Paradoxical Computed Tomography-Derived Fractional Flow Reserve Changes Due to Vessel Morphology and Constituents.

Computed tomography-derived fractional flow reserve decreases from the proximal to the distal with coronary stenosis. According to the principles of fluid dynamics, paradoxical computed tomography-derived fractional flow reserve changes require an unconventional vessel mor-phology and specific site of the vessels with a high driving force. Therefore, only a few articles have reported a paradoxical increase of computed tomography-derived fractional flow reserve. We present a case report of marked computed tomography-derived fractional flow reserve elevation in the middle left anterior descending artery with a severe coronary stenosis. Computed tomography-derived fractional flow reserve was 0.94 just proximal to the stenotic lesion and decreased to 0.65 at the maximum stenosis area but recovered to 0.80 in the distal segment. We speculated that the vessel morphology could have caused a pressure recovery phenomenon, resulting in paradoxical computed tomography-derived fractional flow reserve changes.