A new angiographic method to assess coronary flow reserve—Validation in humans
ABSTRACT Background: Coronary flow reserve (CFR) is defined as the ratio between coronary artery flow during maximal hyperemia and rest. It is considered as a marker for the integrity of the epicardial coronary circulation and the microcirculation. CFR measurement typically requires the introduction of a guide wire into a diseased coronary artery. We tested a new algorithm, which allows to estimate CFR by analysis of coronary angiograms without the need for direct intracoronary measurements. Methods: Twenty seven patients (10 female, mean age 64 ± 11 years) underwent diagnostic cardiac catheterization for the evaluation of chest pain. A Doppler wire was introduced into the diseased coronary artery and CFRdoppler was calculated by the flow velocity ratio between rest and maximal hyperemia, induced by intravenous administration of 140 μg of adenosine per kg bodyweight. This was compared to the angiographically determined CFR (CFRangio) under the same conditions (rest and induced maximal hyperemia) by densitometry. CFRangio was based on the creation of two time density curves representing the disappearance of contrast over time. CFRangio was the resulting ratio between the density values during hyperemia and rest. Results: An excellent correlation was found between CFRdoppler and CFRangio: CFRangio = 1 × CFRdoppler (r = 0.87; P < 0.0001). The average absolute difference between both indeces was 0.36 ± 0.31. Conclusion: Measurement of CFRangio by densitometry is feasible and provides results, which are comparable to Doppler-derived intracoronary flow velocity measurements. © 2009 Wiley-Liss, Inc.