Introduction
Coronary stent fractures (SF) after drug-eluting stent (DES) deployment are potentially associated with serious complications such as in-stent restenosis and stent thrombosis. Overall incidence of SF ranges between 0.8% and 19% of patients with presently used DES (1). Symptomatic SF are rare conditions (1). In this case report, we present two patients with complete SF after multiple stenting causing myocardial infarction.

Case report
Patient 1 had undergone PCI of the proximal RCA with implantation of one everolimus eluting stent (EES). Recurrent in-stent restenosis of the proximal RCA had led to implantation of one sirolimus eluting stent (SES) and one EES. After two years, the patient had undergone another PCI on admission due to inferior ST-Segment-Elevation myocardial infarction (STEMI). Coronary angiography (CAG) had identified a gap within the previously implanted DES in the proximal RCA, indicative of complete stent fracture (type IV) (Figure 1A), and one EES had been deployed. 3 months later, in a setting of Non-ST-Segment-Elevation myocardial infarction (NSTEMI), CAG had shown persistent excessive motion at the hinge point of the RCA within the EES suggesting re-SF, which led to deployment of one zotarolimus eluting stent (ZES) with a good final result (Figure 1B).
After being asymptomatic for 15 months, at the latest presentation the patient was again referred to CAG due to NSTEMI. The CAG again showed SF of all deployed stent layers in the proximal RCA (Figure 1C). Further coronary intervention was abstained from and the patient was planned for single bypass surgery.


Figure 1: Complete SF of an EES, that had lead to STEMI (A), was initially treated with deployment of 1 DES. Due to re-SF causing NSTEMI 1 ZES was implanted (B). However, recurrent type-IV-SF with TIMI-0-flow was observed in a setting of NSTEMI (C).

Patient 2 had undergone CABG surgery more than 20 years prior to the latest admission. With progression of the coronary artery disease, multiple PCI were carried out due to recurrent restenosis of the inserting region of the LIMA-ad-LAD bypass including deployment of 2 EES and application of a paclitaxel-coated balloon. The patient however had been re-admitted due to unstable angina pectoris. CAG had shown type-IV-SF within the previously implanted DES in the inserting region of the LIMA-ad-LAD-bypass (Figure 2A). Re-PCI and deployment of 2 ZES had been performed to stabilize the fracture (Figure 2B).
At the latest admission, only one month after the last PCI, the patient presented with NSTEMI. CAG revealed re-SF of the medial LAD with distal TIMI-0-flow and prominent hinge motion. Recanalisation of the fracture was unsuccessful (Figure 2C). The patient was commenced with conservative infarction therapy. 



Figure 2: Type-IV-SF in the inserting region of the LIMA-ad-LAD-bypass (A) that had previously been treated with implantation of 2 EES and had led to unstable angina pectoris was repaired by deployment of 2 ZES (B). However, re-SF occurred only weeks later and further attempts of intervention remained unsuccessful (C).

Conclusion
This case report describes two rare symptomatic cases of recurrent complete SF of multiple DES at hinge points with excessive motion of the coronary arteries complicated by acute coronary syndrome.

Source
1. Chinikar M, Sadeghipour P. Coronary stent fracture: a recently appreciated phenomenon with clinical relevance. Current cardiology reviews. 2014;10:349-354.