Restenosis after coronary placement of various stent types.

Coronary stent implantation is being performed in an increasing number of patients with a wide spectrum of clinical and lesion characteristics. A variety of stent designs are now available and continuous efforts are being made to improve the stent placement procedure. The objective of this study was to perform a comprehensive analysis of the relation between clinical, lesion, and procedural factors, and restenosis after intracoronary stenting in a large and unselected population of patients. A consecutive series of 4,510 patients with coronary stent placement was analyzed. Exclusion criteria were only a failed procedure and an adverse outcome within the first month after the intervention. Follow-up angiography was performed in 80% of patients at 6 months. Clinical, lesion, and procedural data from all 3,370 patients (4,229 stented lesions) with follow-up angiography were analyzed in a logistic regression model for restenosis (> or =50% diameter stenosis). Clinical factors contributed to the predictive power of the model much less than lesion and procedural factors. The strongest risk factor for restenosis was a small vessel size, with a 79% increase in the risk for a vessel of 2.7 mm versus a vessel of 3.4 mm in diameter. Stent design was the second strongest factor; the incidence of restenosis ranged from 20.0% to 50.3% depending on the stent type implanted. In conclusion, this study demonstrates the predominant role of lesion and procedural factors in determining the occurrence of restenosis after coronary stent placement. Among these factors, stent design appears to play a particularly important role in the hyperplastic response of the vessel wall.

Coronary microvascular reactivity to sympathetic stimulation in patients with idiopathic dilated cardiomyopathy.

UNLABELLED: The objective of this study was to assess noninvasively the microvascular reactivity to sympathetic stimulation in patients with idiopathic dilated cardiomyopathy (IDC) and in healthy volunteers, who underwent cardiac catheterization for exclusion of coronary artery disease. METHODS: Myocardial flow was quantified with 13N-ammonia PET and tracer kinetic modeling at rest and in response to cold pressor testing (CPT). Ten healthy volunteers (8 men, 2 women; mean age +/- SD, 50.7 +/- 15 y) and 10 matched patients (8 men, 2 women; mean age, 52.5 +/- 14 y) with IDC (mean left ventricular ejection fraction, 0.30 +/- 0.12) were included in the study. RESULTS: Myocardial perfusion at rest was not significantly different between the groups. However, myocardial vascular resistance (MVR) was significantly lower in IDC patients at rest than in healthy volunteers. In response to CPT a significant decrease in MVR was found in healthy volunteers (1.9 +/- 0.4 to 1.5 +/- 0.4 mm Hg x 100 g/mL; 22% decrease) but not in IDC patients (1.5 +/- 0.4 to 1.4 +/- 0.3 mm Hg x 100 g/mL; 9% decrease). Consequently, the increase of the myocardial blood flow in response to CPT was significantly lower (P < 0.008) in IDC patients (56 +/- 17 to 66 +/- 18 mL/100g/min; 20% increase) compared with healthy volunteers (52 +/- 12 to 80 +/- 30 mL/100 g/min; 52% increase), whereas both showed comparable hemodynamic reactions. CONCLUSION: The data indicate that CPT in combination with 13N PET imaging is a valuable noninvasive tool for assessment of coronary microvascular reaction to sympathetic stimulation in IDC patients. Lower coronary vascular resistance was found in IDC patients at rest compared with healthy volunteers, suggesting possible exhaustion of sympathetically induced dilation of the coronary microvasculature in IDC patients at rest. This mechanism may explain the impaired flow response to cold in IDC patients in the present study.

Effect of glycoprotein IIb/IIIa receptor blockade with abciximab on clinical and angiographic restenosis rate after the placement of coronary stents following acute myocardial infarction.

OBJECTIVES: In the Intracoronary Stenting and Antithrombotic Regimen-2 trial (ISAR-2), we sought to investigate the effect of abciximab on angiographic and clinical restenosis after stenting following acute myocardial infarction (AMI). We also intended to assess the impact of abciximab on clinical outcome in this setting. BACKGROUND: It is unclear whether abciximab reduces neointima formation after stenting. Such an effect may be particularly prominent in thrombus-containing lesions. METHODS: Patients undergoing stenting within 48 h after onset of AMI were randomly assigned to receive either standard-dose heparin or abciximab plus reduced-dose heparin. Of 401 patients randomized, 366 without 30-day adverse events were eligible for six-month angiographic follow-up. Scheduled angiography was performed in 80% of these patients. RESULTS: By 30 days, the composite clinical end point of death, reinfarction, and target lesion revascularization (TLR) was reached in 5.0% of the abciximab group and in 10.5% of the control group (p = 0.038). At one year, absolute reduction in the composite clinical end point by abciximab was still 5.7% but had lost its statistical significance. Our primary end point, late lumen loss, was 1.26+/-0.85 mm with abciximab and 1.21+/-0.74 mm with standard heparin (p = 0.61), and binary angiographic restenosis rates were 31.1% and 30.6%, respectively (p = 0.92). CONCLUSIONS: In patients undergoing stenting following AMI, abciximab exerted beneficial effects by substantially reducing the 30-day rate of major adverse cardiac events. During one-year follow-up, there was no additional benefit from a reduction in TLR nor did abciximab reduce angiographic restenosis.

Early recovery of coronary flow reserve after stent implantation as assessed by positron emission tomography.

OBJECTIVES: The aim of this study was to quantitatively evaluate myocardial flow reserve in patients early after coronary stent implantation using positron emission tomography. BACKGROUND: Delayed restoration of coronary flow reserve after percutaneous transluminal coronary angioplasty (PTCA) has been observed using a variety of techniques. Altered distal vasoregulation as well as residual stenosis have been considered possible explanations for this phenomenon. Although the implantation of stents may influence some of these mechanisms, little data are available characterizing coronary flow reserve early after stent placement. METHODS: In 14 patients 1.6 +/- 0.6 days after stenting, N-13-ammonia positron emission tomographic studies were performed at rest and during adenosine-induced vasodilation. Myocardial blood flow was quantified using a three-compartment model. Rest and stress flow data, as well as coronary flow reserve of stented vascular territories, were compared with that of remote areas. RESULTS: The stenosis decreased from 72.1 +/- 7.3% to 3.7 +/- 6.7% after stent implantation. Coronary flow in the stented areas did not differ significantly from that in remote areas either at rest (76.1 +/- 18.5 and 75.7 +/- 17.7 ml/min/100 g, respectively), or during maximal vasodilation (205.5 +/- 59.9 and 179.4 +/- 47.4 ml/min/100 g, respectively). In addition, there was no significant difference in the calculated values of coronary reserve of these two regions (2.74 +/- 0.64 and 2.43 +/- 0.55, respectively). CONCLUSIONS: The mechanical support of dilated arteries by a stent not only restores the macroscopic integrity of epicardial arteries, but also results, in contrast to conventional PTCA procedures, in early recovery of flow reserve.

Influence of balloon pressure during stent placement in native coronary arteries on early and late angiographic and clinical outcome: A randomized evaluation of high-pressure inflation.

BACKGROUND: High-pressure dilatation is considered a better stent placement strategy, but this has not yet been proved by appropriately designed studies. The objective of this randomized trial was to assess the role of high-pressure dilatation in the early and late outcome of patients undergoing coronary stent placement. METHODS AND RESULTS: Consecutive patients with coronary stent placement were randomly assigned to high- (15 to 20 atm, 468 patients) or low- (8 to 13 atm, 466 patients) balloon-pressure dilatation. The primary end point of the study was the event-free survival at 1 year. Secondary end points were the incidence of stent thrombosis at 30 days and angiographic restenosis (>/=50% diameter stenosis) at 6 months. The incidence of stent thrombosis was 1.7% in the high-pressure and 1.9% in the low-pressure group (relative risk 0.89; 95% CI 0.30 to 2.56). During the first 30 days, although there was no significant difference in the incidence of Q-wave myocardial infarction, the incidence of non-Q-wave infarction was 6.4% in the high-pressure and 3.4% in the low-pressure group (relative risk 1. 87; 95% CI 1.02 to 3.42). The restenosis rate was 30.4% in the high-pressure and 31.4% in the low-pressure group (relative risk 0. 97; 95% CI 0.75 to 1.26). Event-free survival at 1 year was not significantly different between the groups, with 78.8% in high-pressure patients and 75.5% in patients assigned to low-pressure dilatation (hazard ratio 0.85; 95% CI 0.65 to 1.11). CONCLUSIONS: The systematic use of high-balloon-pressure inflation (15 to 20 atm) during coronary stent placement is not associated with any significant influence on the 1-year outcome of patients undergoing this intervention.

Prognostic value of the modified american college of Cardiology/American heart association stenosis morphology classification for long-term angiographic and clinical outcome after coronary stent placement.

Background-The modified American College of Cardiology/American Heart Association (ACC/AHA) lesion morphology criteria are predictive of early outcome after various coronary catheter interventions. Their potential prognostic value after stent implantation and, in particular, for restenosis and long-term clinical outcome has not been studied. We assessed the prognostic value of the modified ACC/AHA criteria for the long-term angiographic and clinical outcome of patients after coronary stenting. Methods and Results-This study includes 2944 consecutive patients with symptomatic coronary artery disease treated with coronary stent placement. Modified ACC/AHA lesion morphology criteria were used to qualitatively assess the angiograms; type A and B1 lesions were categorized as simple, and type B2 and C lesions were designated complex. Primary end points were angiographic restenosis and 1-year event-free survival. Restenosis rate was 33.2% in complex lesions and 24.9% in simple lesions (P<0.001). It was 21. 7% for type A, 26.3% for type B1, 33.7% for type B2, and 32.6% for type C lesions. One-year event-free survival was 75.6% for patients with complex lesions and 81.1% for patients with simple lesions (P<0. 001). It was 85.2% for patients with type A, 79.4% for type B1, 75. 9% for type B2, and 75.2% type C lesions. The higher risk for restenosis and an adverse outcome associated with complex lesions was also maintained after multivariate adjustment for other clinical and angiographic characteristics. Conclusions-The modified ACC/AHA lesion morphology scheme has significant prognostic value for the outcome of patients after coronary stent placement. Lesion morphology is able to influence the restenosis process and thus the entire 1-year clinical course of these patients.

Effect of glycoprotein IIb/IIIa receptor blockade on recovery of coronary flow and left ventricular function after the placement of coronary-artery stents in acute myocardial infarction.

BACKGROUND: Apart from its established effects on vessel patency after percutaneous coronary revascularization, glycoprotein IIb/IIIa receptor blockade by abciximab may improve myocardial perfusion by inhibition of the interaction of platelets and platelet aggregates with the microvasculature. We investigated the effect of abciximab with stent placement in acute myocardial infarction. METHODS AND RESULTS: In a prospective randomized trial, patients undergoing stenting in acute myocardial infarction within 48 hours after onset of symptoms were randomly assigned to receive either standard-dose heparin or abciximab plus low-dose heparin. Immediately after the procedure and at 14-day angiographic follow-up, we assessed flow velocity in the recanalized vessel with the Doppler wire and regional wall motion by the centerline method. End points were changes in papaverine-induced peak flow velocities and in wall motion indices. We assigned 98 patients to standard heparin and 102 to abciximab. We obtained 152 paired flow measurements and 151 paired left ventricular function studies. Residual stenoses of the treated lesions did not differ between the 2 groups. Improvement of peak flow velocity (mean [95% CI]: 18.1 cm/s [13.6 to 22.6 cm/s], n=80, versus 10.4 cm/s [5.4 to 15.4 cm/s], n=72, P=0.024) and wall motion index (0.44 SD/chord [0.29 to 0.59 SD/chord], n=79 versus 0. 15 SD/chord [0.00 to 0.30 SD/chord], n=72, P=0.007) was significantly greater in patients assigned to abciximab than in those on heparin alone. At follow-up, the abciximab group had a higher global left ventricular ejection fraction than the heparin group (62% [59% to 65%] versus 56% [53% to 59%], P=0.003). CONCLUSIONS: Abciximab had important effects beyond the maintenance of large-vessel patency. It improved the recovery of microvascular perfusion and concomitantly enhanced the recovery of contractile function in the area at risk.

Restenosis rate after intravascular ultrasound-guided coronary stent implantation.

This study was designed to test the hypothesis that patients fulfilling intravascular ultrasound (IVUS) criteria for optimal coronary stent implantation show a reduction in the restenosis rate at 6 months. IVUS guidance for stent dilation may be associated with facilitated stent implantation and an increased acute luminal gain, but it has not yet been determined, whether and to what extent this procedure is associated with a reduction in the restenosis rate. IVUS-guided optimization of Palmaz-Schatz stent placement was performed in 125 consecutive patients, 64 of whom fulfilled IVUS-criteria for optimal stent placement. Another 125 patients served as the non-IVUS control group. In 107 patients (86%) of the non-IVUS control group and 105 patients (84%) of the IVUS group, angiographic follow-up was performed. The IVUS group of patients revealed a significantly lower restenosis rate of 20.9% as compared with 29.9% in the control group (P = 0.033). Patients that met IVUS criteria for optimal stent placement had a larger minimal lumen diameter immediately after stent implantation (3.13 +/- 0.44 vs. 2.95 +/- 0.47 mm; P = 0.045) and at 6-month follow-up (2.23 +/- 0.78 vs. 1.87 +/- 0.76 mm; P = 0.019) as well as a significantly lower restenosis rate (13.5% vs. 28.3%; P = 0.038) as compared with patients that did not fulfil these criteria. Our data suggest that patients fulfilling IVUS criteria for optimal stent placement demonstrate a reduced risk for the development of restenosis. Thus, IVUS investigation identifies factors predictive of restenosis after coronary stent placement.

Myocardial perfusion scintigraphy to evaluate patients after coronary stent implantation.

UNLABELLED: Coronary stent implantation is an increasingly accepted revascularization method. The 20%-30% restenosis rate during the first 6 mo requires a close follow-up of the patients. Since there is very little data available defining the role of perfusion scintigraphy in the management of this population, the aim of this study was to assess the diagnostic performance of stress myocardial perfusion imaging for detecting restenosis in patients after coronary stent implantation. METHODS: In 82 patients, 93 rest or stress SPECT studies were performed using 201Tl and 99mTc-hexakis-2-methoxyisobutyl isonitrile to evaluate 99 vascular territories with implanted coronary stents. The average interval between the stent implantation and the scintigraphic study was 210.5 +/- 129.6 days. The scintiscans were visually evaluated. A stress-induced perfusion defect with reversibility at rest was used as the criterion for stent restenosis. RESULTS: Coronary angiography revealed a stenosis of > 50% diameter in the region of the stent in 19 arteries, while in 80 arteries there was no evidence of restenosis angiographically. With perfusion scintigraphy, 15/19 vascular territories with restenosed stents showed stress-induced perfusion abnormalities (sensitivity = 79%), while 62/80 territories without restenosis did not (specificity = 78%). In territories without a myocardial infarction (n = 48), sensitivity and specificity values were 8/8 (100%) and 36/44 (82%), and in territories with a myocardial infarction (n = 47) 7/11 (64%) and 26/36 (72%), respectively. Side branch stenosis was fairly frequent in patients without stent restenosis but with a reversible perfusion pattern on their scintiscan (8/18); however, these stenoses were induced infrequently by the stents (3 cases). CONCLUSION: Using the criterion of defect reversibility, stress perfusion SPECT can accurately detect restenoses of coronary artery stents. This method is most accurate for evaluating patients without a previous myocardial infarction in the stented vascular territory.

Recovery of myocardial perfusion in acute myocardial infarction after successful balloon angioplasty and stent placement in the infarct-related coronary artery.

OBJECTIVES: This study sought to investigate changes in myocardial perfusion after direct percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (MI). BACKGROUND: After initially successful recanalization of the infarct-related artery, coronary perfusion may deteriorate as a result of reocclusion, distal embolization of platelet aggregates formed at the dilated plaque or microvascular reperfusion injury. This change could offset the benefit from early intervention. METHODS: The study included 19 patients in whom the infarct-related artery was successfully recanalized by PTCA with Palmaz-Schatz stent placement within 24 h after the onset of pain. Basal and papaverine-induced coronary blood flow were assessed by Doppler flow velocity measurements and quantitative coronary angiography. In addition, basal and adenosine-induced myocardial blood flow were measured by nitrogen-13 ammonia positron emission tomography (PET). RESULTS: Immediately after completion of the intervention, the average coronary flow reserve (CR) in the recanalized vessel was 1.56 +/- 0.51; it increased to 2.04 +/- 0.65 at 1 h (p = 0.013) and to 2.66 +/- 0.72 at 2 weeks after reperfusion (p = 0.008, n = 16). PET studies in 12 patients revealed that perfusion defect size and CR in the infarct region (2.19 +/- 0.89 vs. 2.33 +/- 0.86) did not change significantly between day 2 after recanalization and 2 weeks. However, we found significant (p < 0.03) increases in basal (by 26%) and adenosine-induced (by 40%) blood flow in the infarct region. CONCLUSIONS: Despite the persistence of a perfusion defect after successful recanalization of the occluded artery in acute MI, CR of the infarct region improves in most patients within 1 h and further improves within 2 weeks.

Comparison of angiography and intravascular ultrasound for the assessment of lumen size after coronary stent placement: impact of dilation pressures.

This study was designed to assess the extent of potential discrepancies between intravascular ultrasound (IVUS) and quantitative coronary angiography (QCA) measurement of intrastent minimal luminal diameter and to evaluate the impact of dilation pressures and the balloon:artery ratio on the assessment of the minimal lumen diameter (MLD) by these imaging modalities. IVUS is recommended as an adjunct to angiography to assess stent expansion; however, the extent of potential discrepancies between the two imaging modalities is not well defined. Included were 225 patients in whom coronary Palmaz-Schatz stents were successfully placed after PTCA. IVUS and QCA were performed at the end of the intervention. We compared the MLD assessed by QCA and IVUS in the instent and reference site. The MLD assessed by IVUS and QCA were 2.68 +/- 0.41 mm and 3.08 +/- 0.47 mm (P < 0.001), respectively, at the tightest intrastent site and 3.19 +/- 0.50 mm and 3.17 +/- 0.52 ns at the reference site. There was a correlation between the dilation pressure and the difference between QCA- and IVUS-based intrastent MLD measurement (y = -0.05x + 1.11; r = -0.53; P < 0.0001). At low dilation pressures, a significant difference between the image modalities was found, but after high dilation pressures no discrepancies were detected. No relation was found with the balloon:artery ratio. These data provide clear evidence that in the case of low-pressure dilation, the exclusive reliance on data obtained by QCA will not yield sufficiently accurate information on intrastent MLD, whereas after high dilation pressure, the differences between the imaging modalities are minimized.

Antiplatelet effect of ticlopidine after coronary stenting.

OBJECTIVES: This study sought to investigate the contribution of ticlopidine to the inhibition of platelet activation after coronary stent placement. BACKGROUND: After coronary stenting, antiplatelet therapy with aspirin and ticlopidine improves stent patency compared with anticoagulation. However, the specific role of ticlopidine has not been elucidated. METHODS: After successful coronary stent placement, we randomized 22 patients to receive ticlopidine and aspirin (ticlopidine group) and 25 to receive aspirin alone (aspirin group). Surface expression on platelets of the activated fibrinogen receptor and of P-selectin was assessed by flow cytometry. RESULTS: In the aspirin group the percent of platelets with activated fibrinogen receptors increased between days 1 and 5 (p = 0.001), whereas there were no substantial changes in the ticlopidine group. The percent of P-selectin-positive platelets did not change significantly in the aspirin group but decreased in the ticlopidine group (p = 0.019). At day 5 after the intervention, the percent of platelets with activated fibrinogen receptors in the ticlopidine group was significantly lower (median [interquartile range]: 8.5 [3.1 to 17.8] vs. 18.1 [8.5 to 35.5], p = 0.025), and there was a trend to fewer P-selectin-positive platelets than in the aspirin group (5.8 [3.4 to 9.5] vs. 8.8 [4.0 to 15.8], p = 0.073). CONCLUSIONS: Combined antiplatelet therapy with ticlopidine plus aspirin is superior to treatment with aspirin alone in suppressing platelet activation after coronary stenting.

Coronary stent placement in patients with acute myocardial infarction: comparison of clinical and angiographic outcome after randomization to antiplatelet or anticoagulant therapy.

OBJECTIVES: The Intracoronary Stenting and Antithrombotic Regimen (ISAR) trial is a randomized comparison of combined antiplatelet with anticoagulant therapy after coronary Palmaz-Schatz stent placement. The objective of this study was to compare early and late clinical and angiographic outcome in a subgroup of patients with stent placement for acute myocardial infarction. BACKGROUND: Stenting has become a treatment option for acute myocardial infarction, but it is not known which antithrombotic regimen is more adequate after stent implantation. METHODS: One hundred twenty-three patients with successful stenting after acute myocardial infarction were randomized to receive aspirin plus ticlopidine (n = 61) or intense anticoagulant therapy (n = 62). Six-month repeat angiography was performed in 101 (86.3%) eligible patients. RESULTS: During the first 30 days after stenting, patients with antiplatelet therapy had a significantly lower clinical event rate (3.3% vs. 21.0%, p = 0.005) and stent vessel occlusion rate (0% vs. 9.7%, p = 0.03) and a trend to fewer cardiac events (1.6% vs. 9.7%, p = 0.12). After 6 months, the survival rate free of recurrent myocardial infarction was higher in patients with antiplatelet therapy (100% vs. 90.3%, p = 0.03), and the rate of stent vessel occlusion was lower (1.6% vs. 14.5%, p = 0.02). Both groups had comparable restenosis rates (26.5% vs. 26.9%, p = 0.87). CONCLUSIONS: This study demonstrates that combined antiplatelet therapy after stent placement in patients with acute myocardial infarction is associated with an overall better clinical and angiographic outcome than anticoagulant therapy.

Intravascular ultrasound-guided emergency coronary Palmaz-Schatz stent placement without post-procedural systemic anticoagulation.

OBJECTIVE: To test the efficacy of intravascular ultrasound (IVUS)-guided stent placement and to determine the clinical outcome during the first 30 days in those patients who were treated with antiplatelet therapy rather than anticoagulants because they met the IVUS criteria for optimal stent placement. DESIGN: Prospective observational study. PATIENTS: 126 patients with successful, non-elective Palmaz-Schatz stent placement. INTERVENTIONS: IVUS was performed to assess the attachment of stent struts, the coverage of the dissection, and the intrastent minimal lumen area. MAIN OUTCOME MEASURES: Intrastent lumen area, clinical outcome during the first 30 days. RESULTS: In all patients IVUS showed complete apposition and coverage of the dissection. In 23 patients (18%) the IVUS lumen area criterion was achieved. In 75 patients, further balloon dilatation was performed and in 41 IVUS criteria were finally fulfilled. The minimal intrastent lumen area increased from a mean (SD) of 6.81 (1.15) mm2 to 9.56 (2.61) mm2 (P < or = 0.01) between the first and final IVUS investigations. 64 patients (51%) who met the IVUS criteria were treated with aspirin (100 mg) and ticlopidine (250 mg) twice a day. During the first 30 days none of the following events occurred: death, myocardial infarction, repeat intervention, aortocoronary bypass surgery, and subacute stent thrombosis. CONCLUSION: The additional information provided by IVUS examination helped the operator to decide whether further dilatation was needed after a coronary stent had been placed. For patients who met the IVUS criteria for optimal stent placement, antiplatelet therapy was associated with an excellent clinical outcome during the first 30 days.

A randomized comparison of antiplatelet and anticoagulant therapy after the placement of coronary-artery stents.

BACKGROUND: The clinical benefit of coronary-artery stenting performed in conjunction with coronary angioplasty is limited by the risk of thrombotic occlusion of the stent as well as hemorrhagic and vascular complications of intensive anticoagulation. We compared antiplatelet therapy with conventional anticoagulant therapy with respect to clinical outcomes 30 days after coronary-artery stenting. METHODS: After successful placement of Palmaz-Schatz coronary-artery stents, 257 patients were randomly assigned to receive antiplatelet therapy (ticlopidine plus aspirin) and 260 to receive anticoagulant therapy (intravenous heparin, phenprocoumon, and aspirin). The primary cardiac end point was a composite measure reflecting death from cardiac causes or the occurrence of myocardial infarction, aortocoronary bypass surgery, or repeat angioplasty. The primary noncardiac end point comprised death from noncardiac causes, cerebrovascular accident, severe hemorrhage, and peripheral vascular events. RESULTS: Of the patients assigned to antiplatelet therapy, 1.6 percent reached a primary cardiac end point, as did 6.2 percent of those assigned to anticoagulant therapy (relative risk, 0.25; 95 percent confidence interval, 0.06 to 0.77). With antiplatelet therapy, there was an 82 percent lower risk of myocardial infarction than in the anticoagulant-therapy group, and a 78 percent lower need for repeat interventions. Occlusion of the stented vessel occurred in 0.8 percent of the antiplatelet-therapy group and in 5.4 percent of the anticoagulant-therapy group (relative risk, 0.14; 95 percent confidence interval, 0.02 to 0.62). A primary noncardiac end point was reached by 1.2 percent of the antiplatelet-therapy group and 12.3 percent of the anticoagulant-therapy group (relative risk, 0.09; 95 percent confidence interval, 0.02 to 0.31). Hemorrhagic complications occurred only in the anticoagulant-therapy group (in 6.5 percent). An 87 percent reduction in the risk of peripheral vascular events was observed with antiplatelet therapy. CONCLUSIONS: As compared with conventional anticoagulant therapy, combined antiplatelet therapy after the placement of coronary-artery stents reduces the incidence of both cardiac events and hemorrhagic and vascular complications.

Correlation between LDA and ultrasound heart catheter measurements in a stenosed arterial model.

Ultrasound heart catheters are used to measure the velocity in coronary arteries. However, the act of introducing a catheter into the vessel disturbs the very flow being measured. We used laser Doppler anemometry to measure the velocity distribution in an axially symmetric model, both with and without a catheter inserted. The catheter reduced the center-line velocity by as much as 60 percent at a distance of 2 mm downstream from the catheter, and by as much as 25 percent at a distance of 10 mm. This means the velocity measured with an ultrasound catheter does not show the maximum velocity of the undisturbed flow in the tube center. In the constriction, however, the measured velocities with the LDA and ultrasound catheter are almost the same. Thus, catheter measurements in the stenosis achieve accurate results. The velocity profile in the stenosed areas is flattened over nearly the whole cross section. The velocity is extremely reduced only close to the wall. The measurements outside of the stenosis lead to large differences which need to be studied carefully in the future. The disturbed flow finally disappeared 15 mm downstream of the catheter. The measurements were done at steady flow using a glycerine water solution with a dynamic viscosity of 4.35 mPas. In future studies, these experiments will be repeated for pulsatile flow conditions using non-Newtonian blood-like fluids.

Four-year experience with Palmaz-Schatz stenting in coronary angioplasty complicated by dissection with threatened or present vessel closure.

BACKGROUND: Abrupt vessel closure after percutaneous transluminal coronary angioplasty (PTCA) is associated with major adverse events. Different surgical and nonsurgical approaches have been advocated to treat or prevent this complication. This study summarizes our 4-year experience with Palmaz-Schatz stenting for the management of 339 patients with present or threatened occlusion after PTCA. METHODS AND RESULTS: Stent implantation was attempted in a total of 339 and 4959 patients with PTCA during the study period and was successful in 327 (96.5%). During the follow-up, events like death, myocardial infarction, need for revascularization (bypass surgery and repeat in-stent angioplasty), and major vascular complications were recorded. Angiographic follow-up at 6 months was performed in 89.3% of the eligible patients. As part of an initial policy, stenting was intended as a bridge to nonemergency bypass surgery in 26 patients. In 301 patients for whom stenting was intended as permanent treatment, early clinical course (first 4 weeks) was characterized by a 1.3% cardiac mortality and a 4.0% nonfatal myocardial infarction rate; bypass surgery was necessary in 1%, and 6.3% required early repeat PTCA. Surgical repair for peripheral vascular complications was required in 5.6%, and major bleeding events were encountered in 9%. The incidence of subacute stent closure was 6.9%, with subsequent recanalization successful in 86%; subacute stent closure was predicted by presence of vessel occlusion before stenting and localization of the stent in a vessel other than the right coronary artery. Survival rate at 2 years was 95.4%, survival without myocardial infarction was 91.1%, and event-free survival was 70.7%. Survival at 2 years was lower for patients with stents in bypass vein grafts and with myocardial infarction after stenting. Six-month control angiography revealed a restenosis rate of 29.6%. CONCLUSIONS: Patients with present or threatened occlusion after PTCA may benefit from Palmaz-Schatz stenting. It is associated with a low mortality and myocardial infarction rate and with a long-term event-free rate comparable to that of uncomplicated PTCA.