Intraprocedural thrombotic events

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

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 however 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, associated patient and procedural characteristics, and most importantly 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 is expected to render IPTE as a clinical end-point in PCI rather than a mere intraprocedural observation.

Classification

• New thrombus formation
• Increased thrombus size
• Abrupt vessel closure
• No reflow phenomenon (new TIMI flow grade 0 or 1)
• Slow reflow phenomenon (new TIMI flow grade 2)
• Distal embolization
• Loss of side branch
• Intraprocedural stent thrombosis (IPST)

Epidemiology and Demographics

• The overall rate of IPTE is currently estimated to be 3.5-11.4% of all PCI procedures.
• In 2012, McEntegart et al. performed frame-by-frame analysis for 3,428 patients with non-ST elevation acute coronary syndrome (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 McEntegart’s findings.

Natural History, 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.

Adverse Cardiac Events	In-hospital	30-day	1-year
Patients with IPTE	25.6%	30.6%	37%
Patients without IPTE	6.3%	9.3%	20.5%

• 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.

• 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.

References

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