Assessment of coronary anatomy and flow for optimized diagnosis and prognostication in CAD.

This editorial refers to ‘Warranty period of coronary CTA and [15O]H2O PET in symptomatic patients’, by R. Jukema et al., https://doi.org/10.1093/ehjci/jeac258. Positron emission tomography (PET)-determined myocardial perfusion and concurrently myocardial blood flow (MBF) in mL/g/min during pharmacologic stress and at rest with corresponding myocardial flow reserve (MFR) has emerged as a pivotal for the detection of haemodynamically obstructive coronary artery disease (CAD) and/or coronary microvascular dysfunction (CMD).1–3 While the assessment of the relative distribution of the left ventricular radiotracer uptake with PET reliably identifies down-stream and flow-limiting epicardial lesions, it may be less precise in the assessment and characterization of the ischaemia burden in multi-vessel, or it may even miss diffuse ischaemia due to significant flow-limiting left main and/or three-vessel CAD.4 Such limitation in the assessment of the overall ischaemic burden may be overcome by adding the concurrently measured regional and global MFR.5 While PET-determined regional perfusion deficit has been widely established as critical tool for prognostication of patients with suspected CAD, evaluating the concurrently measured global MFR adds further incremental information on future cardiovascular outcome.4–6 In the recent decade, contrast computed tomographic angiography (CTA) has emerged as a reliable clinical imaging tool to exclude obstructive CAD in symptomatic patients with low-to-intermediate probability for the presence of CAD, carrying important diagnostic and prognostic implications.7 For the time being, it remains uncertain whether PET perfusion-flow assessment following coronary CTA provides incremental prognostic information beyond coronary CTA.