Intraprocedural thrombotic events
Synonyms and keywords: IPTE

# Overview
Intraprocedural thrombotic events (IPTE) are a rare group of acute ischemic complications that occur during percutaneous coronary interventions (PCI).  Although by definition IPTE should occur before the end of the PCI procedure; it can come about before or after stent-placement during PCI.       In contrast to other complications that might occur before or after PCI, IPTE has recently been recognized as a special category of complications that include distinctive risk factors and associated patient and procedural characteristics.  Most importantly, IPTE comprises a unique predictor of periprocedural and postprocedural adverse clinical outcomes and overall patient prognosis.  As such, the emergent objective understanding of IPTE and its reproducible effects are expected to render IPTE as a clinical end-point in PCI rather than a mere intraprocedural observation.

# Definition
- Intraprocedural complications comprise a group of acute ischemic complications that occur during PCI procedures.  Although by definition, intraprocedural complications should occur before the end of the PCI procedure; it can however come about before or after stent-placement during PCI.  Intraprocedural complications are currently considered an identifiable, relevant, and reproducible clinical endpoint that carries significant prognostic implications of major adverse cardiovascular events.
- According to Pride et al, intraprocedural complications include transient or sustained loss of side branch, abrupt vessel closure, distal embolization and no reflow phenomenon. McEntegart et al refer to intraprocedural complications as intraprocedural thrombotic events (IPTE) and include the following complications in the definition: abrupt vessel closure, no reflow, slow reflow, distal embolization and new or increasing thrombus formation  referred to as intraprocedural stent thrombosis (IPST).
- The definitions of intraprocedural complications in both studies were mostly similar; with the exception of slow-reflow phenomenon which was mentioned by McEntegart et al. criteria, but not by Pride et al.  The definition of new or worsening thrombus formation was based on the increasing size of the thrombus according to McEntegart et al.; while it was based on objective worsening Thrombolysis In Myocardial Infarction (TIMI) flow grade (TFG) from 2-3 to 0-1 according to Pride et al. In both studies, individual etiologies of IPTE were not mutually exclusive events.
Shown below is a table summarizing the complications included in the definition of intraprocedural complications according to Pride et al and McEntegart et al seperately.

# Epidemiology and Demographics
- The overall rate of IPTE is high, currently estimated by several studies to be between 3.5 and 11.4% of all PCI procedures.
- In 2012, McEntegart et al. performed frame-by-frame analysis for 3,428 patients with ] (NSTEACS) previously enrolled in the ACUITY trial (Acute Catherterization and Urgent Intervention Triage Strategy).  The total incidence of IPTE was 3.5% with varying rates of occurrence among specific etiologies of IPTE. 89.3% of all IPTE occurred at the level of a main branch.
- Similarly in 2012, Pride et al. evaluated 1,452 high-risk patients with NSTTEAS enrolled in the EARLY ACS trial (Early Glycoprotein IIb/IIIa in Non-ST-Segment Elevation Acute Coronary Syndrome ) who underwent angiographic assessment. Incidence of IPTE was 11.4%.
- In contrast to McEntegart, the study by Pride et al. included high-risk patients only.  High-risk criteria were defined by the authors as having at least two of the following: Ischemic changes on electrocardiography (ECG), elevated cardiac enzyme, advanced age  60 years or age between 50-59 with documented coronary artery disease, cerebrovascular disease, or peripheral vascular disease.  It is uncertain whether the inclusion criteria played a role in the increase of IPTE rates in the study as compared to McEntegarts findings.

# Associated Factors
- IPTE has been associated with the following factors:
Low pre-PCI TIMI flow grade (0-2) and corrected TIMI frame count
Low pre-PCI TIMI (0-2)
Decreased  pre-PCI minimal lumen diameter
Increased pre-PCI % stenosis
Baseline cardiac biomarker elevation or ST-deviation
- Low pre-PCI TIMI flow grade (0-2) and corrected TIMI frame count
- Low pre-PCI TIMI (0-2)
- Decreased  pre-PCI minimal lumen diameter
- Increased pre-PCI % stenosis
- Baseline cardiac biomarker elevation or ST-deviation
- Patient profiles do not generally differ among those with IPTE vs. those without IPTE.  Patient characteristics, such as existing diabetes mellitus, hypertension, hyperlipidemia, or prior PCI do not seem to play a role in IPTE.
- The use of specific home medications has also not been shown to be significantly associated with IPTE.  Pride et al. showed that use of early eptifibatide or bailout eptifibatide was significantly associated with less    Normal  0          false  false  false    EN-US  X-NONE  AR-SA                                                                     rates of IPTE.

# Complications and Prognosis
- Patients who experience intraprocedural complications are at higher risk of postprocedural 30-day and one year morbidity and mortality.  Notably, the number of intraprocedural complications also correlates with the severity of periprocedural outcomes.
- Shown below is a table demonstrating the significant difference in rates of adverse cardiac events in patients with and without IPTE.
- The risk of death or myocardial infarction (MI), especially Q-wave MI, within 30 days following PCI is four times higher in patients who experience IPTE, even after adjusting for other possible confounding risk factors.
Shown below is an image depicting the risk of death or MI in relation with the number of IPTE.
- The rates of other cardiac thrombotic and non-thrombotic complications are also significantly increased following IPTE in both the periprocedural time frame and after 1 year post-PCI.  Associated complications include stent thrombosis, unplanned revascularization, target vessel revascularization (TVR), coronary artery bypass graft (CABG), and non-CABG major bleeding.
- After evaluating angiographic results post-PCI in patients with vs. without IPTE, IPTE was found to be more significantly associated with a worse post-PCI TIMI flow grade and myocardial perfusion grade.  Interestingly, IPTE was found to be a more important correlate with 30-day death and MI than pre-PCI elevation of cardiac enzymes in the NSTEACS patient population.  However, the number of patients reported by Pride and colleagues regarding this result was very small; the exact etiology for such findings are yet to be revealed as to whether they are incidental or in fact consequences of prior unrelated cardiac events in these patients.
- Because IPTE sometimes includes adverse outcomes not accounted for in conventional PCI assessments, the addition of IPTE observations in PCI to already known risk factors of adverse outcome seems to provide a more comprehensive and more realistic prognostic impression for patients undergoing PCI.