In the Management of Coronary Artery Disease, Does Routine Pressure Wire Assessment at the Time of Coronary Angiography Affect Management Strategy, Hospital Costs and Outcomes?

· Inclusion criteria o Outline Initial Inclusion Criteria (before entry to cath lab): Patient scheduled for coronary angiography for the: * Elective investigation of known or suspected coronary artery disease OR * Urgent investigation of a recent but stabilised, non-ST elevation acute coronary syndrome event o Outline Angiographic Inclusion Criterion (after angiography): * Presence of significant coronary disease defined as: Any stenosis \>30% reduction in luminal diameter, by visual estimate, in at least one vessel (main or branch) of sufficient calibre to permit the potential performance of PCI - approximately 2.25 mm diameter. * Key Exclusion Criteria * Screening phase exclusion criteria: * ≤ 18 years of age * Previous enrolment in this trial * Currently enrolled into another study unless co-enrolment approved by Chief Investigator (CI) and the clinical trials unit (CTU) * Inability to provide informed consent * Residence outside the United Kingdom (UK) or other issues limiting the ability to secure clinical follow-up data to one year * Non-cardiac pathology that may limit survival in the next year * Clear contraindication to potential future management with CABG or PCI (patients should be a potential candidate for medical therapy or revascularisation with either PCI or surgery) * Heart valve disease of sufficient import to consider valve replacement or other intervention as part of an index management strategy * Hypertrophic cardiomyopathy * Previous coronary artery surgery of any type * Known chronic renal impairment with a current estimated glomerular filtration rate (eGFR) of \< 45 * Anaemia with a current measured haemoglobin of \< 100 * Angiography performed in the context of an ST elevation myocardial infarction event * Any patient who at the time of planned angiography manifests haemodynamic instability, or recurrent sustained ventricular arrhythmia, or Mobitz type II or complete heart block * Any patient who at the time of planned angiography manifests unstable chest pain symptoms at rest or has required the continuing use of intravenous nitrates or regular opioid analgesia to control symptoms * Continuing use of intravenous glycoprotein 2b/3a (GP2b3a) agents before entry to the catheterisation laboratory * Known intolerance, hypersensitivity or contraindication to adenosine - including significant reversible airways disease * Additional investigations planned (or deemed likely to be required) for the assessment of myocardial ischaemia or viability. Examples of proposed tests that would constitute an exclusion criterion would include, but are not limited to, exercise tolerance testing, stress echocardiography, cardiac MRI viability or perfusion scanning or nuclear myocardial perfusion scanning. * Active bleeding at the time of planned index angiography * Pregnant women * Angiographic phase exclusion criteria: * Single vessel occlusive coronary disease (TIMI flow \<3) as sole disease * Patient not suitable for the immediate performance of a pressure wire assessment of all major vessels for any reason, for example: * Patient discomfort * Change in the clinical condition or complication of angiography requiring termination of the procedure or immediate intervention * Significant use of radiographic contrast or X-Ray exposure during the initial angiography * Inadequate angiographic images or failure to intubate any of the coronary vessels * Aorto-ostial disease that would preclude accurate assessment of FFR * Insufficient laboratory time * Uncertain availability of key clinical and trial staff * PW use in coronaries declared unsafe (e.g. tight or long disease) * PW use in coronaries declared unsuitable (e.g. distal disease or complete cross-filling)