Coronary stent thrombosis or scaffold thrombosis refers to an acute thrombus or occlusion in a coronary segment previously treated with a coronary stent or scaffold. It is a severe complication of percutaneous coronary intervention (PCI) and a major adverse cardiovascular event.
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Epidemiology
Coronary stent thrombosis was up to 10% 1 in the past but the incidence was reduced considerably 2.
Risk factors
Factors that increase the likelihood of developing coronary stent thrombosis include 1,2:
-
procedure-related
complex lesion
residual dissection
implantation of an undersized coronary stent
-
stent-related
drug-eluting stents (1st generation)
-
patient-related
premature discontinuation of dual antiplatelet therapy
underlying malignancy
high platelet reactivity
Associations
Coronary stent thrombosis is associated with impaired arterial healing and uncovered struts 1.
Clinical presentation
The typical clinical presentation of stent thrombosis is that of myocardial infarction and includes the detection of a typical rise and fall in cardiac troponin above the 99th percentile URL and one following 3,4:
symptoms of acute myocardial ischemia
new ischemic ECG changes
new pathological Q-waves
The following time intervals of stent or scaffold thrombosis after implantation are distinguished 1-4:
early: <30 days (acute ≤24 hours, subacute 1-30 days)
late: >30 days to 1 year
very late: >1 year
Complications
Complications of coronary stent thrombosis include 1-3:
Pathology
Stent thrombosis is characterized by an acute thrombus or occlusion of a previously stented coronary segment including the adjacent 5 mm proximal or distal to the stent or in a branch arising from the stented segment 4.
Etiology
Causes and pathogenic mechanisms of stent thrombosis include the following 1,2:
interruption or early dual-antiplatelet therapy
stent malapposition or underexpansion
impaired arterial healing/re-endothelialization and uncovered stent struts
localized hypersensitivity reactions
neoatherosclerosis
stent dismantling (in bioresorbable scaffolds)
Radiographic features
Coronary stent thrombosis requires emergency invasive coronary angiography with repeat percutaneous coronary intervention and in this case, any additional imaging will delay treatment. However, there might be occasions, where imaging modalities will reveal findings indicating the diagnosis which have not been previously detected by other means.
Radiographic features are not different from type 1 myocardial infarction and include the following features in an ischemic pattern 3:
new loss of viable myocardium
Echocardiography
Echocardiography might detect new wall motion abnormalities.
CT
Coronary CTA might show stent thrombosis/occlusion.
Coronary angiography
Coronary angiography within emergency repeat percutaneous coronary intervention is the modality of choice to document the diagnosis and will prove stent thrombosis following thrombectomy 4.
MRI
MRI might show signs of acute myocardial infarction corresponding to the respective coronary vascular territory including:
cine imaging: new regional wall motion abnormalities
T2/STIR black blood: hyperintensity indicating myocardial edema and the ‘area at risk’
perfusion imaging: diminished or delayed uptake
IRGE/PSIR: new subendocardial to transmural late gadolinium enhancement ± no reflow phenomenon
Radiology report
The radiological report should include a description of the following features based on the AHA coronary artery segment and cardiac segmentation models:
Coronary angiography/coronary CTA:
stent occlusion
location of the stent
coronary artery stenoses
Echocardiography/cardiac MRI/nuclear medicine:
regional wall motion abnormalities
non-viable myocardium
Treatment and prognosis
The management of coronary stent thrombosis requires emergency percutaneous coronary intervention with revascularization 1.
Differential diagnosis
Stent thrombosis can mimic the appearance or presentation of the following clinical conditions 1:
myocardial infarction (type 1 and type 2)