CFR & Flow Analysis
Coronary flow reserve (CFR) is defined as the ratio of the maximal achievable coronary blood flow to the resting blood flow supply to the myocardium. Contrary to FFR that assesses the severity of an epicardial stenosis to best decide the need for an angioplasty or stent placement, CFR helps assess the combined severity of proximal epicardial and distal microvascular disease is reflects a more global index of cardiac physiology. In fact, incorporation of CFR along FFR determination has been often proposed for a more complete assessment of coronary physiology to decouple the pathological effects of critical epicardial stenoses from diffuse microvascular disease.
CFR measurement is cumbersome and requires application of either thermodilution or dedicated Doppler wires both of which are associated with extra cost, time and a high coefficient of variation. medLYTIC Labs have developed unique accelerated CFD computer models enabling computation of Absolute Blood flow rates (Q) and subsequently Coronary Flow Reserve without thermodilution or dedicated Doppler wires.
Example in the figure shows real-time curves of Coronary Flow Reserve (CFR) and in addition Microvascular Resistance Reserve (MRR) calculated and demonstrated alongside the invasive pressure measurements of hyperemic FFR index. The method incorporates angiographic anatomic information and pressure recordings from standard pressure wires (most accurate version) and has been found to be positively correlated with Doppler wire CFR measurements and with good agreement of classification of invasive CFR measurements. The method is ultrafast and allows for calculation of phasic flow waveforms in almost real-time opening up new frontiers in coronary physiology.