Late thrombosis following treatment of in-stent restenosis with drug-eluting stents after discontinuation of antiplatelet therapy

Thrombin-Induced Platelet-Fibrin Clot Strength Identified by Thrombelastography: A Novel Prothrombotic Marker of Coronary Artery Stent Restenosis

BACKGROUND AND OBJECTIVE

In-stent restenosis (ISR) is a limitation of percutaneous coronary intervention and has been linked to specific clinical and angiographic variables. We aimed to simultaneously assess thrombosis biomarkers and lipid levels in patients with and without ISR.

METHODS

Consecutive patients (n = 170) with a history of coronary stenting undergoing elective angiography were studied. Blood samples for thrombelastography, light transmittance aggregometry, and lipid levels were obtained prior to cardiac catheterization.

RESULTS

Sixty-nine patients (41%) had ISR (>50% luminal diameter stenosis). Among patients with ISR, 40 (58%) had ISR in more than one stent bed. Patients with ISR were more often female (37.7% vs. 21.8%, P = 0.04), had higher thrombin-induced platelet-fibrin clot strength (TIP-FCS) (69.9 mm vs. 65.6 mm, P < 0.001), and a higher ApoB/A1 ratio (0.65 vs. 0.59, P = 0.03). In patients on dual antiplatelet therapy (n = 86), there were no differences in ADP-, arachidonic acid-, and collagen-induced platelet aggregation between groups. The frequency of patients with ISR increased with TIP-FCS quartiles and by ROC analysis, TIP-FCS = 67.0 mm was the cutpoint for identification of ISR (AUC = 0.80 (95%CI 0.73-0.87, P < 0.0001). By multivariate analysis, TIP-FCS ≥67.0 mm strongly associated with ISR (OR = 7.3, P = 0.004).

CONCLUSION

Patients with ISR identified at the time of cardiac catheterization have a prothrombotic phenotype indicated by high TIP-FCS, a novel marker. Studies to confirm the prognostic utility of high TIP-FCS for the development of ISR are ongoing.

Relation of drug-eluting stent strut distribution to stent thrombosis in coronary arteries

The distribution of stent struts is critical to drug deposition and, therefore, may affect the amount of neointima and the risk of thrombosis after drug-eluting stent (DES) implantation. The aim of our study was to evaluate stent strut distribution in the setting of a drug-eluting stent thrombosis (ST). We retrospectively analyzed postprocedural intravascular ultrasound (IVUS) images of 13 patients who subsequently developed ST (14 DES thrombotic lesions) and a control group of 27 patients (30 DES lesions) matched for stent type and presence of chronic renal failure. In addition to standard IVUS measurements, visible struts were counted and maximum interstrut angle was measured at 1-mm intervals. Early ST was defined as < or =30 days after DES deployment and late ST as >30 days after DES deployment. Compared with DES controls, the ST group had a larger maximum interstrut angle (60.8 +/- 8.3 degrees vs 55.7 +/- 4.8 degrees , p = 0.014) and a similar number of stent struts (8.4 +/- 0.6 vs 8.7 +/- 0.6, p = NS). Maximum interstrut angle tended to be larger in late ST than in early ST (66.1 +/- 10.8 degrees vs 57.8 +/- 5.0 degrees , p = 0.071). The incidence of maximum interstrut angles > or =90 degrees and > or =120 degrees observed continuously for > or =2 mm of stent length was higher in the ST group (p = 0.009 and p = 0.096, respectively). In conclusion, DES-treated lesions leading to ST had larger maximum interstrut gaps distributed circumferentially and longitudinally, but a similar number of struts at the time of DES implantation compared with DES controls.

Coronary artery stents: Part I. Evolution of percutaneous coronary intervention

The subspecialty of interventional cardiology has made significant progress in the management of coronary artery disease over the past three decades with the development of percutaneous coronary transluminal angioplasty, atherectomy, and bare-metal and drug-eluting stents (DES). Bare-metal stents (BMS) maintain vessel lumen diameter by acting as a scaffold and prevent collapse incurred by angioplasty. However, these devices cause neointimal hyperplasia leading to in-stent restenosis and requiring reintervention in more than 20% of patients by 6 mo. DES (sirolimus and paclitaxel) prevent restenosis by inhibiting neointimal hyperplasia. However, DESs also delay endothelialization, causing the stents to remain thrombogenic for an extended, yet unknown, period of time. Late stent thrombosis is associated with a 45% mortality rate. Premature discontinuation of antiplatelet therapy, particularly clopidogrel, is the strongest predictor of stent thrombosis. Sixty percent of patients receive stents for off-label (unapproved) indications, which also increases the frequency of stent thrombosis. Clopidogrel and aspirin are the cornerstone of therapy in the prevention of stent thrombosis in both BMS and DES. Recommendations pertaining to the optimal duration of dual-antiplatelet therapy have been debated. Both the Food and Drug Administration and the American Heart Association/American College of Cardiologists, in association with other major societies, have made recommendations to extend the duration of dual-antiplatelet therapy in patients with DES to 1 yr. The 6-wk duration of dual-antiplatelet therapy in patients with BMS remains unchanged. All patients with coronary stents must remain on life-long aspirin monotherapy. Since the introduction of percutaneous transluminal coronary angioplasty for the treatment of coronary atherosclerosis, the practice of percutaneous coronary intervention has undergone a dramatic transformation from simple balloon dilation catheters to sophisticated mechanical endoprostheses. These advancements have impacted the practice of perioperative medicine. In this series of two articles, in Part I we will review the evolution of percutaneous coronary intervention and discuss the issues associated with percutaneous transluminal coronary angioplasty and coronary stenting; in Part II we will discuss perioperative issues and management strategies of coronary stents during noncardiac surgery.

Biocompatibility of tetramethylpyrazine-eluting stents in normal porcine coronary arteries

OBJECTIVE

Drug-eluting stents have been used to markedly decrease in-stent restenosis in 6 months, but they are noticed due to the late thrombogenicity. The purpose of the present study was to evaluate the biocompatibility of Tetramethylpyrazine-eluting stents by investigating the intimal response and thrombogenicity in normal porcine coronary arteries by quantitative coronary angiography (QCA), intravascular ultrasound (IVUS) and histomorphometry.

METHODS

Bare metal stents (BMS) were uniformly spray-coated with Tetramethylpyrazine (TMP 200 microg) and prepared for TMP-eluting stents (TES). Fourteen coronary arteries in 14 pigs underwent stent implantation. Seven TES were implanted in 7 pigs and 7 BMS in other 7 pigs. The stents were deployed with a stent-to-artery ratio of 1.1-1.2/1.0 in order to induce vascular wall injury. QCA and IVUS were performed before and immediately after the implantations and at 28 days (end time point). The analysis on blood cell count, biochemical parameters, status of behavior of pigs were evaluated before the implantation and at the time of 1 and 28 days. Stented-coronary arteries, stented-coronary arteries related ventricular wall, lung, liver and kidney were harvested after euthanasia of animals at the endpoint. Histopathology and histomorphometry had been done to assess the local toxicity of TES to these organs.

RESULTS

All the stents were successfully implanted, however, 4 pigs died of cardiac tamponade or anesthesia. No bone marrow depression and hemolysis was seen. No damage to the function and metabolism of liver and kidney was discovered. No thrombosis was found in control and test groups. Few inflammatory cells were found in the stented-coronary artery walls at each endpoint in both groups. No damage to stented-coronary arteries related ventricular wall, lung, liver and kidney was detected due to TES implantation. Compared with the control group, the neointimal area was significantly reduced in the TES group (60.2+/-23.5% vs 10.0+/-2.1%, P=0.01) by IVUS analysis, but the lumen area in the TES group was increased (4.34+/-0. 93 mm(2) vs 1.29+/-1.02 mm(2), P=0.011), the neointimal area was reduced markedly (1.51+/-0.45 mm(2) vs 4.60+/-1.39 mm(2), P=0.004).

CONCLUSIONS

The biocompatibility of TES in porcine model at 28 days seems to be good and acceptable. Biocompatibility can be evaluated by IVUS and histopathology in a porcine restenosis model.

Intravascular ultrasound parameters associated with stent thrombosis after drug-eluting stent deployment

Drug-eluting stent (DES) thrombosis (ST) can be devastating. The study aim was to evaluate intravascular ultrasound (IVUS) predictors for DES thrombosis by comparing IVUS studies after implantation in 13 patients with 14 DES thrombosis lesions with a group of controls (30 lesions in 27 patients) matched for history of chronic renal failure and type of DES. Five patients (38%) discontinued dual antiplatelet therapy at the time of ST. There were 3 in-stent restenosis lesions (21%) treated using DESs in the ST group compared with 0 in the control group (p <0.05). Compared with the control group, IVUS studies in the ST group showed a smaller minimum stent area (4.6 +/- 1.1 vs 5.6 +/- 1.7 mm(2), p = 0.0489). In the ST group, 11 of 14 stents had a minimum stent area < or =5.0 mm(2) compared with 12 of 30 in the control group (p = 0.0392). Minimum stent area in patients who stopped clopidogrel therapy and developed ST (5.30 +/- 1.15 mm(2)) tended to be larger compared with that in patients who developed ST while using clopidogrel (4.24 +/- 0.96 mm(2), p = 0.091). Within the 5-mm-long proximal and distal reference segments analyzed, the ST group had larger proximal reference maximum plaque burdens and smaller minimum lumen areas, along with a tendency toward similar findings in the distal reference segments. In conclusion, IVUS findings at the time of DES implantation in patients who subsequently developed ST showed a smaller minimum stent area (especially in patients who developed ST while using clopidogrel) and more residual disease at the stent edges.

Drug eluting stents for ST-elevation myocardial infarction: risk and benefit

Drug-eluting stents have been a major advance in percutaneous coronary revascularization. Widespread use of these stents has been spurred by substantial reductions in restenosis rates when compared with bare metal stents. The use of drugeluting stents during ST-segment elevation myocardial infarction has been a common practice and is associated with lower revascularization rates in various studies. Unfortunately, significant concerns regarding the occurrence of late stent thrombosis with this technology persist. A clinical dilemma exists as to whether the benefits of reduced repeat revascularization with DES outweigh the harm caused by a possible increased occurrence of the infrequent but devastating complication of late stent thrombosis. This review with discuss the theoretical risks and benefits of DES for STEMI, the available data regarding their use, and the areas where future studies are needed.

Analysis of 36 reported cases of late thrombosis in drug-eluting stents placed in coronary arteries

Drug-eluting stents (DESs) have decreased the incidence of in-stent restenosis. Within the past 2 years several cases on late stent thrombosis (LST) have been reported. This study analyzed and reviewed all published cases of LST in DESs to explore possible trends not previously reported. We applied a Medline search using the key word "drug eluting stents." All 845 positive matches in March 2006 were screened for case reports of LST in DESs, defined as angiographic stent thrombosis >or=30 days after deployment. We included reported LSTs from randomized trials, observational registry reports, and letters to the editor if information regarding timing from stent deployment to clinical event, vessel, stent diameter and length, and antiplatelet regimen were available. There was no significant difference in the incidence of LST between sirolimus- and paclitaxel-eluting stents. Median time from stent deployment to clinical event was 242 days (total range 39 to 927). If aspirin and clopidogrel were discontinued, median time to clinical event was 7 days (3 to 150). In comparison, if only clopidogrel was discontinued, median time to clinical event was 30 days (14 to 690, p <0.0001). There was no significant difference in stent diameter and length between sirolimus- and paclitaxel-eluting stents. Forty-two percent of events occurred in relation to a surgical procedure for which the 2 antiplatelet agents or clopidogrel alone was discontinued. In conclusion, there was a strong association between occurrence of LST and cessation of dual antiplatelet therapy. Patients who continued on aspirin had a significant delay to the clinical event. Efforts should be made to maintain patients on aspirin during routine surgical procedures.

Contemporary treatment of in-stent restenosis and the incidence of recurrent in-stent restenosis in the era of drug-eluting stents

BACKGROUND

Optimal treatment of in-stent restenosis (ISR) remains uncertain in the era of drug-eluting stents (DES). This study aims to determine contemporary treatment of ISR and to assess recurrent ISR rates in the era of DES.

METHODS

We examined 60 patients presenting for treatment of ISR (one lesion per patient) who were enrolled in the Melbourne Interventional Group Registry (4% of total population of 1423 patients) between April 2004 and January 2005. Twelve-month follow-up is complete for all patients.

RESULTS

The majority of ISR treated occurred in bare metal stents [BMS (n=52, 87%)] and had a focal (<10 mm) pattern of ISR (53%). In-stent restenosis of DES occurred in eight (13%) patients. The majority of ISR were treated with additional stenting with a preference for DES over BMS in almost all cases. At 12 months, one patient died of non-cardiac cause and four patients (7%) presented with recurrent ISR. The incidence of recurrent ISR in DES was 5% (n=3). No late thrombosis was reported despite only 50% of patients having >or=12 months of clopidogrel therapy.

CONCLUSIONS

Our study suggests drug-eluting stents are safe, effective and the preferred therapy for in-stent restenosis. The incidence of recurrent drug-eluting stent restenosis at 12 months is low.

Frequency of coronary arterial late angiographic stent thrombosis (LAST) in the first six months: outcomes with drug-eluting stents versus bare metal stents

Concerns have been raised about the long-term safety of drug-eluting stent (DES) implantation due to late angiographic stent thrombosis (LAST). We investigated the incidence and 6-month clinical and angiographic outcomes of LAST after DES versus bare metal stent (BMS) implantation. This study comprised 6,551 patients treated with BMSs (n = 4,104) or DESs (n = 2,447). LAST was defined as angiographically proved stent thrombotic occlusion with acute ischemic symptoms >30 days after stenting. Major adverse cardiac events were defined as death, Q-wave myocardial infarction, and target lesion revascularization. Patients treated with DESs had a significantly higher risk profile than did patients treated with BMSs. There were 8 cases (0.33%) of LAST in the DES group and 7 (0.17%) in the BMS group, showing similar event rates after risk adjustment (adjusted hazard ratio 1.2, 95% confidence interval 0.1 to 18.4, p = 0.9). Four patients with LAST treated with DESs (50%) and 1 treated with BMSs (14%) were associated with discontinuation of antiplatelet therapy. Two cases (25%) of LAST with DESs occurred in patients on aspirin monotherapy and another 2 cases (25%) occurred in patients on dual antiplatelet therapy. There was no case of in-hospital death associated with LAST events. At 6-month follow-up after LAST events, major adverse cardiac events occurred in only 3 patients (43%) in the BMS group. In conclusion, the incidence of LAST was similar after DES and BMS implantations. LAST treated with DESs was associated with antiplatelet therapy discontinuation in a significant number of patients, and LAST events also developed on dual antiplatelet therapy. Patients with LAST and DESs showed favorable outcomes during follow-up.

Implementing a best-treatment strategy with intracoronary brachytherapy for in-stent restenosis in patients at high risk for recurrence

BACKGROUND

The deployment of drug-eluting stents (DES) to treat bare-metal stent restenosis [in-stent restenosis (ISR)] has become routine practice, with a consequential decline in the use of intracoronary brachytherapy (ICBT). However, there are concerns as to the long-term safety profile of DES, particularly in terms of late stent thrombosis. In addition, an appropriate treatment strategy for stenosis within DES has not been developed. The aim of this study was to examine the efficacy of best treatment with ICBT for ISR in patients at high risk for future recurrence.

METHODS

Forty-seven consecutive patients with symptomatic ISR with at least one or more increased risk criteria for recurrence were treated with beta-radiation. The patients received best treatment based on avoidance of previously reported procedural risk factors for recurrence (incomplete stent apposition, dissection, geographical miss, and damage to the noninjured vessel segment), deferring ICBT when provisional stenting was performed. A beta-radiation dose of 20 Gy was used, and clopidogrel was prescribed for at least 6 months.

RESULTS

Treatment was successful for all patients without in-hospital complications. ICBT increased the total intervention procedure time by 15+/-10 min. ISR length was 25.4+/-11.5 mm. The angiographic minimal luminal diameter (MLD) was 2.24+/-0.43 mm after ICBT versus 0.75+/-0.58 mm at baseline (P<.05). On 9-month follow-up, the MLD was 1.93+/-0.48 mm (P<.05 vs. baseline). Binary restenosis was detected in six (13%) patients. At 29.7+/-9.3 months of follow-up, target lesion revascularization or target vessel (nonlesion) revascularization was performed in 17 (36%) patients. Only one patient suffered a myocardial infarction, and no deaths were observed.

CONCLUSION

The adoption of a best-practice protocol for the use of ICBT to treat ISR can result in a safe and effective clinical and angiographic outcome. Under these circumstances and with appropriate patient selection, ICBT may continue to be of value despite the popular use of DES.

Is late stent thrombosis in drug-eluting stents a real clinical issue? A single-center experience and review of the literature

BACKGROUND

Randomized studies have not found an increased rate of late stent thrombosis (LAST) in drug-eluting stents (DES) compared with bare metal stents (BMS) but those studies were statistically not powered to show such a difference. At the same time there is an increasing number of reports of LAST in DES patients in the current literature.

PATIENTS AND METHODS

We tried to describe the incidence of LAST in an unselected DES and BMS patient population. All patients who underwent stenting in our hospital between October 2003 and March 2006 were included in the study (n=1377). A total of 424 (30.1%) patients were treated with only BMS stents, 520 (37.8%) with paclitaxel-eluting stents (PES), 384 (27.9%) with sirolimus-eluting stents (SES) and 49 (3.6%) with BMS and DES. Long-term follow-up of all patients was used to determine the incidence of LAST as defined by angiographically proven stent thrombosis associated with acute symptoms more than 30 days after stent implantation. Followup was between 1 month and 2 years 7 months (mean 12 months). Patients treated with DES were younger (66+/-11 years) than BMS patients (72+/-10 years; p<0.001) and more often had diabetes (24.2% vs 17.4%; p < 0.001). A previous PCI had been performed in 27.1% of DES patients vs 13.9% of BMS patients (p < 0.001).

RESULTS

There were 9 cases of LAST: 2 with SES (at 6 and 11 months after implantation), 6 with PES (at 6, 9 (2x), 10, 16 and 26 months), and one with BMS (at 22 months). All patients with LAST presented with STEMI and without an angina history that suggested restenosis. Two cases were related to complete cessation of antiplatelet therapy, one because of patient non-compliance (SES), one after aspirin was stopped for orthopedic surgery (BMS). Two cases occurred within 1 month of cessation of clopidogrel therapy and while these patients were on aspirin therapy. Five cases occurred on aspirin monotherapy 2, 3, 4, 10 and 20 months, respectively after planned cessation of clopidogrel. None of the cases occurred under dual antiplatelet therapy. All patients underwent primary PCI; none died.

CONCLUSION

Angiographically proven LAST occurred in our unselected patient population with an incidence of 0.84% in patients treated with DES and 0.21% in BMS patients within a mean follow-up of 12 months (p = 0.36). LAST may indeed occur in clinically stable patients while on aspirin monotherapy. Since LAST led in all patients to STEMI it seems to be a serious clinical issue that prompts further investigation and discussion of length of dual platelet therapy.

Drug-eluting stents for stent thrombosis elevation acute myocardial infarction: do we need randomized trials?

Since their introduction, drug-eluting stents have rapidly altered modern medicine's approach to coronary artery disease. Before the development of drug-eluting stents, standard bare-metal stents were plagued by in-stent restenosis, requiring repeat revascularization in as many as 15-20% of patients during the first 6-12 months following implantation [1]. The currently approved drug-eluting stents have dramatically reduced this complication by using a polymer-impregnated coating that elutes either paclitaxel or sirolimus to inhibit smooth muscle proliferation. The pivotal TAXUS-IV [2] and SIRIUS [3] trials compared drug-eluting stents with standard bare-metal stents and found rates of target vessel revascularization ranging from 3 to 4.1% in stable coronary artery disease patients - far lower than that had been seen previously with conventional standard bare-metal stents. After their approval in April 2003, drug-eluting stents use in clinical practice expanded rapidly. Within 9 months of their introduction, drug-eluting stents comprised 35% of all stent implantations in the United States [4]. In the last year at our own institution, drug-eluting stents comprised over 85% of all stents implanted. Despite their extensive use, data regarding the efficacy and safety of drug-eluting stents in certain clinical scenarios are limited. To date, the only published data supporting drug-eluting stents in ST[corrected]-elevation acute myocardial infarction come from the retrospective Rapamycin-Eluting Stent Evaluated at Rotterdam Cardiology Hospital registry [5] and the randomized, controlled single high-dose bolus tirofiban and sirolimus-eluting stent vs. abciximab and bare-metal stent in myocardial infarction study [6]. In this chapter, we discuss the theoretical risks and benefits of drug-eluting stents for ST elevation acute myocardial infarction, the available data regarding their use, and the areas in which future studies are needed.

Prevalence, Predictors, and Outcomes of Premature Discontinuation of Thienopyridine Therapy After Drug-Eluting Stent Placement

Background— Although drug-eluting stents (DES) significantly reduce restenosis, they require 3 to 6 months of thienopyridine therapy to prevent stent thrombosis. The rate and consequences of prematurely discontinuing thienopyridine therapy after DES placement for acute myocardial infarction (MI) are unknown.

Methods and Results— We used prospectively collected data from a 19-center study of MI patients to examine the prevalence and predictors of thienopyridine discontinuation 30 days after DES treatment. We then compared the mortality and cardiac hospitalization rates for the next 11 months between those who stopped and those who continued thienopyridine therapy. Among 500 DES-treated MI patients who were discharged on thienopyridine therapy, 68 (13.6%) stopped therapy within 30 days. Those who stopped were older, less likely to have completed high school or be married, more likely to avoid health care because of cost, and more likely to have had preexisting cardiovascular disease or anemia at presentation. They were also less likely to have received discharge instructions about their medications or a cardiac rehabilitation referral. Patients who stopped thienopyridine therapy by 30 days were more likely to die during the next 11 months (7.5% versus 0.7%, P <0.0001; adjusted hazard ratio=9.0; 95% confidence interval=1.3 to 60.6) and to be rehospitalized (23% versus 14%, P =0.08; adjusted hazard ratio=1.5; 95% confidence interval=0.78 to 3.0).

Conclusions— Almost 1 in 7 MI patients who received a DES were no longer taking thienopyridines by 30 days. Prematurely stopping thienopyridine therapy was strongly associated with subsequent mortality. Strategies to improve the use of thienopyridines are needed to optimize the outcomes of MI patients treated with DES.

Two-year follow-up of sirolimus-eluting stents for the treatment of proximal left anterior descending coronary artery stenosis

INTRODUCTION

Sirolimus-eluting stents (SES) have demonstrated low target vessel revascularizations and low incidence of angiographic restenosis in several clinical scenarios. The aim of the present study was to assess the efficacy and safety of SES for the treatment of proximal left anterior descending coronary artery (pLAD) lesions.

METHODS

Ninety-six patients with severe pLAD stenosis were enrolled. Angiographic and clinical follow-up were performed at 6 and 24 months, respectively. Death, myocardial infarction (MI), new target lesion revascularization (TLR), and target vessel failure (TVF) were registered. Clinical, angiographic, and procedural variables were analyzed to identify predictors of restenosis.

RESULTS

Mean clinical follow-up was 858+/-158 days (26.5+/-8.3 months). Angiographic procedural success was 100%. Angiographic follow-up showed 8.4% of binary restenosis without edge-restenosis phenomenon. Late loss was 0.15+/-0.65 mm; 15.6% of patients had an adverse cardiac event, with 1% of death, 5.2% of MI, 6.3% of TLR, and 9.4% of TVF. At 2 years, the probabilities of cumulative TVF- and TLR-free survival were 90.6% and 93.7%, respectively. Interestingly, no adverse cardiac events were registered between the first and second years. Female gender (OR 10.7 CI 95%[1.7-66.7]) and in-stent restenosis (OR 8.2, CI 95%[1.2-56.4]) were found as independent predictors of binary restenosis. Advanced chronic renal failure showed a strong trend toward worse outcome in terms of binary restenosis (P=0.063).

CONCLUSIONS

SES for the treatment of pLAD stenosis proved safe and effective in a long-term follow-up with low incidence of adverse cardiac events and restenosis. Female gender and in-stent restenosis were predictors of binary restenosis.

Very late thrombosis after sirolimus-eluting stent implantation

Drug-eluting stents are widely used to prevent restenosis after coronary angioplasty. We here report a case of stent thrombosis within a sirolimus-eluting stent occurring two years after stent implantation, while the patient was on chronic aspirin therapy. The patient presented with acute ST-elevation myocardial infarction and pulmonary oedema; stent thrombosis was successfully treated with coronary angioplasty and deployment of a new coronary stent. This case suggests that long-term follow-up is needed in clinical studies on drug-eluting stents.