Excerpt

Coronary CT angiography (CCTA) is a reliable tool for diagnosing coronary artery disease (CAD). However, beam-hardening artifacts caused by metallic stent struts may impair detection and quantification of in-stent restenosis (ISR). A new non-invasive technique, which is based on computational fluid dynamics and simulated maximal coronary hyperaemia, uses CCTA data to estimate fractional flow reserve (FFR_CT) providing accurate functional information in addition to anatomic assessment of coronary artery stenoses. Recent studies demonstrated that FFR_CT is a feasible and safe modality to guide treatment strategies in patients with stable CAD. However, applicability of FFR_CT for coronary stent evaluation has not been investigated. A 62-year-old man with multi-vessel CAD underwent implantation of four drug-eluting stents, two in the right coronary artery (RCA), one in the left anterior descending artery (LAD) and one in the left circumflex artery (LCX), respectively. After one year, he was evaluated with CCTA and FFR_CT because of chest pain. No “de novo” coronary stenoses or significant ISR were detected by CCTA that showed good opacification of RCA (panel a), LAD and LCX stents. Particularly, RCA stents were deemed free from significant ISR with only mild decrease of attenuation values in the distal vessel (panel b, HF: Hounsfield Units). On the contrary, FFR_CT analysis showed a marked drop in the numeric value (<0.50) (panel c) distal to the RCA stented segment. FFR_CT analysis of LAD and LCX was normal (panel c). Invasive coronary angiography confirmed severe ISR of RCA (panel d) prompting percutaneous coronary intervention with a drug-eluting balloon (Fig. 1). …