Computed tomography angiography-derived microvascular resistance: is less always more?

Approximately 40% of patients with non-obstructive epicardial coronary artery disease (CAD) present with associated coronary microvascular dysfunction (CMD) and/or coronary vasospasm1. Despite its high prevalence and clinical relevance, this condition remains largely underdiagnosed, with affected patients experiencing impaired quality of life, recurrent hospitalisations, and adverse cardiovascular outcomes. According to the latest European Society of Cardiology (ESC) Guidelines on chronic coronary syndromes (CCS), the comprehensive evaluation of patients with angina/ischaemia and non-obstructive coronary arteries (ANOCA/INOCA) requires invasive coronary angiography (ICA) with direct haemodynamic assessment – using thermodilution or Doppler techniques – and pharmacological vasomotor testing2. Non-invasive diagnostic modalities may also aid in identifying ANOCA/INOCA through the measurement of coronary flow reserve (CFR); however, these approaches require the prior exclusion of obstructive epicardial CAD2. Consequently, a substantial unmet diagnostic need persists in the non-invasive evaluation of CMD.