Coronary artery bypass graft (CABG) surgery is the commonest type of heart operation performed. During this, arteries or veins (termed 'grafts') are used to supply blood around blockages within the blood vessels that supply the heart. Unfortunately, these grafts can sometimes fail, and patients can also experience complications like heart attacks and strokes, after surgery. It is known that vein grafts are more likely to narrow over time. Additionally, treating vein graft failure is very challenging, as repeat surgery is riskier and procedures to stent open the veins can also fail. However, it is not fully understood why these complications occur.
In this study, the investigators will use an imaging technique called a total-body Positron Emission Tomography (PET) scan. This uses special radioactive dyes (radiotracers) to look at what is happening inside vein grafts. With this technique, the investigators will also be able to see what is happening to the heart, brain and wider parts of the body after CABG surgery.
This study will aim to recruit 70 participants in total (maximum 150). 40 (maximum of 120) of these participants will have recently undergone CABG surgery and received ≥1 vein graft. The remaining 30 will have undergone CABG surgery ≥5 years ago and will have symptoms suggestive of vein graft failure.
The study will last a total of 36 months and will involve participants undertaking the following assessments:
1. Total-body Positron Emission Tomography and Computed Tomography (PET-CT) scan 2. Ultrasound scan of the heart (echocardiogram) 3. A blood test - up to four tablespoons (60 mL) of blood will be taken for immediate testing and the remainder will be stored for future ethically approved studies.
Males and females over 18 years of age
Patients undergoing CABG surgery for multivessel coronary artery disease, who receive at least one saphenous vein graft
Males and females over 18 years of age
Patients who underwent CABG surgery ≥ 5 years prior to recruitment for multivessel disease and received 2 or more saphenous vein grafts
Patients with a life expectancy of < 2 years
Renal failure (estimated glomerular filtration rate <30 mL/min/1.73 m2)
Patients on immunosuppressive therapies
Females of child-bearing age who are pregnant or breastfeeding,
We will recruit two populations of patients following CABG surgery. Participants will be prospectively recruited following CABG surgery (cohort 1), or identification of clinically suspected saphenous vein graft failure (cohort 2). Recruitment will for both cohorts will be from a single, tertiary centre (Royal Infirmary of Edinburgh).
Cohort
Prospective
Hybrid [18F]-GP1, [68Ga]-DOTATATE, [68Ga]-FAPI total-body positron emission tomography and coronary computed tomography coronary angiography
RadiationPatients undergo hybrid \[18F\]-GP1, \[68Ga\]-FAPI and \[68Ga\]-DOTATATE total body PET-CT imaging (Biograph Vision Quadra, Siemens) and contrast-enhanced electrocardiogram gated CT coronary angiogram (CTCA), within 28 days (+/- 28 days) of their CABG surgery and again at 12 month follow-up.
Hybrid [18F]-GP1, [68Ga]-DOTATATE, [68Ga]-FAPI total-body positron emission tomography and coronary computed tomography coronary angiography
RadiationPatients undergo hybrid \[18F\]-GP1, \[68Ga\]-FAPI and \[68Ga\]-DOTATATE total body PET-CT imaging (Biograph Vision Quadra, Siemens) and contrast-enhanced electrocardiogram gated CT coronary angiogram (CTCA), prior to their clinical invasive coronary angiography.
Platelet activation
The degree and location of platelet activation within saphenous vein grafts, measured using standard uptake values and tissue-to-background ratios of \[18F\]-GP1.
Fibroblast activation
The degree and location of fibroblast activation within saphenous vein grafts, measured using standard uptake values and tissue-to-background ratios of \[68Ga\]-FAPI.
Macrophage activation
The degree and location of macrophage activation within saphenous vein grafts, measured using standard uptake values and tissue-to-background ratios of \[68Ga\]-DOTATATE.
Systemic cardiovascular disease
The secondary endpoints will include the presence of systemic thrombotic, fibrotic or inflammatory cardiovascular disease, assessed through biomarker and CT imaging analyses.
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University of Edinburgh
Lead sponsor
NHS Lothian
Collaborator
