Chest pain without significant coronary stenosis after implantation of sirolimus-eluting stents

We encountered a case of exercise-induced chest pain after the implantation of sirolimus-eluting stents (SESs). She had no history of previous chest pain, and an exercise stress test just after the implantation of the SESs was negative without any symptoms. However, six months after the implantation of the SESs, she began to experience frequent episodes of severe chest pain on effort in spite of there being no significant coronary stenosis. Interestingly, severe coronary vasoconstriction was induced by an intracoronary administration of acetylcholine, and exercise stress testing revealed positive findings with chest pain and ST-T segment depression on ECG. An intensive treatment with two types of calcium channel blockers could readily and completely abolish the exercise-induced chest pain and ST-T segment depression on the ECG. In view of these findings, we presumed that coronary microvessel dysfunction and/or exercise-induced coronary vasoconstriction leading to myocardial ischemia had appeared 6 months after the implantation of the SESs. Although the pathogenesis of this phenomenon could not be completely elucidated, the anatomical and functional abnormalities of the coronary arteries associated with the implantation of the SESs may have been one of the most important mechanisms.