Coronary artery occluded lesion with a discrepancy in diagnosis between CT-derived fractional flow reserve (FFRCT) and invasive coronary angiography

Coronary computed tomography angiography (CCTA) and CT-derived fractional flow reserve (FFRCT) findings have high diagnostic accuracy and are consistent with invasive coronary angiography (ICA) which is the gold standard diagnostic technique for coronary artery disease. The differential diagnosis between total and subtotal coronary occlusion plays an important role in determining the treatment strategy. Subtotal coronary occlusion composed of vulnerable tissue can occasionally appear as total coronary occlusion on ICA, which may be inconsistent with CCTA and FFRCT findings. We present a case report of discrepant findings between CCTA (subtotal coronary occlusion) and ICA (total coronary occlusion). The stenotic lesion was filled with vulnerable tissue (low-attenuation plaque volume 20.3 mm3 and intermediate-attenuation plaque volume 71.6 mm3), which could be dilated with vasodilator during maximal hyperemia, resulting in the acquisition of CCTA and FFRCT images. We were able to diagnose subtotal coronary occlusion and identify the overall anatomical structure of the vessels before percutaneous coronary intervention (PCI), allowing successful and uncomplicated PCI.