Restenosis after successful percutaneous transluminal coronary angioplasty: serial angiographic follow-up of 229 patients

The predictive value of exercise QRS duration changes for post-PTCA coronary events

BACKGROUND

The sensitivity and predictive values of exercise ECG testing using ST-T criteria after percutaneous transluminal coronary angioplasty (PTCA) are low, precluding its routine use for screening for restenosis. The predictive value of QRS duration criteria during exercise testing (ET) ECG after PTCA for future coronary events has not been reported. The aim of the study was to compare QRS duration changes with ST-T criteria during ET, as a predictor of coronary events after PTCA.

METHODS

A prospective study of 206 consecutive patients who underwent ET at a mean of 34 +/- 14 days after their first PTCA, and were the followed for a mean of 23 +/- 9 months. Patients were divided by QRS duration into two groups-Q1: ischemic response (QRS duration prolongation of more than 3 ms relative to the resting duration), and Q2: normal response (QRS duration shortening or without change from resting duration). Patients were also divided by their ST-T response, S1: ischemic response, and S2: normal response.

RESULTS

During follow-up 52 patients (58%) experienced restenosis or MI, or underwent CABG-Q1: 44 (85%), Q2: 8(15%) (P < 0.0002), S1: 8 (15%), S2: 44 (85%), (P < 0.641), two patients died-Q1: 1 (1%) and Q2: 1 (1%). For QRS and ST-T, the relative risk of having at least one of the coronary events was 4.02 (CI 2.1-9.9) versus 1.13 (CI 0.8-2.9), respectively. The sensitivity for future coronary events was 85% and 52% and the specificity was 48% and 98% for the QRS and ST-T criteria, respectively.

CONCLUSION

QRS prolongation during peak ET ECG after PTCA is a more sensitive marker than ST-T criteria for detection of patients at risk for later coronary events.

Reno, a European postmarket surveillance registry, confirms effectiveness of coronary brachytherapy in routine clinical practice

PURPOSE

To assess, by a European registry trial, the clinical event rate in patients with discrete stenotic lesions of coronary arteries (de novo or restenotic) in single or multiple vessels (native or bypass grafts) treated with beta-radiation.

MATERIALS AND METHODS

Between April 1999 and September 2000, 1098 consecutive patients treated in 46 centers in Europe and the Middle East with the Novoste Beta-Cath System were included in Registry Novoste (RENO).

RESULTS

Six-month follow-up data were obtained for 1085 patients. Of 1174 target lesions, 94.1% were located in native vessels and 5.9% in a bypass graft; 17.7% were de novo lesions, 4.1% were restenotic, and 77.7% were in-stent restenotic lesions. Intravascular brachytherapy was technically successful in 95.9% of lesions. Multisegmental irradiation, using a manual pullback stepping maneuver to treat longer lesions, was used in 16.3% of the procedures. The in-hospital rate of major adverse cardiac events was 1.8%. At 6 months, the rate was 18.7%. Angiographic follow-up was available for 70.4% of the patients. Nonocclusive restenosis was seen in 18.8% and total occlusion in 5.7% of patients. A combined end point for late (30-180 days) definitive or suspected target vessel closure was reached in 5.4%, but with only 2% of clinical events. Multivariate analysis was performed for major adverse cardiac events and late thrombosis.

CONCLUSIONS

Data obtained from the multicenter RENO registry study, derived from a large cohort of unselected consecutive patients, suggest that the good results of recent randomized controlled clinical trials can be replicated in routine clinical practice.

Exercise stress testing, myocardial perfusion imaging and stress echocardiography for detecting restenosis after successful percutaneous transluminal coronary angioplasty: a review of performance

When chest symptoms recur in a patient who underwent percutaneous transluminal coronary angioplasty (PTCA), it is necessary to rule out restenosis (R). Three main noninvasive tests suggest the presence of R: exercise stress test (XT), myocardial perfusion imaging (MPI) and stress echocardiography (s-echo). The objectives of this review were: (1) to estimate the pretest probability of R as a function of time after PTCA in symptomatic patients and (2) to obtain an approximation of the diagnostic parameters of the XT, MPI and s-echo for detecting R. A MEDLINE search (English-language, years: 1980-2001) was conducted to identify studies examining post-PTCA functional testing for diagnosing R. Data from the studies were pooled. Comparing studies was often difficult due to varying methodology in the studies. Pretest probability of R in symptomatic patients increases in a nonlinear fashion from 20% or less at 1 month, to nearly 90% at 1-year postangioplasty. The approximated accuracy of the XT, MPI, and s-echo for detecting R was 62, 82 and 84%, respectively. During the first month after PTCA, none of the noninvasive modalities is able to accurately detect R. Late (7-9 months) after PTCA, the pretest probability of R is high and therefore the noninvasive measure may be spared. Our analysis suggests that MPI and s-echo should be preferred over the XT for diagnosing R.

Late acute thrombotic occlusion after endovascular brachytherapy and stenting of femoropopliteal arteries

OBJECTIVES

The aim of this article is to underline the importance of this complication after endovascular brachytherapy (EVBT) and intravascular stenting of the femoropopliteal arteries occurring in a running randomized trial.

BACKGROUND

Endovascular brachytherapy has been proposed as a promising treatment modality to reduce restenosis after angioplasty. However, the phenomenon of late acute thrombotic occlusion (LATO) in patients receiving EVBT after stenting is of major concern.

METHODS

In an ongoing prospective multicenter trial, patients were randomized to undergo EVBT (iridium 192; 14 Gy at a depth of the radius of the vessel +2 mm) after percutaneous recanalization of femoropopliteal obstructions. Of the 204 patients who completed the six months follow-up, 94 were randomized to EVBT.

RESULTS

Late acute thrombotic occlusion occurred exclusively in 6 of 22 patients (27%) receiving EVBT after intravascular stenting and always in concomitance with reduction of antithrombotic drug prevention (clopidogrel). Conversely, none of the 13 patients with stents and without EVBT (0%; p < 0.05) and none of the 72 patients (0%; p < 0.01) undergoing EVBT after simple balloon angioplasty presented LATO.

CONCLUSIONS

Late thrombotic occlusion occurs not only in patients undergoing EVBT after percutaneous coronary recanalization but also after stenting of the femoropopliteal arteries and may compromise the benefits of endovascular radiation. The fact that all our cases with LATO occurred concomitantly with stopping clopidogrel may indicate a possible rebound mechanism. An intensive and prolonged antithrombotic prevention is probably indicated in these patients.

Prognostic value of exercise cardiac tomography performed late after percutaneous coronary intervention in symptomatic and symptom-free patients

The long-term prognostic value of single-photon emission computed tomography (SPECT) performed late after percutaneous coronary intervention (PCI) has not been extensively evaluated. Moreover, the role of myocardial ischemia at SPECT in symptom-free patients after PCI is not clear. This study was designed to determine the long-term prognostic value of SPECT in predicting cardiac events after PCI in symptomatic and symptom-free patients. Exercise technetium-99m sestamibi SPECT was performed in 206 patients between 12 and 18 months after PCI. All patients were followed for a mean period of 37 +/- 16 months. Cardiac death, nonfatal myocardial infarction, and late revascularization procedures were considered to be events. Myocardial ischemia at SPECT was detectable in 44 patients. During follow-up, 24 patients experienced events (cardiac death in 4 patients, myocardial infarction in 10, and late revascularization in 10). At univariate analysis, the summed stress score (p <0.05) and summed difference score (p <0.001) were significant predictors of cardiac events. Event-free survival curves showed a higher event rate in patients with than without ischemia (p <0.001). The occurrence of cardiac events was higher in the presence of ischemia at SPECT in symptomatic and symptom-free patients (both p <0.001). The results of this study demonstrate that the extent and severity of myocardial ischemia at exercise SPECT performed between 12 and 18 months after PCI predicts cardiac events during long-term follow-up in symptomatic and symptom-free patients.

Five-year angiographic outcome in patients without restenosis following coronary balloon angioplasty: a comparison between non diabetic and diabetic lesions

Few studies have investigated the long-term angiographic outcome of successful coronary balloon angioplasty (CBA) among diabetic and nondiabetic dilated lesions. The purpose of this study was to evaluate and compare the long-term (>5 years) outcomes of diabetic and nondiabetic CBA lesions which had remained patent 3-12 months after intervention. Twenty-five patients (45 lesions) with diabetes mellitus and 79 patients (138 lesions) without diabetes mellitus were enrolled as subjects. All patients who underwent CBA without restenosis within 3-12 months of the initial CBA based on follow-up angiographic evaluation were included. Quantitative coronary angiograms performed before, immediately after CBA, during the 3-12-month period (mean 4.1 +/- 1.0 months), and at or after 5 years (mean 6.4 +/- 2.0 years) were compared. There was no significant difference in the reference diameter between nondiabetic and diabetic lesions at any of the four time points studied. The minimum lumen diameter before and immediately after the procedure and at the 3-12-month follow-up did not differ significantly between the two groups. At >5-year follow-up. the minimum lumen diameter was significantly (P = 0.005) decreased in diabetic lesions. Total occlusion occurred in 9% (4/45) of the diabetic lesions compared to only 1%, (1/138) in the nondiabetic lesions (P = 0.007). Diabetic lesions showed significant (P = 0.049) narrowing between the 3-12 month period and >5-year follow-up. Fifty-one percent (18/35) of the nondiseased vessels in the diabetic patients at the time of enrollment had new stenosis during the follow-up periods. In conclusion, compared to nondiabetic lesions, patients with diabetic lesions who underwent CBA were more predisposed to have stenotic progression and total occlusion.

Differential gene expression in vascular smooth muscle cells in primary atherosclerosis and in stent stenosis in humans

OBJECTIVE

We sought to identify differentially expressed genes in human in stent stenosis (ISS) to provide insights into the mechanism of disease.

METHODS AND RESULTS

Using representation difference analysis, we examined differential gene expression between cultured normal human medial vascular smooth muscle cells (VSMCs) and cells from primary atherosclerotic plaques or ISS sites. Specific groups of genes were overexpressed in ISS and plaque VSMCs, including cell cycle regulatory proteins and cell matrix and contractile proteins. Differential expression was validated by virtual Northern analysis, reverse transcriptase-polymerase chain reaction, in situ hybridization, and immunohistochemistry. All ISS genes were expressed by normal intima and had even higher expression in primary plaque VSMCs.

CONCLUSIONS

ISS VSMCs have a stable gene expression profile reflecting an intimal pattern, intermediate between normal medial and primary plaque VSMCs. Differential expression profiling may identify markers of disease that are overexpressed in ISS and also help elucidate the origin of the ISS lesion.

A meta-analysis of the angiotensin-converting enzyme gene polymorphism and restenosis after percutaneous transluminal coronary revascularization: evidence for publication bias

BACKGROUND

The insertion/deletion polymorphism of the gene encoding angiotensin-converting enzyme is a controversial risk factor for restenosis after percutaneous transluminal coronary revascularization in patients. Genetic association studies addressing this issue are frequently hampered by insufficient power. Therefore, we conducted a meta-analysis of this association, taking into account the possibility of publication bias.

METHODS

We used the MEDLINE database and reviewed citations in relevant articles to identify 12 studies. Information on the design of the studies, the detailed genotype distribution, the angiographic follow-up rate, and the restenosis rate were categorized by use of a standardized protocol.

RESULTS

Overall, DD (deletion-deletion) homozygotes had a higher restenosis risk than II (insertion-insertion) carriers (odds ratio 1.22, 95% CI 1.04-1.44, P <.05). However, the published studies were significantly heterogeneous, especially those addressing in-stent restenosis. Smaller studies tended to have positive results more frequently, which is characteristic of publication bias. Correcting for publication bias, we estimated the odds ratio to be 1.15 (95% CI 0.98-1.32, not significant). None of the published studies met all rules of genetic epidemiology.

CONCLUSION

We conclude that a clinically significant association of the angiotensin-converting enzyme polymorphism with restenosis after percutaneous transluminal coronary revascularization in patients is unlikely. This meta-analysis provides evidence that the pooled estimate based on published literature, which favors an association, is distorted by publication bias. Hence, screening for this mutation in clinical practice is not justified. Future research should preferentially focus on gene-gene interaction and comply with the rules of genetic epidemiology.

Clinical and angiographic results with the Coroflex Coronary Stent System

This is the first prospective study investigating the safety and efficacy of the new Coroflex Coronary Stent System regarding the incidence of major adverse cardiac events and the angiographic results during 6-month follow-up. The balloon-expandable Coroflex Stent is composed of stainless steel 316L, designed as a "slotted tube" with a 0.04" (0.97 mm) low crossing profile and high flexibility. A metal coverage of 12% allows easy side branch access. Between September 1998 and December 1998 five centers enrolled 113 patients with stable or unstable angina and a single de novo lesion in vessel sizes > or = 2.75 mm. Procedural success was achieved in all 113 (100%) patients. During hospital stay one (0.88%) patient sustained a non-Q-wave myocardial infarction. Three patients died of a noncardiac reason during the 6-month follow-up. Quantitative coronary angiography (QCA) showed a minimal luminal diameter prior to intervention of 0.78 +/- 0.32 mm after PTCA 2.77 +/- 0.43 mm, and after 6 months a decrease to 2.06 +/- 0.76 mm, resulting in a loss index of 0.29 +/- 0.52 and a restenosis rate of 15.6% by QCA (n = 64) and 12.0% by visual estimation of additional 19 patients not suitable for QCA. The results of the Coroflex study demonstrated a low incidence of clinical events and complications and was combined with a low loss index and restenosis rate.

Results of Prevention of REStenosis with Tranilast and its Outcomes (PRESTO) trial

BACKGROUND

Restenosis after percutaneous coronary intervention (PCI) is a major problem affecting 15% to 30% of patients after stent placement. No oral agent has shown a beneficial effect on restenosis or on associated major adverse cardiovascular events. In limited trials, the oral agent tranilast has been shown to decrease the frequency of angiographic restenosis after PCI.

METHODS AND RESULTS

In this double-blind, randomized, placebo-controlled trial of tranilast (300 and 450 mg BID for 1 or 3 months), 11 484 patients were enrolled. Enrollment and drug were initiated within 4 hours after successful PCI of at least 1 vessel. The primary end point was the first occurrence of death, myocardial infarction, or ischemia-driven target vessel revascularization within 9 months and was 15.8% in the placebo group and 15.5% to 16.1% in the tranilast groups (P=0.77 to 0.81). Myocardial infarction was the only component of major adverse cardiovascular events to show some evidence of a reduction with tranilast (450 mg BID for 3 months): 1.1% versus 1.8% with placebo (P=0.061 for intent-to-treat population). The primary reason for not completing treatment was > or =1 hepatic laboratory test abnormality (11.4% versus 0.2% with placebo, P<0.01). In the angiographic substudy composed of 2018 patients, minimal lumen diameter (MLD) was measured by quantitative coronary angiography. At follow-up, MLD was 1.76+/-0.77 mm in the placebo group, which was not different from MLD in the tranilast groups (1.72 to 1.78+/-0.76 to 80 mm, P=0.49 to 0.89). In a subset of these patients (n=1107), intravascular ultrasound was performed at follow-up. Plaque volume was not different between the placebo and tranilast groups (39.3 versus 37.5 to 46.1 mm(3), respectively; P=0.16 to 0.72).

CONCLUSIONS

Tranilast does not improve the quantitative measures of restenosis (angiographic and intravascular ultrasound) or its clinical sequelae.

Mouse genetic evidence that tranilast reduces smooth muscle cell hyperplasia via a p21(WAF1)-dependent pathway

OBJECTIVE

N-(3'4'-dimethoxycinnamoyl)-anthranilic acid (tranilast) is a drug that has been shown to reduce the incidence of restenosis after angioplasty in middle-scale clinical trials. Despite clinical interest in this drug, the pharmacological actions of tranilast remain relatively unexplored at a molecular level.

METHODS AND RESULTS

We evaluated the effects of tranilast on vascular smooth muscle cell (VSMC) proliferation in wild-type mice and in mice lacking a cyclin-dependent kinase inhibitor, p21(WAF1) (p21). Tranilast potently inhibited the proliferation of VSMC cultures derived from wild-type mice, but VSMCs derived from p21-deficient (p21-/-) mice were unaffected by this treatment. In a mouse femoral artery model of vascular injury, tranilast administration to wild-type mice led to an upregulation of p21 expression and a decrease in the number of proliferating VSMCs, as determined by immunostaining for proliferating cell nuclear antigen. In contrast, tranilast had no effect on the number of proliferating cell nuclear antigen-positive cells in the injured arteries of p21-/- mice. Administration of tranilast significantly reduced the neointimal VSMC hyperplasia in wild-type mice at 4 weeks but had no effect on lesion formation in p21-/- mice.

CONCLUSIONS

Our findings provide genetic evidence that tranilast inhibits intimal hyperplasia via a p21-dependent pathway, an activity that may contribute to its efficacy in the prophylactic treatment of postangioplasty restenosis.

Correlates of coronary blood flow before and after percutaneous coronary intervention and their relationship to angiographic and clinical outcomes in the RESTORE trial. Randomized Efficacy Study of Tirofiban for Outcomes and REstenosis

BACKGROUND AND OBJECTIVES

Slower blood flow in the setting of acute myocardial infarction (MI) has been related to adverse outcomes, but the relationship of coronary blood flow after percutaneous transluminal coronary angioplasty (PTCA) in the setting of acute coronary syndromes to adverse outcomes and restenosis has not been well described. We sought to evaluate the correlates of pre- and post-PTCA coronary blood flow to shed light on potential modifiable determinants.

METHODS

The RESTORE trial (Randomized Efficacy Study of Tirofiban for Outcomes and REstenosis) was a randomized, double-blind, placebo-controlled trial of tirofiban in patients undergoing balloon angioplasty or directional atherectomy within 72 hours of occurrence of either unstable angina pectoris or acute MI. Coronary blood flow was assessed with the corrected TIMI frame count (CTFC), and clinical outcomes were assessed at 30 days.

RESULTS

In addition to tighter and longer minimum lumen diameters (MLDs), the multivariate correlates of slower flow before PTCA also included the presence of thrombus, collaterals, left coronary artery lesion location, acute MI, and >8F catheter size. As well as the above variables, type C and D dissection grades were related to slower post-PTCA CTFC. Death, or the composite of death/MI/coronary artery bypass graft at 30 days, was more frequent among patients with slower post-PTCA CTFCs and those with post-PTCA thrombus. In a multivariate model correcting for reference segment diameter and MLD, the post-PTCA CTFC was an independent predictor of late lumen loss and the follow-up MLD at 6 months. As a single index that integrates functional and anatomical aspects of the post-PTCA results, the ratio of CTFC/MLD was associated with death/MI by 30 days.

CONCLUSIONS

In addition to MLD, variables such as the presence of thrombus, left coronary artery lesion location, and dissection grade also are associated with slower coronary blood flow after PTCA. In turn, post-PTCA CTFCs were an independent predictor of late lumen loss and follow-up MLDs. Furthermore, patients who die or who sustain other adverse cardiac events have slower coronary blood flow and greater thrombus burden after PTCA.

Rat and human aortic smooth muscle cells display differing migration and matrix metalloproteinase activities in response to dexamethasone

OBJECTIVE

The steroid dexamethasone inhibits neointimal hyperplasia development in rats but not in humans. This study investigates the differential effects of dexamethasone on rat and human smooth muscle cell migration and matrix metalloproteinase (MMP) activity.

METHODS

Rat aortic smooth muscle cells were harvested from Sprague-Dawley rats. Human aortic smooth muscle cells were obtained from Clonetics. Boyden chamber migration assays were performed with chemoattractant (platelet-derived growth factor) and varying concentrations of dexamethasone (10(-9) to 10(-5) mol/L). Zymography of culture media was used to assess MMP activity, and Western blot analysis was used for quantification of MMP-2 and tissue inhibitor of MMP-2 (TIMP-2) secretion.

RESULTS

Dexamethasone inhibits rat aortic smooth muscle cell migration in a dose-dependent fashion. An increase in concentrations of dexamethasone does not effect human aortic smooth muscle cell migration. Rat aortic smooth muscle cell MMP-2 activity is inhibited with dexamethasone in a dose-dependent fashion, and human aortic smooth muscle cell MMP-2 activity is unchanged with dexamethasone. MMP-2 secretion is inhibited with dexamethasone in rat aortic smooth muscle cells but remains unaltered in human aortic smooth muscle cells. Dexamethasone increases rat aortic smooth muscle cell TIMP-2 secretion, and human aortic smooth muscle cell TIMP-2 secretion remains constant.

CONCLUSION

Dexamethasone inhibits rat aortic smooth muscle cell migration, MMP-2 activity, and MMP-2 secretion and increases TIMP-2 secretion. These effects are not observed in human aortic smooth muscle cells. These findings may explain why dexamethasone inhibits neointimal hyperplasia in animal models but is ineffective in humans. Inhibition of human smooth muscle cell migration in vitro may be useful in predicting the effectiveness of future therapeutic agents for treatment of neointimal hyperplasia in humans.

A prospective single-center registry for the use of intracoronary gamma radiation in patients with diffuse in-stent restenosis

Based on single-center prospective registry data, the study evaluates short- and long-term results of intracoronary gamma radiation in patients with diffuse in-stent restenosis in the reality of routine clinical practice. Percutaneous coronary intervention and subsequent catheter-based irradiation with iridium-192 was performed in 84 vessels (81 patients) with diffuse in-stent restenosis. Repeat coronary angiography was performed in 35 patients with clinical restenosis. With a mean follow-up of 12.0 +/- 0.5 months, major adverse cardiac events were observed in 29 (34.5%) patients, including 2 cases of cardiac death, 3 myocardial infarctions, 21 target lesion revascularizations, and 4 target vessel revascularizations. Five of six patients with total occlusion of the target vessel at baseline developed target lesion restenosis. Late total occlusion of the target vessel was observed in four patients. The 1-year event-free survival rate was 69.8%. Total occlusion of the target vessel at baseline was the single independent predictor of cardiac events at 1-year follow-up (P < 0.001). In patients with a target lesion in the left anterior descending artery, predictors of cardiac events also included female sex (P = 0.014), current smoking (P = 0.014), stenting during brachytherapy session (P = 0.02), and smaller reference vessel diameter at baseline (P = 0.01). The results of our registry are similar to those of randomized trials. As applied in routine clinical practice, intracoronary gamma radiation is a feasible, safe, and effective tool in the treatment of diffuse in-stent restenosis. Late events in the entire group were predicted by total occlusion at baseline.

Inaccuracy in manual multisegmental irradiation in coronary arteries

PURPOSE

Retrospective evaluation of the accuracy of manual multisegmental irradiation with a source train for irradiation of long (re)stenotic lesions in coronary arteries, following percutaneous transluminal coronary angioplasty (PTCA).

MATERIAL AND METHODS

Thirty-six patients were treated with intracoronary irradiation following PTCA with manual multisegmental irradiation. These patients were included in the multicenter, multinational 'European Surveillance Registry with the Novoste Beta-Cath system' (RENO). In all 36 patients the target length (i.e. PTCA length plus 5-mm margin at each side) was too long for the available source train lengths (30 and 40 mm). In 33 patients the radiation delivery catheter was manually positioned twice and in three patients three times in series, trying to avoid any gap or overlap. The total number of junctions was 39. Following a successful PTCA procedure the site of angioplasty was irradiated using the Novoste Beta-Cath afterloader with a 5-F non-centered catheter which accommodates the sealed beta-emitting (90)Sr/(90)Y source train or dummy source train. Radiation was delivered first to the distal part of the target length. Fluoroscopic images of this source position were stored in the computer memory. For irradiation of the proximal part of the target length, the delivery catheter had to be retracted over a distance equal to the source length used for the distal part. This was done by a continuous overlay video loop with ECG-gated replay of the image stored in the computer memory. The dummy source was used to position the delivery catheter so that the junction between both source positions was as precise as possible. Measurements of gap or overlap between the source positions were performed retrospectively on printed images. Doses were calculated, in accordance with the Novoste study protocol, at a distance of 2 mm from the source axis (=dose prescription distance) in several points along the irradiated length.

RESULTS

Interventional or PTCA length varied between 33 and 95 mm. The lesion sites were in the left anterior descending artery, (n=6), right coronary artery (n=20), left circumflex artery (n=6) and one vein graft. The administered radiation dose was determined by the vessel diameter and the presence of a stent. This dose, prescribed at a distance of 2 mm from the source axis, varied between 16 and 22 Gy. No gap or overlap was seen between the two source trains in only two out of 39 cases. In 16 cases there was a gap ranging between 0.6 and 9.6 mm and 18 cases showed an overlap of 0.5-14.4 mm. In three patients the measurement was not possible. In case of a gap the minimal dose calculated at 2 mm from the source axis varies between 0 and 87% of the prescribed dose, depending on the distance between both sources. In case of overlap the maximal dose varies between 110 and 200% of the prescribed dose at 2 mm from the source axis.

CONCLUSIONS

The results show the inaccuracy of manual multisegmental irradiation using a source train in coronary arteries, causing unacceptable dose inhomogeneities at a distance of 2 mm from the source axis at the junction between both source positions. Moreover, a perfect junction will never be possible due to movement of the non-centered radiation delivery catheter in the vessel lumen, as applied in this study. Manual multisegmental irradiation is therefore not recommended. Using longer line sources or source trains or preferably an automated stepping source is a more reliable and safer technique for treatment of long lesions.

The impact of tranilast on restenosis after coronary angioplasty: the Second Tranilast Restenosis Following Angioplasty Trial (TREAT-2)

BACKGROUND

The Tranilast Restenosis Following Angioplasty Trial showed that oral administration of 600 mg/day of tranilast for 3 months markedly reduced the restenosis rate after percutaneous transluminal coronary angioplasty (PTCA) for de novo lesions.

METHODS

We conducted the second multicenter, randomized, double-blinded placebo-controlled trial. A total of 297 patients with 329 lesions were randomly assigned to treatment with tranilast or a placebo for 3 months after successful PTCA for both de novo and restenotic lesions. Angiographic follow-up examination was done at 3 months, and angiograms were interpreted with a quantitative approach.

RESULTS

Two hundred thirty-nine lesions (72.6%) in 216 of the patients (72.7%) met the criteria and were included in the assessment of restenosis. Lesion restenosis was defined as a loss of 50% or more of the initial gain, and the restenosis rates were 18.8% in the tranilast group (n = 112) and 44.1% in the placebo group (n = 127; P =.00005). The restenosis rate, defined as a percent stenosis of > or = 50% at follow-up examination, was also significantly lower in the tranilast group (25.9% versus 41.9%; P =.012). The numbers of restenotic lesions were 38 (33.9% of 112) in the tranilast group and 30 (23.6% of 127) in the placebo group. In restenotic lesions, the lesion restenosis rate was significantly lower in the tranilast subgroup (18.4% versus 53.3% with the first restenosis criterion; P =.004).

CONCLUSION

The oral administration of tranilast for 3 months markedly reduced the restenosis rate after PTCA, even in restenotic lesions.

Ultrastructure of intramural coronary arteries in pigs with hypertrophic cardiomyopathy

Pigs with hypertrophic cardiomyopathy diagnosed by echocardiographic examination were selected for study from a genetic breeding herd. Under dissecting microscopic examination, intramural coronary arteries in the septum and left ventricular free wall of euthanized pigs were collected for ultrastructural study. The major lesions of wall thickening included degeneration or denudation of endothelium, subendothelial edema, proliferation of collagen fiber, and hyperplasia of smooth muscle cells. Smooth muscle cells proliferated and migrated through the internal elastic lamella into the intima, which caused the early lesion of wall thickening of the intramural coronary arteries. The extent of smooth muscle cell proliferation was related to the severity of endothelial damage. The smooth muscle cells in the intima were identified by immunohistochemical staining (i.e., smooth muscle actin [SMA] stain). Three major types of severe wall thickening with narrow lumen were observed in the intramural coronary arteries. Edema in the intima caused the major lesion of Type I wall thickening. The internal elastic lamella was broken into small interrupted fragments, and fine fragments of elastic fibers surrounded by the cellular processes of smooth muscle were observed in Type I lesions. Many smooth muscle cells proliferated in the intima and media, which constituted the major lesion of Type II wall thickening of the intramural coronary arteries. Many vacuolized, degenerated smooth muscle cells with fewer sarcoplasmic myofilaments could be clearly observed in the Type II lesions. In advanced cases, severe vacuolization and degeneration of smooth muscle cells with the presence of many bizarrely shaped smooth muscle cells in the walls of the intramural coronary arteries could be observed, which caused the major lesion of Type III wall thickening. Pigs with hypertrophic cardiomyopathy, characterized by spontaneously occurring lesions in intramural coronary arteries, may prove a valuable animal model for human disease.

Flufenamic acid: growth modulating effects on human aortic smooth muscle cells in vitro

PURPOSE

The aim of the study was to examine the effects of flufenamic acid on proliferation, clonogenic activity, migratory ability, cell-cycle distribution, and p44/42-mitogen-activated protein kinase (MAPK) expression on serum-stimulated human aortic smooth muscle cells (haSMCs) in vitro.

MATERIALS AND METHODS

HaSMCs were treated with flufenamic acid in three different doses (40 micromol/L, 200 micromol/L, 400 micromol/L) for 4 days, and then flufenamic-acid-free culture medium was supplemented every 4 days until day 20 after initial treatment. The growth kinetics were assessed. Cell-cycle analysis was performed by flow cytometry. The clonogenic activity was evaluated with use of colony formation assays. The migratory ability was investigated by stimulation with platelet derived growth factor (PDGF-BB) in 24 well plates with 8-microm pore membrane inserts. The p44/42 MAPK was detected by Western blot technique.

RESULTS

Flufenamic acid inhibited the proliferation (400 micromol/L treatment over 4 d; 179,700 +/- 49,800 vs 747,900 +/- 144,000; P <.001), clonogenic activity (400 micromol/L treatment over 4 d; 1 +/- 0.3 vs 50 +/- 1.4; P <.001) and migratory ability (400 micromol/L treatment over 4 d; 8 cells +/- 2 vs 48 cells +/- 15; P <.001) of haSMCs in a dose-dependent manner. Cell-cycle analysis revealed a G2/M-phase block (400 micromol/L treatment over 4 d; 28.9 +/- 1.5 vs 9.5 +/- 3.2; P <.001). The expression of p44/42 MAPK was reduced for a treatment with 400 micromol/L flufenamic acid (controls, 427 BLU +/- 0.305 vs treatment group, 190 BLU +/- 106; P <.05)

CONCLUSION

Flufenamic acid inhibits the proliferation and migration of haSMCs. Further experiments with animal models concerning stenosis and restenosis are necessary to evaluate the potential of this promising drug.

Topical application of beta-radiation to reduce intimal hyperplasia after carotid artery balloon injury in rabbit. A possible application for brachytherapy in vascular surgery

PURPOSE

Endovascular brachytherapy for the prevention of intimal hyperplasia (IH) and restenosis after balloon/stent angioplasty has proven effective both in animal preparations and clinical trials. A variety of beta-emitting isotopes and catheter-based devices have been developed for the delivery of low-dose radiation in clinical coronary and peripheral trials. No platform, however, has yet been developed for brachytherapy in concert with vascular surgical operations. The purpose of this study was to evaluate the vascular histopathologic response following balloon injury to rabbit carotid arteries with and without topically applied low-dose beta-radiation.

METHODS

The beta-emitting isotope strontium-90 (Sr-90) was conjugated onto the matrix of polypropylene (PLYP) mesh. Rabbit carotid arteries were balloon-injured with a #2 embolectomy catheter. Six carotid arteries were wrapped with nonradioactive PLYP mesh (controls) and Sr-90 ( approximately 90 microCi) PLYP mesh in order to deliver low-dose radiation to the vessel wall from the external (adventitial) surface. Tissue was harvested at 6 weeks and processed for histologic examination.

RESULTS

There was consistent blockade of fibrocellular neointima formation with virtually no neointima present in all treated segments, compared to moderate neointima formation in controls. Medial thinning and smooth muscle cell (SMC) necrosis were also associated with topical brachytherapy.

CONCLUSION

beta-Radiation applied by an externally wrapped PLYP mesh labeled with Sr-90 markedly suppressed neointima formation in an animal vascular surgical injury model. Further studies, however, are necessary to determine a suitable isotope and dosage for clinical application.

Treatment of coronary artery disease in hemodialysis patients: PTCA vs. stent

This retrospective study examined the utilization of coronary stent placement versus PTCA in hemodialysis patients with obstructive coronary disease. Prior studies have demonstrated suboptimal results with PTCA owing primarily to high rates of restenosis. We identified 19 hemodialysis patients who received a percutaneous coronary intervention who were matched with individuals without renal failure undergoing same vessel revascularization. Our study found that 71% of hemodialysis patients receiving PTCA had a recurrent cardiac event defined by subsequent angina, myocardial infarction, or cardiac death. At follow-up, 30% of patients who received stent placement had recurrent cardiac events. Intracoronary stent placement is both safe and feasible and produces more favorable clinical outcomes in the management of coronary disease in hemodialysis patients.

The effect of intravenous immunoglobulins on intimal thickening in a mouse model of arterial injury

Inflammatory mechanisms appear to influence the progression of intimal thickening in experimental models of arterial injury. Intravenous immunoglobulin (IVIG) is a polyspecific preparation of human immunoglobulin (Ig)G employed for treatment of autoimmune disorders. In this study, we sought to investigate whether treatment with IVIG could influence intimal thickening in a model of murine arterial injury. Intimal thickening was induced by placement of a periadventitial cuff over the right femoral artery of male C57BL/6 mice. In the first experiment, IVIG or human serum albumin (HSA) (10 mg/mouse) were administered intraperitoneally for five consecutive days starting 1 day prior to cuff placement. In the second experiment, IVIG or HSA treatment were delivered similarly, but initiated 3 days following induction of arterial injury. Neointimal area and intimal/medial ratio were significantly reduced in mice treated with IVIG prior to cuff placement as compared with HSA treatment. No differences were noted with regard to neointimal area or intimal/medial ratio, between IVIG- and HSA-treated mice when the treatment was commenced 3 days following induction of injury. IVIG treatment reduced the proliferative capacity of splenocytes to the non-specific mitogen Con-A. Treatment with IVIG was associated with a significantly enhanced secretion of interleukin (IL)-10) by the respective splenocytes in comparison with HSA-treated mice. No effect of IVIG was evident on the secretion of IL-4 or IFN-gamma. Thus, IVIG has proven beneficial in ameliorating intimal thickening in a mouse model of arterial injury. The effect could be mediated by upregulation of T-cell secretion of the anti-inflammatory cytokine IL-10.

Final results of the CAPAS trial

BACKGROUND

The Cutting Balloon (Interventional Technologies Inc) is a new-concept balloon that incorporates 3 to 4 blades to create sharp incisions on the luminal surface of the lesion during dilation without causing severe tearing injury to the vessel wall. It may reduce restenosis and improve clinical outcome.

METHODS

Two hundred forty-eight lesions were randomly assigned to Cutting Balloon angioplasty (CBA, 120 lesions) or conventional balloon angioplasty (PTCA, 128 lesions). Inclusion criteria were type B/C lesions (American College of Cardiology/American Heart Association classification) and reference diameter <3.0 mm by visual image on angiogram. Quantitative coronary angiography was performed before and after percutaneous coronary angioplasty and at 3-month follow-up. The primary end point was restenosis, defined as >/=50% diameter stenosis at follow-up. Clinical event rates at 1 year were assessed.

RESULTS

Baseline characteristics were similar. Reference diameter was small in both groups (2.16 vs 2.18 mm, CBA vs PTCA). Preprocedural percent diameter stenosis (%DS) was similar (69.8% vs 69.6%). However, postprocedural and follow-up %DS were lower (26.2% vs 28.9%, P =.072; 40.8% vs 47.5%, P =.011) in the CBA group. Restenosis was significantly lower (25.2% vs 41.5%, P =.009) in the CBA group. At 1 year, event-free survival was achieved in 72.8% of the CBA group and in 61.0% of the PTCA group (P =.047).

CONCLUSION

These findings suggest that CBA provides superior angiographic and clinical outcomes in comparison with PTCA in small coronary arteries.

Comparative results of coronary intervention in patients with variant angina versus those with non-variant angina

Coronary angioplasty is reported to be feasible and safe in patients with coronary spasm and fixed stenosis. However, the long-term results are not positive. We compared the results of coronary angioplasty in 20 patients with variant angina versus 17 patients with non-variant angina among 231 consecutive patients with vasospastic angina. Coronary angioplasty was performed successfully in all 37 patients without any complications. Stenting for coronary dissection or recoil was performed in 8 patients, directional coronary atherectomy was selected for ostial lesion of left anterior descending coronary artery stenosis in 2 patients, and standard balloon angioplasty was performed in 27 patients. There were no clinical differences between the two groups. The restensois rate in patients with variant angina was similar to that in patients with non-variant angina (30% vs 29%, ns). There was no relationship between the provoked spasm and restenosis. During the follow-up period, no major complications were observed in patients with variant angina or those with non-variant angina. In conclusion, full medication with calcium channel antagonists and isosorbide dinitrate, and treatment by coronary angioplasty including the use of new devices, were useful treatments for patients with coronary vasospasm and significant organic stenosis. There was no difference concerning the results of coronary intervention between the patients with variant angina and those with non-variant angina.

Combination of minimally invasive coronary bypass and percutaneous transluminal coronary angioplasty in the treatment of double-vessel coronary disease: Two-year follow-up of a new hybrid procedure compared with "on-pump" double bypass grafting

OBJECTIVE

Percutaneous transluminal coronary angioplasty (PTCA) or surgery can be chosen as first-line therapies in multiple-vessel coronary disease. A mammary-to-left anterior descending (LAD) graft is the most important statistical determinant of a favorable outcome after coronary artery bypass grafting (CABG) and can be performed with lower morbidity off pump through a minithoracotomy. PTCA and stenting of the "non-LAD" vessels compete with CABG in terms of patency rates. Our purpose was to compare a combination of minimally invasive direct coronary artery bypass (MIDCAB) and PTCA with double CABG as a treatment for double-vessel coronary artery disease involving the proximal LAD.

METHODS

Two matched groups of 20 patients with double-vessel coronary disease undergoing either sequential MIDCAB and PTCA (group 1) or double CABG on cardiopulmonary bypass (group 2) were compared. Angiographic control, complications, hospital costs, quality of life, and 2-year follow-up of ischemia are reported.

RESULTS

All bypasses were patent at early control. Three adverse events were noted in group 1 and 17 in group 2. The hybrid-procedure group exhibited a shorter intensive care unit stay, fewer blood products transfused, less pain, better early quality of life, faster return to work, and similar cost. Three patients required a second PTCA in group 1, one of which for restenosis. At 2 years all the patients are asymptomatic with no residual ischemia.

CONCLUSIONS

We conclude from this pilot study that the hybrid procedure is feasible and appears to be a safe therapy for double-vessel coronary artery disease and that it appears to generate less perioperative morbidity than classic double CABG does. Therefore we believe that there is room to undertake prospective randomized studies on a larger-scale basis.

ESDN, a novel neuropilin-like membrane protein cloned from vascular cells with the longest secretory signal sequence among eukaryotes, is up-regulated after vascular injury

A novel cDNA has been isolated from primary culture of human coronary arterial cells by a signal sequence trap method, and designated ESDN (endothelial and smooth muscle cell-derived neuropilin-like molecule). ESDN is a type-I transmembrane protein with the longest cleavable secretory signal sequence among eukaryotes. ESDN contains a CUB domain and a coagulation factor V/VIII homology domain, which reminds us of the structure of neuropilins. ESDN also harbors an LCCL domain, which is shared by Limulus factor C and Coch. Mouse and rat counterparts were also identified revealing >84% amino acid identity with human ESDN. The human ESDN gene was mapped between D3S1552 and D3S1271. Northern blot analysis showed that ESDN mRNA was expressed in various tissues; particularly highly expressed in cultured vascular smooth muscle cells. The ESDN expression was up-regulated in platelet-derived growth factor-BB-stimulated vascular smooth muscle cells in vitro and neointima of the balloon-injured carotid artery in vivo. Overexpression of ESDN in 293T cells suppressed their bromodeoxyuridine uptake. In addition, ESDN protein was strongly expressed in nerve bundles in rodents. Thus, ESDN is considered to play a role in regulation of vascular cell growth and may have a wide variety of functions in other tissues including the nervous system, like neuropilins.

Mechanisms of angioplasty and stent restenosis: implications for design of rational therapy

Restenosis after angioplasty or stenting remains the major limitation of both procedures. A vast array of drug therapies has been used to prevent restenosis, but they have proven to be predominantly unsuccessful. Recent trends in drug therapy have attempted to refine the molecular and biological targets of therapy, based on the assumption that a single biological process or molecule is critical to restenosis. In contrast, both stenting and brachytherapy, which are highly nonspecific, can successfully reduce restenosis after angioplasty or stenting, respectively. This review examines the biology of both angioplasty and stent stenosis, focussing on human studies. We also review the landmark human trials that have definitively proven successful therapies, such as stenting and brachytherapy. We suggest that the successful trials of stenting and brachytherapy and the failure of other treatments have highlighted the shortcomings of conventional animal models of arterial intervention, and gaps in our knowledge of human disease. In contrast to arguments advocating gene therapy, these studies suggest that the most likely successful drug therapy will have a wide therapeutic range, targeting as many of the components or biological processes contributing to restenosis as possible.

Arterial remodeling and coronary artery disease: the concept of "dilated" versus "obstructive" coronary atherosclerosis

Traditionally, the development of coronary artery disease (CAD) was described as a gradual growth of plaques within the intima of the vessel. The outer boundaries of the intima, the media and the external elastic membrane (EEM), were thought to be fixed in size. In this model plaque growth would always lead to luminal narrowing and the number and severity of angiographic stenoses would reflect the extent of coronary disease. However, histologic studies demonstrated that certain plaques do not reduce luminal size, presumably because of expansion of the media and EEM during atheroma development. This phenomenon of "arterial remodeling" was confirmed in necropsy specimens of human coronary arteries. More recently, the development of contemporary imaging technology, particularly intravascular ultrasound, has allowed the study of arterial remodeling in vivo. These new imaging modalities have confirmed that plaque progression and regression are not closely related to luminal size. In this review, we will analyze the role of remodeling in the progression and regression of native CAD, as well as its impact on restenosis after coronary intervention.

Substantial reduction of platelet adhesion by heparin-coated stents

Although optimized antiplatelet medication has improved the clinical outcome after coronary stenting, vessel occlusion and restenosis still remain a relevant clinical problem. Platelets play a key role in this process. Therefore, the authors compared the platelet adhesion on different stent surface modifications (electropolished without coating or coated with carbon, carbon and additional heparin, silicon carbide, or heparin alone) to investigate their role in reducing platelet adhesion. All stents and additional stainless steel plates were incubated in heparinized whole blood with radiolabeled platelets. After washing the stents and plates four times, radioactivity caused by the adhesion of radiolabeled platelets was measured. The adhesion of radiolabeled platelets, compared to uncoated, electropolished stents, was reduced through silicon carbide coating to 58.6%, by carbon coating with additional heparin to 32.9%, and heparin coating alone to 7.7%. Stent coating with heparin is the most effective among the examined coatings in reducing platelet adhesion in vitro.

Impaired fibrinolysis determines the outcome of percutaneus transluminal coronary angioplasty (PTCA)

BACKGROUND

Coronary artery stenosis lesions dilated by percutaneus transluminal coronary angioplasty (PTCA) show a disappointingly frequent recurrence of stenosis. We have investigated the possible role of fibrinolysis and various platelet-release factors - specifically in the locality of the affected vessel - by following 19 patients for 6 months after PTCA.

METHODS

PTCA was performed on 19 patients with a significant primary coronary stenosis, proven by quantitative CAAS analysis. Blood for measurement of local fibrinolysis and platelet activity was drawn from the aortic root and the coronary sinus, at three times: just before PTCA, 10 min after it, and 6 months later.

RESULTS

The incidence of restenosis at the 6 months follow-up was 37%. PTCA almost doubled the platelet-derived growth factor level (PDGF) in coronary sinus blood in all patients. The seven restenosis patients had a substantially higher tissue plasminogen activator inhibitor antigen (PAI-1ag) level in the aortic root before PTCA than the 12 who remained stenosis-free (mean 62.4 +/- 31.6 ng mL -1 compared with 33.1 + 25.3; P < 0.04) and a lower tissue plasminogen activator activity (t-PAac) level (mean 0.32 +/- 0.19 IU mL-1 compared with 0.68 +/- 0.34; P < 0.03). This was corroborated by the levels of tissue plasminogen activator inhibitor activity (PAI-1ac). At reassessment after 6 months, the restenosis patients had developed, in coronary sinus blood, a large rise of PAI-1ac (7.7 +/- 4.8 IU mL-1 rising to 15.7 +/- 13.9, P < 0.04) and a large rise of of PAI-1ag (48.8 +/- 31.3 ng mL-1 vs. 72.4 +/- 47.2; P < 0.03). But no such increase occurred in the patients who remained stenosis-free. Conclusion Our results indicate that the minor balloon injury, which is inseparable from PCTA, stimulates the local release of PDGF. We suggest that, in those patients whose fibrinolytic activity is inherently low, this rise of PDGF could be a major causative factor in restenosis. We also discuss the possibility that the preoperative level of PAI-1ac could provide a limited but useful prediction of the outcome of PTCA.

The role of acute wall recoil and late restenosis: results of the OCBAS trial (Optimal Coronary Balloon Angioplasty with Provisional Stenting versus Primary Stent)

Early deterioration of minimal luminal diameter immediately after PTCA, has been associated with an increase of late restenosis. Lesions with no early loss after PTCA have a low restenosis rate. Coronary stents reduce restenosis in lesions exhibiting early wall recoil. The purpose of the OCBAS study was to compare two strategies during coronary interventions; provision vs. elective stenting. 116 patients with good PTCA results were randomized to stent (n = 57) or to optimal PTCA (n = 59). After randomization in PTCA group, 13.5% of the patients crossed over to stent due to early loss (provisional stenting). Baseline demographic and angiographic characteristics were similar in both groups of patients. At 7.6 months, 96.6% of the entire population had a follow-up angiographic study; 98.2% in the stent and 94.9% in the PTCA group. Immediate and follow-up angiographic data showed that acute gain was significantly higher in the stent than in the PTCA group (1.95 vs. 1.5 mm; P < 0.03). However, late loss was significantly higher in the stent than the PTCA groups (0.63 +/- 0.59 vs. 0.26 +/- 0.44, respectively; P = 0.01). Hence, net gain with both techniques was similar (1.32 +/- 0.3 vs. 1.24 +/- 0.29 mm for the stent and PTCA groups respectively; P = NS). Angiographic restenosis rate at follow-up (19.2% in stent vs. 16.4% in PTCA; P = NS) and TVR (17.5 in stent vs. 13.5% in PTCA; P = NS) were also similar. Furthermore, event-free survival was 80.8% in the stent versus 83.1% in the PTCA group (P = NS). Overall costs (hospital and follow-up) were US$591,740 in the stent versus US$398,480 in the PTCA group (P < 0.02). The strategy of the PTCA with delay angiogram and provisional stent if early loss occurs, had similar restenosis rate and TVR than universal use of bare stents.

Late (> 48 hr) myocardial infarction after PTCA: clinical and angiographic characteristics of infarction related or not to the angioplasty site

Since late myocardial infarctions after percutaneous coronary interventions have not been well characterized, we intended to evaluate the characteristics of myocardial infarctions occurring > 48 hr after balloon angioplasty of native coronary arteries or saphenous vein grafts. The Montreal Heart Institute database (1985-1996) was interrogated for all patients readmitted with a diagnosis of MI more than 48 hr after successful percutaneous transluminal coronary angioplasty (PTCA). We compared the clinical, procedural, and angiographic variables between MIs related or not to the index PTCA site. One hundred and ninety-three patients presented with late myocardial infarction (MI) following balloon angioplasty. The median time elapsed between PTCA and MI was 55 days compared to 968 days when MI was unrelated to the PTCA site. MIs related to the PTCA site were more likely non-Q-wave (76% vs. 35%, P = 0.0001) with less marked CK-MB rise. Angiography showed less complex lesions (63% vs. 90%, P = 0.001) and better thrombolysis in myocardial infarction (TIMI) grade flow (TIMI II to III, 66% vs. 56%, P = 0.01) when the culprit lesion was at the PTCA site. Independent predictors of MI at the PTCA site were vein graft dilation, female sex, and residual stenosis post-PTCA. Myocardial infarctions occurring late after PTCA have a distinct time course and present specific characteristics according to their relationship or not to the previously dilated site.

Lipid peroxidation may predict restenosis after coronary balloon angioplasty

The present study assessed whether lipid peroxidation in plasma might predict restenosis after coronary balloon angioplasty. A total of 87 patients, who had undergone successful coronary balloon angioplasty using standard techniques, were enrolled. Fasting blood samples before the intervention were measured for plasma levels of thiobarbituric acid reactive substances (TBARS, an indicator of lipid peroxidation). Angiography was carried out before and 15 min after angioplasty, and at follow-up (4 months after angioplasty), and evaluated using a quantitative approach. There were 23 patients with restenosis (group R) and 64 patients without restenosis (group N) after coronary balloon angioplasty. The plasma TBARS level (mean+/-SEM) of 4.3+/-0.1 micromol/L in group R was significantly higher than that of 3.2+/-0.1 micromol/L in group N (p<0.01). There were no significant differences in other parameters, including plasma lipid levels, between the 2 groups. The plasma level of TBARS positively correlated with lumen loss of the coronary artery at the time of follow-up angiography (r=0.57, p<0.01). Our results suggest that oxidative stress contributes to restenosis and indicate that an elevated plasma level of TBARS may be a reliable predictor of restenosis.

Follow-up Study after Intracranial Percutaneous Transluminal Cerebral Balloon Angioplasty

SUMMARY

To find the angiographic lesions specific characteristics appropriate for intracranial percutaneous transluminal cerebral angioplasty (PTCBA). Forty-two clinically symptomatic patients with 42 haemodynamically significant intracranial lesions (% diameter stenosis > 70) were treated by PTCBA between January 1992 and May 1996. Before the angioplasty treatment, the patients were classified into three groups according to the angiographic lesions' characteristics summarised as follows: type A, a short and concentric stenosis; type B, a tubular lesion, or an extreme eccentric lesion; and type C, a diffuse lesion. They were followed after PTCBA from one month to six years to compare between the three groups. Primary end points were death, stroke, or bypass surgery. The clinical success rates in type A, B and C groups were 92%, 86% and 33% (p=0.0032), respectively. Cumulative risks of fatal or nonfatal ischaemic stroke / ipsilateral bypass surgery in type A, B and C groups were 8%, 26% and 87% (p < 0.0001), respectively. The cumulative risk of 8% in type A group patients appeared to be smaller than in historical studies. PTCBA for intracranial simple (type A) lesions produces a favourable clinical outcome for symptomatic patients.

Effect of cilostazol on restenosis after coronary angioplasty and stenting in comparison to conventional coronary artery stenting with ticlopidine

BACKGROUND

The role of antiplatelet therapy with ticlopidine plus aspirin in the prevention of subacute thrombosis after coronary artery stenting has been established. However, restenosis remains a major limitation in coronary artery stenting.

METHODS

To compare the effect of cilostazol on restenosis after coronary angioplasty and stenting with that of ticlopidine after coronary artery stenting, 213 patients with 230 lesions who underwent successful coronary interventions were evaluated. Optimal results (residual stenosis less than 30%) were obtained by balloon angioplasty in 112 lesions, 64 lesions were treated with aspirin 81 mg/day (balloon-aspirin group) and 48 lesions with cilostazol 200 mg/day and aspirin 81 mg/day (balloon-cilostazol group). Stent implantation was performed in the remaining 118 lesions; 55 lesions were treated with ticlopidine 200 mg/day and aspirin 243 mg/day (stent-ticlopidine group) and 63 lesions with cilostazol 200 mg/day and aspirin 81 mg/day (stent-cilostazol group). Concomitant medications were continued for 4 to 6 months of follow-up.

RESULTS

No adverse events including acute occlusion and subacute thrombosis occurred in any groups. Although immediate gain and minimal lumen diameter immediately after angioplasty were significantly larger in stent groups than those in balloon groups, net gain at follow-up was significantly larger in cilostazol groups (1.54+/-0.83 mm in balloon-cilostazol group and 1.65+/-0.78 mm in stent-cilostazol group) than other groups (1.02+/-0.81 mm in balloon-aspirin group and 1.21+/-0.70 in stent-ticlopidine group) as a result of significantly lower late loss and loss index in cilostazol groups. The restenosis rate was significantly lower in cilostazol groups (12.5% in balloon-cilostazol group and 14.3% in stent-cilostazol group) than other groups (43.8% in balloon-aspirin group and 32.7% in stent-ticlopidine group). The rate of recurrent angina was significantly lower in cilostazol groups (4.3% in balloon-cilostazol group and 1.9% in stent-cilostazol group) than in other groups (17.5% in balloon-aspirin group and 14.0% in stent-ticlopidine groups).

CONCLUSIONS

Both optimal balloon angioplasty with cilostazol and coronary artery stenting with cilostazol have a potential to reduce restenosis compared with optimal balloon angioplasty with aspirin or conventional coronary artery stenting with ticlopidine plus aspirin.

Delivery of endothelial cells to balloon-dilated rabbit arteries with use of a local delivery catheter

PURPOSE

Experiments were performed to determine if a local delivery catheter could deliver endothelial cells that would be retained on the luminal surface of balloon-dilated arteries.

MATERIALS AND METHODS

Six New Zealand White rabbits underwent carotid catheterization, arteriography, and balloon angioplasty of an external iliac artery. A local delivery catheter (Dispatch) was then positioned at the site of angioplasty and the 3-mm balloon was inflated. Cultured rabbit endothelial cells (1.26 +/- 0.3 x 10(6) ), previously stained with fluorescent dye PKH26, were delivered to the artery in three infusions separated by 10 minutes. The delivery balloon was deflated and removed 25 minutes after the last delivery. The arteries were then perfusion-fixed in situ at physiologic pressure, removed, and divided into four segments, and the segments were rapidly frozen and cryosectioned. Eight sections from each arterial segment were examined by means of epifluorescence microscopy. The luminal surface of each artery was visually divided into eight sectors of equal length and each sector was assigned a score based on the degree of endothelial coverage (0 = no coverage, 1 = <50% coverage, 2 = >50% coverage).

RESULTS

The endothelial coverage score for the six arteries averaged 0.40 +/- 0.46 (SD; range, 0.04-1.24). Areas of each artery receiving scores of 0, 1, and 2 averaged 68%, 25%, and 7%, respectively. Average coverage scores were 0.42, 0.38, 0.51, and 0.28 for individual segments along the length of the artery.

CONCLUSIONS

The Dispatch local delivery catheter is able to deliver endothelial cells that adhere to balloon-dilated arteries. Although the magnitude of cellular retention was modest and varied among arteries, the retention along the length of each artery was constant.

Treatment planning dosimetric parameters for a (90)Y coil source used in intravascular brachytherapy

BACKGROUND

(90)Y coil sources have been used in animal and clinical trials for treatment of restenosis in intravascular brachytherapy (IVBT). This study aims to determine the American Association of Physicists in Medicine (AAPM) Task Group-60 (TG-60) dosimetric quantities in regions surrounding the balloon wall for use in treatment planning computer systems.

METHODS

The Monte Carlo method was used to determine the dose distribution, using MCNP4B2 code. The coil source was modeled by a hollow cylinder of 2.9 cm length centered in a balloon (2.5 mm diameter) filled with carbon dioxide (CO(2)) at 5 atm. Scoring voxels consisted of contiguous annular disk shells with 0.1 mm spacing in the radial direction and 0.2 mm spacing in the longitudinal direction. The scoring region ranges from the center of the source to 1.0 cm in the longitudinal direction, and from 0.13 to 1 cm in the radial direction. In the plane containing the source axis, the Monte Carlo-generated doses in rectilinear coordinates are converted to polar coordinates.

RESULTS

The dose rate of the source is provided in both Cartesian and polar coordinates. The dose rate constant [D(r(0),theta(0))], anisotropy function [F(r,theta)], and radial dose function [g(r)] were generated from these values and listed in tabular format. At shallow angles and longer distances from the source center, large values of the anisotropy function resulted, deviating two orders of magnitude from unity. CONCLUSIONS The doses given to the intima, media, and adventitia are very crucial quantities in IVBT. The calculated TG-60 dosimetric quantities, used commonly in conventional brachytherapy applications, provide a means for the user to determine the three-dimensional dose surrounding the balloon catheter. These parameters can be used in future treatment planning system for IVBT. We also discuss the need to develop a new formalism specific to longer sources used in IVBT.

SMART: The microstent's ability to limit restenosis trial

In this randomized, prospective, multicenter trial (n = 661) of patients with de novo or restenotic coronary lesions, 330 patients received the MicroStent(R) II (MSII), and 331 received the Palmaz-Schatz (PS) stent. The short-term procedural success rates were 94.4% and 95.7%, respectively (P = 0.47). The 30-day cumulative incidence of major adverse events [death, myocardial infarction, CVA, target lesion revascularization (TLR)] was 6.4% for the MSII and 4.5% for the PS stent (P = 0.31). The in-stent binary restenosis rate at 6 months was 25.2% for the MSII and 22.1% for the PS stent (P = 0.636). Using Kaplan-Meier estimates, the incidence of clinically driven TLR was 8.9% for the MSII and 9.2% for the PS stent at 180 days; at 270 days, it was 12.8% and 12.1%, respectively (P = 0.83). MSII and the PS stents were comparable with respect to short-term procedural success, complications, and late clinical and angiographic restenosis.

Initial and follow-up results of the Tenax coronary stent

The Tenax coronary stent is laser sculpted from high precision 316 L stainless steel using advanced production procedures. An a-SiC: H (hydrogen-rich amorphous silicon carbide) coating reduces its thrombogenicity and improves its biocompatibility. From April to July 1998, 266 stents were implanted in 241 patients (aged 62.7 +/- 10.5 years) in five centers. The clinical indication for intervention was unstable angina (33.2%) and recent myocardial infarction (29.5%) in many cases. Most lesions (53.8%) had complex characteristics (Class B2 or C). The target vessel was the LAD in 42.5% and the right coronary artery in 36.8% of all cases. Four primary stent deployment failures occurred and implantation was successful in 259 (97.4%) of 266 stents. No death and no Q-wave myocardial infarction or emergency CABG occurred during hospital stay. Clinical success, defined as successful deployment without procedural or clinical event, was achieved in 230 (95.4%) of 241 patients. One-year clinical follow-up shows a low need for target lesion revascularization (17/237 [7.1%] patients) and a 15.8% rate of major adverse cardiac events (36/237 patients). The clinical and angiographic outcomes of our study suggest that the hybrid, amorphous hydrogenated silicon carbide coated design is promising and merits further evaluation in larger clinical trials.

Benchmarking operator performance in percutaneous coronary intervention: a novel approach using 30-day events

The infrequency of adverse in-hospital events limits scorecarding individual angioplasty operators. We assessed 30-day events for this purpose. Thirty-nine operators performed 1,950 coronary interventions from 1 April to 30 September 1998. Thirty-day follow-up was obtained in 1,896 (97.2%), who form the basis for this analysis. We recorded 16 baseline variables and chose an endpoint of mortality or target vessel revascularization. The endpoint occurred in 103 (5.4%) patients by 30 days. Independent predictors were identified by multivariate modeling. The expected event rate for the set of patients treated by each operator was determined. Two operators had significantly more adverse events by 30 days than predicted and two others had an event rate approaching significance. Two of these four performed at least 60 procedures during the 6-month period. With 30-day events, operators whose complication rates exceed laboratory standards can be identified with achievable sample sizes. Volume alone does not appear to be sufficient assurance of quality outcomes.

Novel beta-emitting poly(ethylene terephthalate) surface modification

Restenosis after percutaneous interventions in coronary and peripheral arteries leads to repeat procedures and surgery in a significant number of patients. We have previously demonstrated that irradiation of an arterial site using an endovascular source (brachytherapy) is highly effective in preventing the restenotic process. To this end, a novel beta radiation delivery system was developed, based on the adsorption of (32)P (o-phosphoric acid) by pH-sensitive chitosan hydrogel on a poly(ethylene terephthalate) (PET) balloon surface. The PET balloon surface was treated with oxygen plasma and coated with chitosan hydrogel. Covalent bonds, ionic bonds, and hydrogen bonds all contribute to the adhesion between chitosan hydrogel and PET. In the aqueous phosphoric acid (PA) solution, the -NH(2) groups of chitosan were protonated by PA and the adsorption of PA occurred at the same time. The effect of PA concentration and temperature on adsorption efficiency and kinetics were studied. More than 70% PA was adsorbed on the sample surface in 0.2 mM PA solution. The surface of samples was also investigated by attenuated total reflection-Fourier transform infrared spectroscopy and scanning electron microscopy. PET surface may be modified to carry high activity beta emitters; such materials may be useful in a therapeutic setting