Do not offer additional aspirin if there is clear evidence that people are already taking aspirin regularly or are allergic to it. [2010] 1.3.3.16 Follow the NICE guideline on stable angina while waiting for the results of investigations if symptoms are typical of stable angina. [2010] 1.3.4 Diagnostic testing for people in whom stable angina cannot be excluded by clinical assessment alone The Guideline Development Group emphasised that the recommendations in this guideline are to make a diagnosis of chest pain, not to screen for CAD. Most people diagnosed with non-anginal chest pain after clinical assessment need no further diagnostic testing. However in a very small number of people, there are remaining concerns that the pain could be ischaemic. 1.3.4.1 Include the typicality of anginal pain features (see recommendation 1.3.3.1) in all requests for diagnostic investigations and in the person's 1.3.4.2 Use clinical judgement and take into account people's preferences and comorbidities when considering diagnostic testing. [2010] 1.3.4.3 Offer 64-slice (or above) CT coronary angiography if: clinical assessment (see recommendation 1.3.3.1) indicates typical or atypical angina or clinical assessment indicates non-anginal chest pain but 12-lead resting ECG has been done and indicates ST-T changes or Q waves. [2016] 1.3.4.4 For people with confirmed CAD (for example, previous MI, revascularisation, previous angiography), offer non-invasive functional testing when there is uncertainty about whether chest pain is caused by myocardial ischaemia. See the section on use of non-invasive functional testing for myocardial ischaemia for further guidance on non-invasive functional testing. An exercise ECG may be used instead of functional See also NICE's medical technologies guidance on HeartFlow FFRCT for estimating fractional flow reserve from coronary CT angiography. 