Prevention of stent thrombosis: challenges and solutions

Figures & data

Table 1 Academic Research Consortium classification of stent thrombosis based on timing of events

Acute stent thrombosis*	0–24 hours after stent implantation
Subacute stent thrombosis*	24 hours to 30 days after stent implantation
Late stent thrombosis	30 days to one year after stent implantation
Very late stent thrombosis	One year after stent implantation

Note:

* The term “early stent thrombosis” can be used to supplant acute and subacute stent thrombosis, according to the original Academic Research Consortium document. Copyright © 2007. Cutlip DE, Windecker S, Mehran R, et al. Academic Research Consortium. Academic Research Consortium clinical end points in coronary stent trials: a case for standardized definitions. Circulation. 2007;115:2344–2351.²

Table 2 “Trilevel of Certainty” classification of stent thrombosis proposed by the Academic Research Consortium

Definite stent thrombosis: angiographic confirmation of stent thrombosis

Presence of a thrombus that originates in the stent or in the segment 5 mm proximal or distal to the stent and presence of at least one of the following criteria within a 48-hour time window:

• Acute onset of ischemic symptoms at rest

• New ischemic electrocardiographic changes that suggest acute ischemia

• Typical rise and fall in cardiac biomarkers

• Nonocclusive thrombus

• Intracoronary thrombus

• Occlusive thrombus

• TIMI 0 or TIMI 1 intrastent or proximal to a stent up to the most adjacent proximal side branch or main branch

Definite stent thrombosis: 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

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 myocardial infarction 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

Considered to have occurred with any unexplained death from 30 days after intracoronary stenting until end of trial follow-up

Note: Copyright © 2007. Cutlip DE, Windecker S, Mehran R, et al. Academic Research Consortium. Academic Research Consortium clinical end points in coronary stent trials: a case for standardized definitions. Circulation. 2007;115:2344–2351.²

Abbreviation: TIMI, thrombolysis in myocardial infarction.

Table 3 Risk of early stent thrombosis according to clinical presentation

	Stable Angina	UA/NSTEMI	STEMI
Bare-metal stents, %	0–0.5	1.4–1.6	0–2.9
Drug-eluting stents, %	0.3–0.4	1.2–1.9	0–3.1

Note: Reproduced with permission from Lippincott Williams and Wilkins/Wolters Kluwer Health: Cook S, Windecker S. Early stent thrombosis: past, present, and future. Circulation. 2009;119:657–659.⁷

Abbreviations: STEMI, ST segment elevation myocardial infarction; NSTEMI, non-ST segment elevation myocardial infarction; UA, unstable angina.

Table 4 Select material characteristics of drug-eluting stents

Stent type	Paclitaxel-eluting stent	Sirolimus-eluting stent	Everolimus-eluting stent	Zotarolimus-eluting stent
Strut^Citation30 thickness, μm	97–132	140	81	91
Platform^Citation30 material	Stainless steel	Stainless steel	Cobalt or platinum-chromium	Cobalt-chromium
Propensity for ST versus BMS	Greater	Greater	Lower or similar	Lower or similar

Abbreviations: ST, stent thrombosis; BMS, bare metal stent.

Figure 1 Incomplete stent strut coverage.

Notes: (A) A well-expanded stent with adequate stent strut coverage by endothelialization. (B) Poor neointimal coverage of similar stent struts, creating a risk factor for stent thrombosis. Red indicates arterial wall; blue indicates neointimal coverage; gray indicates stent strut.

Table 5 Risk factors associated with higher rates of stent thrombosis

Stent characteristics	APT associations	Angioplasty-related factors	Lesion-related factors	Medical comorbidities
First-generation DES	Discontinuation of APT	Stent underexpansion	Length	Diabetes (insulin-dependent)
Inflammation or hypersensitivity to DES coating	APT resistance	Incomplete strut coverage	Location	Renal failure
		Stent malapposition	Diameter	Low ejection fraction
		Stent-associated dissection	Complexity	ACS as presentation
		Downstream/upstream CAD	Underlying clinical presentation (STEMI)	Predisposing thrombogenic conditions
		Vulnerable neoatheromas within stents	Multivessel CAD	Cigarette smoking

Abbreviations: ACS, acute coronary syndrome; APT, antiplatelet therapy; DES, drug-eluting stent; CAD, coronary artery disease; STEMI, ST segment elevation myocardial infarction.

Table 6 Major clinical trials from which data for stent thrombosis have been derived

RCT/registry	Stent comparison	Patients (n)	Acuity of CAD	Results related to ST (%)
SIRIUS^Citation62	SES vs BMS	1,058	De novo CAD	0.4 vs 0.8 (P=0.448)
C-SIRIUS^Citation69	SES vs BMS	100	De novo CAD (small vessel)	0.01 vs 0.01 (P=1.0)
TAXUS-I^Citation70	PES vs BMS	61	De novo CAD or restenotic lesion	0 vs 0
TAXUS-II^Citation71	PES-SR vs PES-MR vs BMS	536	De novo CAD	2.7 vs 1.7 vs 0.8 (P=0.32)
TAXUS-IV^Citation72	PES vs BMS		De novo CAD (single vessel)	0.8 vs 0.8 (P=0.98)
TAXUS-V ISR^Citation73	Brachytherapy vs PES (Extrapolated)	396	ISR in prior BMS	2.6 vs 1.6 (P=0.72)
OPTIMIST^Citation74,*	DES vs BMS vs unascertained stent	100	Angiographically proven ST	50 vs 39 vs 11
SPIRIT IV^Citation67	EES vs PES	3,687	De novo CAD	0.2 vs 0.8 (P=0.004)
COMPARE^Citation68	EES vs PES (Extrapolated)	1,800	De novo CAD	0.7 vs 2.6 (P=0.002)
ACUITY^Citation75	DES (89%) vs BMS (11%)	3,405	ACS	1.4 vs 1.4 (P=1.00)

Note:

* OPTIMIST trial primarily looked at optimal angiographic reperfusion rates in patients with angiographically proven ST.

Abbreviations: RCT, randomized controlled trial; CAD, coronary artery disease; ST, stent thrombosis; BMS, bare metal stent; SES, sirolimus-eluting stent; ISR, in-stent restenosis; DES, drug-eluting stent; PES, paclitaxel-eluting stent; SR, slow release; MR, moderate release; EES, everolimus-eluting stent; ACS, acute coronary syndrome; vs, versus.

Figure 2 Strategies to prevent stent thrombosis.

Abbreviations: IVUS, intravenous ultrasound; OCT, optical coherence tomography; ST, stent thrombosis.

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