Coronary endothelial function: a novel acetylcholine infusion protocol with continuous thermodilution

The assessment of coronary microvascular and vasomotor function is essential in evaluating patients with angina and non-obstructive coronary arteries (ANOCA)1. Traditionally, endothelium-dependent microvascular function is assessed by measuring blood velocity with Doppler during acetylcholine (Ach) infusion into the coronary artery2. Doppler wires are currently commercially unavailable, so we aimed to utilise continuous thermodilution which measures absolute coronary blood flow (CBF) in mL/min with a pressure/temperature sensor-tipped wire and saline infusion through a dedicated catheter (RayFlow, Hexacath, Paris, France)3. This method is safe, reproducible, and operator-independent3,4, however, it’s role in the assessment of endothelial function by infusing Ach mixed with saline via the RayFlow catheter, has not been described.