Cambridge BRC

Cardiovascular - Recent Highlights

Scientists develop new technique that could improve heart attack prediction

First use of PET and CT to look at disease processes leading to heart attack

Building on work pioneered in Cambridge 10 years ago, scientists have developed a new imaging approach that could help improve how doctors predict a patient’s risk of having a heart attack.

The British Heart Foundation (BHF) funded project, a collaboration between scientists from the Universities of Cambridge and Edinburgh, is the first to demonstrate the potential of combined PET and CT imaging to highlight the disease processes causing heart attacks directly within the coronary arteries.

The research, published recently in the Journal of the American College of Cardiology (JACC), involved imaging over 100 people with a CT calcium scan to measure the amount of calcified or hardened plaques in their coronary arteries. This is a standard test, which is commonly used to predict heart attack risk but cannot distinguish calcium that has been there for some time from calcium that is actively building up.

The patients were also injected with two contrast agents that show up on PET imaging scans, and which can be used to track various metabolic pathways in the body. One of these tracers, 18F-sodium fluoride (18F-NaF), is a molecule taken up by cells in which active calcification is occurring. The 18F-NaFcan then be visualised and quantified during a PET scan.

The researchers wanted to see if they could identify patients with active, ongoing calcification because these patients may be at higher risk of heart attack than patients in whom the calcium developed a long time ago. The results showed that increased 18F-NaF activity could be observed in specific coronary artery plaques in patients who had many other high-risk markers of cardiovascular disease.

Dr James Rudd, HEFCE Senior Lecturer at the Department of Medicine and joint senior author of the paper, said:

'Our results show, for the first time, that certain areas of atherosclerosis within the coronary arteries, previously thought to be inert, are actually highly active and have the potential to cause heart attack. Once identified, they might be targeted with drug therapy more effectively.

'Additionally, we might be able to improve our ability to predict an individual person's future risk of heart attack using this fairly straightforward imaging test in selected people.

'This research exploits longstanding scientific links between my research team in Cambridge and Professor Newby's in Edinburgh, with core support from the Cambridge NIHR Biomedical Research Centre, HEFCE and the British Heart Foundation.'

Section: 
Cardiovascular

Pulmonary Vascular Diseases Unit

Papworth Hospital is a nationally designated centre for the diagnosis and treatment of patients with severe pulmonary arterial hypertension (PAH) and is the only centre designated to undertake pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension (CTEPH). The BRC funding allocated to the Pulmonary Vascular Diseases Unit (PVDU) at Papworth supports two research nurses who are central to the success of our translational programme. Significant added value has come from the reallocation of internal funds to support two clinical research fellows within the Unit.

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Papworth Hospital is a nationally designated centre for the diagnosis and treatment of patients with severe pulmonary arterial hypertension (PAH) and is the only centre designated to undertake pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension (CTEPH). The BRC funding allocated to the Pulmonary Vascular Diseases Unit (PVDU) at Papworth supports two research nurses who are central to the success of our translational programme. Significant added value has come from the reallocation of internal funds to support two clinical research fellows within the Unit.

As evidence of successful training of fellows provided by the BRC, one recent fellow is now an MRC clinical training fellow and another has been awarded a Clinical Lecturer position within the Translational Medicine and Therapeutics programme to undertake translational research in pulmonary hypertension.

The research outputs from the PVDU have doubled since the introduction of BRC funding. BRC support has enabled closer collaborative links between the basic science laboratories within CUH and the PVDU at Papworth, leading to high impact publications and the identification of new biomarkers. Research highlights over the past year have been the publication of a Phase II proof-of-concept and safety study supporting the use of an entirely novel class of therapy in this condition, tyrosine kinase inhibition, and the identification of levels of inflammatory cytokines as strong predictors of survival in PAH9.

Aortic Stiffness/Hypertension

We have demonstrated in two populations that traditional cardiovascular risk factors, other than blood pressure, have little role in aortic stiffening. We have also identified a novel chromosomal region linked to aortic stiffness that has been replicated in several cohorts. Using a collection of human aortae we have shown that this area codes for a novel mRNA sequence and likely protein, that we are urgently investigating using expression analysis and biomechanical testing of aortic rings.

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We have demonstrated in two populations that traditional cardiovascular risk factors, other than blood pressure, have little role in aortic stiffening. We have also identified a novel chromosomal region linked to aortic stiffness that has been replicated in several cohorts. Using a collection of human aortae we have shown that this area codes for a novel mRNA sequence and likely protein, that we are urgently investigating using expression analysis and biomechanical testing of aortic rings.

Heart Failure

The BRC has supported complex interventional studies of cardioprotection during PCI by both providing some of the required infrastructure and fostering a change in culture regarding clinical academic activity. The studies form a central aspect of the academic activity of one of the clinical lecturers supported by the BRC, who is now seeking to secure an intermediate fellowship to continue the studies after completion of his training.

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The BRC has supported complex interventional studies of cardioprotection during PCI by both providing some of the required infrastructure and fostering a change in culture regarding clinical academic activity. The studies form a central aspect of the academic activity of one of the clinical lecturers supported by the BRC, who is now seeking to secure an intermediate fellowship to continue the studies after completion of his training.

The BRC also supports a research fellow investigating whether more detailed patient selection enhances the response to Cardiac Resynchronisation therapy (CRT ' biventricular pacing). The study recruited 210 patients attending the Wellcome Trust Clinical Research Facility before device implantation, and is a collaboration between Papworth and CUH. An interim analysis was used to inform changes in the routine care of this group of patients including adoption of more extensive pre-implantation imaging and selection of the site of left ventricular pacing, optimisation of the device immediately following implantation, and the establishment of a clinic to optimise the device using non-invasive cardiac output measurements (which have been demonstrated to be equivalent to, and much easier to perform, than detailed echocardiography). The changes in the CRT clinic evolved directly through the research programme which itself was carefully developed after a pilot study of 50 patients who assisted in the design of the larger study reported above. A measure of success is the almost complete follow-up that has been achieved at the 6-month assessment.

The framework of the BRC (including the biochemical laboratory to analyse peptides and other metabolic hormones) has also enabled experimental medicine studies to assess the utility of GLP-1 to protect the heart against stunning and ischaemic LV dysfunction. These were initially supported by an experimental medicine grant from the BHF and MRC, and after encouraging results a further recent award has been made by the MRC to continue these studies. The clinical fellow undertaking this work has collaborated closely both within the BRC cardiovascular group, and with interventional colleagues to extend the studies of cardioprotection during PCI.

Virtual Histology in Vulnerable Atherosclerosis (VIVA)

This study is an investigator-led prospective study of 'Virtual Histology'-intravascular ultrasound (VH-IVUS) in patients with acute coronary syndrome or stable angina undergoing PCI. VH-IVUS is based upon spectral analysis of ultrasound backscatter, with different plaque components exhibiting a defined spectrum.

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This study is an investigator-led prospective study of 'Virtual Histology'-intravascular ultrasound (VH-IVUS) in patients with acute coronary syndrome or stable angina undergoing PCI. VH-IVUS is based upon spectral analysis of ultrasound backscatter, with different plaque components exhibiting a defined spectrum.

The radiofrequency signal is mathematically transformed into a colour-coded representation, including lipid, fibrous tissue, calcification, and necrotic core. 170 patients were prospectively enrolled and underwent 3-vessel VH-IVUS pre-PCI, in both stable angina and acute coronary syndrome patients (primary PCI). Troponin-I (cTnI) was measured pre-PCI and 24 hours post-PCI. The combined primary endpoint of major adverse cardiovascular events (MACE) included unplanned revascularization, myocardial infarction (MI) and death, with a secondary endpoint of post-PCI MI (MI 4a). This study shows that this new imaging technique can prospectively identify patients at high risk for MACE, validating the technique for interventional studies and to identify high-risk patients for targeted treatment. The study was funded by the BRC, and then subsequently supported by the BHF.

Vulnerable Plaque Imaging

The cardiovascular PET programme examines non-invasive measurement of inflammation, hypoxia and other markers of high-risk atherosclerotic plaque disease. The BRC has funded a trainee vascular surgeon who is supervising 2 ongoing translational research studies. One prospective study is investigating the determinants of aortic aneurysm expansion over a 3-year period, hypothesising that inflammation, hypoxia or neovascularisation detected by PET/CT or MRI at baseline is predictive of future aneurysm expansion.

[Read more...]

The cardiovascular PET programme examines non-invasive measurement of inflammation, hypoxia and other markers of high-risk atherosclerotic plaque disease. The BRC has funded a trainee vascular surgeon who is supervising 2 ongoing translational research studies. One prospective study is investigating the determinants of aortic aneurysm expansion over a 3-year period, hypothesising that inflammation, hypoxia or neovascularisation detected by PET/CT or MRI at baseline is predictive of future aneurysm expansion.

A second trial is examining the mechanism of the increased risk of cardiovascular death in patients with rheumatoid arthritis, using PET/CT to detect changes in arterial inflammation in patients on anti-TNF therapy. We have shown that rheumatoid patients have increased aortic inflammation on FDG PET/CT imaging, which is reduced by anti-TNF therapy. Further studies are investigating the effect of anti TNF therapy on aortic and carotid plaque inflammation. We have also shown that supplementation with BH4 improves endothelial function but not aortic stiffness in rheumatoid patients, proving that reduced NO bioavailability is not responsible for increased stiffness. It is likely that these two ongoing studies will yield high-impact papers, and BRC funding for personnel and equipment was key to generating pilot data to allow subsequent substantive grant funding (from the British Heart Foundation (BHF) in both cases).

There are also fruitful collaborations with industry. One study, just completed, was the first multicentre FDG PET/CT vascular imaging study in the world. The BRC-funded PET/CT machine was the hub of this study, with London and Oxford also providing imaging services. 99 subjects with atherosclerosis were recruited and imaged to determine whether a novel anti-atherosclerosis drug was efficacious at lowering baseline inflammation. The study was carried out with GSK, and the results will be presented in late November 2010 at the American Heart Association meeting. BRC funding has also allowed 'discipline hopping' studies, such as the collaborations with Prof Morrell and Dr Pepke-Zaba at Papworth, where PET/CT is being used to investigate pulmonary artery inflammation in subjects with pulmonary hypertension.