Coronary in-stent restenosis
Coronary in-stent restenosis (ISR) is referred to as an increasing loss of the stented arterial lumen after a percutaneous coronary intervention (PCI) and coronary stent placement which requires revascularization.
However, there are different clinical and angiographic definitions:
Angiographic evidence of in-stent restenosis is defined as re-narrowing of the previously stented arterial lumen >50% compared to the diameter of the respective vessel.
Clinical evidence of in-stent restenosis is defined by a new lesion within the stent associated with symptoms and signs of myocardial ischemia.
Coronary in-stent restenosis is the most common complication after percutaneous coronary intervention but has been reduced step-by-step with the introduction of coronary stents and subsequent improvements in stent technology. Clinical restenosis is less common than angiographic restenosis with rates of ≤5% and 10% after 12 months for newer generation drug-eluting stents 1,2.
Factors that increase the likelihood of developing coronary in-stent restenosis include 1,3:
- small vessel lumen
- residual stenosis after stent placement
- longer stent length
- complex or bifurcated lesion
- bare-metal stent
- 1st generation drug-eluting stents
- thick struts
- premature discontinuation of dual antiplatelet therapy
- diabetes mellitus
- chronic renal insufficiency
Clinical symptoms of restenosis include angina, ischemic changes on electrocardiogram and/or positive cardiac biomarkers e.g. troponins. About 18% of patients with in-stent restenosis present with acute coronary syndrome 3.
If left untreated in-stent restenosis can develop the following complications 1-5:
Coronary in-stent restenosis usually occurs as a result of a reaction to arterial wall injury and can be focal or diffuse. It is considered as a distinct pathophysiological process with the following contributing factors 1-4:
- prolapse of the disrupted plaque
- elastic recoil of the arterial wall
- constrictive negative remodeling
- neointimal hyperplasia
Demonstration of a luminal diameter reduction >50% within the stent or the adjacent 5 mm proximal and distal to it are referred to as angiographic in-stent restenosis 1,3. Imaging modalities with the capacity to demonstrate myocardial ischemia such as stress echo, nuclear stress imaging or a cardiac stress MRI can be used to objectify clinical restenosis in the stent-related vascular territory.
Stress echocardiography might reveal stress-induced wall motion abnormalities in the respective coronary vascular territory of the stented coronary artery.
CT imaging of coronary stents is considered challenging 7. Still, it is a non-invasive option for the evaluation in regard to coronary in-stent stenosis in some patients (e.g. who decline ICA for the time being) and depending on the type and size (≥3mm) of the coronary stent might reveal good results. A high-end CT scanner will be highly beneficial for this task 6,7.
Invasive coronary angiography (ICA) will depict angiographic evidence of in-stent restenosis as a reduction in luminal diameter of >50% within the stent lumen or a re-narrowing of >75% of the cross-sectional vessel area acquired by imaging modalities using a 3D data set 1,2.
A cardiac MRI stress test might show a perfusion defect or stress-related wall motion abnormalities corresponding to the respective coronary vascular territory and can also detect complications as myocardial infarction 4.
- cardiac CT
- stent stenosis
- location of the stent
- other coronary artery stenoses
- cardiac stress test
- signs of myocardial ischemia
Treatment and prognosis
Coronary in-stent restenosis requires repeat revascularization and most patients can be treated again with percutaneous coronary intervention and repeat stenting with a newer generation drug-eluting stent or drug-coated balloon angioplasty 2-4 alternatively they can be treated with bypass surgery 4.
Coronary in-stent restenosis can mimic the appearance or presentation of the following clinical conditions 1:
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- 5. Thygesen K, Alpert JS, Jaffe AS, Chaitman BR, Bax JJ, Morrow DA, White HD. Fourth Universal Definition of Myocardial Infarction (2018). (2018) Journal of the American College of Cardiology. 72 (18): 2231-2264. doi:10.1016/j.jacc.2018.08.1038 - Pubmed
- 6. Hickethier T, Wenning J, Bratke G, Maintz D, Michels G, Bunck AC. Evaluation of soft-plaque stenoses in coronary artery stents using conventional and monoenergetic images: first experience and comparison of two different dual-energy techniques. (2020) Quantitative imaging in medicine and surgery. 10 (3): 612-623. doi:10.21037/qims.2020.02.11 - Pubmed
- 7. Li Y, Yu M, Li W, Lu Z, Wei M, Zhang J. Third generation dual-source CT enables accurate diagnosis of coronary restenosis in all size stents with low radiation dose and preserved image quality. (2018) European radiology. 28 (6): 2647-2654. doi:10.1007/s00330-017-5256-3 - Pubmed