A 67-year-old woman was admitted with an acute coronary syndrome. Angiographic examination revealed diffuse severe stenosis of the left circumflex artery. A Pressure Wire Certus (St. Jude Medical, St. Paul, MN, USA) was passed to the second post-lateral (PL) branch. To prevent side-branch occlusion, a SION wire (Asahi Intecc Co., Aichi, Japan) was left in the first PL branch, and a SION blue wire (Asahi Intecc) was placed in the second obtuse marginal branch. We implanted an everolimus-eluting stent (PROMUS Element 2.5 × 24 mm, Boston Scientific, Natick, MA, USA) in the culprit lesion. After retrieving the protection wire in first PL branch with resistance, we performed post-dilatation. However, the intravascular ultrasound images showed that the proximal portion of the implanted stent had elongated approximately 2 mm to the left main trunk (LMT), although the position of the distal edge of the stent was unchanged. We decided to additionally place a stent from the ostium of the LMT to the proximal left anterior descending coronary artery, and a biolimus-eluting stent (NOBORI 3.0 × 18 mm, Terumo Co., Tokyo, Japan) was implanted successfully. Longitudinal stent elongation might be caused by the small number of links between the hoops of a stent, originally intended to improve deliverability.