary heart disease.

DESIGN AND SETTING

Double-blind randomised crossover studies in a university teaching hospital.

PATIENTS

32 healthy non-smoking volunteers and 20 patients with prior myocardial infarction.

INTERVENTIONS

All 52 subjects were exposed for 1 h to dilute diesel exhaust (particle concentration 300 μg/m³) or filtered air.

MAIN OUTCOME MEASURES

Heart rhythm and heart rate variability were monitored during and for 24 h after the exposure using continuous ambulatory electrocardiography and assessed using standard time and frequency domain analysis.

RESULTS

No significant arrhythmias occurred during or following exposures. Patients with coronary heart disease had reduced autonomic function in comparison to healthy volunteers, with reduced standard deviations of the NN interval (SDNN, p < 0.001) and triangular index (p < 0.001). Diesel exhaust did not affect heart rate variability compared with filtered air (p > 0.05 for all) in healthy volunteers (SDNN 101 ± 6 vs 91 ± 6, triangular index 20 ± 1 vs 21 ± 1) or patients with coronary heart disease (SDNN 47 ± 5 vs 38 ± 4, triangular index 8 ± 1 vs 7 ± 1).

CONCLUSIONS

Brief exposure to dilute diesel exhaust does not alter heart rhythm or heart rate variability in healthy volunteers or well-treated patients with stable coronary heart disease. Autonomic dysfunction does not appear to be a dominant mechanism that can explain the observed excess in cardiovascular events following exposure to combustion-derived air pollution.

Characterisation and reproducibility of a human ex vivo model of thrombosis

BACKGROUND

The Badimon chamber is a clinical ex vivo model of thrombosis that mimics flow conditions within the coronary circulation of man. The aims of this study were to characterise thrombus formation in the chamber and evaluate its reproducibility.

METHODS

Using blood from 24 healthy human volunteers, thrombus formation was assessed at low and high shear rates with porcine aortic tunica media as the thrombogenic substrate. Thrombus area was measured histomorphometrically. Reproducibility was assessed by paired measurements made both within and between days. Platelet activation was assessed before and at selected points within the extracorporeal circuit using flow cytometry, and fibrin content and distribution within the thrombus were assessed by immunohistochemistry.

RESULTS

Total thrombus area was highly reproducible within and between days in the low shear ([mean thrombus area, mean difference ± SEM] 8,018μm(2), 58±204μm(2) and 8,177μm(2), -154±168μm(2) respectively) and high shear chambers (11,802μm(2), -52±175μm(2) and 11,877μm(2), 220±181μm(2) respectively). Total thrombus area was greater in the high compared to the low shear chamber (11,970±285μm(2)versus 7,892±298μm(2); P<0.0001). Transit through the extracorporeal circuit did not result in platelet activation which was only detected after blood passed across the perfusion chambers (P=0.02 for platelet-monocyte aggregate formation and P=0.05 for P-selectin expression). Thrombus in the low shear chamber contained a greater proportion of fibrin (25.0±6.0% versus 8.3±1.6%, P<0.001).

CONCLUSIONS

The Badimon chamber provides a highly reproducible technique for the assessment of ex vivo platelet-rich thrombus formation in man.

Functional interplay between platelet activation and endothelial dysfunction in patients with coronary heart disease

Platelet-monocyte binding and surface P-selectin expression are sensitive markers of platelet activation. Endothelium-derived factors are known to inhibit platelet activation and may confer important anti-atherothrombotic effects. We assessed the relationship between platelet activation and endothelium-dependent vasomotion in patients with coronary heart disease (CHD). Twenty male patients with stable CHD were compared with 20 healthy men. Platelet-monocyte binding and platelet surface expression of P-selectin were assessed using two-colour flow cytometry on whole blood. Forearm blood flow was assessed in patients using venous occlusion plethysmography during intra-arterial infusions of substance P, acetylcholine and sodium nitroprusside. Platelet activation was higher in patients than healthy men (platelet-monocyte binding, 27 +/- 3 vs. 20 +/- 1%; P < 0.05). In patients with CHD, there was an inverse correlation between maximal substance P induced vasodilatation and both platelet-monocyte binding (P = 0.003) and P-selectin expression (P = 0.02). A similar correlation was observed between platelet-monocyte binding and the vasomotor response to acetylcholine (P = 0.08) but not with sodium nitroprusside. In patients with stable coronary heart disease, there is a strong inverse relationship between markers of platelet activation and endothelium-dependent vasomotor function. This may explain the pathophysiological mechanism linking endothelial vasomotor dysfunction and the risk of acute atherothrombotic events.

Association between calcific aortic stenosis and hypercholesterolemia: is there a need for a randomized controlled trial of cholesterol-lowering therapy?

BACKGROUND

Calcific aortic stenosis may have common etiological factors with atherosclerosis.

HYPOTHESIS

In this retrospective, case-control study, we aimed to determine whether there is an association between hypercholesterolemia and calcific aortic valve stenosis.

METHODS

Consecutive patients undergoing single aortic or mitral valve replacement in a regional cardiothoracic surgical center were reviewed and preoperative patient characteristics were recorded: demographics, comorbidity (including coronary artery disease and associated risk factors), serum total cholesterol, lipid-lowering therapy, and serum creatinine.

RESULTS

Serum total cholesterol concentrations were significantly higher in patients with calcific aortic stenosis than in controls (6.2+/-1.1 vs. 5.3+/-1.1 mmol/l; p < 0.001). The significant difference in serum cholesterol concentrations remained following correction for gender and body mass index (p = 0.02) and when patients with coronary artery disease were excluded (6.3+/-1.1 vs. 5.3+/-1.4 mmol/l; p<0.001). Subgroup analysis demonstrated that the association between elevated serum cholesterol concentrations and calcific aortic stenosis was particularly strong in patients with tricuspid aortic valves (6.4+/-1.2 vs. 5.3+/-1.1 mmol/l; p < 0.001) compared with those with bicuspid valves (5.9+/-1.1 vs. 5.3+/-1.1 mmol/l; p = 0.06).

CONCLUSIONS

We conclude that hypercholesterolemia is associated with calcific aortic stenosis and may be implicated in its pathogenesis and progression. We believe that there is now a need for a randomized, controlled trial of cholesterol-lowering therapy in patients with calcific aortic stenosis.

Adverse cardiovascular effects of air pollution

Air pollution is increasingly recognized as an important and modifiable determinant of cardiovascular disease in urban communities. Acute exposure has been linked to a range of adverse cardiovascular events including hospital admissions with angina, myocardial infarction, and heart failure. Long-term exposure increases an individual's lifetime risk of death from coronary heart disease. The main arbiter of these adverse health effects seems to be combustion-derived nanoparticles that incorporate reactive organic and transition metal components. Inhalation of this particulate matter leads to pulmonary inflammation with secondary systemic effects or, after translocation from the lung into the circulation, to direct toxic cardiovascular effects. Through the induction of cellular oxidative stress and proinflammatory pathways, particulate matter augments the development and progression of atherosclerosis via detrimental effects on platelets, vascular tissue, and the myocardium. These effects seem to underpin the atherothrombotic consequences of acute and chronic exposure to air pollution. An increased understanding of the mediators and mechanisms of these processes is necessary if we are to develop strategies to protect individuals at risk and reduce the effect of air pollution on cardiovascular disease.

Diesel exhaust inhalation increases thrombus formation in man

AIMS

Although the mechanism is unclear, exposure to traffic-derived air pollution is a trigger for acute myocardial infarction (MI). The aim of this study is to investigate the effect of diesel exhaust inhalation on platelet activation and thrombus formation in men.

METHODS AND RESULTS

In a double-blind randomized crossover study, 20 healthy volunteers were exposed to dilute diesel exhaust (350 microg/m(3)) and filtered air. Thrombus formation, coagulation, platelet activation, and inflammatory markers were measured at 2 and 6 h following exposure. Thrombus formation was measured using the Badimon ex vivo perfusion chamber. Platelet activation was assessed by flow cytometry. Compared with filtered air, diesel exhaust inhalation increased thrombus formation under low- and high-shear conditions by 24% [change in thrombus area 2229 microm(2), 95% confidence interval (CI) 1143-3315 microm(2), P = 0.0002] and 19% (change in thrombus area 2451 microm(2), 95% CI 1190-3712 microm(2), P = 0.0005), respectively. This increased thrombogenicity was seen at 2 and 6 h, using two different diesel engines and fuels. Diesel exhaust also increased platelet-neutrophil and platelet-monocyte aggregates by 52% (absolute change 6%, 95% CI 2-10%, P = 0.01) and 30% (absolute change 3%, 95% CI 0.2-7%, P = 0.03), respectively, at 2 h following exposure compared with filtered air.

CONCLUSION

Inhalation of diesel exhaust increases ex vivo thrombus formation and causes in vivo platelet activation in man. These findings provide a potential mechanism linking exposure to combustion-derived air pollution with the triggering of acute MI.

Role of the endothelium in the vascular effects of the thrombin receptor (protease-activated receptor type 1) in humans

OBJECTIVES

The purpose of this study was to determine the role of the endothelium in the vascular actions of protease-activated receptor type 1 (PAR-1) activation in vivo in man.

BACKGROUND

Thrombin is central to the pathophysiology of atherothrombosis. Its cellular actions are mediated via PAR-1. Protease-activated receptor type 1 activation causes arterial vasodilation, venoconstriction, platelet activation, and tissue-type plasminogen activator release in man.

METHODS

Dorsal hand vein diameter was measured in 6 healthy volunteers before and after endothelial denudation. Forearm arterial blood flow, plasma fibrinolytic factors, and platelet activation were measured in 24 healthy volunteers during venous occlusion plethysmography. The effects of inhibition of prostacyclin, nitric oxide (NO), and endothelium-derived hyperpolarizing factor on PAR-1 responses were assessed during coadministration of aspirin, the "NO clamp" (L-N(G)-monomethyl arginine and sodium nitroprusside), and tetraethylammonium ion, respectively.

RESULTS

Endothelial denudation did not affect PAR-1-evoked venoconstriction (SFLLRN; 0.05 to 15 nmol/min). Although aspirin had no effect, SFLLRN-induced vasodilation (5 to 50 nmol/min) was attenuated by the NO clamp (p < 0.0001) and tetraethylammonium ion (p < 0.05) and abolished by their combination (p < 0.01). The NO clamp augmented SFLLRN-induced tissue-type plasminogen activator and plasminogen activator inhibitor type 1 antigen (p < 0.0001) release, but tetraethylammonium ion and aspirin had no effect. SFLLRN-induced platelet activation was unaffected by NO or prostacyclin inhibition.

CONCLUSIONS

Acting via PAR-1, thrombin causes contrasting effects in the human vasculature and has a major interaction with the endothelium. This highlights the critical importance of endothelial function during acute arterial injury and intravascular thrombosis, as occurs in cardiovascular events including myocardial infarction and stroke.

Exposure to concentrated ambient particles does not affect vascular function in patients with coronary heart disease

BACKGROUND

Exposure to fine particulate air pollution is associated with increased cardiovascular morbidity and mortality. We previously demonstrated that exposure to dilute diesel exhaust causes vascular dysfunction in humans.

OBJECTIVES

We conducted a study to determine whether exposure to ambient particulate matter causes vascular dysfunction.

METHODS

Twelve male patients with stable coronary heart disease and 12 age-matched volunteers were exposed to concentrated ambient fine and ultrafine particles (CAPs) or filtered air for 2 hr using a randomized, double-blind cross-over study design. We measured peripheral vascular vasomotor and fibrinolytic function, and inflammatory variables-including circulating leukocytes, serum C-reactive protein, and exhaled breath 8-isoprostane and nitrotyrosine-6-8 hr after both exposures.

RESULTS

Particulate concentrations (mean +/- SE) in the exposure chamber (190+/-37 microg/m(3)) were higher than ambient levels (31+/-8 microg/m(3)) and levels in filtered air (0.5+/-0.4 microg/m(3); p<0.001). Chemical analysis of CAPs identified low levels of elemental carbon. Exhaled breath 8-isoprostane concentrations increased after exposure to CAPs (16.9+/-8.5 vs. 4.9+/-1.2 pg/mL, p<0.05), but markers of systemic inflammation were largely unchanged. Although there was a dose-dependent increase in blood flow and plasma tissue plasminogen activator release (p<0.001 for all), CAPs exposure had no effect on vascular function in either group.

CONCLUSIONS

Despite achieving marked increases in particulate matter, exposure to CAPs--low in combustion-derived particles--did not affect vasomotor or fibrinolytic function in either middle-aged healthy volunteers or patients with coronary heart disease. These findings contrast with previous exposures to dilute diesel exhaust and highlight the importance of particle composition in determining the vascular effects of particulate matter in humans.

An unusual cause of severe mitral regurgitation: aberrantly inserted chordae tendineae

We present a case of aberrantly inserted chordae tendineae causing severe mitral regurgitation and requiring surgical correction. This is an extremely rare finding illustrating a distinct mechanism of mitral regurgitation.

Ischemic and thrombotic effects of dilute diesel-exhaust inhalation in men with coronary heart disease

BACKGROUND

Exposure to air pollution from traffic is associated with adverse cardiovascular events. The mechanisms for this association are unknown. We conducted a controlled exposure to dilute diesel exhaust in patients with stable coronary heart disease to determine the direct effect of air pollution on myocardial, vascular, and fibrinolytic function.

METHODS

In a double-blind, randomized, crossover study, 20 men with prior myocardial infarction were exposed, in two separate sessions, to dilute diesel exhaust (300 mug per cubic meter) or filtered air for 1 hour during periods of rest and moderate exercise in a controlled-exposure facility. During the exposure, myocardial ischemia was quantified by ST-segment analysis using continuous 12-lead electrocardiography. Six hours after exposure, vasomotor and fibrinolytic function were assessed by means of intraarterial agonist infusions.

RESULTS

During both exposure sessions, the heart rate increased with exercise (P<0.001); the increase was similar during exposure to diesel exhaust and exposure to filtered air (P=0.67). Exercise-induced ST-segment depression was present in all patients, but there was a greater increase in the ischemic burden during exposure to diesel exhaust (-22+/-4 vs. -8+/-6 millivolt seconds, P<0.001). Exposure to diesel exhaust did not aggravate preexisting vasomotor dysfunction, but it did reduce the acute release of endothelial tissue plasminogen activator (P=0.009; 35% decrease in the area under the curve).

CONCLUSIONS

Brief exposure to dilute diesel exhaust promotes myocardial ischemia and inhibits endogenous fibrinolytic capacity in men with stable coronary heart disease. Our findings point to ischemic and thrombotic mechanisms that may explain in part the observation that exposure to combustion-derived air pollution is associated with adverse cardiovascular events. (ClinicalTrials.gov number, NCT00437138 [ClinicalTrials.gov].).

Endothelial fibrinolytic capacity predicts future adverse cardiovascular events in patients with coronary heart disease

OBJECTIVE

The endothelium-derived fibrinolytic factor tissue plasminogen activator (t-PA) is a major determinant of vessel patency after coronary plaque rupture and thrombosis. We assessed whether endothelial fibrinolytic capacity predicts atherothrombotic events in patients with coronary heart disease.

METHODS AND RESULTS

Plasma t-PA and plasminogen activator inhibitor (PAI)-1 concentrations were measured during intrabrachial substance P infusion in 98 patients with angiographically proven stable coronary heart disease. Forearm blood flow was measured during infusion of substance P and sodium nitroprusside. Cardiovascular events (cardiovascular death, myocardial infarction [MI], ischemic stroke [CVA], and emergency hospitalization for unstable angina) were determined during 42 months of follow-up. Patients experiencing a cardiovascular event (n=19) had similar baseline characteristics to those free of events. Substance P caused a dose-dependent increase in plasma t-PA concentrations (P<0.001). However, net t-PA release was 72% lower in the patients who experienced death, MI, or CVA, and 48% lower in those who suffered death, MI, CVA or hospitalization for unstable angina (P<0.05). Major adverse cardiovascular events were most frequent in those with the lowest fibrinolytic capacity (P=0.03 for trend); patients with the lowest quartile of t-PA release had the highest rate of adverse events (P=0.01).

CONCLUSION

Endothelial fibrinolytic capacity, as measured by stimulated t-PA release, predicts the future risk of adverse cardiovascular events in patients with coronary heart disease. We suggest that endothelial fibrinolytic capacity is a powerful novel determinant of cardiovascular risk.

Tissue plasminogen activator genetic polymorphisms do not influence tissue plasminogen activator release in patients with coronary heart disease

OBJECTIVES

To determine if polymorphisms of the tissue plasminogen activator (t-PA) gene influence acute endogenous t-PA release in patients with coronary heart disease (CHD).

METHODS

Forearm blood flow and plasma t-PA concentrations were measured in response to intra-brachial infusion of substance P and sodium nitroprusside in 96 patients with stable CHD. Genotyping was performed using a Taqman polymerase chain reaction assay specifically designed to detect the polymorphisms of interest: (i) Alu-repeat insertion/deletion sequence; (ii) C-->T substitution in an upstream enhancer region (-7351 C/T); (iii) T-->C in exon 6 (20 099 T/C); and (iv) T-->A (27 445 T/A) in intron 10.

RESULTS

Substance P and sodium nitroprusside caused dose-dependent increases in forearm blood flow in all patients (P < 0.001 for all) that were independent of the four genetic polymorphisms. Similarly, there were no differences in basal plasma t-PA antigen concentrations or net t-PA release between genotypes. Compared to non-smokers, smokers exhibited impaired substance P-induced vasodilatation (P < 0.001) and t-PA release (P = 0.05).

CONCLUSIONS

Despite confirming our previous findings in cigarette smokers, we have found no effect of polymorphisms of the t-PA gene on two complementary aspects of endothelial function. We conclude that genetic variation of the t-PA locus is unlikely to have a major influence on acute t-PA release in subjects with established CHD.

Emerging medical treatments for aortic stenosis: statins, angiotensin converting enzyme inhibitors, or both?

Aortic stenosis is the most common adult heart valve condition seen in the Western world and its incidence continues to rise. No established disease modifying treatments retard progression of the stenotic process. Recent insights into the pathogenesis of calcific aortic stenosis suggest that the disease mimics atherosclerosis. The natural history and progression of calcific aortic stenosis are described with particular emphasis on new and emerging medical treatments that may modify the disease process. In particular, statins and angiotensin converting enzyme inhibitors appear to hold promise but definitive evidence from large clinical trials is awaited.

Vascular and fibrinolytic effects of intra-arterial tumour necrosis factor-alpha in patients with coronary heart disease

Elevated plasma t-PA (tissue plasminogen activator) and serum CRP (C-reactive protein) concentrations are associated with an adverse cardiovascular risk. In the present study, we investigated whether acute local inflammation causes vascular dysfunction and influences t-PA release in patients with stable coronary heart disease. Serum CRP, plasma t-PA and PAI-1 (plasminogen activator inhibitor type 1) concentrations were determined in 95 patients with stable coronary heart disease. A representative subpopulation of 12 male patients received an intra-brachial infusion of TNF-alpha (tumour necrosis factor-alpha) and saline placebo using a randomized double-blind cross-over study design. Forearm blood flow and plasma fibrinolytic and inflammatory variables were measured. Serum CRP concentrations correlated with plasma t-PA concentrations (r=0.37, P<0.001) and t-PA/PAI-1 ratio (r=-0.21, P<0.05). Intra-arterial TNF-alpha caused a rise in t-PA concentrations (P<0.001) without affecting blood flow or PAI-1 concentrations. TNF-alpha pretreatment impaired acetylcholine- and sodium nitroprusside-induced vasodilatation (P<0.001 for both) whilst doubling bradykinin-induced t-PA release (P=0.006). In patients with stable coronary heart disease, plasma fibrinolytic factors correlate with a systemic inflammatory marker and local vascular inflammation directly impairs vasomotor function whilst enhancing endothelial t-PA release. We suggest that the adverse prognosis associated with elevated plasma t-PA concentrations relates to the underlying causative association with vascular inflammation and injury.

Diesel exhaust inhalation causes vascular dysfunction and impaired endogenous fibrinolysis

BACKGROUND

Although the mechanisms are unknown, it has been suggested that transient exposure to traffic-derived air pollution may be a trigger for acute myocardial infarction. The study aim was to investigate the effects of diesel exhaust inhalation on vascular and endothelial function in humans.

METHODS AND RESULTS

In a double-blind, randomized, cross-over study, 30 healthy men were exposed to diluted diesel exhaust (300 microg/m3 particulate concentration) or air for 1 hour during intermittent exercise. Bilateral forearm blood flow and inflammatory factors were measured before and during unilateral intrabrachial bradykinin (100 to 1000 pmol/min), acetylcholine (5 to 20 microg/min), sodium nitroprusside (2 to 8 microg/min), and verapamil (10 to 100 microg/min) infusions 2 and 6 hours after exposure. There were no differences in resting forearm blood flow or inflammatory markers after exposure to diesel exhaust or air. Although there was a dose-dependent increase in blood flow with each vasodilator (P<0.0001 for all), this response was attenuated with bradykinin (P<0.05), acetylcholine (P<0.05), and sodium nitroprusside (P<0.001) infusions 2 hours after exposure to diesel exhaust, which persisted at 6 hours. Bradykinin caused a dose-dependent increase in plasma tissue plasminogen activator (P<0.0001) that was suppressed 6 hours after exposure to diesel (P<0.001; area under the curve decreased by 34%).

CONCLUSIONS

At levels encountered in an urban environment, inhalation of dilute diesel exhaust impairs 2 important and complementary aspects of vascular function in humans: the regulation of vascular tone and endogenous fibrinolysis. These important findings provide a potential mechanism that links air pollution to the pathogenesis of atherothrombosis and acute myocardial infarction.

Progressive coronary calcification despite intensive lipid-lowering treatment: a randomised controlled trial

OBJECTIVES

To evaluate the effect of intensive lipid-lowering treatment on coronary artery calcification in a substudy of a trial recruiting patients with calcific aortic stenosis.

METHODS

In a double blind randomised controlled trial, 102 patients with calcific aortic stenosis and coronary artery calcification were randomly assigned by the minimisation technique to atorvastatin 80 mg daily or matched placebo. Coronary artery calcification was assessed annually by helical computed tomography.

RESULTS

48 patients were randomly assigned to atorvastatin and 54 to placebo with a median follow up of 24 months (interquartile range 24-30). Baseline characteristics and coronary artery calcium scores were similar in both groups. Atorvastatin reduced serum low density lipoprotein cholesterol (-53%, p < 0.001) and C reactive protein (-49%, p < 0.001) concentrations whereas there was no change with placebo (-7% and 17%, p > 0.95 for both). The rate of change in coronary artery calcification was 26%/year (0.234 (SE 0.037) log arbitrary units (AU)/year; n = 39) in the atorvastatin group and 18%/year (0.167 (SE 0.034) log AU/year; n = 49) in the placebo group, with a geometric mean difference of 7%/year (95% confidence interval -3% to 18%, p = 0.18). Serum low density lipoprotein concentrations were not correlated with the rate of progression of coronary calcification (r = 0.05, p = 0.62).

CONCLUSION

In contrast to previous observational studies, this randomised controlled trial has shown that, despite reducing systemic inflammation and halving serum low density lipoprotein cholesterol concentrations, statin treatment does not have a major effect on the rate of progression of coronary artery calcification.

Do inhaled carbon nanoparticles translocate directly into the circulation in humans?

RATIONALE

Increased exposure to particulate air pollution (PM(10)) is a risk factor for death and hospitalization with cardiovascular disease. It has been suggested that the nanoparticulate component of PM(10) is capable of translocating into the circulation with the potential for direct effects on the vasculature.

OBJECTIVE

The study's aim was to determine the extent to which inhaled technetium-99m ((99m)Tc)-labeled carbon nanoparticles (Technegas) were able to access the systemic circulation.

METHODS AND MAIN RESULTS

Ten healthy volunteers inhaled Technegas and blood samples were taken sequentially over the following 6 h. Technegas particles were 4-20 nm in diameter and aggregated to a median particle diameter of approximately 100 nm. Radioactivity was immediately detected in blood, with levels increasing over 60 min. Thin-layer chromatography of whole blood identified a species that moved with the solvent front, corresponding to unbound (99m)Tc-pertechnetate, which was excreted in urine. There was no evidence of particle-bound (99m)Tc at the origin. gamma Camera images demonstrated high levels of Technegas retention (95.6 +/- 1.7% at 6 h) in the lungs, with no accumulation of radioactivity detected over the liver or spleen.

CONCLUSIONS

The majority of (99m)Tc-labeled carbon nanoparticles remain within the lung up to 6 h after inhalation. In contrast to previous published studies, thin-layer chromatography did not support the hypothesis that inhaled Technegas carbon nanoparticles pass directly from the lungs into the systemic circulation.

A randomized trial of intensive lipid-lowering therapy in calcific aortic stenosis

BACKGROUND

Calcific aortic stenosis has many characteristics in common with atherosclerosis, including hypercholesterolemia. We hypothesized that intensive lipid-lowering therapy would halt the progression of calcific aortic stenosis or induce its regression.

METHODS

In this double-blind, placebo-controlled trial, patients with calcific aortic stenosis were randomly assigned to receive either 80 mg of atorvastatin daily or a matched placebo. Aortic-valve stenosis and calcification were assessed with the use of Doppler echocardiography and helical computed tomography, respectively. The primary end points were change in aortic-jet velocity and aortic-valve calcium score.

RESULTS

Seventy-seven patients were assigned to atorvastatin and 78 to placebo, with a median follow-up of 25 months (range, 7 to 36). Serum low-density lipoprotein cholesterol concentrations remained at 130+/-30 mg per deciliter in the placebo group and fell to 63+/-23 mg per deciliter in the atorvastatin group (P<0.001). Increases in aortic-jet velocity were 0.199+/-0.210 m per second per year in the atorvastatin group and 0.203+/-0.208 m per second per year in the placebo group (P=0.95; adjusted mean difference, 0.002; 95 percent confidence interval, -0.066 to 0.070 m per second per year). Progression in valvular calcification was 22.3+/-21.0 percent per year in the atorvastatin group, and 21.7+/-19.8 percent per year in the placebo group (P=0.93; ratio of post-treatment aortic-valve calcium score, 0.998; 95 percent confidence interval, 0.947 to 1.050).

CONCLUSIONS

Intensive lipid-lowering therapy does not halt the progression of calcific aortic stenosis or induce its regression. This study cannot exclude a small reduction in the rate of disease progression or a significant reduction in major clinical end points. Long-term, large-scale, randomized, controlled trials are needed to establish the role of statin therapy in patients with calcific aortic stenosis.

Phosphodiesterase type 5 inhibition does not reverse endothelial dysfunction in patients with coronary heart disease

OBJECTIVES

To investigate whether sildenafil citrate, a selective phosphodiesterase type 5 inhibitor, may improve endothelial vasomotor and fibrinolytic function in patients with coronary heart disease.

DESIGN

Randomised double blind placebo controlled crossover study.

PATIENTS AND METHODS

16 male patients with coronary heart disease and eight matched healthy men received intravenous sildenafil or placebo. Bilateral forearm blood flow and fibrinolytic parameters were measured by venous occlusion plethysmography and blood sampling in response to intrabrachial infusions of acetylcholine, substance P, sodium nitroprusside, and verapamil.

MAIN OUTCOME MEASURES

Forearm blood flow and acute release of tissue plasminogen activator.

RESULTS

Mean arterial blood pressure fell during sildenafil infusion from a mean (SEM) of 92 (1) to 82 (1) mm Hg in patients and from 94 (1) to 82 (1) mm Hg in controls (p < 0.001 for both). Sildenafil increased endothelium independent vasodilatation with sodium nitroprusside (p < 0.05) but did not alter the blood flow response to acetylcholine or verapamil in patients or controls. Substance P caused a dose dependent increase in plasma tissue plasminogen activator antigen concentrations (p < 0.01) that was unaffected by sildenafil in either group.

CONCLUSIONS

Sildenafil does not improve peripheral endothelium dependent vasomotor or fibrinolytic function in patients with coronary heart disease. Phosphodiesterase type 5 inhibitors are unlikely to reverse the generalised vascular dysfunction seen in patients with coronary heart disease.

Calcific aortic stenosis: same old story?

Calcific aortic stenosis is the commonest adult valvular heart condition seen in the western world. Its prevalence is continuing to rise, with predominance in older patients who are frequently undergoing successful aortic valve replacement. This review discusses the natural history of calcific aortic stenosis, highlights recent insights into its pathogenesis, and outlines current medical and surgical management. The potential role of novel therapeutic interventional strategies is discussed.

Contrast agent increases doppler velocities and improves reproducibility of aortic valve area measurements in patients with aortic stenosis

Observer variability may limit assessment of aortic stenosis by Doppler echocardiography. This study aimed to assess whether echocardiographic contrast agent improves reproducibility of aortic valve area (AVA) measurements for patients with aortic stenosis. In all, 20 patients with aortic stenosis (67 +/- 10 years old) underwent noncontrast and contrast Doppler echocardiography on 2 occasions, 3 weeks apart. Intraobserver and interobserver coefficients of reproducibility were 0.36 and 0.20 cm for left ventricular outflow tract (LVOT) diameter, and 0.38 and 0.24 cm(2) for AVA, respectively. Although intraobserver reproducibility was unaffected, contrast improved interobserver reproducibility for LVOT diameter (mean of differences -0.02 +/- 0.07 cm vs 0.01 +/- 0.10 cm, P <.05) and AVA (mean of differences 0.02 +/- 0.10 cm(2) vs 0.07 +/- 0.12 cm(2), P <.05). Prevalve and postvalve velocities were increased with contrast compared with noncontrast imaging (prevalve, 1.07 +/- 0.20 vs 0.94 +/- 0.19 m/s, P <.01; postvalve, 3.76 +/- 0.87 vs 3.47 +/- 0.78 m/s, P <.01). We conclude that contrast significantly increases Doppler velocities and produces modest improvements in reproducibility of LVOT diameter and AVA. We suggest that, when assessing patients with aortic stenosis, contrast agents should be considered in patients who are difficult to image with poor baseline LVOT images or Doppler studies, or where there is poor interobserver reproducibility.

Aortic valve calcification on computed tomography predicts the severity of aortic stenosis

AIM

Incidental aortic valve calcification is often detected during computed tomography. The aim was to compare the severity of valvular stenosis and calcification in patients with aortic stenosis.

MATERIALS AND METHODS

One hundred and fifty-seven patients aged 68+/-11 years (range: 34-85) with aortic valve stenosis underwent multislice helical computed tomography and Doppler echocardiography performed by independent, blinded observers. The aortic valve calcium score was determined using automated computer software calibrated with a phantom.

RESULTS

Doppler echocardiography demonstrated a post-valve velocity of 3.45+/-0.66 m/s and a peak gradient of 49+/-11 mmHg. Computed tomography showed excellent reproducibility and the median aortic valve calcium score was 5858 AU (interquartile range, 1555-14,596). The computed tomography aortic valve calcium score positively correlated with the Doppler post-valve velocity and peak gradient (r=0.54, p<0.0001 for both) of the aortic valve. All patients with severe aortic stenosis had a calcium score of >3700 AU.

CONCLUSION

Calcification of the aortic valve is closely associated with the severity of aortic stenosis, and heavy calcification suggests the presence of severe aortic stenosis that requires urgent cardiological assessment. Patients with lesser degrees of aortic valve calcification should be screened for aortic stenosis and monitored for disease progression.

Immunopathogenesis of HIV-related heart muscle disease: current perspectives

As more effective antiretroviral therapies improve survival times, growing numbers of HIV-positive patients are at risk of developing end-organ damage or neoplasia. Heart muscle disease is the most important cardiovascular manifestation of HIV infection and seems set to become increasingly prevalent. This may take the form of either a dilated cardiomyopathy or isolated left or right ventricular dysfunction, is associated with a poor prognosis, and results in symptomatic heart failure in up to 5% of HIV patients. The precise cause of HIV-associated cardiomyopathy remains unclear but is undoubtedly complex, and most probably multifactorial. This report examines our current understanding of the immunopathogenesis of HIV-associated cardiomyopathy.

Randomised controlled trial of continuous positive airway pressure and standard oxygen therapy in acute pulmonary oedema; effects on plasma brain natriuretic peptide concentrations

AIMS

The study aim was to compare the effects of continuous positive airway pressure (CPAP) on clinical outcomes and plasma neurohormonal concentrations in patients with acute pulmonary oedema.

METHODS AND RESULTS

In addition to standard therapy, 58 consecutive patients were randomized to receive 60% inhaled oxygen with or without CPAP at 7.5 cmH(2)O pressure. Clinical variables, symptoms and oxygenation were monitored and plasma epinephrine, norepinephrine and brain natriuretic peptide (BNP) concentrations estimated at 0, 1, 6 and 24 h. CPAP was associated with less breathlessness at 1 h (P<0.001), no treatment failures and more rapid resolution in respiratory rate (P<0.001), heart rate (P<0.001) and acidosis (P<0.005). Length of hospital stay was similar but there was a trend for a reduction in overall hospital mortality in the CPAP group (0.10>P>0.05). Plasma BNP concentrations rose progressively (P<0.001) before falling below admission concentrations at 24 h. Plasma neurohumoral concentrations were unaffected by CPAP treatment but were elevated in patients who died or had acute myocardial infarction.

CONCLUSION

CPAP produces a more rapid clinical and symptomatic improvement in patients with acute pulmonary oedema, particularly within the first hour. CPAP is a useful adjunctive treatment in the early management of acute heart failure.

Antiplatelet treatment in unstable angina: aspirin, clopidogrel, glycoprotein IIb/IIIa antagonist, or all three?

Evidence on the role of antiplatelet agents in patients with non-ST elevation acute coronary syndrome is reviewed, and a strategy for their use in unstable angina is presented