Biomedical subjects

I P Kay

Publications and source records attributed to I P Kay.

At least 19 recordsLinked to original sources

PubMed2002

Angiographical follow-up after radioactive "Cold Ends" stent implantation: a multicenter trial.

BACKGROUND: Radioactive stents with an activity of 0.75 to 12 microCi have shown >40% edge restenosis due to neointimal hyperplasia and negative remodeling. This trial evaluated whether radioactive Cold Ends stents might resolve edge restenosis by preventing remodeling at the injured extremities. METHODS AND RESULTS: The 25-mm long (15-mm radioactive center and 5-mm nonradioactive ends) Cold Ends stents had an activity of 3 to 12 microCi at implantation. Forty-three stents were implanted in 43 patients with de novo native coronary artery disease. Two procedural, 1 subacute, and 1 late stent thrombosis occurred. A restenosis rate of 22% was observed with a shift of the restenosis, usually occurring at the stent edges of radioactive stents, into the Cold Ends stents. The most severe restenosis occurred at the transition zone from radioactive to nonradioactive segments, a region located in dose fall-off. CONCLUSION: Cold Ends stents did not resolve edge restenosis.

Adult↗

PubMed2002

Initial observation regarding changes in vessel dimensions after balloon angioplasty and stenting followed by catheter-based beta-radiation. Is stenting necessary in the setting of catheter-based radiotherapy?

AIMS: We sought to compare the effect of intracoronary beta-radiation on the vessel dimensions in de novo lesions using three-dimensional intravascular ultrasound quantification after balloon angioplasty and stenting. METHODS AND RESULTS: Forty patients (44 vessels; 28 balloon angioplasty and 16 stenting) treated with catheter-based beta-radiation and 18 non-irradiated control patients (18 vessels; 10 balloon angioplasty and 8 stenting) were investigated by means of three-dimensional volumetric intravascular ultrasound analysis post-procedure and at 6-8 months follow-up. Total vessel (EEM) volume enlarged after both balloon angioplasty and stenting (+37 mm(3) vs +42 mm(3), P=ns), but vessel wall volume (plaque plus media) also increased similarly (+33 mm(3) vs +49 mm(3), P=ns) in the irradiated patients. Lumen volume remained unchanged in both groups (+3 mm(3) vs -7 mm(3), P=ns). In the stent-covered segments, neointima at follow-up was significantly smaller in the irradiated group than the control group (8 mm(3) vs 27 mm(3), P=0.001, respectively), but the total amount of tissue growth was similar in both groups (33 mm(3) vs 29 mm(3), P=ns). CONCLUSIONS: Intracoronary beta-radiation induces vessel enlargement after balloon angioplasty and/or stenting, accommodating tissue growth. Additional stenting may not play an important role in the prevention of constrictive remodelling in the setting of catheter-based intracoronary beta-radiotherapy.

Aged↗

PubMed2001

Radioactive stents delay but do not prevent in-stent neointimal hyperplasia.

BACKGROUND: Restenosis after conventional stenting is almost exclusively caused by neointimal hyperplasia. Beta-particle-emitting radioactive stents decrease in-stent neointimal hyperplasia at 6-month follow-up. The purpose of this study was to evaluate the 1-year outcome of (32)P radioactive stents with an initial activity of 6 to 12 microCi using serial quantitative coronary angiography and volumetric ECG-gated 3D intravascular ultrasound (IVUS). METHODS AND RESULTS: Of 40 patients undergoing initial stent implantation, 26 were event-free after the 6-month follow-up period and 22 underwent repeat catheterization and IVUS at 1 year; they comprised half of the study population. Significant luminal deterioration was observed within the stents between 6 months and 1 year, as evidenced by a decrease in the angiographic minimum lumen diameter (-0.43+/-0.56 mm; P:=0.028) and in the mean lumen diameter in the stent (-0.55+/-0. 63 mm; P:=0.001); a significant increase in in-stent neointimal hyperplasia by IVUS (18.16+/-12.59 mm(3) at 6 months to 27.75+/-11. 99 mm(3) at 1 year; P:=0.001) was also observed. Target vessel revascularization was performed in 5 patients (23%). No patient experienced late occlusion, myocardial infarction, or death. By 1 year, 21 of the initial 40 patients (65%) remained event-free. CONCLUSIONS: Neointimal proliferation is delayed rather than prevented by radioactive stent implantation. Clinical outcome 1 year after the implantation of stents with an initial activity of 6 to 12 microCi is not favorable when compared with conventional stenting.

Adult↗

PubMed2001

Geographical miss during catheter-based intracoronary beta-radiation: incidence and implications in the BRIE study. Beta-Radiation In Europe.

OBJECTIVES: We sought to determine the incidence and causes of geographical miss (GM) and to evaluate its impact on edge restenosis after intracoronary beta-radiation therapy. BACKGROUND: Edge restenosis is a limitation of intracoronary beta-radiation therapy. Geographical miss is the situation in which the radiation source does not fully cover the injured segment and may lead to edge restenosis. METHODS: We analyzed 175 vessels treated according to the Beta-Radiation In Europe (BRIE) study protocol. The effective irradiated segment (EIRS) and both edges were studied with quantitative coronary angiography. The edges of the EIRS that were injured constituted the GM edges. Restenosis was defined as diameter stenosis >50% at follow-up. Geographical miss was determined by simultaneous electrocardiographic-matched, side-by-side projection of the source and balloons deflated at the injury site, in identical angiographic projections surrounded by contrast. RESULTS: Geographical miss affected 41.2% of the edges and increased edge restenosis significantly compared with non-GM edges (16.3% vs. 4.3%, respectively, p = 0.004). Restenosis was increased both in the proximal (p = 0.05) and distal (p = 0.02) GM edges compared with noninjured edges. Geographical miss associated with stent injury significantly increased edge restenosis (p = 0.006), whereas GM related to balloon injury did not significantly increase edge restenosis (p = 0.35). The restenosis in the EIRS was similar between vessels with and without GM (24.3% and 21.6%, respectively, p = 0.8). CONCLUSIONS: Geographical miss is strongly associated with restenosis at the edges of the EIRS. This effect is more prominent when caused by stenting. Geographical miss does not increase restenosis in the EIRS.

Adult↗

PubMed2001

Clinical and angiographical follow-up after implantation of a 6--12 microCi radioactive stent in patients with coronary artery disease.

AIMS: This study is the contribution by the Thoraxcenter, Rotterdam, to the European(32)P Dose Response Trial, a non-randomized multicentre trial to evaluate the safety and efficacy of the radioactive Isostent in patients with single coronary artery disease. METHODS AND RESULTS: The radioactivity of the stent at implantation was 6--12 microCi. All patients received aspirin indefinitely and either ticlopidine or clopidogrel for 3 months. Quantitative coronary angiography measurements of both the stent area and the target lesion (stent area and up to 5 mm proximal and distal to the stent edges) were performed pre- and post-procedure and at the 5-month follow-up. Forty-two radioactive stents were implanted in 40 patients. Treated vessels were the left anterior descending coronary artery (n=20), right coronary artery (n=10) or left circumflex artery (n=10). Eight patients received additional non-radioactive stents. Lesion length measured 10+/-3 mm with a reference diameter of 3.07+/-0.69 mm. Minimal lumen diameter increased from 0.98+/-0.53 mm pre-procedure to 2.29+/-0.52 mm (target lesion) and 2.57+/-0.44 mm (stent area) post-procedure. There was one procedural non-Q wave myocardial infarction, due to transient thrombotic closure. Thirty-six patients returned for angiographical follow-up. Two patients had a total occlusion proximal to the radioactive stent. Of the patent vessels, none had in-stent restenosis. Edge restenosis was observed in 44%, occurring predominantly at the proximal edge. Target lesion revascularization was performed in 10 patients and target vessel revascularization in one patient. No additional clinical end-points occurred during follow-up. The minimal lumen diameter at follow-up averaged 1.66+/-0.71 mm (target lesion) and 2.12+/-0.72 (stent area); therefore late loss was 0.63+/-0.69 (target lesion) and 0.46+/-0.76 (stent area), resulting in a late loss index of 0.65+/-1.15 (target lesion) and 0.30+/-0.53 (stent area). CONCLUSION: These results indicate that the use of radioactive stents is safe and feasible, however, the high incidence of edge restenosis makes this technique currently clinically non-applicable.

Adult↗

PubMed2001

The pattern of restenosis and vascular remodelling after cold-end radioactive stent implantation.

BACKGROUND: Edge restenosis is a major problem after radioactive stenting. The cold-end stent has a radioactive mid-segment (15.9 mm) and non-radioactive proximal and distal 5.7 mm segments. Conceptually this may negate the impact of negative vascular remodelling at the edge of the radiation. METHOD AND RESULTS: ECG-gated intravascular ultrasound with three-dimensional reconstruction was performed post-stent implantation and at the 6-month follow-up to assess restenosis within the margins of the stent and at the stent edges in 16 patients. Angiographic restenosis was witnessed in four patients, all in the proximal in-stent position. By intravascular ultrasound in-stent neointimal hyperplasia, with a >50% stented cross-sectional area, was seen in eight patients. This was witnessed proximally (n=2), distally (n=2) and in both segments (n=4). Echolucent tissue, dubbed the 'black hole' was seen as a significant component of neointimal hyperplasia in six out of the eight cases of restenosis. Neointimal hyperplasia was inhibited in the area of radiation: Delta neointimal hyperplasia=3.72 mm3 (8.6%); in-stent at the edges of radiation proximally and distally Delta neointimal hyperplasia was 7.9 mm3 (19.0%) and 11.4 mm3 (25.6%), respectively (P=0.017). At the stent edges there was no significant change in lumen volume. CONCLUSIONS: Cold-end stenting results in increased neointimal hyperplasia in in-stent non-radioactive segments.

Brachytherapy↗

PubMed2001

Three dimensional intravascular ultrasonic assessment of the local mechanism of restenosis after balloon angioplasty.

OBJECTIVE: To assess the mechanism of restenosis after balloon angioplasty. DESIGN: Prospective study. PATIENTS: 13 patients treated with balloon angioplasty. INTERVENTIONS: 111 coronary subsegments (2 mm each) were analysed after balloon angioplasty and at a six month follow up using three dimensional intravascular ultrasound (IVUS). MAIN OUTCOME MEASURES: Qualitative and quantitative IVUS analysis. Total vessel (external elastic membrane), plaque, and lumen volume were measured in each 2 mm subsegment. Delta values were calculated (follow up - postprocedure). Remodelling was defined as any (positive or negative) change in total vessel volume. RESULTS: Positive remodelling was observed in 52 subsegments while negative remodelling occurred in 44. Remodelling, plaque type, and dissection were heterogeneously distributed along the coronary segments. Plaque composition was not associated with changes in IVUS indices, whereas dissected subsegments had a greater increase in total vessel volume than those without dissection (1.7 mm(3) v -0.33 mm(3), p = 0.04). Change in total vessel volume was correlated with changes in lumen (p < 0.05, r = 0.56) and plaque volumes (p < 0.05, r = 0.64). The site with maximum lumen loss was not the same site as the minimum lumen area at follow up in the majority (n = 10) of the vessels. In the multivariate model, residual plaque burden had an influence on negative remodelling (p = 0.001, 95% confidence interval (CI) -0.391 to -0.108), whereas dissection had an effect on total vessel increase (p = 0.002, 95% CI 1.168 to 4.969). CONCLUSIONS: The mechanism of lumen renarrowing after balloon angioplasty appears to be determined by unfavourable remodelling. However, different patterns of remodelling may occur in individual injured coronary segments, which highlights the complexity and influence of local factors in the restenotic process.

Angioplasty, Balloon, Coronary↗

PubMed2001

Uncomplicated moderate coronary artery dissections after balloon angioplasty: good outcome without stenting.

OBJECTIVE: To study the relation between moderate coronary dissections, coronary flow velocity reserve (CFVR), and long term outcome. METHODS: 523 patients undergoing balloon angioplasty and sequential intracoronary Doppler measurements were examined as part of the DEBATE II trial (Doppler endpoints balloon angioplasty trial Europe). After successful balloon angioplasty, patients were randomised to stenting or no further treatment. Dissections were graded at the core laboratory by two observers and divided into four categories: none, mild (type A-B), moderate (type C), severe (types D to F). Patients with severe dissections (n = 128) or without available reference vessel CFVR (n = 139) were excluded. The remaining 256 patients were divided into two groups according to the presence (group A, n = 45) or absence (group B, n = 211) of moderate dissection. RESULTS: Following balloon angioplasty, there was no difference in CFVR between the two groups. At 12 months follow up, a higher rate of major adverse cardiac events was observed overall in group A than in group B (10 (22%) v 23 (11%), p = 0.041). However, the risk of major adverse events was similar in the subgroups receiving balloon angioplasty (group A, 6 (19%) v group B, 16 (16%), NS). Among group A patients, the adverse events risk was greater in those randomised to stenting (odds ratios 6.603 v 1.197, p = 0.046), whereas there was no difference in risk if the group was analysed according to whether the CFVR was < 2.5 or >/= 2.5 after balloon angioplasty. CONCLUSIONS: Moderate dissections left untreated result in no increased risk of major adverse cardiac events. Additional stenting does not improve the long term outcome.

Aortic Dissection↗

PubMed2000

Methodological and clinical implications of the relocation of the minimal luminal diameter after intracoronary radiation therapy. Dose Finding Study Group.

OBJECTIVES: The aims of the study were to determine the incidence of relocation of the minimal luminal diameter (MLD) after beta-radiation therapy following balloon angioplasty (BA) and to describe a new methodological approach to define the effect of brachytherapy on treated coronary stenoses. BACKGROUND: Luminal diameter of coronary lesions may increase over time following angioplasty and irradiation. As a result, the MLD at follow-up may be relocated from its location preintervention, which may induce misleading results when a restricted definition of the target segment by quantitative coronary angiography (QCA) is performed. METHODS: Patients treated with BA followed by intracoronary brachytherapy according to the Dose-Finding Study constituted the study population. A historical cohort of patients treated with BA was used as control group. To be included in the analysis, an accurate angiographic documentation of all instrumentations during the procedure was mandatory. In the irradiated patients, four regions were defined by QCA: vessel segment (VS), target segment (TS), injured segment (INS), and irradiated segment (IRS). RESULTS: Sixty-five patients from the Dose-Finding Study and 179 control patients were included. At follow-up, MLD was relocated more often in the radiation group (78.5% vs. 26.3%; p < 0.0001). The rate of >50% diameter stenosis differed among the four predefined regions: 3.1% in the TS; 7.7% in the INS; 9.2% in the IRS and 13.8% in the VS. CONCLUSIONS: Relocation of the MLD is commonly demonstrated after BA and brachytherapy, and it should be taken into account during the analysis of the results of radiation clinical trials.

Angioplasty, Balloon↗

PubMed2000

Three-dimensional intravascular ultrasound assessment of noninjured edges of beta-irradiated coronary segments.

BACKGROUND: The "edge effect," late lumen loss at the margins of the treated segment, has become an important issue in the field of coronary brachytherapy. The aim of the present study was to assess the edge effect in noninjured margins adjacent to the irradiated segments after catheter-based intracoronary beta-irradiation. METHODS AND RESULTS: Fifty-three vessels were assessed by means of 3-dimensional intravascular ultrasound after the procedure and at 6- to 8-month follow-up. Fourteen vessels (placebo group) did not receive radiation (sham source), whereas 39 vessels were irradiated. In the irradiated group, 48 edges (5 mm in length) were identified as noninjured, whereas 18 noninjured edges were selected in the placebo group. We compared the volumetric intravascular ultrasound measurements of the noninjured edges of the irradiated vessels with the fully irradiated nonstented segments (IRS, n=27) (26-mm segments received the prescribed 100% isodose) and the noninjured edges of the vessels of the placebo patients. The lumen decreased (6 mm(3)) in the noninjured edges of the irradiated vessels at follow-up (P:=0. 001). We observed a similar increase in plaque volume in all segments: noninjured edges of the irradiated group (19.6%), noninjured edges of the placebo group (21.5%), and IRS (21.0%). The total vessel volume increased in the IRS in the 3 groups. No edge segment was subject to repeat revascularization. CONCLUSIONS: The edge effect occurs in the noninjured margins of radiation source train in both irradiated and placebo patients. Thus, low-dose radiation may not play an important role in this phenomenon, whereas nonmeasurable device injury may be considered a plausible alternative explanation.

Angioplasty, Balloon↗

PubMed2000

Positive geometric vascular remodeling is seen after catheter-based radiation followed by conventional stent implantation but not after radioactive stent implantation.

BACKGROUND: Recent reports demonstrate that intracoronary radiation affects not only neointimal formation but also vascular remodeling. Radioactive stents and catheter-based techniques deliver radiation in different ways, suggesting that different patterns of remodeling after each technique may be expected. METHODS AND RESULTS: We analyzed remodeling in 18 patients after conventional stent implantation, 16 patients after low-activity radioactive stent implantation, 16 patients after higher activity radioactive stent implantation, and, finally, 17 patients who underwent catheter-based radiation followed by conventional stent implantation. Intravascular ultrasound with 3D reconstruction was used after stent implantation and at the 6-month follow-up to assess remodeling within the stent margins and at its edges. Preprocedural characteristics were similar between groups. In-stent neointimal hyperplasia (NIH) was inhibited by high-activity radioactive stent implantation (NIH 9.0 mm(3)) and by catheter-based radiation followed by conventional stent implantation (NIH 6.9 mm(3)) compared with low-activity radioactive stent implantation (NIH 21.2 mm(3)) and conventional stent implantation (NIH 20.8 mm(3)) (P:=0.008). No difference in plaque or total vessel volume was seen behind the stent in the conventional, low-activity, or high-activity stent implantation groups. However, significant increases in plaque behind the stent (15%) and in total vessel volume (8%) were seen in the group that underwent catheter-based radiation followed by conventional stent implantation. All 4 groups demonstrated significant late lumen loss at the stent edges; however, edge restenosis was seen only in the group subjected to high-activity stent implantation and appeared to be due to an increase in plaque and, to a lesser degree, to negative remodeling. CONCLUSIONS: Distinct differences in the patterns of remodeling exist between conventional, radioactive, and catheter-based radiotherapy with stenting.

Adult↗

PubMed2000

Angiographic and clinical outcome of mild to moderate nonocclusive unstented coronary artery dissection and the influence on coronary flow velocity reserve. The Debate I Study Group.

Limited data are available regarding the angiographic healing rate and physiologic impact of coronary artery dissections. Therefore, we studied the impact of coronary dissections on coronary flow velocity and outcome as well as their healing rate at 6-month follow-up balloon angioplasty. Of 297 patients who underwent balloon angioplasty, 225 underwent intracoronary Doppler measurements and 184 had Doppler and angiographic assessment at 6-month follow-up. Dissections were scored by an independent core lab (Cardialysis BV) and divided in 4 groups: mild (types A to B), moderate (type C), severe (D to F), and patients without dissections. Severe dissections (types D to F) were excluded from the analysis. Clinical, angiographic, and Doppler data were compared among the remaining 3 patient groups. From the 67 dissections detected after balloon angioplasty, only 3 (4.5%) remained unhealed at follow-up. Immediately after balloon angioplasty, the moderate dissection group was associated with a lower coronary flow velocity reserve than the patients with mild (2.16 +/- 0.60 vs 2.82 +/- 1.00, p = 0.037) or no dissections (2.16 +/- 0.60 vs 2.71 +/- 0.88, p = 0.046), respectively. In addition, higher recurrence of angina at 30 days was observed in the moderate group rather than in the mild group (5 [50%] vs 8 [16%], p = 0.0160) and in the patients without dissections (11 [12%], p = 0.007). After standard balloon angioplasty, the occurrence of unhealed dissections is a rare phenomenon. An impaired coronary flow reserve was observed after the development of nonocclusive type C dissections, which was associated with a worse short-term outcome.

Angioplasty, Balloon, Coronary↗

PubMed2000

Geographic miss: a cause of treatment failure in radio-oncology applied to intracoronary radiation therapy.

BACKGROUND: A recognized limitation of endovascular beta-radiation therapy is the development of new stenosis at the edges of the irradiated area. The combination of injury and low-dose radiation may be the precursor of this phenomenon. We translated the radio-oncological concept of "geographic miss" to define cases in which the radiation source did not fully cover the injured area. The aims of the study were to determine the incidence and causes of geographic miss and evaluate the impact of this inadequate treatment on the outcome of patients treated with intracoronary beta-radiation. METHODS AND RESULTS: We analyzed 50 consecutive patients treated with beta-radiation after percutaneous coronary intervention. The prescribed dose ranged between 12 and 20 Gy at 2 mm from the source axis. By means of quantitative coronary angiography, the irradiated segment (IRS) and both edges were studied before and after intervention and at 6-month follow-up. Edges that were injured during the procedure constituted the geographic miss edges. Twenty-two edges were injured during the intervention, mainly because of procedural complications that extended the treatment beyond the margins of the IRS. Late loss was significantly higher in geographic miss edges than in IRSs and uninjured edges (0.84+/-0.6 versus 0.15+/-0.4 and 0.09+/-0.4 mm, respectively; P<0.0001). Similarly, restenosis rate was significantly higher in the injured edges (10% within IRS, 40.9% in geographic miss edges, and 1.9% in uninjured edges; P<0.001). CONCLUSIONS: These data support the hypothesis that the combination of injury and low-dose beta-radiation induces deleterious outcome.

Angioplasty, Balloon, Coronary↗

PubMed2000

Residual plaque burden, delivered dose, and tissue composition predict 6-month outcome after balloon angioplasty and beta-radiation therapy.

BACKGROUND: Inhomogeneity of dose distribution and anatomic aspects of the atherosclerotic plaque may influence the outcome of irradiated lesions after balloon angioplasty (BA). We evaluated the influence of delivered dose and morphological characteristics of coronary stenoses treated with beta-radiation after BA. METHODS AND RESULTS: Eighteen consecutive patients treated according to the Beta Energy Restenosis Trial 1.5 were included in the study. The site of angioplasty was irradiated with the use of a beta-emitting (90)Sr/(90)Y source. With the side branches used as anatomic landmarks, the irradiated area was identified and volumetric assessment was performed by 3D intracoronary ultrasound imaging after treatment and at 6 months. The type of tissue, the presence of dissection, and the vessel volumes were assessed every 2 mm within the irradiated area. The minimal dose absorbed by 90% of the adventitial volume (D(v90)Adv) was calculated in each 2-mm segment. Diffuse calcified subsegments and those containing side branches were excluded. Two hundred six coronary subsegments were studied. Of those, 55 were defined as soft, 129 as hard, and 22 as normal/intimal thickening. Plaque volume showed less increase in hard segments as compared with soft and normal/intimal thickening segments (P<0.0001). D(v90)Adv was associated with plaque volume at follow-up after a polynomial equation with linear and nonlinear components (r = 0.71; P = 0.0001). The multivariate regression analysis identified the independent predictors of the plaque volume at follow-up: plaque volume after treatment, D(v90)Adv, and type of plaque. CONCLUSIONS: Residual plaque burden, delivered dose, and tiss composition play a fundamental role in the volumetric outcome at 6-month follow-up after beta-radiation therapy and BA.

Angioplasty, Balloon, Coronary↗

PubMed2000

Three-dimensional intravascular ultrasonic volumetric quantification of stent recoil and neointimal formation of two new generation tubular stents.

Currently, several different designs of coronary stents are available. However, only a few of the new generation stents have been investigated in large randomized trials. Mechanical behavior of first-generation stents (Palmaz-Schatz, Gianturco-Roubin) may not be applied to the new designs. We investigated the chronic mechanical behavior (recoil) of 2 stents recently approved by the Food and Drug Administration (MULTILINK and NIR). Forty-eight patients with single-stent implantation (23 MULTILINK and 25 NIR) were assessed by means of volumetric 3-dimensional intravascular ultrasound analysis after the procedure and at 6-month follow-up. In addition, volumetric assessment of neointimal formation was performed. No significant chronic stent recoil was detected in both groups (delta MULTILINK stent volume: +5.6+/-41 mm3 [p = NS] and delta NIR stent volume + 2.1+/-26 mm3 [p = NS]). A similar degree of neointimal formation at 6 months was observed between the 2 stents (MULTILINK 46+/-31.9 mm3 vs NIR 39.9+/-27.6 mm3, p = NS). In conclusion, these 2 second-generation tubular stents did not show chronic recoil and appeared to promote similar proliferative response after implantation in human coronary arteries.

Cell Division↗

PubMed2000

The ESSEX (European Scimed Stent Experience) study.

The aim of the study was to assess the safety and feasibility of implantation of the Scimed Radius stent. Secondary objectives were to assess the result of stent placement by quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS). The ESSEX study was a prospective, multicenter, observational study in which candidates for a single elective stent implantation, in a de novo or restenotic lesion, reference diameter 2.75-4.00 mm and target lesion < 14 mm in length, were enrolled. QCA at baseline, postprocedure, and 6-month follow-up was performed. IVUS was used to assess optimal stent implantation. One hundred and three patients were enrolled. Forty-four percent of the patients had unstable angina. Stent implantation was technically successful in all patients. Additional stents were implanted in 17 patients for procedural dissection (16) and spasm (1). Ninety-seven percent of patients were event-free at 1 month and 76% at 6-month follow-up. Angiographic restenosis rates for de novo lesions and for all patients were 19% and 21%, respectively. Clinical events occurred at 1- and 6-month follow-up in 2.9% and 24.3% of patients, respectively. No patients suffered subacute thrombosis. Retrospective analysis of peak balloon inflation pressure (< or = 12 and > 12 atm) as a determinant of clinical, QCA, and IVUS outcomes suggested no benefit or detrimental effect from optimization with high-pressure balloon inflation. Implantation of the self-expanding Radius stent is safe and efficacious. Based on registry data, clinical, angiographic, and IVUS, data comparable with modern balloon-expandable stents were obtained.

Adult↗

PubMed2000

Statistical methods to improve the precision of the treadmill exercise test.

OBJECTIVES: The study systematically compared different measures of ST segment depression from the treadmill exercise test. BACKGROUND: The value of the treadmill exercise test for objectively measuring treatment effects is limited by random error in the measurement of ST depression and may be biased by regression to the mean or by the decision to terminate the test. METHODS: Treadmill exercise was performed in 21 subjects with ischemic heart disease 1 h after isosorbide dinitrate 10 mg or placebo in a double-blind randomized crossover study. A 12-lead electrocardiogram (ECG) was recorded every 30 s during and at peak exercise. The relative sample size needed to detect the nitrate effect was compared for different summary measures of ST depression. RESULTS: The ST depression measured from a single unmatched lead at longest equivalent sub-maximal exercise needed the lowest sample size to detect the nitrate effect in paired comparisons (p = 0.000006). Averaging over multiple leads or times did not improve detection of the nitrate effect. The rate of increase in ST depression (in mm/min) calculated by linear regression needed a similar sample size (x1.32, 95% CI 0.62 to 2.58). A larger sample size was needed for ST depression at peak exercise (x2.9, CI 1.3, 11.1) and exercise duration (x4.5, CI 1.5, 38). Time to 1-mm ST depression was the least efficient measurement (relative sample size x15.5, CI 1.6, >1,000). Comparison of matched leads resulted in >2-fold differences in estimates of the nitrate effect because of bias from regression to the mean. CONCLUSIONS: Maximal ST depression at longest equivalent sub-maximal exercise and the maximal rate of increase in ST depression had less bias and random variation than did other commonly used measures. The rate of increase in ST depression is preferred because it can be calculated in either paired or unpaired studies.

Administration, Oral↗

PubMed2000

Relationship between tensile stress and plaque growth after balloon angioplasty treated with and without intracoronary beta-brachytherapy.

AIMS: We investigated the influence of tensile stress on plaque growth after balloon angioplasty with and without beta-radiation therapy. METHODS AND RESULTS: Thirty-one consecutive patients successfully treated with balloon angioplasty were analysed qualitatively and quantitatively by means of an ECG-gated three-dimensional intravascular ultrasound post-procedure and at follow-up. Eighteen patients were irradiated with catheter-based beta-radiation ((90)Sr/(90)Y source) and 13 were not (control). Studied segments were divided into 2 mm subsegments. Thus 184 irradiated and 111 non-irradiated subsegments were included. Tensile stress was calculated according to Laplace's law. The radiation dose was calculated by means of dose-volume histograms. Plaque growth was positively correlated to tensile stress in both the radiation and control groups (r=0.374, P=0.0001 and r=0.305, P=0.001). Low-dose subsegments (<6 Gy) had a significant correlation (r=0.410, P=0.0001) whereas no correlation was observed in the effective-dose subsegments (> or = 6 Gy). Multivariate analysis identified tensile stress as the only independent predictor of plaque increase in non-irradiated subsegments, whereas actual dose and plaque morphology were stronger predictors in irradiated subsegments. CONCLUSION: The results of this study suggest that plaque growth is related to tensile stress after balloon angioplasty. Intracoronary brachytherapy may alter the biophysical process on plaque growth when the prescribed dose is effectively delivered.

Aged↗