Aims: The PRISON IV trial investigated the next-generation sirolimus-eluting stent (SES) with ultra-thin struts and biodegradable polymer against the second-generation everolimus-eluting stent (EES) with thin struts and durable polymer in patients with successfully recanalised chronic total occlusions (CTO). In this study, we examined the secondary optical coherence tomography endpoints.
Methods and results: The main PRISON IV trial randomised 330 patients to either SES or EES. At nine months, 281 (85%) patients underwent repeat angiography. Of these, 60 consecutive patients received optical coherence tomography divided over both stent groups. The mean number of struts analysed was 750±337 and 633±358 in SES and EES patients, respectively (p=0.07). The minimal lumen area, minimal stent area, maximal neointima area and neointimal thickness were comparable between the groups (4.8±2.1 and 4.4±1.5 mm2; 5.3±1.8 and 5.3±1.4 mm2; 2.5±2.0 and 2.2±1.5 mm2; 0.7±1.7 and 0.4±0.2 mm). The percentage of uncovered struts was higher with EES (6.2±7.5% and 11.9±13.4%, p=0.04), whereas the percentage of malapposed struts and mean number of coronary evaginations were significantly higher with SES (2.9±4.0% and 1.2±2.4%, p=0.02; 18.5±17.7 and 5.3±3.1, p=0.004).
Conclusions: The optical coherence tomography findings of this substudy demonstrated improved strut coverage with ultra-thin strut SES with bioresorbable polymer compared to thin-strut EES with durable polymer in CTO. On the other hand, SES showed a higher rate of stent strut malappositon and coronary evaginations. The clinical relevance of these findings remains to be demonstrated.