The Age of Diagnostic Coronary Angiography Is Over
Andrew J M Lewis
Br J Cardiol. 2017;24(3):105-107.
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Diagnostic coronary angiography died some time ago, so why has it still not yet been buried alongside the exploratory laparotomy? The problem is clear: despite over half a century of experience, almost two-thirds of those undergoing elective diagnostic angiograms do not have obstructive coronary artery disease. Even in contemporary National Health Service (NHS) cardiac catheter laboratories, non-flow limiting coronary disease or angiographically normal coronary arteries remain common findings. Coronary angiography is now, arguably, the last invasive procedure to be performed with primarily diagnostic intent on this scale. How do we move to a situation in which invasive angiography is instead performed primarily to deliver therapeutic intervention, while identifying patients suitable for reassurance, medical therapy or surgery long before they reach the cath lab?
In 2017, computed tomography (CT) straightforwardly offers the best alternative to invasive angiography for the anatomical assessment of epicardial coronary disease. Rapid advances in row detector width, the introduction of dual sources, and new image reconstruction protocols now enable high-resolution, single-heartbeat coronary imaging with sub-millisievert doses, though clinical uptake in the UK is inconsistent and lags behind European, Asian and North American centres. One reason for this is the perception that standard CT angiography shares the same inherent limitation as standard invasive angiography: the inability to confidently determine which epicardial coronary stenoses of intermediate severity will benefit from intervention. A lesion of intermediate severity on CT, therefore, frequently results either in an invasive angiogram (with or without fractional flow reserve [FFR] assessment) or a further non-invasive test; CT computational estimates of FFR and perfusion imaging are not yet widely available or accepted by referring clinicians. As a result, the use of functional imaging tests, which indirectly assess myocardial ischaemia by measuring surrogate markers, such as perfusion or regional wall motion during vasodilator, inotropic, or exercise stress (Table 1), remains high.