Clinical event adjudication: Stent thrombosis
For the list of clinical event adjudication definitions, click here

# Stent thrombosis
This chapter presents stent thrombosis definitions used in the Clinical Event Committee adjudication processes. These definitions are current as of 3/26/10.

# Stent Thrombosis: Timing
Stent thrombosis should be reported as a cumulative value over time and at the various individual time points as specified below.  Time 0 is defined as the time point after the guiding catheter has been removed and the subject has left the cardiac catheterization laboratory.

## Timing
- Acute stent thrombosis1: 0-24 hours post stent implantation
- Subacute stent thrombosis1: > 24 hours  30 days post stent implantation
- Late stent thrombosis2: > 30 days  1 year post stent implantation
- Very late stent thrombosis2: > 1 year post stent implantation
1Acute or subacute can also be replaced by the term early stent thrombosis.  Early stent thrombosis (0-30 days) will be used herein.
2Includes primary as well as secondary late stent thrombosis; secondary late stent thrombosis is a stent thrombosis after a target lesion revascularization.

# Stent Thrombosis: Categories
We propose three categories of evidence to define stent thrombosis, as follows:

## 1. Definite Stent Thrombosis
Definite stent thrombosis is considered to have occurred by either angiographic or pathologic confirmation:

### a. Angiographic confirmation of stent thrombosisa
- Thrombolysis in Myocardial Infarction (TIMI) flow is:
TIMI flow grade 0 with occlusion originating in the stent or in the segment 5 mm proximal or distal to the stent region in the presence of a thrombusb,c OR
TIMI flow grade 1, 2, or 3 originating in the stent or in the segment 5 mm proximal or distal to the stent region in the presence of a thrombusb,c
- TIMI flow grade 0 with occlusion originating in the stent or in the segment 5 mm proximal or distal to the stent region in the presence of a thrombusb,c OR
- TIMI flow grade 1, 2, or 3 originating in the stent or in the segment 5 mm proximal or distal to the stent region in the presence of a thrombusb,c
AND at least one of the following criteria has been fulfilled within a 48 our time window:
- New acute onset of ischemic symptoms at rest (typical chest pain with duration > 20 minutes)
- New ischemic ECG changes suggestive of acute ischemia
- Typical rise and fall in cardiac biomarkers (See definition of non-procedural-related MI (i.e. spontaneous MI) in Chapter 4.
a The incidental angiographic documentation of stent occlusion in the absence of clinical signs or symptoms is not considered a confirmed stent thrombosis (silent occlusion).
b Non-occlusive thrombus:  Intracoronary thrombus is defined as a (spheric, ovoid, or irregular) non-calcified filling defect or lucency surrounded by contrast material (on three 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
c Occlusive thrombus:  TIMI 0 or TIMI 1 flow intra-stent or proximal to a stent up to the most adjacent proximal side branch or main branch (if originating from the side branch)

### b. Pathologic Confirmation of Stent Thrombosis
Evidence of recent thrombus within the stent determined at autopsy or via examination of tissue retrieved following thrombectomy.

## 2. Definite Stent Thrombosis
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
 In patients undergoing PCI for STEMI, one may consider excluding unexplained death within 30 days of the procedure as evidence of probable stent thrombosis.

## 3. Possible Stent Thrombosis
Possible stent thrombosis is considered to have occurred with any unexplained death from 30 days following intracoronary stenting until end of trial follow-up.