Stent thrombosis definition

# Overview
Coronary stent thrombosis (ST) is the sudden occlusion of a stented coronary artery due to formation of thrombosis. The clinical consequences of ST are frequently catastrophic and include death in 20-48% or major myocardial infarction (MI) in 60-70% of the cases.  

# Issues with Interpreting Data
- Some clinical trials excluded patients who underwent repeat target vessel revascularization. Given that this is more likely to be on a bare metal stent (BMS), there might have been room for bias.
- In some studies definition of late ST may have underestimated the true incidence of ST due to the exclusion of unexplained myocardial infarction (MI)s in the territory of the stented vessels and late deaths, which may have been due to stent thromboses.
- In some trials the patient who presented for revascularization of BMS patients were exluded which may have biased the interpretation of the results.
To resolve this issue and standardize the diagnosis, Academic Research Consortium(ARC) came up with the definitions of stent thrombosis which will be discussed in this section.

# Definition Based on Timing of Stent Thrombosis (ST)
- Acute stent thrombosis: 0 to 24 hrs after stent implantation
- Subacute stent thrombosis: > 24 hours to 30 days after stent implantation
- Late stent thrombosis: >30 days to 1 year after stent implantation
- Very late stent thrombosis: >1 year after stent implantation

# Definition Based on Certainty of ST

## Definite Stent Thrombosis
1) Angiographic confirmation of stent thrombosis: The presence of intracoronary thrombus that originates in the stent or in the segment 5 mm proximal or distal to the stent and presence of at least 1 of the following criteria within a 48-hour time window:
- Acute onset of ischemic symptoms at rest
- New ischemic ECG changes that suggest acute ischemia
- Typical rise and fall in cardiac biomarkers
- Nonocclusive thrombus-Intracoronary thrombus is defined as a (spheric, ovoid, or irregular) noncalcified filling defect or lucency surrounded by contrast material (on 3 sides or within a coronary stenosis) seen in multiple projections, or persistence of contrast material within the lumen, or a visible embolization of intraluminal material downstream.
- Occlusive thrombus-TIMI 0 or TIMI 1 intrastent or proximal to a stent up to the most adjacent proximal side branch or main branch (if originates from the side branch).
2) Pathological confirmation of stent thrombosis: Evidence of recent thrombus within the stent determined at autopsy or via examination of tissue retrieved following thrombectomy.

## Probable Stent Thrombosis
Clinical definition of probable stent thrombosis is considered to have occurred after intracoronary stenting in the following cases:
- Any unexplained death within the first 30 days
- Irrespective of the time after the index procedure, any MI that is related to documented acute ischemia in the territory of the implanted stent without angiographic confirmation of stent thrombosis and in the absence of any other obvious cause.

## Possible Stent Thrombosis
Clinical definition of possible stent thrombosis is considered to have occurred with any unexplained death from 30 days after intracoronary stenting until end of trial follow-up.
It should be noted that the incidental angiographic documentation of stent occlusion in the absence of clinical signs or symptoms is not considered a confirmed stent thrombosis (silent occlusion).