Objectives: Percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) lesions are to be considered as complex coronary interventions, with a higher rate of procedural unsuccess and complications compared to less complex PCI. After successful CTO PCI patients have a higher risk of restenosis and re-occlusions. The use of intracoronary imaging, especially intravascular ultrasound (IVUS), plays a major role in this context, being able to provide information about lesion length, morphology and vessel dimensions. With this study, we aim to evaluate if standardized IVUS use compare to visual estimation, changes stent size choice in the CTO-PCI setting.

Methods & Results: Data from 82 patients who had undergone IVUS guided CTO PCI at the Center for Cardiology – University Medical Center Mainz were analysed. We evaluated demographic, clinical, angiographic, and periprocedural information. The median age of the total collective was 63 (40-86) years. The median of estimated proximal vessel diameter was 3.00 mm (2.25- 4.5 mm) and the median of the estimated distal vessel diameter was 2.75 mm (2.25- 4.5 mm). With IVUS assessment the median of the distal vessel diameter was 3 mm  (2.3-4.5 mm) and the median of the proximal vessel diameter was 3.8mm (2.5-6.2 mm). The median diameter of the implanted drug eluting stent (DES) in the distal vessel was 2.75 mm (2.00-4.00 mm) and in the proximal vessel 3.5mm (2.25-4.00 mm).  Distal vessel diameter was underestimated in 70% (58/82) of the patients, IVUS measurement revealed a larger vessel diameter. A larger stent diameter was implanted in the distal vessel in 50% (41/82; p 0.05) of patients. Proximal vessel diameter was underestimated in 87.8 % (58/82) of the patients, IVUS measurement revealed a larger vessel diameter. A larger stent diameter was implanted in the proximal vessel in 87.8% (72/82; p 0.05) of patients. The restenosis rate after 6 month was 8.5%.

Conclusion: IVUS guided CTO PCI is safe an feasible. Proximal and distal vessel diameter is often underestimated by visual estimation. The use of IVUS influences the stent size choice of the operator with a low rate of re-stenosis in the follow-up (8.5%).