The effectiveness of excimer laser coronary atherectomy with contrast medium for underexpanded stent: The findings of optical frequency domain imaging.

Stent underexpansion is a risk factor for in-stent restenosis (ISR) and stent thrombosis. Although excimer laser coronary atherectomy (ELCA) with contrast medium was shown to be effective to improve stent underexpansion in undilatable lesions, precise mechanism of this technique was not well understood. We report a case of ISR with stent underoptimal implantation within a circumferential-calcified atherosclerotic plaque beneath the stent strut that could not be dilated by repeated high-pressure balloon inflations. After rotational atherectomy, the mechanism of the underexpanded lesion could be obtained by optical frequency domain imaging (OFDI). High-pressure balloon could not dilate the underexpanded stent. Since ELCA with saline flush only gave intimal erosions and minor dissections, additional high-pressure balloon was also ineffective. Finally, ELCA with contrast medium could disrupt the calcific lesion beneath the underexpanded stent. The angiographic and OFDI findings confirmed the full stent expansion could be accomplished by further balloon dilatation with an ordinary pressure. ELCA with contrast medium is feasible to improve stent underexpansion by disrupting the calcified plaque behind the stent strut.