Assessment of coronary stenoses by myocardial perfusion imaging during pharmacologic coronary vasodilation. VII. Validation of coronary flow reserve as a single integrated functional measure of stenosis severity reflecting all its geometric dimensions.

The purpose of this study was to determine whether coronary flow reserve measured by flow meter correlated with or could be predicted by quantitative coronary arteriography accounting for all dimensions of a coronary artery stenosis. Five dogs were chronically instrumented with an inflatable stenosing cuff, a Doppler flow velocity meter, proximal and distal coronary artery catheters and aortic and pulmonary artery catheters. For 18 stenoses over a wide range of severity, orthogonal coronary arteriograms were analyzed quantitatively at rest to predict coronary flow reserve based on fluid dynamic equations. The X-ray-predicted coronary flow reserve correlated closely with that measured directly by implanted flowmeter with an r value of 0.91, a regression equation of X-ray-predicted coronary flow reserve = 1.08 (measured coronary flow reserve) - 0.08 and 95% confidence limits (+/- 2 SD) of 0.66. Neither percent diameter narrowing alone nor absolute stenosis diameter alone correlated well with measured coronary flow reserve. Results confirm that coronary flow reserve is a single integrated measure of coronary stenosis severity reflecting all its geometric dimensions. Flow reserve correlated closely with and was accurately predicted by quantitative coronary arteriography taking into account all stenosis dimensions. This study establishes the theoretical and experimental basis for using coronary flow reserve as a single, integrated functional measure of stenosis severity reflecting all of its geometric characteristics.