Letter to the editor: “A novel angiographic fractional flow reserve”

Abstract

TO THE EDITOR: We read with great interest the article "Quantification of absolute coronary flow reserve and relative fractional flow reserve in a swine animal model using angiographic image data," published in the American Journal of Physiology-Heart and Circulatory Physiology (5). Fractional flow reserve (FFR) is an epicardial lesion-specific parameter to determine the functional coronary stenosis, which is determined by pressure difference and resistance (1-3). Specifically, Molloi and colleagues (5) present a novel angiography-derived FFR (FFRa) computed from blood flow (Qa) through the time-density curve based on the first-pass analysis technique. Accordingly, relative FFRa was calculated as the ratio of the normalized Qa in left anterior descending to the left circumflex artery during hyperemia. Relative FFRa correlated linearly with quantitative flow probe-based FFR (FFRq) (relative FFRa ϭ 0.86 FFRq ϩ 0.05; r ϭ 0.90; P Ͻ 0.0001) (5).Pressure-wire derived FFR is a well-established hemodynamic index to assess the ischemic severity of stenosis and the necessity for cardiac revascularization (1, 2). However, the risk of crossing the lesion and high cost of pressure wire greatly restrict its clinical application (