Impact of clinical and haemodynamic factors on coronary flow reserve and invasive coronary flow capacity in non-obstructed coronary arteries: a patient-level pooled analysis of the DEBATE and ILIAS studies

Coronary flow reserve (CFR) is a physiological index for the assessment of myocardial flow impairment due to focal or microcirculatory coronary artery disease (CAD). Coronary flow capacity (CFC) is another flow-based concept in diagnosing ischaemic heart disease, based on hyperaemic average peak velocity (hAPV) and CFR. We evaluated clinical and haemodynamic factors which potentially influence CFR and CFC in non-obstructed coronary arteries.Intracoronary Doppler flow velocity measurements to obtain CFR and CFC were performed after inducing hyperaemia in 390 non-obstructed vessels of patients who were scheduled for elective percutaneous coronary intervention (PCI) of another vessel. Akaike's information criterion (AIC) revealed age, female gender, history of myocardial infarction, hypercholesterolaemia, diastolic blood pressure, oral nitrates and rate pressure product as independent predictors of CFR and CFC. After regression analysis, age and female gender were associated with lower CFR and age was associated with worse CFC in angiographically non-obstructed vessels.Age and female gender are associated with lower CFR, and age with worse CFC in an angiographically non-obstructed coronary artery. CFC seems to be less sensitive to variations in clinical and haemodynamic parameters than CFR and is therefore a promising tool in contemporary clinical decision making in the cardiac catheterisation laboratory.