A 52 year old female with a history of hyperlipidemia
presented to the emergency department with intermittent diffuse chest discomfort and throat tightness after walking approximately one block. Her past medical history is significant for two mid left anterior descending arteries (mLAD). Cypher sirolimus stents (2.5 mm × 23 mm, 2.5 mm × 8 mm) placed in 2008 when she presented with similar symptoms. She has no allergies or past surgical history. Family history is notable for a mother with hypertension
and a father with diabetes. She drinks socially and has never smoked or uses other substances. Her medications were aspirin, amlodipine, pitavastatin, synthroid and a multivitamin. Of note, plavix was discontinued one year after stent placement. Electrocardiogram
demonstrated normal sinus rhythm without any significant ST changes. Physical exam was unremarkable. Cardiac enzymes were negative. During stress echocardiogram, the patient was able to complete 11 METS without any symptoms. There was no inducible ischemia or wall motion abnormalities at >85% MPHR (mean peak heart rate) with a rest ejection fraction of 60%. CT angiography (CTA) revealed two sequential stents in which in stent restenosis (ISR) was unable to be excluded.
Furthermore, it appeared that the proximal end of the first stent was outside the vessel lumen (Figure 1). Coronary angiography
was performed which revealed a 70-80% stenosis in the mLAD with ISR and careful review of the angiogram
, however, revealed that there was contrast outside the proximal stent (Figure 2). In order to further dissect the mechanism, optical coherence tomography
(OCT) was used which interestingly demonstrated positive remodelling, late incomplete stent apposition (ISA) and ISR in the proximal and distal stents (Figures 3-5). In addition, multiple interstrut hollows (MIH), cavities between and outside the stent struts at the site of stent implantation, were identified which another finding is shown to be associated with ISA [1
]. Interestingly, OCT revealed that the proximal edge of the proximal stent was essentially occluded and therefore the guide wire travelled outside the stent due to positive remodelling. The wire subsequently dove into the distal stent and finally exited (Figure 6). Since studies have shown that the staining outside the sirolimus stent (peri-stent contrast staining) within 12 months after implantation and late incomplete stent apposition were associated with increased target lesion revascularization as well as very late stent thrombosis [1
], we decided that percutaneous coronary intervention may not be the ideal treatment. Instead, we opted for minimally invasive coronary artery
bypass graft (CABG) surgery.
CABG X 1 (LIMA-LAD) was performed successfully and the patient was discharged five days later. Intriguingly, there was macroscopic inflammation
observed in the mLAD area where the sirolimus stents were deployed which is in agreement with previous reports linking these types of stents with ISA and inflammation [6
]. Autopsy studies have shown that inflammatory cells
diffusely infiltrate in the media causing medial disruption and destruction which likely results in loss of elastic integrity of the vessel wall leading to positive remodeling [6
This case highlights the value of multi-modality imaging which revealed a cypher related process (inflammation, positive remodelling and late incomplete stent apposition) despite a negative stress test. Since ISA is associated with an increased risk of very late stent thrombosis
, this finding has significant clinical consequences. In fact, it was this observation that led us to reason that we need a more permanent solution for treatment and therefore we referred the patient for CABG. It also raises important issues such as how long dual anti-platelet therapy should be continued in patients who have these types of stents. In conclusion, this case illustrates the limitations of angiography which is simply luminography, the complementary roles of CTA and OCT and how multi-modality imaging can play a crucial role in helping direct clinical-decision making.