MICA: CT-derived fractional flow reserve (FFRCT) for the improved management of chest pain patients

Chest pain may be a symptom that is related to a narrowing of the heart blood vessels (coronary artery disease [CAD]). This chest pain, known as angina, can result in a reduced quality of life and, if not diagnosed and managed appropriately, could result in a heart attack. Coronary disease remains the largest cause of death in the United Kingdom today, with one death every 4 minutes. Guidelines recommend the use of tests to help diagnose and manage chest pain 'angina' patients. Coronary computed tomography angiography (CCTA) is a test that takes images of the heart blood vessels. It is the main test for patients presenting with angina, as it is excellent at saying when the heart blood vessels are normal, and can be reassuring for patients. However, when narrowing's are present CCTA lacks the ability to tell whether they are causing the patient's symptoms.
A new technology, CT-derived fractional flow reserve (FFRCT) uses the CCTA images to make a 3D model of the heart blood vessels that shows whether there is a limitation in the blood flow to the heart which is causing the symptoms. The National Institute for Health and Care Excellence (NICE) recommends the use of FFRCT in a chest pain pathway. However, use of this new technology remains limited due to funding restrictions and uncertainty as to its benefit in the NHS.
This study aims to determine the extent to which the new FFRCT technology is safe and reliable, provides a quicker time to diagnosis for the patient, reduces the need for further tests and thus represents good value to the NHS.

Coronary Computed Tomography Angiography (CCTA) is recommended as the first-line diagnostic test for patients with suspected angina and coronary artery disease (CAD). The accurate diagnosis of CAD is important to allow the appropriate medical treatment and post-test risk stratification to identify patients that might benefit from revascularisation. FFRCT is a non-invasive physiological test that can assess flow limitation across a coronary stenoses with high diagnostic accuracy and good correlation to invasive FFR. FFRCT has been shown in trials to reduce the total number of inappropriate invasive coronary angiograms (ICAs) post-CCTA and increase the revascularization treatment rate. FFRCT has the potential to improve diagnostic certainty, reduce unnecessary downstream tests and the patients time to treatment. NHS trusts and clinical commissioning groups (CCGs) are hesitant to find alternative innovation technology funding due to the current budgetary constraints. This has resulted in significant delay in funding and adopting the technology. To address this issue, NHS England awarded HeartFlow an Innovation and Technology Payment (ITP) to increase the uptake of the technology.The NHS should benefit by reducing the number of invasive tests and the wider economy will benefit from fewer lost working days. The ITP programme will end in April 2020, and as yet only two CCGs have agreed to continue funding FFRCT. A key hurdle is that there remains a lack of 'real world practice' evidence to support the clinical trial data, particularly in the UK healthcare setting. This grant application is aimed at addressing this problem, using real world patient data, retrospectively collected to assess hard clinical outcomes and costs to determine the true impact of FFRCT within the NHS patient care pathway.

Approximately 7 million people are living with cardiovascular disease (CVD) in the UK. CVD remains the major cause of death in the population, responsible for 25% of all deaths. There has been great success in the treatment of CVD over the last 30 years with a steady decline in mortality. However, there remains a high burden of overall CVD as morbidity increases. The cost of CVD is thus substantial, representing £9 billion of direct healthcare related costs and £19 billion in indirect costs to the economy of patients living with CVD.10 CAD is the most common form of CVD. This occurs when there is atherosclerosis of the coronary arteries due to several risk factors, including age, hypercholesterolaemia, smoking, obesity and family history. The most common symptom of CAD is chest pain (angina). In 2000, 634,000 patients consulted their general practitioner 2.35 million times at a cost of £700 million. The 2007 British Cardiac Patients Association angina survey demonstrated that >50% of angina sufferers have at least one attack per week, and that 66% of sufferers feel their symptoms have a moderate-severe impact upon their quality of life. If left undiagnosed or untreated, CAD may result in myocardial infarction, which is responsible for 66,000 deaths per annum.
The accurate diagnosis of CAD is important to allow the appropriate medical treatment and post-test risk stratification to identify patients that might benefit from revascularisation.

FFRCT is a non-invasive physiological test that can assess flow limitation across a coronary stenoses with high diagnostic accuracy and good correlation to invasive FFR. FFRCT has been shown in trials to reduce the total number of inappropriate invasive coronary angiograms (ICAs) post-CCTA, by reducing the number of cases with no obstructive coronary artery disease. This increases the revascularization treatment rate, which represents a more efficient use of the expensive catheter angiography laboratory. Patients could therefore be receiving the test with the highest accuracy, improving diagnostic certainty, thereby reducing unnecessary downstream tests and the time to treatment.

The NHS should benefit by reducing the number of invasive tests and the wider economy will benefit from fewer lost working days. In addition, the ITP has allowed national coverage of FFRCT which has the potential to remove regional variations in clinical practice and spending costs. NHS England Rightcare data has highlighted the regional variation in clinical practice across the clinical commissioning groups (CCG's), in particular the elective and non-elective healthcare spending costs and <75 years mortality rates. The existing evidence for the use of FFRCT is based on randomised controlled trials, registry studies and economic analysis from a US providers' perspective. There is no real-world comparative data, and no literature from the perspective of NHS practice, which differs from the more 'invasive' approach in the US. This research will answer whether an NHS FFRCT pathway is better for the patients in terms of safety, reducing unnecessary alternative tests and time to treatment compared to previous diagnostic pathways- including CCTA, stress echocardiography, stress perfusion MRI and nuclear scintingraphy. The impact on the NHS will be determined by comparing costs of a CCTA and selective FFRCT pathway to those of a standard of care pathway as well as the number of hospital visits. This research has the potential to increase the effectiveness of public services and influence health policy