Lesion-to-lesion independence of restenosis after treatment by conventional angioplasty, stenting, or directional atherectomy. Validation of lesion-based restenosis analysis

Optical coherence tomography substudy of a prospective multicentre randomised post-market trial to assess the safety and effectiveness of the Firehawk cobalt-chromium coronary stent (rapamycin target-eluting) system for the treatment of atherosclerotic lesions: TARGET All Comers

AIMS

Durable polymer drug-eluting stents (DP-DES) may contribute to persistent inflammation, delayed endothelial healing and subsequent late DES thrombosis. The aim of this optical coherence tomography (OCT) substudy was to compare healing and neointimal coverage of a novel bioabsorbable polymer sirolimus-eluting stent (Firehawk®) (BP-DES) versus the DP-DES (XIENCE) at 90 days in an all-comers patient population.

METHODS AND RESULTS

The TARGET All Comers study is a prospective multicentre randomised post-market trial of 1,656 patients randomised 1:1 to Firehawk or XIENCE at 21 centres in 10 European countries. The TARGET OCT substudy enrolled 36 consecutive patients with 52 lesions at six centres proficient in OCT. Follow-up OCT was performed at three months or prior to revascularisation when occurring before the three-month window. The substudy was designed for non-inferiority of the primary endpoint of neointimal thickness. At follow-up, the mean neointimal thickness by OCT (52 lesions: Firehawk, n=24; XIENCE, n=28), was not significantly different between groups (Firehawk 75.5 μm vs. XIENCE V 82.3 μm) meeting the primary endpoint of non-inferiority (pnoninferiority<0.001). The percentage of stent strut coverage was high in both groups (strut level: 99.9±0.3% vs. 100±0.1%, p=0.26), and the proportion of malapposed struts (1.0±1.6% vs. 1.2±2.0%, p=0.51) was low in both groups.

CONCLUSIONS

Based on OCT, the Firehawk BP-DES has a similar healing response three months after implantation compared to the DP-DES, with near complete strut coverage, moderate neointima formation and minimal strut malapposition.

Intra-individual head-to-head comparison of Sirolimus®- and Paclitaxel®-eluting stents for coronary revascularization. A randomized, multi-center trial

BACKGROUND

Despite the known effects of drug-eluting stents (DES), other cofactors attributed to patient characteristics affect their success. Interest focused on designing a study minimizing these factors to answer continuing concerns on the heterogeneity of response to different DESs. The study's aim was to investigate the feasibility and impact of an intra-individual comparison design in patients (pts) with two coronary artery stenosis treated with a Sirolimus- (SES) and a Paclitaxel- (PES) eluting stent.

METHODS AND RESULTS

The study was conducted as a prospective, randomized, multi-center trial in 112 pts who consented to treatment with a SES and a PES. Pts were eligible if they suffered from the presence of two single primary target lesions in two different native coronary arteries. Lesions were randomized to either SES or PES treatment. The primary endpoint was in-stent luminal late loss (LLL), as determined by quantitative angiography at 8 months; clinical follow up was obtained at 1, 8, and 12 months additionally. The LLL (0.13 ± 0.28 mm SES vs. 0.26 ± 0.35 mm PES, p=0.011) showed less neointima in SES. With a predefined cut-off criterion of 0.2mm difference in LLL, 53/87 pts SES and PES were similar effective. 34/87 pts had a divergent result, 26 pts had greater benefit from SES while 8 pts had greater benefit from PES. Overall, MACE (MI, TLR, and death) occurred in 19 (17%) pts. Based on lesion analysis of 108 lesions treated with SES and 110 lesions treated with PES, 5 (4.6%) lesions with SES and 3 (2.7%) lesions with PES required repeated TLR.

CONCLUSION

An intra-individual comparison design to assess differences in efficacy of different DESs is feasible, safe and achieves similar results to inter-individual studies. This study is among the first to show that failure of one DES does not necessarily implicate failure of another DES and vice versa.

Reduction of neointimal hyperplasia after coronary stenting by pioglitazone in nondiabetic patients with metabolic syndrome

BACKGROUND

This study investigates whether pioglitazone reduces neointimal hyperplasia after coronary stenting in nondiabetic patients with metabolic syndrome (MS) using intravascular ultrasound (IVUS). Pioglitazone, a novel insulin-sensitizing thiazolidinedione, has been shown to reduce neointimal hyperplasia after coronary stenting in patients with type 2 diabetes. However, the effect of pioglitazone on in-stent restenosis in nondiabetic patients with MS remains unknown.

METHODS AND RESULTS

Twenty-eight nondiabetic patients with MS after bare-metal stent implantation were randomized to 6-month treatment with or without 30 mg/d of pioglitazone (pioglitazone group [PIO] of 14 patients with 16 lesions and control group [CONT] of 14 patients with 16 lesions). At baseline and at 6-month follow-up, assessment of insulin resistance and visceral fat accumulation, quantitative coronary angiographic analysis, and IVUS measurements were performed. Pioglitazone treatment improved insulin resistance and decreased visceral fat accumulation without significant changes in plasma glucose levels, glycosylated hemoglobin A1c levels, and lipid profiles. Intimal index (intimal area/stent area) and intimal area were reduced in PIO compared with CONT (13% +/- 7% vs 21% +/- 13%, P = .033; 1.28 +/- 0.76 mm2 vs 1.90 +/- 1.16 mm2, P = .084; respectively). Binary restenosis rate was 0% in PIO versus 31% in CONT (P = .043).

CONCLUSIONS

This is the first randomized, prospective IVUS study demonstrating that pioglitazone reduces neointimal hyperplasia after coronary stenting in nondiabetic patients with MS. Our data suggest that pioglitazone treatment may represent a novel therapeutic tool to target in-stent restenosis in nondiabetic patients with MS.

The angiotensin II receptor blocker candesartan cilexetil reduces neointima proliferation after coronary stent implantation: a prospective randomized study under intravascular ultrasound guidance

OBJECTIVES

The purpose of this study was to evaluate whether an angiotensin II receptor blocker, candesartan cilexetil, reduced neointima formation after coronary stent implantation by way of serial intravascular ultrasound analysis.

BACKGROUND

Previous experimental studies have suggested that angiotensin II receptor blocker reduced neointima formation after vascular injury. However, it is unclear whether candesartan cilexetil has a similar effect on human coronary artery.

METHODS

We recruited 50 consecutive patients with stable angina pectoris and 60 stenotic lesions. Patients were prospectively randomized into 2 groups: (1) 25 patients with 31 lesions received candesartan cilexetil (4-12 mg/d), and (2) 25 patients with 29 lesions did not receive the drug. Follow-up intravascular ultrasound was performed 6 m after the stent implantation. Cross-sectional images were obtained at 1-mm intervals within the stent, and the stent volume (SV), lumen volume (LV), and neointima volume (NV = SV - LV) were calculated using Simpson's rule. The percentage neointima volume obstruction (%NV) was calculated as NV/SV x 100.

RESULTS

Clinical and angiographic backgrounds were comparable between the 2 groups. At follow-up, the candesartan group had smaller SV and larger LV (SV, 156.3 +/- 53.7 vs 165.4 +/- 61.8 mm3 , ns; LV, 122.2 +/- 49.0 vs 113.1 +/- 45.5 mm3 , ns), and significantly smaller NV and significantly smaller %NV than the control group (NV, 34.2 +/- 16.6 vs 52.3 +/- 32.6 mm3 , P < .01; %NV, 22.7 +/- 10.9% vs 31.3 +/- 13.4%, P < .01).

CONCLUSIONS

Candesartan treatment decreases neointima formation and hence may reduce in-stent restenosis.

Prediction of sites of coronary atherosclerosis progression:In vivo profiling of endothelial shear stress, lumen, and outer vessel wall characteristics to predict vascular behavior

PURPOSE OF REVIEW

Native atherosclerosis and in-stent restenosis are focal and evolve independently. The endothelium regulates arterial behavior by responding to its local environment of hemodynamic stresses, in particular, shear stress. Identification of endothelial shear stress and arterial wall characteristics may allow for the prediction of the progression of atherosclerosis. Accurate identification of arterial segments at high risk for progression may permit preemptive intervention strategies to avoid adverse coronary events.

RECENT FINDINGS

In vitro studies indicate that low endothelial shear stress upregulates the genetic and molecular responses leading to the initiation and progression of atherosclerosis, and promotes inflammation and formation of other features characteristic of vulnerable plaque. Physiologic endothelial shear stress is vasculoprotective and fosters quiescence of the endothelium and vascular wall. High endothelial shear stress promotes platelet aggregation. Recent studies have now provided evidence that endothelial shear stress and vascular wall morphology along the course of human coronary arteries can be characterized in vivo, and, in serial studies, may actually predict the focal areas in which atherosclerosis progression occurs.

SUMMARY

Rapidly evolving methodologies are able to characterize the arterial wall and the local hemodynamic environmental factors likely responsible for progression of coronary disease in humans. These new diagnostic modalities allow for identification of plaque progression. Future studies need to identify the factors responsible for vulnerable plaque formation. The current availability of drug-eluting stents with a low risk of restenosis allows for consideration of preemptive intervention strategies for these high-risk vascular sites such that future adverse coronary events can be averted.

Cost-effectiveness of bypass surgery versus stenting in patients with multivessel coronary artery disease

PURPOSE

To compare the cost-effectiveness of surgical and angioplasty-based coronary artery revascularization techniques, in particular, angioplasty with primary stenting.

METHODS

We used data from the Study of Economics and Quality of Life, a substudy of the Bypass Angioplasty Revascularization Investigation (BARI), to measure the outcomes and costs of angioplasty and bypass surgery in patients with multivessel coronary artery disease who had not undergone prior coronary artery revascularization. Using a Markov decision model, we updated the outcomes and costs to reflect technology changes since the time of enrollment in BARI, and projected the lifetime costs and quality-adjusted life-years (QALYs) for the two procedures from the time of initial treatment through death. We accounted for the effects of improved procedural safety and efficiency, and prolonged therapeutic effects of both surgery and stenting. This study was conducted from a societal perspective.

RESULTS

Surgical revascularization was less costly and resulted in better outcomes than catheter-based intervention including stenting. It remained the preferred strategy after adjusting the stent outcomes to eliminate the costs and events associated with target lesion restenosis. Among angioplasty-based strategies, primary stent use cost an additional 189,000 US dollars per QALY gained compared with a strategy that reserved stent use for treatment of suboptimal balloon angioplasty results.

CONCLUSION

Bypass surgery results in better outcomes than angioplasty in patients with multivessel disease, and at a lower cost.

Isolated post-challenge hyperglycemia in patients with normal fasting glucose concentration exaggerates neointimal hyperplasia after coronary stent implantation

Postprandial hyperglycemia has been shown to increase the risk of cardiovascular disease as much as overt diabetes mellitus does. The aim of this study was to determine whether isolated post-challenge hyperglycemia during an oral glucose tolerance test (OGTT) is related to exaggerated neointimal proliferation after coronary stent implantation. Forty seven coronary lesions treated with stents in 40 patients who had normal fasting glucose levels (<110 mg/dl) were categorized into the following 2 groups according to the results of a 75-g OGTT: 29 lesions in 24 patients with normal glucose tolerance (NGT group) and 18 lesions in 16 patients with abnormal glucose tolerance (AGT group). Although there were no differences in angiographic characteristics before and immediately after stenting between the 2 groups, the minimal lumen diameter was significantly smaller (p=0.04) and the degree of stenosis and late loss were also significantly greater (p=0.01 and p=0.047) in the AGT group than in the NGT group at 6-month follow-up. Multiple regression analysis including the insulin concentrations during an OGTT revealed that the 120-min plasma glucose concentration after glucose load significantly correlated with late loss (p=0.0018) and the degree of stenosis (p=0.0100) at follow-up. It is concluded that isolated post-challenge hyperglycemia exaggerates neointimal hyperplasia after coronary stent implantation.

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.

Determination of in vivo velocity and endothelial shear stress patterns with phasic flow in human coronary arteries: a methodology to predict progression of coronary atherosclerosis

BACKGROUND

Although the coronary arteries are equally exposed to systemic risk factors, coronary atherosclerosis is focal and eccentric, and each lesion evolves in an independent manner. Variations in shear stress elicit markedly different humoral, metabolic, and structural responses in endothelial cells. Areas of low shear stress promote atherosclerosis, whereas areas of high shear stress prevent atherosclerosis. Characterization of the shear stresses affecting coronary arteries in humans in vivo may permit prediction of progression of coronary disease, prediction of which plaques might become vulnerable to rupture, and prediction of sites of restenosis after percutaneous coronary intervention.

METHODS

To determine endothelial shear stress, the 3-dimensional anatomy of a segment of the right coronary artery was determined immediately after directional atherectomy by use of a combination of intracoronary ultrasound and biplane coronary angiography. The geometry of the segment was represented in curvilinear coordinates and a computational fluid dynamics technique was used to investigate the detailed phasic velocity profile and shear stress distribution. The results were analyzed with several conventional indicators and one novel indicator of disturbed flow.

RESULTS

Our methodology identified areas of minor flow reversals, significant swirling, and large variations of local velocity and shear stress--temporally, axially, and cirumferentially--within the artery, even in the absence of significant luminal obstruction.

CONCLUSIONS

We have described a system that permits, for the first time, the in vivo determination of pulsatile local velocity patterns and endothelial shear stress in the human coronary arteries. The flow phenomena exhibit characteristics consistent with the focal nature of atherogenesis and restenosis.

Lesion-to-lesion relationship of the restenosis process after placement of coronary stents

The interrelation between multiple stented lesions within one patient in the restenosis process is only partially understood. From 492 patients with follow-up angiograms after coronary stent placement, 115 patients underwent multilesion procedures involving 233 lesions. In randomly chosen 39 patients with 79 lesions, additional intravascular ultrasound (IVUS) studies were performed to measure intimal hyperplasia cross-sectional area (CSA) and thickness. A general linear model with intraclass correlation was used to calculate the coefficient of correlation rho (rho = 1.0 indicates perfect correlation; rho = 0.0 indicates no correlation) of late loss, late loss index, intimal hyperplasia CSA, and intimal hyperplasia thickness. Multivariate analysis showed restenosis in the companion lesion (odds ratio 4.68, 95% confidence interval 1. 68-12.92, P = 0.003) and small minimal lumen diameter preintervention (odds ratio 0.28, 95% confidence interval 0.11-0.73, P = 0.009) to be predictors of restenosis. There was a weak correlation between multiple lesions within the same patient for late lumen loss rho = 0.28 (95% confidence interval 0.10-0.46, P < 0. 001) and late loss index. IVUS analysis demonstrated correlation of intimal hyperplasia CSA rho = 0.40 (95% confidence interval 0.06-0. 74, P = 0.009) and of intimal hyperplasia thickness. In conclusion, late loss and intimal hyperplasia demonstrate a correlation between multiple stented lesions within one patient. In addition to known lesion related factors, restenosis in a companion lesion is a predictor for restenosis. Cathet. Cardiovasc. Intervent. 51:266-272, 2000.

Troglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with non-insulin dependent diabetes mellitus: a serial intravascular ultrasound study

OBJECTIVES

The aim of the present study was to determine whether troglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with non-insulin dependent diabetes mellitus (NIDDM).

BACKGROUND

Increased in-stent restenosis in patients with diabetes mellitus is due to accelerated neointimal tissue proliferation after coronary stent implantation. Troglitazone inhibits intimal hyperplasia in experimental animal models.

METHODS

We studied 62 stented lesions in 52 patients with plasma glucose levels (PG) > or = 11.1 mmol/liter at 2 h after 75 g oral glucose load. The study patients were randomized into two groups: the troglitazone group of 25 patients with 29 stents, who were treated with 400 mg of troglitazone, and the control group of 27 patients with 33 stents. All patients underwent oral glucose tolerance tests before and after their six-month treatment period. The sum of PG (sum of PG) and the sum of insulin levels (sum of IRI) were measured. Serial (postintervention and at six-month follow-up) intravascular ultrasound studies were performed. Cross-sectional images within stents were taken at every 1 mm, using an automatic pullback. Stent areas (SA), lumen areas (LA), and intimal areas (IA = SA - LA) were measured and averaged over a number of selected image slices. The intimal index was calculated as intimal index = averaged IA/averaged SA x 100%.

RESULTS

There were no differences between the two groups before treatment in sum of PG (31.35 +/- 3.07 mmol/liter vs. 32.89 +/- 4.87 mmol/liter, respectively, p = 0.2998) and sum of IRI (219.6 +/- 106.2 mU/liter vs. 209.2 +/- 91.6 mU/liter, respectively, p = 0.8934). However, reductions in sum of PG at the six-month follow-up in the troglitazone group were significantly greater than those in the control group (-21.4 +/- 8.8% vs. -4.5 +/- 7.4%, respectively, p < 0.0001). Likewise, decreases in sum of IRI were greater in the troglitazone-treated group (-31.4 +/- 17.9% vs. -1.9 +/- 15.1%, respectively, p < 0.0001). Although, there were no differences between the two groups in SA at postintervention (7.4 +/- 2.2 mm2 vs. 7.3 +/- 1.7 mm2, respectively, p = 0.9482) and at follow-up (7.3 +/- 2.3 mm2 vs. 7.3 +/- 1.8 mm2, respectively, p = 0.2307), the LA at follow-up in the troglitazone group was significantly greater than that in the control group (5.3 +/- 1.7 mm2 vs. 3.7 +/- 1.7 mm2, respectively, p = 0.0002). The IA at follow-up in the troglitazone group was significantly smaller than that in the control group (2.0 +/- 0.9 mm2 vs. 3.5 +/- 1.8 mm2, respectively, p < 0.0001). This was also true for intimal index (27.1 +/- 11.5% vs. 49.0 +/- 14.4%, respectively, p < 0.0001).

CONCLUSIONS

Serial intravascular ultrasound assessment shows that administration of troglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with NIDDM.

Intravascular hemodynamic factors responsible for progression of coronary atherosclerosis and development of vulnerable plaque

The initiation, localization, growth, composition, and rupture of intracoronary atheromatous plaque-factors that define the natural history of coronary artery disease-are all dependent on inhomogenieties and irregularities of intracoronary local blood flow and endothelial shear stress. Restenosis of mechanically recanalized coronary arteries may be related in part to similar abnormalities of disturbed local flood flow and shear stress. Low or reversed shear stress leads to plaque development and progression. High shear stress contributes significantly to plaque rupture. Regions of hemodynamic stasis caused by major luminal irregularities may lead to thrombosis and myocardial infarction without plaque rupture. This review outlines the mechanisms that link hemodynamic factors to plaque development and rupture and describes in some detail recently developed techniques that, for the first time, make it possible to determine these factors in vivo in patients during routine cardiac catheterization procedures.

Impact of end-stage renal disease on clinical and angiographic outcomes after coronary stenting

Although patients with end-stage renal disease (ESRD) are at high risk for restenosis that requires repeat revascularization after balloon angioplasty, their restenosis rate after coronary stenting is still unknown. Over a 4-year period, we performed coronary stenting on 40 lesions in 34 patients with ESRD. We compared these lesions with 80 lesions from patients without renal disease who underwent coronary stenting in the STARS and WINS clinical trials, matched for treatment site, diabetes, lesion length, and reference vessel diameter. Quantitative coronary angiography was performed on all lesions and clinical outcomes were assessed at 9-month follow-up. Clinical and angiographic characteristics were well matched between the 2 groups and acute clinical success rates were similar. Despite comparable initial angiographic results over the 9-month follow-up period, repeat target lesion revascularization was twice as frequent in the ESRD group compared with the control group (35% vs 16%, p <0.05). After adjusting for differences in postprocedural minimum lumen diameter and other angiographic and clinical characteristics, ESRD remained the most important predictor of late target lesion revascularization (relative risk = 2.3, p = 0.04). In addition, overall 9-month mortality was higher for ESRD patients than for the control population (18% vs 2%, p <0.01). Thus, despite similar angiographic results, patients with ESRD are at higher risk for target lesion revascularization after coronary stenting than controls. Nonetheless, most patients with ESRD do not develop restenosis after stent placement, suggesting an important role for stenting in the management of this challenging population.

Hyperinsulinemia during oral glucose tolerance test is associated with increased neointimal tissue proliferation after coronary stent implantation in nondiabetic patients: a serial intravascular ultrasound study

OBJECTIVES

The purpose of this study was to determine whether hyperinsulinemia during the oral glucose tolerance test is associated with increased neointimal tissue proliferation after coronary stent implantation in nondiabetic patients.

BACKGROUND

Although hyperinsulinemia induces increased vascular smooth muscle cell proliferation in experimental models, it has not been determined whether hyperinsulinemia is associated with increased neointimal tissue proliferation after coronary stent implantation.

METHODS

Serial (postintervention and six-month follow-up) intravascular ultrasound (IVUS) was used to study 67 lesions treated with Palmaz-Schatz stents in 55 nondiabetic patients. Cross-sectional images within stents were taken at every 1 mm, using an automatic pullback, and a neointimal index was calculated as the ratio between the averaged neointimal area and averaged stent area. All patients underwent a 75-g oral glucose tolerance test. Plasma glucose (PG) and immunoreactive insulin (IRI) levels were measured at baseline and 1 and 2 h after the glucose load. The sum of PGs (sigmaPG) and the sum of IRIs (sigmaIRI) were calculated. Body mass index (BMI), lipid levels, and glycosylated hemoglobin levels were measured.

RESULTS

There were 27 patients with normal glucose tolerance, and 28 patients with impaired glucose tolerance (IGT). The neointimal index in patients with IGT was greater than that in patients with normal glucose tolerance (42.9 +/- 14% vs. 24.9 +/- 8.3%, respectively, p < 0.0001). Linear regression analysis showed that the neointimal index at follow-up correlated well with sigmaPG (p < 0.0001), fasting IRI (p < 0.0001), sigmaIRI (p < 0.0001), triglyceride level (p = 0.018), and BMI (p < 0.0001). Multiple regression analysis revealed that sigmaIRI (p = 0.0002) and sigmaPG (p = 0.0034) were the best predictors of the greater neointimal index at follow-up.

CONCLUSIONS

Serial IVUS assessment shows that hyperinsulinemia during an oral glucose tolerance test is associated with increased neointimal tissue proliferation after coronary stent implantation in nondiabetic patients.

Propensity and mechanisms of restenosis in different coronary stent designs: complementary value of the analysis of the luminal gain-loss relationship

OBJECTIVES

This study sought to investigate the influence of stent design on the long-term angiographic outcome.

BACKGROUND

The proportional relationship between vessel injury and late luminal loss in percutaneous revascularization should be best appreciated in coronary stenting, where recoil and shrinkage are theoretically minimal. It is unclear whether all stent designs can counterbalance this reactive loss by achieving a large initial luminal gain (bigger is better).

METHODS

In 523 lesions successfully stented, the long-term angiographic results of slotted-tube (n = 331), coil (n = 85), multicellular (n = 70) and self-expandable mesh (n = 37) stent designs were compared using the angiographic gain-loss relationship (GLR).

RESULTS

Restenosis rate was 10% for multicellular, 20% for slotted-tube, 46% for coil and 49% for self-expandable designs (p = 0.001). At a difference with other designs, no significant GLR was found in coil stents, suggesting additional mechanisms of luminal loss (i.e., plaque protrusion, stent compression) to neointimal proliferation. Significant differences in late loss between stents were found within each quartile of luminal gain, suggesting a specific role of design in luminal loss. Multivariate analysis identified use of coil and self-expandable stents, vessel size, minimal luminal diameter preintervention, luminal gain and stent length as variables with independent predictive value for several indices of angiographic long-term outcome.

CONCLUSIONS

The analysis of GLR: 1) demonstrates that stent design influences late luminal loss; 2) challenges the applicability of the widely accepted "bigger is better" approach to all stent designs; and 3) appears as a valuable tool in assessing long-term stent performance.

Long-term angiographic results of stenting in chronic total occlusions: influence of stent design and vessel size

BACKGROUND

Although coronary stenting has decreased the high restenosis rate associated with percutaneous transluminal coronary angioplasty of chronic total occlusions (CTOs), the results are still less satisfactory than those found in nonoccluded lesions, at least as reported with the Palmaz-Schatz stent. The present work compares the restenosis rate of other stent designs with that of the Palmaz-Schatz stent.

METHODS

We studied the long-term angiographic outcome of 120 CTOs successfully recanalized with balloon-expandable stents and without concomitant debulking techniques. Angiographic follow-up and full quantitative coronary angiography analysis was prospectively performed in all patients. Three different stent designs were compared: Palmaz-Schatz (n = 47), coil (n = 24), and multicellular (n = 49). Particular attention was paid to their performance in vessels of 3 mm or less and greater than 3 mm in diameter. Restenosis was defined as a 50% or greater diameter stenosis at follow-up.

RESULTS

Multicellular stents were implanted more frequently in the left anterior descending artery and in patients with multivessel disease. No other significant differences in clinical or angiographic baseline characteristics, including vessel size, were noted between groups. At follow-up, multicellular stents presented a lower restenosis rate (22% vs 36% and 58% in the Palmaz-Schatz and coil stent groups, respectively; P =.01 ) and larger minimal luminal diameters (1.92 +/- 0.85 mm vs 1.73 +/- 0.98 and 1.38 +/- 0.83 mm in the Palmaz-Schatz and coil stent groups, respectively; P = 0.0). The superiority of the multicellular stent design resulted from a lower restenosis rate in vessels of 3.0 mm or less in diameter (20% vs 47% and 79% in the Palmaz-Schatz and coil stent groups, respectively; P =.006).

CONCLUSIONS

These results suggest that the restenosis rate after stent recanalization of CTOs is influenced by both stent design and vessel size and may indicate a superiority of multicellular over Palmaz-Schatz and coil stent designs for this purpose.

Restenosis after Angioplasty in Patients with Left Ventricular Dysfunction

Clinical and angiographic rates of restenosis after angioplasty were compared in 80 patients (group A) with ejection fractions below 40% (mean, 28.3% ± 5.2%) and 50 (group B) with ejection fractions above 50% (mean, 58% ± 5.4%). Mean angina class improved to the same degree in both groups after angioplasty. Recurrence of significant angina within 6 to 12 months affected 30 patients (38%) in group A compared to 12 (24%) in group B (p > 0.05). Angiographic restenosis occurred in 42 patients (53%) in group A compared to 14 (28%) in group B (p = 0.006). Restenosis after single-vessel angioplasty was 46% in group A and 25% in group B (p > 0.05), after multivessel angioplasty it was 62% in group A and 33% in group B (p = 0.05). In group A, restenosis was more frequent in the left anterior descending coronary artery (46%) compared to the right coronary (41%) or circumflex (30%). Higher rates of restenosis occurred in patients with prior coronary artery bypass grafting (64%) or recanalization of chronic total occlusion (61%). Angina was a less reliable indication of restenosis in group A. We attribute the higher rate of restenosis in patients with low ejection fractions partly to low coronary perfusion pressure.

Economic impact on physicians and hospitals of proposed changes in Medicare reimbursement for coronary interventions

BACKGROUND

The federal government is implementing changes in reimbursement for angioplasty and coronary stenting. These include reductions in physician reimbursement and a redesignation of intracoronary stents to a different diagnosis-related group than other methods of intracoronary intervention.

OBJECTIVE

The aim of this study was to examine the financial impact on physicians and hospitals of proposed federal reimbursement policies for percutaneous coronary revascularization procedures.

METHODS

We modeled the financial effects of 3 different stenting strategies: strategy I is the most conservative, with stents reserved for addressing lab complications; strategy II stents are used for suboptimal results after attempts at conventional percutaneous transluminal coronary angioplasty (PTCA); strategy III is the most aggressive, with initial stenting of all accessible lesions. We used economic data on PTCA and stent costs from a 1996 dataset and made assumptions about PTCA and stent success rates and restenosis rates based on published data.

RESULTS

Under current reimbursement policies, physician revenues and profits are approximately equal under all 3 stenting strategies. After the proposed changes, there is a slight financial incentive for physicians to pursue the more aggressive strategy III, but the major financial effect is a substantial overall decline in revenues with any of the 3 strategies. For hospitals, the present situation strongly favors the more conservative strategies, but after the proposed changes the more aggressive stenting strategies will be more profitable, thus realigning physician and hospital incentives. Health care delivery organizations that combine physician and hospital income streams achieve the greatest financial stability.

CONCLUSIONS

Current reimbursement policies for angioplasty and stenting have created misaligned incentives between physicians and hospitals. Proposed changes do not present physicians with large economic incentives to pursue aggressive versus conservative stent strategies but substantially address the current disparity in hospital financial incentives.

Intravascular ultrasound predictors of angiographic restenosis in lesions treated with Palmaz-Schatz stents

OBJECTIVES

This study sought to evaluate the clinical, procedural, preinterventional and postinterventional quantitative coronary angiographic (QCA) and intravascular ultrasound (IVUS) predictors of restenosis after Palmaz-Schatz stent placement.

BACKGROUND

Although Palmaz-Schatz stent placement reduces restenosis compared with balloon angioplasty, in-stent restenosis remains a major clinical problem.

METHODS

QCA and IVUS studies were performed before and after intervention (after stent placement and high pressure adjunct balloon angioplasty) in 382 lesions in 291 patients treated with 476 Palmaz-Schatz stents for whom follow-up QCA data were available 5.5 +/- 4.8 months (mean +/- SD) later. Univariate and multivariate predictors of QCA restenosis (> or = 50% diameter stenosis at follow-up, follow-up percent diameter stenosis [DS] and follow-up minimal lumen diameter [MLD]) were determined.

RESULTS

Three variables were the most consistent predictors of the follow-up angiographic findings: ostial lesion location, IVUS preinterventional lesion site plaque burden (plaque/total arterial area) and IVUS assessment of final lumen dimensions (whether final lumen area or final MLD). All three variables predicted both the primary (binary restenosis) and secondary (follow-up MLD and follow-up DS) end points. In addition, a number of variables predicted one or more but not all the end points: 1) restenosis (IVUS preinterventional lumen and arterial area); 2) follow-up DS (QCA lesion length); and 3) follow-up MLD (QCA lesion length and preinterventional MLD and DS and IVUS preinterventional lumen and arterial area).

CONCLUSIONS

Ostial lesion location and IVUS preinterventional plaque burden and postinterventional lumen dimensions were the most consistent predictors of angiographic in-stent restenosis.

Predictive factors of restenosis after coronary stent placement

OBJECTIVES

The objective of this study was to identify clinical, lesional and procedural factors that can predict restenosis after coronary stent placement.

BACKGROUND

Coronary stent placement reduces the restenosis rate compared with that after percutaneous transluminal coronary angioplasty (PTCA). However, restenosis remains an unresolved issue, and identification of its predictive factors may allow further insight into the underlying process.

METHODS

All patients with successful coronary stent placement were eligible for this study unless they had had a major adverse cardiac event during the 1st 30 days after the procedure. Of the 1,349 eligible patients (1,753 lesions), follow-up angiography at 6 months was performed in 80.4% (1,084 patients, 1,399 lesions). Demographic, clinical, lesional and procedural data were prospectively recorded and analyzed for any predictive power for the occurrence of late restenosis after stenting. Restenosis was evaluated by using three outcomes at follow-up: binary restenosis as a diameter stenosis > or =50%, late lumen loss as lumen diameter reduction and target lesion revascularization (TLR) as any repeat PTCA or coronary artery bypass surgery involving the stented lesion.

RESULTS

Multivariate analysis demonstrated that diabetes mellitus, placement of multiple stents and minimal lumen diameter (MLD) immediately after stenting were the strongest predictors of restenosis. Diabetes increased the risk of binary restenosis with an odds ratio (OR) [95% confidence interval] of 1.86 [1.56 to 2.16] and the risk of TLR with an OR of 1.45 [1.11 to 1.80]. Multiple stents increased the risk of binary restenosis with an OR of 1.81 [1.55 to 2.06] and that of TLR with an OR of 1.94 [1.66 to 2.22]. An MLD <3 mm at the end of the procedure augmented the risk of binary restenosis with an OR of 1.81 [1.55 to 2.06] and that of TLR with an OR of 2.05 [1.77 to 2.34]. Classification and regression tree analysis demonstrated that the incidence of restenosis may be as low as 16% for a lesion without any of these risk factors and as high as 59% for a lesion with a combination of these risk factors.

CONCLUSIONS

Diabetes, multiple stents and smaller final MLD are strong predictors of restenosis after coronary stent placement. Achieving an optimal result with a minimal number of stents during the procedure may significantly reduce this risk even in patients with adverse clinical characteristics such as diabetes.

Superficial femoral artery stenoses: characteristics of progressing lesions

PURPOSE

The purpose of this study was to assess the effect of superficial femoral artery (SFA) stenosis morphologic characteristics and lesion location on the rate of atherosclerotic disease progression.

METHODS

We identified 19 patients who required arteriography for treatment of critical leg ischemia and who had previously undergone arteriography of that leg when minimal or no symptoms were present. These initial incidental arteriographic evaluations were performed during evaluation of arterial disease in another vascular bed from 4 to 81 months (mean, 32 months) previously. Distinct SFA stenoses or occlusion on the final arteriogram (n = 98) were characterized by their location, length, stenosis severity, and morphologic appearance on the initial arteriogram. The contribution of patient-specific risk factors to disease progression was also assessed.

RESULTS

Stenosis progression occurred independently among multiple lesions within the same patient (negligible intraclass correlation coefficient, r = 0.06). Lesions in the adductor canal region were more likely to occlude than lesions elsewhere in the SFA (adjusted odds ratio = 10.7; p = 0.03). Severity of initial lesion stenosis also was predictive of occlusion (adjusted odds ratio = 1.8; p = 0.04). However, most progressing lesions (93%) actually arose in areas of initially mild disease (stenoses < 50%) despite more severe initial lesions elsewhere. Increasing age (p = 0.023) and previous contralateral leg bypass (p = 0.036) were also associated with increasing rates of lesion progression. Smooth-asymmetric lesions progressed 11% more slowly than other lesion types (p = 0.003).

CONCLUSIONS

Our analysis of atherosclerotic SFA lesion progression in patients with critical ischemia shows that initial stenosis severity was associated with higher occlusion rates and that smooth-asymmetric lesions progressed more slowly than lesions with other morphologic characteristics. Severe stenoses usually arose from minimally diseased regions and progressed more rapidly than preexisting, more highly stenotic lesions. Most SFA occlusions resulted from disease progression in the adductor canal region whether or not antecedent lesions were seen on arteriography and whether or not more severe stenoses were initially present elsewhere. Increased age and history of previous contralateral bypass were patient-specific predictors of lesion progression.

Determinants and correlates of target lesion calcium in coronary artery disease: a clinical, angiographic and intravascular ultrasound study

OBJECTIVES

This report used intravascular ultrasound and quantitative coronary angiography to explore the relation between lesion-associated calcium and risk factors, clinical presentation and angiographic severity of coronary artery stenoses.

BACKGROUND

Coronary artery calcium is a marker for significant coronary atherosclerosis. Noninvasive procedures are being proposed as screening tests for coronary artery disease. Intravascular ultrasound identification of tissue calcium has been validated in vitro.

METHODS

Independent chart review, preintervention intravascular ultrasound imaging and coronary angiography were used to study primary native vessel lesions in 1,442 patients. Target lesions and reference segments were evaluated according to previously published quantitative and qualitative methods. Results are presented as mean value +/- SD.

RESULTS

Overall, 1,043 lesions contained target lesion calcium (72%); the arc of target lesion calcium was 110 +/- 109 degrees. Lesions with an ultrasound plaque burden > 0.75 or an angiographic diameter stenosis > 0.25 had a prevalence of calcium of at least 65%, with a mean arc > 100 degrees. Intermediate lesions had as much target lesion calcium as did angiographically severe lesions. Using multivariate linear regression analysis, patient age, stable (vs. unstable) angina and the intravascular ultrasound lesion site and reference segment plaque burden (but not the angiographic diameter stenosis) were the independent predictors of the arc of target lesion calcium (all p < 0.0001).

CONCLUSIONS

Intravascular ultrasound analysis shows that coronary calcification correlates with plaque burden but not with degree of lumen compromise. Thus, the noninvasive detection of coronary calcium is predictive of future cardiac events, presumably because coronary calcification is a marker for overall atherosclerotic plaque burden. Coronary calcium increases with increasing patient age and is less common in unstable lesion subsets.

Effects of curvature and stenosis-like narrowing on wall shear stress in a coronary artery model with phasic flow

To gain insight into the details of intracoronary flow we have used computational fluid dynamic techniques to determine the velocity and wall shear stress distributions in both steady- and phasic-flow models of a curved coronary artery with several degrees of stenosis. The steady-flow Reynolds number was 500 and the peak phasic flow Reynolds number was 700. Without stenosis and at 25% (area) stenosis wall shear stress and velocities are higher at the outer wall than the inner wall but retain the same direction as the superimposed flow. At higher stenoses laminar flow separation occurs and the inner wall is exposed to shear stresses that vary widely, both temporally and spatially.

Effect of restenosis at one previously dilated coronary site on the probability of restenosis at another previously dilated coronary site

The purpose of this study was to determine whether in patients with 2 sites dilated by percutaneous transluminal coronary angioplasty (PTCA), the sites undergo restenosis independently. Although restenosis remains a critical limitation after PTCA, there is little information separating site- and patient-dependent determinants of restenosis. In particular, if patients with 2 sites dilated have restenosis at 0 or 2 sites more frequently and at 1 site less frequently than expected by random chance, then patient-related factors may be important in the restenosis process. The source of data was the clinical data base at Emory University. Patients who had previously coronary surgery or PTCA, and those who underwent PTCA in the setting of acute myocardial infarction were excluded. In all, 515 patients with 2 sites dilated undergoing angiographic restudy at 4 months to 1 year after PTCA formed the study population. Site 1 was the first site dilated. At site 1, 224 of 515 sites (45%) were restenotic, and at site 2, 193 (33%) were restenotic. Multiple clinical and angiographic variables were analyzed as possible correlates of restenosis. The most powerful univariate and multivariate correlate of restenosis at either site 1 or 2 was the behavior of the other site. If site 2 was patent, then site 1 was restenotic 28% of the time compared with 69% if site 2 was restenotic. If site 1 was patent, site 2 was restenotic 20% of the time compared with 60% if site 1 was restenotic. This relation was stronger if the 2 sites were in the same coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Balloon postdilation can safely improve the results of successful (but suboptimal) directional coronary atherectomy

This study investigates whether adjunctive balloon angioplasty can be safely used to improve acute results in cases where directional coronary atherectomy alone has provided a successful (but suboptimal) outcome. Between October 1, 1990, and October 1, 1992, directional coronary atherectomy was performed successfully in 198 of 228 lesions. Individual operators believed that most acute results were satisfactory after atherectomy alone (group I, n = 115) with a minimal lumen diameter that increased from 0.82 +/- 0.45 to 3.21 +/- 0.65 mm after atherectomy, for an acute gain in lumen diameter of 2.39 +/- 0.73 mm and a residual stenosis of 6 +/- 13%. In 42% of lesions (group II, n = 83), however, results were considered suboptimal after atherectomy alone, with a minimal lumen diameter that increased from 0.85 +/- 0.45 to 2.83 +/- 0.64 mm, a smaller acute gain of 1.96 +/- 0.72 mm, and a mean residual stenosis of 17 +/- 14% (although all residual stenoses were < 50%, 19% had a residual stenosis > 30%). Adjunctive balloon angioplasty in these group II lesions provided an additional gain of 0.34 +/- 0.38 mm, bringing the total acute gain for group II lesions to 2.32 +/- 0.78 mm and the residual stenosis to 9 +/- 13%, similar to that of group I patients who underwent atherectomy alone. This strategy resulted in a 7 +/- 13% overall residual stenosis for the study population, with no higher incidence of periprocedural complications or adverse late clinical outcomes in group II patients.(ABSTRACT TRUNCATED AT 250 WORDS)