The Complementary Value of Absolute Coronary Flow in the Assessment of Patients with Ischaemic Heart Disease

Abstract

Fractional flow reserve (FFR) is the current gold standard invasive assessment of coronary artery disease (CAD). FFR reports coronary blood flow (CBF) as a fraction of a hypothetical and unknown normal value. Although used routinely to diagnose CAD and guide treatment, how accurately FFR predicts actual CBF changes remains unknown. In this study, we compared fractional CBF with absolute CBF (aCBF, in ml min−1), measured with a computational method during standard angiography and pressure wire assessment, on 203 diseased arteries (143 patients). We found a substantial correlation between the two measurements (r = 0.89 and Cohen’s kappa = 0.71). Concordance between fractional and absolute CBF reduction was high when FFR was >0.80 (91%) but reduced when FFR was ≤0.80 (81%), 0.70–0.80 (68%) and, particularly, 0.75–0.80 (62%). Discordance was associated with coronary microvascular resistance, vessel diameter and mass of myocardium subtended, all factors to which FFR is agnostic. Assessment of aCBF complements FFR and may be valuable to assess CBF, particularly in cases within the FFR ‘gray zone’.

Validation of a novel numerical model to predict regionalized blood flow in the coronary arteries

“…Clinically, the patient cohort for which absolute Q assessment will be of value and thresholds for intervention are currently unknown and subject to ongoing research. 30 Fournier et al have previously reported a difference in hyperaemic LAD flow between healthy and mildly disease arteries of 65 mL/min. 27 Given the reported error in the current study, at the current stage of development, virtuQ assessment of absolute Q in minimally diseased arteries may be of limited clinical utility.…”

Sex differences in coronary microvascular resistance measured by a computational fluid dynamics model

“…Further exclusion criteria for all cases included ST-segment elevation myocardial infarction within the preceding 60 days, any contraindication to adenosine or contrast media, previous coronary artery bypass surgery, patient age below 18 years, chronic total occlusion, severe valvular disease and an inability to consent. This was a post hoc analysis of the Complementary Value of Absolute Coronary Flow in the Assessment of Patients with Ischaemic Heart Disease (the COMPAC-Flow) study ( 12 ), in which computational fluid dynamics- (CFD-) derived absolute flow reduction in CAD was assessed using the virtuQ™ software package ( 13 ). The study was approved by Regional Ethics Committees (16/NW/0897 and 08/H1308/193) and informed consent was obtained.…”