Safety of absolute coronary flow and microvascular resistance measurements by thermodilution

Assessment of the microcirculation of the heart has gained interest over recent years. This is partly due to the fact that up to 50% of patients with chest pain visiting the catherization laboratory do not present with significant epicardial stenosis (so-called Angina with Non Obstructive Coronary Artery disease (ANOCA).1Most knowledge regarding microvascular resistance came from non-invasive imaging, from invasive index of microvascular resistance2, or from doppler wires3, both being semi-quantitative and operator dependent.Recently, direct quantitative measurement of coronary blood flow and microvascular resistancehas become possible by thermodilution with saline infusion, using a pressure-temperature guidewire and a multisidehole infusion catheter. Such measurements have been validated versus Positron Emission Tomography (PET)4, have a high reproducibility and are operator independent.5 Procedural safety has been reported before5, but long term safety and absence of late complications have not been described yet. The present study evaluates the safety of absolute flow measurements, both periprocedural, at 30 days and to one year follow-up.