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. Using HeartFlow FFRCT may avoid the need for invasive coronary angiography and revascularisation for some patients 1.3.5 Additional diagnostic investigations 1.3.5.1 Offer non-invasive functional imaging (see the section on use of non- invasive functional testing for myocardial ischaemia) for myocardial ischaemia if 64-slice (or above) CT coronary angiography has shown CAD of uncertain functional significance or is non-diagnostic. [2016] 1.3.5.2 Offer invasive coronary angiography as a third-line investigation when the results of non-invasive functional imaging are inconclusive. [2016] 1.3.6 Use of non-invasive functional testing for myocardial ischaemia 1.3.6.1 When offering non-invasive functional imaging for myocardial ischaemia use: myocardial perfusion scintigraphy with single photon emission computed tomography (MPS with SPECT) or stress echocardiography or first-pass contrast-enhanced magnetic resonance (MR) perfusion or MR imaging for stress-induced wall motion abnormalities. Take account of locally available technology and expertise, the person and their preferences, and any contraindications (for example, disabilities, frailty, limited ability to exercise) when deciding on the imaging method. [This recommendation updates and replaces recommendation 1.1 of NICE's technology appraisal guidance on myocardial perfusion scintigraphy for the diagnosis and management of angina and myocardial infarction]. [2016] 1.3.6.2 Use adenosine, dipyridamole or dobutamine as stress agents for MPS with SPECT and adenosine or dipyridamole for first-pass contrast- enhanced MR perfusion. [2010] 1.3.6.3 Use exercise or dobutamine for stress echocardiography or MR imaging for stress-induced wall motion abnormalities. [2010] 1.3.6.4 Do not use MR coronary angiography for diagnosing stable angina. 1.3.6.5 Do not use exercise ECG to diagnose or exclude stable angina for people without known CAD. 