Pressure- and 3D-derived coronary Flow Reserve with Hydrostatic Pressure Correction - A Validation by Intracoronary Doppler Measurements

Purpose: To develop a method of coronary flow reserve (CFR) calculation derived from threedimensional (3D) coronary angiographic parameters and intracoronary pressure data during fractional flow reserve (FFR) measurement. Methods: Altogether 19 coronary arteries of 16 native and 3 stented vessels were reconstructed in 3D. The measured distal intracoronary pressures were corrected to the hydrostatic pressure based on the height differences between the levels of the vessel orifice and the sensor position. Classical fluid dynamic equations were applied to calculate the flow during the resting state and vasodilatation on the basis of morphological data and intracoronary pressure values. 3D-derived coronary flow reserve (CFR p-3D ) was defined as the ratio between the calculated hyperemic and the resting flow and was compared to the CFR values simultaneously measured by the Doppler sensor (CFR Doppler ). Results: Haemodynamic calculations using the distal coronary pressures corrected for hydrostatic pressures showed a strong correlation between the individual CFR p-3D values and the CFR Doppler measurements (r=0.89, p<0.0001). Hydrostatic pressure correction increased the specificity of the method from 46.1% to 92.3% for predicting an abnormal CFR Doppler <2. Conclusions : CFR p-3D calculation with hydrostatic pressure correction during FFR measurement facilitates a comprehensive haemodynamic assessment, supporting the complex evaluation of macro- and microvascular coronary artery disease.