Risk Factor For Stent Thrombosis Research Articles

Venous stent patency is independent of total stented length in nonthrombotic iliac vein and post-thrombotic venous stenoses

ObjectiveVenous stenting has become the preferred treatment of symptomatic outflow obstruction due to nonthrombotic iliac vein lesions (NIVLs) and post-thrombotic venous stenoses (PTs). A paucity of data exists regarding the effect of stent length on patency rates after intervention. We evaluated the association between stent length and patency in patients treated for iliofemoral venous outflow obstruction. MethodsThe institutional review board approved the present study. A total of 161 patients had undergone venous stenting for NIVLs and thrombotic disease from January 2016 to April 2021. For thrombotic disease, patients with PTs and those with acute deep vein thrombosis (DVT) with underlying outflow obstruction were included. The patient characteristics evaluated included gender, age, body mass index, diagnosed thrombophilia, a history of venous thromboembolism, and CEAP (clinical, etiologic, anatomic, pathophysiologic) score. All the patients had undergone multiplanar venography and intravascular ultrasound during the index procedure. The intravascular ultrasound findings were used to determine the diameter and length of the implanted stents. The patients were placed into two groups, those with stented lengths ≤100 mm and those with stented lengths >100 mm. The primary end point was stent patency between the two groups using duplex ultrasound at 6 months. ResultsA total of 108 patients (58.3% female) had had 6-month duplex ultrasound scans available for review. Their mean age was 55.6 ± 17.2 years. The mean body mass index was 31.7 ± 6.9 kg/m2. Overall, the 6-month patency was 89.9%. Of the 108 patients, 56 (51.9%) had had a total stented length of ≤100 mm with a 6-month patency of 92.9%. The remaining 52 patients (48.1%) had had a total stented length >100 mm with a 6-month patency of 86.5%. The rate of patency did not differ significantly between the two groups (P = .222). Stent patency at 6 months for patients with NIVLs was 98% (40 of 41). Stent patency for patients with PTs was 84% (32 of 38). Patency for patients with acute DVT who had undergone stenting after thrombectomy was 86% (25 of 29). Overall, 10 patients with thrombotic disease, including PT and acute DVT, had developed stent thrombosis. The total stented length was not predictive of the loss of patency. ConclusionsThese findings suggest that the length of stent coverage does not confer an increased likelihood of stent thrombosis for patients with iliofemoral venous obstruction. Interventionalists should treat the affected venous segments identified on intravascular ultrasound and effectively stent from normal to normal venous areas, regardless of the stent length required. These results suggest that the total stented length is not a risk factor for stent thrombosis for both NIVL and thrombotic iliofemoral venous lesions.

Calcified nodule progression-related stent thrombosis after polymer-based paclitaxel-eluting nitinol stent implantation for femoropopliteal artery.

Although a previous study reported favorable durability of Eluvia (Boston Scientific, Marlborough, Mass), a polymer-based paclitaxel-eluting stent (PB-PES), stent thrombosis has been reported in 1.7% of cases.1 Calcified lesions are considered risk factors for stent thrombosis.2 Nodular calcification occasionally progresses beyond the stent strut, causing restenosis and stent thrombosis.3

Cut-off value of strut-vessel distance for the resolution of acute incomplete stent apposition in the early phase using serial optical coherence tomography after cobalt-chromium everolimus-eluting stent implantation

ObjectiveThe purpose of this study was to identify a cut-off value to predict the resolution of incomplete-stent-apposition (ISA) after cobalt-chromium everolimus-eluting stent (CoCr-EES) implantation at early follow-up. BackgroundTo date, appropriate stent apposition at the acute period using intracoronary imaging has been recommended because persistent ISA is considered to be a risk factor for stent thrombosis. We examined the indices for resolving acute ISA. In particular, we determined the cut-off value for strut vessel distance (SV-distance) as visualized by optical coherence tomography (OCT) at 8 months after CoCr-EES implantation. However, the cut-off value of SV-distance for the earlier resolution of ISA is unclear. MethodsA total of 95 cases and 103 stents were registered in the MECHANISM Elective substudy. The SV-distance was measured at the deepest site of the target malapposition and every 1 mm from the proximal edge to the distal edge of the mal-apposed area using OCT. Cut-off values for ISA resolution at 1 and 3 months were estimated by SV-distance using receiver operating characteristic analysis. ResultsThe total number of analyzed struts was 14,418 at the 1-month follow-up and 11,986 at the 3-month follow-up. The optimal SV-distance cut-off values just after stent implantation to predict ISA resolution were 185 µm at the 1-month follow-up and 195 μm at the 3-month follow-up. ConclusionFor resolution of ISA, SV-distance cut-off values of 185 µm at 1 month postimplantation and 195 μm at 3 months postimplantation can be used as the index of endpoint of the percutaneous coronary intervention.

568 Imaging and quantitative estimation of thrombus burden in patients with ST elevation acute myocardial infarction (STEMI) with the use of micro-computed tomography-A methodological approach

Abstract Funding Acknowledgements Operational Program "Human Resources Development, Education and Lifelong Learning" - co-financed by the European Social Fund and Greek national funds Background Acute myocardial infarction with ST elevation (STEMI) remains one of the leading causes of mortality. High thrombus burden has been proven to be an independent risk factor for stent thrombosis and for Major Adverse Clinical outcomes. However randomized controlled trials concerning thrombus aspiration showed controversial results, providing no evidence of benefits for thrombus aspiration. A possible explanation is that aspiration was performed as a routine strategy, whereas these patients should be considered as a heterogeneous group and they should be risk-stratified. Thus, it is important to classify patients according to the volume of thrombus burden. The currently existing classifications of thrombus burden are based on visual assessment of angiographic characteristics and they are not reflecting the volume of the thrombi in actual numbers. To the best of our knowledge, never before has the exact volume of thrombus burden been quantified. Purpose The study aims to assess for the first time, through the application of innovative technologies (micro-Computed Tomography, micro-CT), important characteristics of aspirated thrombi (volume and density), which might be linked to certain clinical outcomes, in patients with STEMI. Methodology After being aspirated, thrombi are preserved in formalin. As they consist of soft tissue with low X-ray absorption, thrombi have to be stained using contrast enhancing chemicals prior to scanning; in particular a solution containing 0.3% phosphotungstic acid is used (Metscher protocol). The scanning procedure results into a series of projection images arranged in the form of image stacks which, in turn, are reformed in sections with the use of special software, which applies a modified algorithm of backward projection Feldkamp. The resulting sections are combined to create the 3D models which are further analyzed to extract useful measurements for the characteristics of the thrombi, such as volume and density. Results From January 2018 to May 2019, 66 patients were enrolled in the study. Mean age was 60.36 (±11.71) years and the majority of them (78.7%) were men. Revascularization was achieved in mean 358 ± 255 minutes from symptom onset. Distal embolization was observed in 27.5% of the patients and no-reflow phenomenon was seen in 11.6%. Angiographically evident residual thrombus burden was observed in 6 patients (8.7%). Micro-CT managed to effectively quantify the volume and the density of aspirated thrombi. Mean volume was 12.98 ± 10.84 mm3, mean density was 2992 ± 872 HU and mean surface was 0.206 ± 0.19. Conclusion Micro-CT can be used as a tool to effectively assess important characteristics of aspirated thrombi, which might be linked to certain clinical outcomes. This method could become the gold standard for the exact measurement of thrombus burden and could be used in larger, clinically-oriented trials to help stratify patients with thrombus burden according to their risk for adverse outcomes. Abstract 568 Figure. Coronary thrombi as depicted on micro-CT

Determinants of high platelet reactivity in patients with acute coronary syndromes treated with ticagrelor

High platelet reactivity (HPR) is a risk factor for stent thrombosis, a potentially lethal complication of percutaneous coronary intervention. HPR is also associated with increased risk of myocardial infarction and death in invasively-treated patients with acute coronary syndrome (ACS). HPR occurs even in ACS patients treated with ticagrelor, a state-of-the-art antiplatelet agent, especially during the first hours of treatment. Patient-level pharmacodynamic data obtained from 102 ACS subjects enrolled in two prospective, pharmacodynamic trials were analysed in order to identify clinical features related with increased odds of on-ticagrelor HPR during the first two hours after ticagrelor loading dose in ACS patients. Presence of ST-segment elevation myocardial infarction (versus non-ST-segment elevation ACS) and morphine co-administration were the strongest predictors of HPR at 1 and 2 hours after ticagrelor loading dose according to linear regression analyses, multiple backward stepwise logistic regression analyses and generalized estimating equation model. By pinpointing simple to recognize clinical features, the results of this study facilitate identification of ACS patients who have the highest odds of HPR during the initial phase of treatment with ticagrelor, and who could potentially benefit from alternative treatment strategies.

TEMPORAL TRENDS IN STENT COVERAGE OF BIORESORBABLE POLYMER AND DURABLE POLYMER DRUG-ELUTING STENTS: A META-ANALYSIS OF STRUT-LEVEL OPTICAL COHERENCE TOMOGRAPHY DATA

Delayed strut coverage is an important risk factor for stent thrombosis. The endothelialization rate of bioresorbable polymer drug-eluting stents (BP DES) may be better compared to durable polymer 2nd generation drug eluting stents (DP DES). We pooled data from all optical coherence tomography (OCT

Major risk factors of stent thrombosis in patients with acute coronary syndrome

Major risk factors of stent thrombosis in patients with acute coronary syndrome

TCT-506 Cut-off value of malapposition volume on resolution of acute incomplete stent apposition at one month using serial optical coherence tomography after cobalt- chromium everolimus-eluting stent implantation in patients with stable coronary artery disease.

A previous optical coherence tomography (OCT) study showed that incomplete stent apposition (ISA) of drug eluting stents is a major risk factor for stent thrombosis. The cobalt-chromium everolimus-eluting stent (CoCr- EES) incorporating a highly biocompatible stent is used in combination with short

Thirty days only double antiplatelet therapy after drug-eluting stenting: could a 'short-term' treatment be advantageous?

Thirty days only double antiplatelet therapy after drug-eluting stenting: could a 'short-term' treatment be advantageous?

PP052 Hospital-based Health Technology Assessment Of Prasugrel In Patients With Stent: Outpatient Use

INTRODUCTION:A reference hospital, specialized in cardiology, has standardized clopidogrel, ticagrelor and recently the incorporation of prasugrel was approved with an estimate of fifteen patients with stent implantation monthly. Stent thrombosis is a rare but serious complication and it is recommended that patients be treated with antiplatelet therapy. Considering the existing therapeutic options and the low adherence to treatment, a cost study was requested to discuss a disinvestment proposal.METHODS:Perspective of the hospital; Population: patients with myocardial infarction and stent implantation; Intervention: prasugrel; Comparators: clopidogrel and ticagrelor; Outcomes of interest: stent thrombosis and major bleeding; and types of study: meta-analyses and randomized clinical trials. Literature review was performed in the Medline database, via Pubmed and performed meta-analysis. Cost estimates: data collection made in the institution's database.RESULTS:Thirteen articles were selected; there are no differences in the outcomes for prasugrel and ticagrelor; discontinuation of treatment is the most important risk factor for stent thrombosis and major bleeding is an important predictor of nonadherence to treatment. Quantitative analysis: three clinical trials. All showed a superiority of prasugrel and ticagrelor over clopidogrel for outcome of stent thrombosis (Odds Ratio, OR .60 Confidence Interval, CI 95 percent [.40; .90]), which was committed by the heterogeneity of studies (I2 = 64 percent); and favorable outcome for clopidogrel compared to ticagrelor and prasugrel for the outcome of major bleeding (OR 1.28 CI 95 percent [1.10; 1.50]). Annual cost with treatment of the fifteen patients: clopidogrel = USD5,765.86; prasugrel = USD41,047.48; and ticagrelor = USD44,081.30.CONCLUSIONS:The evidences found support the opening of a disinvestment process and suggest to the managers of the institution a reflection on: strategy to optimize adherence to treatment; and especially in the cost of opportunity with new technologies about 10 times more expensive.

Hypersensitivity to ticagrelor and low response to clopidogrel: a case report

Ticagrelor is widely used to treat acute coronary syndrome. Hypersensitivity reaction of ticagrelor is rarely recognized. A low response to clopidogrel, which occurs in up to 23% of patients, is an independent risk factor for stent thrombosis. Management of patients with a low response to clopidogrel and ticagrelor hypersensitivity who are undergoing antithrombotic therapy remains to be a challenge. Herein, we report a patient with low response to clopidogrel and ticagrelor hypersensitivity, who was successfully managed using aspirin and warfarin.

Peripheral Stent Thrombosis Leading to Acute Limb Ischemia and Major Amputation: Incidence and Risk Factors in the Aortoiliac and Femoropopliteal Arteries

PurposeTo report the real-world incidence and risk factors of stent thrombosis in the aortoiliac and femoropopliteal arteries in case of bare nitinol stent (BNS) or covered nitinol stent (CNS) placement from a single-centre retrospective audit.Materials and MethodsMedical records of consecutive patients treated with peripheral stent placement for claudication or critical limb ischemia were audited for definite stent thrombosis defined as imaging confirmed stent thrombosis that presented as acute limb-threatening ischemia. Cases were stratified between aortoiliac and femoropopliteal anatomy. Cox regression analysis was employed to adjust for baseline clinical and procedural confounders and identify predictors of stent thrombosis and major limb loss.Results256 patients (n = 277 limbs) were analysed over a 5-year period (2009–2014) including 117 aortoiliac stents (34 CNS; 12.8 ± 5.0 cm and 83 BNS; 7.8 ± 4.0 cm) and 160 femoropopliteal ones (60 CNS; 21.1 ± 11.0 cm and 100 BNS; 17.5 ± 11.9 cm). Median follow-up was 1 year. Overall stent thrombosis rate was 6.1% (17/277) after a median of 43 days (range 2–192 days) and affected almost exclusively the femoropopliteal segment (12/60 in the CNS cohort vs. 4/100 in the BNS; p = 0.001). Annualized stent thrombosis rates (per 100 person-years) were 12.5% in case of CNS and 1.4% in case of BNS (HR 6.3, 95% CI 2.4–17.9; p = 0.0002). Corresponding major amputations rates were 8.7 and 2.5%, respectively (HR 4.5, 95% CI 2.7–27.9; p = 0.0006). On multivariable analysis, critical leg ischemia and CNS placement were the only predictors of stent thrombosis. Diabetes, critical leg ischemia, femoropopliteal anatomy, long stents and CNS were independent predictors of major amputations.ConclusionsPlacement of long femoropopliteal covered nitinol stents is associated with an increased incidence of acute stent thrombosis and ensuing major amputation. Risks are significantly lower in the aortoiliac vessels and with use of bare nitinol stents.

An Underexpanded Stent Does not Forgive

Resistant coronary lesions regularly challenge physicians performing percutaneous coronary interventions (PCI) and specific techniques may be required to achieve procedural success. Underestimation of a resistant lesion may result in implanting an underexpanded stent due to insufficient plaque modification. Stent underexpansion is a risk factor for stent thrombosis and particularly difficult to treat. We present herein a case of a resistant right coronary artery lesion, insufficiently modified before stenting and finally treated with an underexpanded stent which could not be expanded by balloon post-dilatation at the initial intervention. Two inferior wall myocardial infarctions ensued one and three years later, both due to stent thrombosis despite intensive dual antiplatelet therapy and both treated by primary PCI. The stent could only be expanded by aggressive non-compliant balloon dilatation at the last procedure. The case presentation is followed by a brief discussion concerning techniques to successfully treat resistant coronary lesions and underexpanded stents.

Causes, assessment, and treatment of stent thrombosis--intravascular imaging insights.

Stent thrombosis is a rare, but serious, complication of percutaneous coronary intervention and is associated with severe morbidity and mortality. In addition to clinical and pathological studies, intravascular imaging has advanced our understanding of the mechanisms underlying stent thrombosis. In particular, intravascular imaging has been used to study stent underexpansion, malapposition, uncovered struts, and neoatherosclerosis as risk factors for stent thrombosis. Intravascular ultrasonography and optical coherence tomography can be used to guide stent implantation and minimize the risk of stent thrombosis. Additionally, optical coherence tomography offers the unique potential to tailor treatment of stent thrombosis to address the specific mechanism underlying the thrombotic event. Bioresorbable stent technologies have been introduced with the goal of further reducing the incidence of stent thrombosis, and intravascular imaging has had an integral role in the development and assessment of these new devices. In this Review, we present insights gained through intravascular imaging into the causes of stent thrombosis, and the potential utility of intravascular imaging in the optimization of stent deployment and treatment of stent thrombosis events.

Stent thrombosis: current management and outcomes.

Stent thrombosis (ST) is an uncommon but highly morbid complication of percutaneous coronary interventions. The mechanisms leading to ST are heterogeneous, likely accounting for the variable timing and outcomes of ST. For the clinician, it is important to recognize major risk factors for ST, including discontinuation of dual antiplatelet therapy. Once ST occurs, management includes intensive antithrombotic and antiplatelet therapies. Newer antiplatelet agents may reduce the risk of ST and possibly minimize adverse outcomes after presentation with ST.

Computational Modelling of Multi-folded Balloon Delivery Systems for Coronary Artery Stenting: Insights into Patient-Specific Stent Malapposition.

Despite the clinical effectiveness of coronary artery stenting, percutaneous coronary intervention or "stenting" is not free of complications. Stent malapposition (SM) is a common feature of "stenting" particularly in challenging anatomy, such as that characterized by long, tortuous and bifurcated segments. SM is an important risk factor for stent thrombosis and recently it has been associated with longitudinal stent deformation. SM is the result of many factors including reference diameter, vessel tapering, the deployment pressure and the eccentric anatomy of the vessel. For the purpose of the present paper, virtual multi-folded balloon models have been developed for simulated deployment in both constant and varying diameter vessels under uniform pressure. The virtual balloons have been compared to available compliance charts to ensure realistic inflation response at nominal pressures. Thereafter, patient-specific simulations of stenting have been conducted aiming to reduce SM. Different scalar indicators, which allow a more global quantitative judgement of the mechanical performance of each delivery system, have been implemented. The results indicate that at constant pressure, the proposed balloon models can increase the minimum stent lumen area and thereby significantly decrease SM.

Late-Breaking Clinical Trial Abstracts

### Late-Breaking Clinical Trials: Risk and Benefit of Dual Antiplatelet Therapy #### Increased Risk of Ischemic Events Upon Discontinuation of Prasugrel After 12 or 30 Months of Therapy Following Placement of the Taxus Liberte Paclitaxel-Eluting Coronary Stent Kirk N Garratt1, Ronald D Jenkins2, Thomas K Pow3, W. Douglas Weaver4, Laura Mauri5, De J Kereiakes6, Kenneth J Winters7, Thomas Christen8, Dominic J Allocco8, David P Lee9; 1Cardiac Interventions, Lenox Hill Heart and Vascular Institute, New York, NY; 2Cardiac Interventions, Heart Clinics Northwest, Coeur d'Alene, ID; 3Cardiac Interventions, Great Lakes Heart Institute, St Joseph, MI; 4Cardiology, Henry Ford Hosp, Detroit, MI; 5Div of Cardiovascular Medicine, Brigham and Women's Hosp, Boston, MA; 6Cardiology, The Christ Hosp Heart and Vascular Cntr/The Lindner Rsch Cntr, Cincinnati, OH; 7Lilly Rsch Laboratories, Eli Lily and Company, Indianapolis, IN; 8Clinical Sciences, Boston Scientific, Marlborough, MA; 9Cardiovascular Medicine Clinic, Standford, Stanford, CA Introduction : The TAXUS Liberte Post-approval Study (TL-PAS) studied long-term clinical outcomes for the TL stent in conjunction with the use of prasugrel and aspirin. A portion of patients from TL-PAS contributed to the Dual Anti-Platelet Therapy (DAPT) trial. Methods : Eligible and consecutive patients in the United States treated with TL stents were enrolled into TL-PAS (N=4199). Those meeting inclusion and exclusion criteria were recruited for participation in the DAPT trial (N=3904). Patients received open-label prasugrel plus aspirin for 12 months after stent placement. At 12 months, patients without ischemic or bleeding events continued aspirin therapy and were randomized 1:1 to continued blinded treatment with either prasugrel or placebo for an additional 18 months (N=2202). At 30 months, study drugs were discontinued, and aspirin was continued through at least 33 months after stent placement. Events were adjudicated by a clinical events committee and monitored by the TL-PAS Data Monitoring Committee (DMC). Results : Nearly 3 years following randomization, the DMC noted a significant increase …

Impact of hemodialysis on local vessel healing and thrombus formation after drug-eluting stent implantation

BackgroundAlthough hemodialysis (HD) is a suggested risk factor for stent thrombosis, its contribution to local vessel healing after drug-eluting stent (DES) implantation is unclear. MethodsA total of 121 patients (152 lesions treated with DES) who underwent 8-month follow-up coronary angiography with optical coherence tomography (OCT) were enrolled, and the findings were compared between patients with and without HD. To match baseline differences, mid-term OCT findings of 42 propensity score-matched lesions (21 non-HD vs. 21 HD) were compared. Effects of HD on the efficacy of antiplatelet therapy were also evaluated by VerifyNow assay (Accumetrics, San Diego, CA, USA). ResultsPatients with HD had a significantly higher rate of thrombus formation than those without (64% vs. 33%, p=0.007), although the baseline parameters and lesion characteristics differed between the groups. Multivariate logistic regression analysis revealed that HD was associated with an increased risk of thrombus formation (odds ratio 5.991, 95% confidence interval: 1.972–18.199, p=0.002). Even after propensity-matching for patient background and balancing of angiographic and OCT variables, the risk of thrombus formation remained significantly higher in HD patients. The P2Y12-reaction unit was significantly increased after HD (Pre HD: 211±75 vs. Post HD: 262±59, p=0.01), but patients without HD showed no increase during the same elapsed time (221±88 vs. 212±96, p=0.19). ConclusionsHD is a potential risk factor for subclinical thrombus attachment after DES therapy. Systemic problems, such as residual platelet reactivity, associated with HD as well as local vessel features in HD patients might contribute to the increased incidence of thrombus attachment and subsequent onset of thrombotic event after DES implantation.

Stent Thrombosis after Coronary Stent Implantation: A Protective Effect of High-Dose Statin Therapy?

Objectives: To assess independent predictors of stent thrombosis (ST) in an all-comer trial. Methods: This is an observational case-control study based on a retrospective analysis of the Basel Stent Kosten Effektivitäts Trial (BASKET) (n = 826). Patients with ST were compared to controls with regard to baseline parameters. Multivariate models were performed to identify independent predictors of ST. Results: At 36 months, there were 53 (6.4%) patients with ST, 17 (32%) of whom had early ST and 36 (68%) of whom had late/very late ST. Patients with ST were at a higher cardiovascular risk but received lower doses of statins than the controls (n = 212). Stents in ST patients were longer, had more overlap and were not as well expanded, with significantly more remaining stenoses than the stents in the controls. Multivariable analysis revealed interventions in saphenous vein grafts, malapposed stents, an overlap >3 mm, complex coronary anatomy and treatment with low-dose/no statins as risk factors for ST, while interventions in saphenous vein grafts, underexpanded or malapposed stents, a history of myocardial infarction and treatment with low-dose/no statins were risk factors for late ST. Conclusions: The use of statins might have a protective effect against ST. This observation is new, hypothesis-generating and should be evaluated in an adequately powered randomized trial.

The risk for stent thrombosis after discontinuation of clopidogrel for PCI patients waiting for surgery

Purpose: A treatment dilemma currently exists in patients receiving P2Y12 inhibitors for coronary artery disease who require surgery. Product labels for P2Y12 inhibitors include a warning for thrombotic cardiac events after premature discontinuation. However, the same labels, as well as treatment guidelines, recommend to discontinue P2Y12 inhibitors 5-7 days before surgery. Premature clopidogrel discontinuation is the most pronounced risk factor for stent thrombosis (ST), and therefore, patients awaiting surgery who discontinued clopidogrel may be at increased risk for ST. However, the absolute risk of ST is unknown. This study aimed to determine the absolute risk of ST in PCI patients who premature discontinue clopidogrel and to evaluate the risk of ST post discontinuation as a function of time and duration after PCI. Methods: Reanalysis of a ST Registry including all ST patients (cases, n=437) and control patients (n=866) as part of an all-comer PCI Registry (n=21,009) was performed to determine the 1) absolute risk of ST by extrapolation of clopidogrel discontinuation rates from the ST Registry to PCI Registry, 2) risk of ST as a function of time (≤7, 8-14, 15-30 days) post discontinuation, and 3) risk of ST as a function of duration of clopidogrel therapy ≤30, ≤180 days after PCI. Clopidogrel discontinuation was variable at that time in the Netherlands, mostly because health insurance companies reimbursed anywhere between 1-12 months. Results: Clopidogrel was discontinued in 30.7% and 13.5% of the cases and controls. Of cases 37.3%, 15.7%, and 6.0% experienced ST within 7, 8-14, and 15-30 days post discontinuation. The relative risk was highest ≤7 days post discontinuation (HR 36.8; 14.6-92.4) vs. 8-14 (HR 34.9; 7.5-162.7) and 15-30 days (HR 17.7; 1.8-169.2), also after adjusting for confounding factors (adjusted HR ≤7 vs. 8-14 days: HR 53.2; 7.5-377.5; HR 29.2; 3.45-247.3). The relative risk ≤7 days post discontinuation was similar when ST occurred within 30 or 180 days after PCI (HR 33.2; 8.4-131.9; HR 28.2; 9.3-85.7). Further, the absolute risk of ST within 7 days post discontinuation was importantly increased when it occurred within ≤30, and 31-180 days after index PCI compared 181-365 days after PCI (absolute risk: 41.0%; 25.2%; 5.9%). Conclusion: Patients who premature discontinue clopidogrel are at risk for ST within 7 days post discontinuation, in particular within 180 days after index PCI. For patients awaiting surgery within 180 days after PCI, it might be optional to reduce this risk by using a rapid reversible platelet inhibitor to sustain P2Y12 inhibition until surgery.