Current status of carotid artery stenting in Japan-problems in the post-approval period

Carotid artery stenting (CAS) has been approved as a safe and effective method of treating carotid stenosis. The Japanese post-marketing study (J-CASES-PMS) revealed a low rate of major adverse events after CAS similar to that found in other international clinical trials. This favorable result might be due to precise adherence to the guidelines and the training system. However, structural issues with the filter device, which is the only approved protection method, have caused some pitfalls. In particular, ischemic complications are quite frequent among patients with no-flow phenomenon and with minute or liquid-like debris passing through the filter mesh. These complications are closely associated with the quality and volume of plaque. To evaluate the plaque image and to design the safest strategy including a balloon or multiple combined protection methods is a critically important preoperative process. Although all European clinical trials with or without filter protection have finally disclosed disadvantageous results for CAS, improvements in the appropriate protection strategy in Japan should be reviewed since the time of off-label use.