Publications by authors named "James D. Cameron"

Background: Dobutamine effects on the relationships of the peak velocity of left ventricular (LV) long-axis systolic motion (s') with systolic excursion (SExc), systolic duration (SDur) and heart rate, of LV long-axis early diastolic excursion (EDExc) with SExc, and of the peak velocity of LV long-axis early diastolic motion (e') with EDExc, early diastolic duration (EDDur) and isovolumic relaxation time (IVRT') are unknown.

Methods: Two groups of adult subjects, one young and healthy ( = 10), and one with impaired LV long-axis function ( = 10), were studied, with the aim of identifying consistent findings for the two groups and for the septal and lateral walls. Dobutamine was infused at doses of 5 and 10 µg/kg/min.

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Article Synopsis
  • The study investigates the link between pericoronary adipose tissue (PCAT) attenuation, a measure of coronary inflammation, and stent failure in patients who underwent percutaneous coronary intervention (PCI).
  • Using computer tomography coronary angiography (CTCA), the authors analyzed patients who had a stent placed and underwent follow-up angiography within five years to define stent failure.
  • Results indicated that patients with stent failure had higher PCAT attenuation at baseline, suggesting a significant association between coronary inflammation and the likelihood of stent failure.
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Subclinical leaflet thrombosis (LT) may occur following surgical and transcatheter aortic valve replacement. Computed tomography (CT) has become an established imaging modality to diagnose subclinical LT following bioprosthetic aortic valve replacement. Even so, there is a limited (but growing) experience in utilizing CT imaging for this indication.

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Article Synopsis
  • Computed tomography coronary angiography (CTCA) is used to diagnose coronary artery disease (CAD) and assess high-risk plaques (HRP) that may lead to acute coronary syndrome (ACS).
  • A study of 1,257 patients showed that those with HRP had significantly higher rates of ACS compared to those without plaques, particularly in patients with obstructive stenosis (OS).
  • The presence of low-attenuation plaques (LAP) and OS were key indicators for predicting future ACS events, highlighting their importance in risk assessment.
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Background Exercise stress testing for cardiovascular assessment in kidney transplant candidates has been shown to be a feasible alternative to pharmacologic methods. Exercise stress testing allows the additional assessment of exercise capacity, which may have prognostic value for long-term cardiovascular outcomes in pre-transplant recipients. This study aimed to evaluate the prognostic value of exercise capacity on long-term cardiovascular outcomes in kidney transplant candidates.

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Background: Non-invasive computed tomography (CT)-derived fractional flow reserve (FFR) is computed from standard coronary CT angiography (CTA) datasets and provides accurate vessel-specific ischaemia assessment of coronary artery disease (CAD). To date, the technique and its diagnostic performance has not been verified in the Australian clinical context. The aim of this study was to describe and compare the diagnostic performance of FFR and CTA for the detection of vessel-specific ischaemia as determined by invasive fractional flow reserve (FFR) in the Australian patient population.

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Background: Instantaneous wave-free ratio (iFR) can reliably assess the physiological significance of coronary artery disease (CAD). Previous studies have demonstrated its interchangeability with other non-hyperaemic pressure ratios (NHPR), but there is no data exploring whether this association is maintained in patients with severe aortic stenosis (AS).

Methods: Forty-two patients (67 lesions) with severe AS were recruited and underwent invasive pressure-wire assessment.

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Objective: To determine the association between prosthesis geometry with leaflet thrombosis (LT).

Background: Leaflet thrombosis following transcatheter aortic valve replacement (TAVR) is a recognised entity. The association between prosthesis geometry with LT is unclear but maybe a potential modifiable factor in its prevention.

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An abnormal left ventricular contractile reserve is often seen in patients undergoing stress echocardiogram and may indicate the presence of obstructive coronary artery disease. The techniques and indexes used to identify abnormal left ventricular contractile response and its prognostic value in the absence of known causes has not been well studied. To describe the characteristics and clinical outcomes associated with an abnormal left ventricular contractile response, we performed a systematic review that identified 27 eligible studies.

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Background: Hypo-attenuated leaflet thickening (HALT) may occur following transcatheter aortic valve replacement (TAVR), however, it remains unclear if HALT is a predictor of haemodynamic valve deterioration (HVD).

Aim: To determine the impact of HALT on the occurrence of HVD.

Methods: We prospectively evaluated 186 patients for the presence of HALT at a median of 6 weeks following TAVR (Interquartile-range [IQR] 4-12 weeks).

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Background: High-risk plaques (HRP) detected on coronary computed tomography angiography (CTA) confer an increased risk of acute coronary syndrome (ACS). Pericoronary adipose tissue attenuation (PCAT) is a novel biomarker of coronary inflammation. This study aimed to evaluate the association of PCAT with HRP and subsequent ACS development in patients with stable coronary artery disease (CAD).

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Introduction: Carnosine, an over the counter food supplement, has been shown to improve glucose metabolism as well as cardiovascular risk factors in animal and human studies through its anti-inflammatory, antioxidative, antiglycating and chelating properties. The aim of this study is to establish if carnosine supplementation improves obesity, insulin sensitivity, insulin secretion, cardiovascular risk factors including arterial stiffness and endothelial function, and other risk factors related to diabetes and cardiovascular disease in the overweight and obese population.

Methods And Analysis: Fifty participants will be recruited to be enrolled in a double-blind randomised controlled trial.

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Background: Patients with severe aortic stenosis (AS) exhibit systemic endothelial dysfunction, which can be associated with myocardial ischaemia in absence of obstructive coronary disease. Transcatheter aortic valve replacement (TAVR) is used to treat severe AS in patients with high or prohibitive surgical risk. However, it remains unknown whether endothelial function recovers post-TAVR.

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Background: The clinical predictors and sequelae of leaflet thrombosis (LT) following transcatheter aortic valve replacement (TAVR) is still unclear. Therefore, our aim was to determine the clinical predictors and sequelae at mid-term follow-up of computed tomography (CT)-defined LT following TAVR.

Methods And Results: We performed a prospective evaluation with a 320-multislice CT following TAVR for the presence of LT, defined as hypo-attenuated leaflet thickening (HALT).

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Article Synopsis
  • The study investigates the safety, feasibility, and validity of using computed tomography-derived fractional flow reserve (CT-FFR) to assess coronary artery disease in patients with severe aortic stenosis, where traditional methods haven't been validated.
  • Forty-two patients underwent both invasive FFR and coronary CT angiography (CTA), with most CTA images being interpretable for CT-FFR computation, and no complications reported from the procedures.
  • The results showed a significant correlation between FFR and CT-FFR, with diagnostic accuracy of 76.7% for vessels and 76.9% for patients, indicating that CT-FFR could potentially be a reliable tool for assessing coronary artery disease
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The use of fractional flow reserve (FFR) in guiding revascularisation improves patient outcomes and has been well-established in clinical guidelines. Despite this, the uptake of FFR has been limited, likely attributable to the perceived increase in procedural time and use of hyperaemic agents that can cause patient discomfort. This has led to the development of instantaneous wave-free ratio (iFR), an alternative non-hyperaemic pressure ratio (NHPR).

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Background: Hyperphosphatemia is associated with increased fibroblast growth factor 23 (FGF23), arterial calcification, and cardiovascular mortality. Effects of phosphate-lowering medication on vascular calcification and arterial stiffness in CKD remain uncertain.

Methods: To assess the effects of non-calcium-based phosphate binders on intermediate cardiovascular markers, we conducted a multicenter, double-blind trial, randomizing 278 participants with stage 3b or 4 CKD and serum phosphate >1.

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Background: Quantitative flow ratio (QFR) is an estimate of fractional flow reserve (FFR) and is derived from 3-dimensional quantitative coronary angiography. The DILEMMA score is an angiographic technique developed to predict FFR. Unlike other diastolic indices such as instantaneous wave-free ratio (iFR), diastolic pressure ratio (dPR) and dPR, neither QFR nor DILEMMA score require pressure wires.

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Background/purpose: Coronary artery disease (CAD) is common in patients undergoing transcatheter aortic valve replacement (TAVR), although its prognostic significance is questionable. Significant CAD stratified using SYNTAX score (SS) has been associated with greater mortality, yet it is unknown whether the functional impact of CAD also impacts outcomes in this cohort. DILEMMA score (DS) is a validated angiographic functional scoring tool that correlates with fractional flow reserve and instantaneous wave-free ratio.

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Epicardial adipose tissue (EAT) is associated with cardiovascular risk. The longitudinal change in EAT volume (EATv) and density (EATd), and potential modulators of these parameters, has not been described. We prospectively recruited 90 patients with non-obstructive coronary atherosclerosis on baseline computed tomography coronary angiography (CTCA) performed for suspected coronary artery disease to undergo a repeat research CTCA.

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