Functional and Anatomical Diagnosis of Coronary Artery Stenoses: A Retrospective Study in Humans

Fractional flow reserve (FFR: ratio of distal to proximal pressure of a stenotic section) is used to evaluate hemodynamic significance of epicardial stenosis. However, FFR and coronary flow reserve (CFR: ratio of hyperemic blood velocity to that of resting condition) are used in conjunction to evaluate combination of both epicardial and microvascular disease. It has been proposed that optimization of cutoff values for diagnostic parameters in determining stenosis severity depends on coupling functional (pressure and velocity) and anatomical data (% area stenosis). We hypothesize that, pressure drop coefficient (CDP: the ratio of trans-stenotic pressure drop to distal dynamic pressure) which has the functional information of pressure and velocity in its formulation correlates significantly with FFR and CFR, and lesion flow coefficient (LFC: ratio of % area stenoses to CDP at throat region) which combines both functional and anatomical (% area stenoses) information in its formulation correlates significantly with FFR, CFR and % area stenosis. We retrospectively analyzed the hemodynamic information from Meuwissen et al [3] to test this hypothesis. It was observed that, CDP, a functional index based on pressure drop and velocity, correlated linearly and significantly with FFR and CFR. And, LFC (combined functional and anatomic parameter) also correlated significantly with FFR, CFR (both hemodynamic endpoints) and % area stenosis (anatomic endpoint).