Extrait

Background and study aims In many people, as they get older, fatty deposits build up in the walls of the vessels which carry blood to the heart and brain. These fatty deposits are called plaques and occur as part of a process called atherosclerosis (hardening of the arteries). In some people, these plaques rupture and this can form a clot that blocks off the blood flow to the part of the body supplied by that vessel. This is how heart attacks and strokes occur. Atherosclerosis occurs over many years, and this causes gradual narrowing of vessels. Some people experience symptoms when the narrowing becomes severe, such as chest pain while walking. This is because the blood flow to the heart is limited. When people develop symptoms, we are able to perform tests such as x-ray angiography to detect these narrowed vessels. Once we know this process has occurred, we can start medications to help prevent heart attacks and strokes. However, many patients do not experience symptoms to warn them that they may be at risk of developing a heart attack or stroke. In fact, often the small plaques that do not cause symptoms are more prone to rupture. Therefore we want to look for better ways to identify people who are at increased risk of developing heart attacks and strokes, before they occur. If we are able to do this, then treatment can be started to help stabilise plaques and prevent future events. We know from previous research that the plaques that are inflamed have a higher risk of causing problems. We also know that if a plaque doesn’t rupture, after a while the inflammation decreases and the plaques becomes hardened due to build-up of calcium and thickening of the tissue surrounding it. The tests that we currently use for look for signs of atherosclerosis in the neck and heart arteries, such as ultrasound and x-ray angiography, are not able to see inflammation in the vessel wall and therefore cannot predict whether a plaque is likely to cause a problem in the future. These tests can only tell us whether or not the inside of the vessels are already narrowed. Using a sophisticated type of scanning called Positron Emission Tomography (PET) it is possible to see areas of vessel wall inflammation by tagging inflammatory cells with radioactive substances called tracers that make them show up on images. PET imaging needs to be combined with a computed tomography (CT) scan so that we can see exactly where the areas of tracer are concentrated in the vessels. The CT scan can also show us if the vessels are calcified, and if we use contrast we can see if the inside of the vessels are narrowed. 18F-Fluorodeoxyglucose (FDG) is a PET tracer commonly used in cancer imaging, which we know can also show inflammation in the neck arteries. However, for several reasons it is difficult to use 18F-FDG to look at inflammation in the heart arteries (which are smaller and constantly moving). The aim of this study is to see if inflammation in the fatty deposits in the neck and heart arteries can be detecting using PET imaging with a newer tracer, called 68Ga-DOTATATE, and to determine whether this tracer is better than FDG for this purpose. Who can participate? We are asking people who have had a recent heart attack or stroke, and also those who have evidence of narrowed arteries with some or no symptoms, to participate in this study. What does the study involve? This will involve attending the PET/CT department for two PET and CT scans focused on the heart and neck arteries. One PET scan will be performed using 18F-FDG and the other with 68Ga-DOTATATE. As part of clinical care, some participants who have had a stroke will go on to have an operation to remove a plaque from the blood vessels in the neck. We will ask permission from these participants to examine this plaque under a microscope to see how it compares with the results of the scans. What are the possible benefits and risks of participating? The PET scans use radioactive tracers, which are safe and are used in usual clinical practice without any serious side effects. There is also some exposure to radiation from the CT part of the scan. The results of this study will help us to better understand the causes of heart attack and stroke, and could help to improve the diagnosis and treatment of these conditions in the future. Where is the study run from? Cambridge University Hospitals NHS Foundation Trust (UK). When is the study starting and how long is it expected to run for? The study started in August 2014 and runs for two years. Who is funding the study? The Wellcome Trust (UK). Who is the main contact? Dr James Rudd [email protected]

Critère d'inclusion

• Topic: Cardiovascular disease; Subtopic: Cardiovascular (all Subtopics); Disease: Cardiovascular

Liens

• isrctn
• ictrp