Late stent thrombosis in patients receiving ticlopidine and aspirin after sirolimus-eluting stent implantation

Experimental assessment of effects of antiproliferative drugs of drug-eluting stents on endothelial cells

BACKGROUND

Late and very late stent thrombosis after drug-eluting stent implantation is a major concern. The present study evaluated difference in the effects of sirolimus, paclitaxel and zotarolimus on endothelial cells.

METHODS

Mouse endothelial cells were seeded in a 6-well plate. Cells were cultured with an antiproliferative drug at the expected concentrations for each well for 24 hours before making 3 scratch lines with a pipette tip. After a 4.5 hour incubation period, 3 reference scratch lines, vertically across the original scratch lines, were made in the same way. The experiment was repeated at least 6 times (6 plates). Measurements were performed at 9 crossings of each well. Wound healing ratio was calculated as 1-(distance of the first scratch/distance of the second scratch). % cell migration was calculated as (wound healing ratio at an expected drug concentration/wound healing ratio with no drug) × 100. Average % cell migration at 54 crossings of 6 plates was calculated.

RESULTS

Paclitaxel inhibited cell migration in a concentration-dependent manner. On the other hand, concentration-dependent inhibition was not observed for sirolimus or zotarolimus. Sirolimus showed a stronger inhibitory effect on migration of endothelial cells compared to zotarolimus.

CONCLUSIONS

The difference in the effect of antiproliferative drugs of drug-eluting stents on endothelial cells may be associated with relatively faster re-endothelialization of zotarolimus-eluting stent compared to the 1st generation DES.

A new generation of biodegradable polymer-coated sirolimus-eluting stents for the treatment of coronary artery disease: final 5-year clinical outcomes from the CREATE study

AIMS

The aim of the present study was to evaluate the five-year safety and efficacy of a biodegradable polymer-coated sirolimus-eluting stent with six months dual antiplatelet therapy in daily practice.

METHODS AND RESULTS

Two thousand and seventy-seven daily practice patients, exclusively treated with biodegradable polymer-coated sirolimus-eluting stents (EXCEL; JW Medical Systems, Weihai, China), were prospectively enrolled in the multicentre CREATE study. Clinical follow-up was completed in 1,982 patients (95.4%) at five-year follow-up. The rates of cardiac death, non-fatal myocardial infarction (MI), target lesion revascularisation and overall major adverse cardiac events (MACE) at five-year follow-up were 3.0%, 1.5%, 3.7% and 7.4%, respectively. The rates of definite or probable stent thrombosis (ST) at five years and definite ST from one to five years were 1.1% and 0.3%, respectively. Heart failure (hazard ratio [HR]: 3.324, 95% confidence interval [CI]: 1.729-6.391, p<0.001) and prior MI (HR: 2.664, 95% CI: 1.358-5.227, p=0.004) were independent predictors of ST. Landmark analysis of a propensity score matched patient cohort showed that patients with or without clopidogrel treatment after six months had similar clinical outcomes.

CONCLUSIONS

The present study demonstrates satisfactory and sustained five-year clinical safety and efficacy profiles as evidenced by the low rates of MACE and ST for the EXCEL, a biodegradable polymer-based sirolimus-eluting stent, when patients were treated with six months dual antiplatelet therapy in daily practice.

Efficacy and safety of low-dose clopidogrel in Japanese patients after drug-eluting stent implantation: a randomized pilot trial

In Japan, a lower maintenance dose of ticlopidine is used than in the United States and Europe. Therefore a lower maintenance dose of clopidogrel may also be considered appropriate in Japanese patients. The present randomized pilot study evaluated the efficacy and safety of 50 mg clopidogrel in Japanese patients who underwent drug-eluting stent (DES) implantation. A total of 200 patients with 277 lesions who underwent intravascular ultrasound-guided DES implantation were enrolled. The subjects were allocated to the 50- or 75-mg clopidogrel group. All patients received 100 mg aspirin daily before the procedure, and this continued indefinitely. The duration of clinical follow-up was 21.8 ± 5.7 months in the 75-mg group and 21.9 ± 6.1 months in the 50-mg group (P = 0.96). During follow-up, no cardiac death, myocardial infarction, or stent thrombosis was observed in either group. Side effects of clopidogrel were observed in 4 patients (4.0 %) in the 75-mg group and in 4 patients (4.0 %) in the 50-mg group. Following this randomized pilot study, it may be justified to perform a large-scale randomized study comparing 50- and 75-mg dosing of clopidogrel in Japanese patients undergoing coronary stent implantation.

Recovery of Endothelial Function After Sirolimus-Eluting Stent Implantation

Whether endothelial dysfunction after sirolimus-eluting stent (SES) implantation is persistent has not been fully evaluated. Endothelial function was evaluated in 152 lesions that underwent follow-up coronary angiography after SES implantation. Lesions were classified into 2 groups according to the duration between SES implantation and follow-up: ≤12 months (n = 95) and >12 months (n = 57). Changes in coronary diameter in response to 10−8 mol/L (−2.4% ± 6.3% vs −4.9% ± 3.8%, P < .01) and 10−7 mol/L acetylcholine (Ach; −4.6% ± 7.6% vs −10.7% ± 9.1%, P < .001) in segment proximal to SES were significantly attenuated in the >12-month group than in the ≤12-month group. There were less changes in coronary diameter in response to 10−8 mol/L (−2.3% ± 4.6% vs −6.9% ± 5.0%, P < .001) and 10−7 mol/L Ach (−6.5% ± 11.4% vs −16.8% ± 10.5%, P < .001) in segment distal to SES in the >12-month group. Endothelial dysfunction may diminish long after SES implantation.

Late restenosis following sirolimus-eluting stent implantation

OBJECTIVES

This serial angiographic study evaluated the incidence and predictors of late restenosis after sirolimus-eluting stent (SES) implantation.

BACKGROUND

Previous studies showed late restenosis (i.e., late catch-up phenomenon) after implantation of 7-hexanoyltaxol-eluting stents and nonpolymeric, paclitaxel-eluting stents.

METHODS

Between August 2004 and December 2006, SES implantation was performed in 1,393 patients with 2,008 lesions, in whom 8-month and 2-year follow-up coronary angiography were planned.

RESULTS

Of 2,008 lesions, 1,659 (83%) underwent 8-month follow-up angiography (8.3 ± 2.2 months). Restenosis was observed in 122 lesions (7.4%). Coronary angiography 2 years (1.9 ± 0.4 years) after SES deployment was performed in 1,168 lesions (74% of lesions without restenosis at 8-month follow-up angiography). Late restenosis was observed in 83 lesions (7.1%). There was significant decrease in minimum luminal diameter (MLD) between 8-month and 2-year follow-up (2.56 ± 0.56 mm vs. 2.35 ± 0.71 mm, p < 0.001). Multivariate analysis showed in-stent restenosis before SES implantation and MLD at 8-month follow-up as independent predictors of late restenosis.

CONCLUSIONS

Between 8-month and 2-year follow-up after SES implantation, MLD decreases, which results in late restenosis in some lesions. In-stent restenosis before SES implantation and MLD at 8-month follow-up are independent predictors of late restenosis.

Long-term safety and efficacy of low-dose clopidogrel in Japanese patients undergoing coronary stenting: a preliminary study

This study evaluated long-term safety and efficacy of low-dose (50-mg) clopidogrel in Japanese patients undergoing coronary stenting. A total of 126 patients with 153 lesions who consented to take a 50-mg maintenance dose of clopidogrel to prevent stent thrombosis were enrolled. The duration of clinical follow-up was 13.9 ± 9.7 months. There was one early stent thrombosis (0.65%). Neither late nor very late stent thrombosis was observed in patients on clopidogrel plus aspirin. Side effects of clopidogrel were observed in 9 patients (7.1%). This preliminary study shows that 50-mg maintenance dose of clopidogrel may be acceptable in Japanese patients undergoing coronary stenting.

Bare metal stent restenosis is benign clinical entity in Japanese patients

Recently, several studies have showed that bare metal stent (BMS) restenosis is not a benign clinical entity. However, clinical presentation of BMS restenosis in Japanese patients has not been fully evaluated. Follow-up coronary angiography after BMS implantation was performed in 473 patients with 523 lesions. Of these, BMS restenosis was observed in 167 lesions (31.9%). Clinical presentation of BMS restenosis was classified into 4 categories: 1) acute myocardial in-farction, 2) unstable angina, 3) stable angina, and 4) no symptom. Acute myocardial infarction (0%) and unstable angina (3.8%) were infrequent clinical presentations in patients with BMS restenosis compared to stable angina (26.9%) and no symptom (69.2%). BMS restenosis may be a benign clinical entity in Japanese patients.

Antiplatelet effect of 50-mg maintenance dose of clopidogrel compared to 200 mg ticlopidine: a preliminary study

In the United States and Europe, patients with coronary stents are maintained on 75 mg clopidogrel. Because the maintenance dose of ticlopidine in patients with coronary stents is 100 mg twice daily in Japan and 250 mg twice daily in the United States and Europe, in Japanese patients a lower dose of clopidogrel may achieve an antiplatelet effect comparable to 200 mg ticlopidine. Platelet aggregation was evaluated in 104 consecutive patients on 50 mg clopidogrel plus aspirin (n = 54) and 200 mg ticlopidine plus aspirin (n = 50). Platelets were stimulated with adenosine diphosphate (5 and 20 mumol/l) and aggregation was assessed by optical aggregometry. There was no significant difference in platelet aggregation induced with 5 (37% +/- 11% vs 38% +/- 15%, not significant) and 20 mumol/l adenosine diphosphate (48% +/- 13% vs 51% +/- 12%, not significant) between 50 mg clopidogrel and 200 mg ticlopidine. In Japanese patients, there is the possibility that a maintenance dose of 50 mg clopidogrel on platelet inhibition is comparable to 200 mg ticlopidine.

Cost analysis of sirolimus-eluting stents in the Japanese health insurance system

The cost-effectiveness of drug-eluting stents (DES) has been evaluated in the United States and Europe, however, there is little information from Japan. The present study evaluated the cost-effectiveness of sirolimus-eluting stents (SES) in Japan. In-hospital and follow-up costs of 25 consecutive patients undergoing SES implantation in a de novo lesion were evaluated. A control group for comparison was composed of 25 consecutive patients undergoing bare metal stent (BMS) implantation in a de novo lesion before the introduction of SES. There was no significant difference in resource use between the SES and BMS groups. Procedural cost (yen1,049,200 +/- 208,793 versus yen896,590 +/- 117,984, P = 0.01) was higher in the SES group than in the BMS group because of the higher reimbursement price of SES (yen378,000 versus yen258,000). In-hospital cost (yen1,202,891 +/- 208,793 versus yen1,050,280 +/- 177,984, P < 0.01) was higher in patients treated with SES. Less target lesion revascularization (4% versus 20%, P = 0.2) in patients with SES reduced the difference; aggregate 1-year cost was not significantly different (yen1,479,481 +/- 284,343 versus yen1,463,640 +/- 495,803, P = 0.9). It is concluded that SES may be cost-effective even in Japan.

Long-term clinical and angiographic follow-up in patients with isolated ostial stenosis of the left coronary artery

BACKGROUND

Isolated ostial stenosis (IOS) of the left coronary artery is a rare disease of unknown etiology, and the long-term prognosis and angiographic characteristics of affected patients have not been fully studied.

METHODS AND RESULTS

The present study investigated 57 patients with stenosis of the left main trunk (LMT) who underwent coronary artery bypass grafting (CABG). They were categorized into 3 groups, based on the angiographic findings: Group I comprised 9 patients with IOS; Group II comprised 12 patients with left coronary ostial stenosis in the presence of distal vessel obstructions; Group III comprised 36 patients with stenosis of LMT excluding ostial stenosis and associated with distal vessel obstruction. The patients underwent serial angiography at 1, 5, and 10 years after CABG. Middle aged women with fewer coronary risk factors were more common in Group I compared with Groups II and III (P<0.01). The patency rate of the internal thoracic artery grafts was significantly higher in Groups II and III than in Group I (P<0.05). In Group I, the percentage stenosis of LMT lesions decreased significantly (P<0.05), but there was no difference in the other groups.

CONCLUSIONS

IOS had clinical characteristics and time course distinct from those of atherosclerotic LMT disease.

Early stent thrombosis because of stent dislodgement in a coronary artery aneurysm

Stent thrombosis is one of the most feared complications after coronary stenting, because it often presents in a catastrophic way, triggering death or acute myocardial infarction. Previous studies report mechanical risk factors of stent thrombosis such as stent underexpansion and vessel dissection. This is a case report of early stent thrombosis associated with bare metal stent dislodgement because of dissolution of a mural thrombus in an unappreciated coronary artery aneurysm.

Use of antiplatelet agents for prevention of ischemic stroke

Overall management to lower risk for ischemic stroke is multifaceted. Management includes measures to treat risk factors for accelerated atherosclerosis and stroke, antithrombotic therapies to lower the risk for thromboembolism, and surgery to treat a defined arterial or cardiac lesion. Treatment decisions are made on a case-by-case basis, with most patients receiving some combination of medication and recommendations for lifestyle modification. Some patients will also undergo surgical or endovascular interventions. This article discusses antithrombotic treatment for ischemic stroke prevention, placing major emphasis on the indications for and administration of antiplatelet therapy.

Effect of 150-mg vs 300-mg loading doses of clopidogrel on platelet function in Japanese patients undergoing coronary stent placement

BACKGROUND

The loading dose of ticlopidine is 500 mg in both the US and Europe and 200 mg in Japan. A lower loading dose of clopidogrel might achieve adequate platelet inhibition in Japanese patients.

METHODS AND RESULTS

Platelet aggregation was serially measured at baseline, and 2, 4, 6, and 8 h after 150-mg (n=20) and 300-mg (n=20) clopidogrel loading. Platelets were stimulated with 5 and 20 micromol/L adenosine diphosphate (ADP) and aggregation was assessed by optical aggregometry. Pretreatment ADP-induced platelet aggregation in the 150-mg clopidogrel group did not differ from that of the 300-mg group. The administration of 300-mg clopidogrel loading dose resulted in lower platelet aggregation 2 h after the administration (5 micromol/L ADP: 53+/-9% vs 61+/-12%, p<0.05 and 20 micromol/L ADP: 61+/-10% vs 68+/-9%, p<0.05). A lower platelet aggregation induced with 20 micromol/L ADP was still observed 4 h after the 300-mg clopidogrel loading (58+/-10% vs 65+/-9%, p<0.05).

CONCLUSIONS

The 150-mg clopidogrel loading does not achieve rapid platelet inhibition. The 300-mg loading dose should be used to suppress platelet function rapidly even in Japanese patients undergoing coronary stent placement.

Safety and efficacy of low-dose clopidogrel in Japanese patients undergoing coronary stenting: preliminary 30-day clinical outcome

BACKGROUND

A lower maintenance dose of clopidogrel may be appropriate in Japanese patients because the maintenance dose of ticlopidine is lower in Japan than that used in the United States.

METHODS AND RESULTS

A total of 126 patients with 153 lesions who consented to take 50-mg clopidogrel to prevent stent thrombosis were enrolled. There was 1 case of early stent thrombosis (0.65%). Side-effects of clopidogrel occurred in 5 patients (4.0%).

CONCLUSION

This preliminary study shows that 50 mg clopidogrel may be acceptable in Japanese patients.