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

Comparison of clinical outcomes of two different types of paclitaxel-coated balloons for treatment of patients with coronary in-stent restenosis

Drug-coated balloon (DCB) angioplasty has been shown to be a promising option for the treatment of coronary in-stent restenosis (ISR). We compared the clinical outcomes of patients with ISR who were treated with two commonly used paclitaxel-containing DCBs, the Pantera Lux (PL) and SeQuent Please (SP). A total of 491 patients with 507 ISR lesions [PL-DCB in 127 (26%) patients and SP-DCB in 364 (74%) patients] underwent DCB angioplasty for ISR lesions. The major adverse cardiac events (MACEs), including cardiac death, target lesion-related myocardial infarction, and target lesion revascularization, were assessed. There were no significant differences in each occurrence of MACE and cardiac death: 16 MACEs (61 per 1000 person-years) in the PL-DCB group and 55 (60 per 1000 person-years) MACEs in the SP-DCB group, log-rank p = 0.895, and three cardiac deaths (11 per 1000 person-years) in the PL-DCB group and ten cardiac deaths (11 per 1000 person-years) in the SP-DCB group, log-rank p = 0.849. Diabetes mellitus under insulin treatment [hazard ratio (HR) 2.71; 95% confidence interval (CI) 1.31-5.60; p = 0.007], chronic kidney disease (HR 1.99; 95% CI 1.01-3.92; p = 0.045), early-onset ISR (HR 1.99; 95% CI 1.18-3.36; p = 0.010), and recurrent ISR (HR 1.89; 95% CI 1.08-3.32; p = 0.026) were associated with the occurrence of MACE after DCB angioplasty. There was no significant difference of MACE between PL-DCB and SP-DCB treatment in patients with ISR. Patients with insulin-treated diabetes, chronic kidney disease, early-onset ISR, and recurrent ISR were at a higher risk of MACE after DCB angioplasty.

Influence of insulin resistance on in-stent restenosis in patients undergoing coronary drug-eluting stent implantation after long-term angiographic follow-up

OBJECTIVE

Previous studies have reported that insulin resistance is related to early in-stent restenosis (ISR) after coronary stenting. This study aimed to evaluate the influence of insulin resistance on the long-term angiographic outcome in patients undergoing coronary drug-eluting stent (DES) implantation.

MATERIALS AND METHODS

Within a single hospital-based cohort of patients (n=529) who underwent coronary DES implantation, angiographic follow-up was performed successfully for 417 study patients at 12-48 months after coronary stenting. ISR was defined as stenosis of at least 50% of the luminal diameter. Fasting plasma glucose and fasting plasma insulin were measured. Insulin resistance was expressed by the homeostasis model assessment index (HOMA-IRI).

RESULTS

Among the 417 patients who completed angiographic follow-up (mean 17.5±10.2 months), 58 patients (13.9%) had ISR whereas the remaining 359 patients (86.1%) did not have ISR. Patients with ISR had higher insulin resistance index (IRI) than nonrestenosis patients (P=0.004). Multiple logistic regression analysis (logit) showed that IRI was associated significantly with ISR (adjusted odds ratio 1.476, 95% confidence interval 1.227-1.776; P<0.001). In the nondiabetes subgroup of 309 patients, IRI was higher in patients with ISR than in nonrestenosis patients, as confirmed in a separate logit analysis (adjusted odds ratio 1.456, 95% confidence interval 1.152-1.839; P=0.002). Multiple linear regression analysis showed that IRI was associated significantly with in-stent diameter stenosis degree (P=0.043).

CONCLUSION

Insulin resistance was associated with ISR in patients undergoing coronary DES implantation at long-term angiographic follow-up.

Pioglitazone decreases coronary artery inflammation in impaired glucose tolerance and diabetes mellitus: evaluation by FDG-PET/CT imaging

OBJECTIVES

The aim of this study was to compare the effect of pioglitazone with glimepiride on coronary arterial inflammation with serial (18)F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) combined with computed tomography (CT) angiography.

BACKGROUND

Recent studies have shown that FDG-PET combined with CT is a reliable tool to visualize and quantify vascular inflammation. Although pioglitazone significantly prevented the progression of coronary atherosclerosis and reduced the recurrence of myocardial infarction in patients with type 2 diabetes mellitus (DM), it remains unclear whether pioglitazone could attenuate coronary artery inflammation.

METHODS

Fifty atherosclerotic patients with impaired glucose tolerance or type 2 DM underwent determination of blood chemistries, anthropometric and inflammatory variables, and FDG-PET/CT angiography, and then were randomized to receive either pioglitazone or glimepiride for 16 weeks. Effects of the treatments on vascular inflammation of the left main trunk were evaluated by FDG-PET/CT angiography at baseline and end of the study. Vascular inflammation of the left main trunk was measured by blood-normalized standardized uptake value, known as a target-to-background ratio.

RESULTS

Three patients dropped out of the study during the assessment or treatment. Finally, 25 pioglitazone-treated patients and 22 glimepiride-treated patients (37 men; mean age: 68.1 ± 8.3 years; glycosylated hemoglobin: 6.72 ± 0.70%) completed the study. After 16-week treatments, fasting plasma glucose and glycosylated hemoglobin values were comparably reduced in both groups. Changes in target-to-background ratio values from baseline were significantly greater in the pioglitazone group than in the glimepiride group (-0.12 ± 0.06 vs. 0.09 ± 0.07, p = 0.032), as well as changes in high-sensitivity C-reactive protein (pioglitazone vs. glimepiride group: median: -0.24 [interquartile range (IQR): -1.58 to -0.04] mg/l vs. 0.08 [IQR: -0.07 to 0.79] mg/l, p = 0.031).

CONCLUSIONS

Our study indicated that pioglitazone attenuated left main trunk inflammation in patients with impaired glucose tolerance or DM in a glucose-lowering independent manner, suggesting that pioglitazone may protect against cardiac events in patients with impaired glucose tolerance or DM by suppressing coronary inflammation. (Anti-Inflammatory Effects of Pioglitazone; NCT00722631).

Pioglitazone induces regression and stabilization of coronary atherosclerotic plaques in patients with impaired glucose tolerance

AIMS

To observe the effects of pioglitazone on coronary plaque area, plaque burden, serum high-sensitivity C-reactive protein, adiponectin and plasma endothelin-1 levels in patients with impaired glucose tolerance and coronary borderline lesions.

METHODS

Thirty patients were randomly divided into two groups: a pioglitazone group and a control group. The latter was administered placebo in addition to standard therapy; the former pioglitazone 15 mg/d in addition to standard therapy. Before treatment and 6 months later, left ventricular ejection fraction, serum lipid profile, high-sensitivity C-reactive protein, adiponectin and plasma endothelin-1 levels were detected. Coronary plaque area and plaque burden were examined using intravascular ultrasound.

RESULTS

No significant differences were found in left ventricular ejection fraction and serum lipid levels pre- and post-trial. Compared with the control group, 6 months' treatment with pioglitazone significantly decreased coronary plaque burden (50.7 ± 11.1 vs. 64.1 ± 10.3%, P < 0.05), plaque area (6.22 ± 2.03 vs. 8.31 ± 4.29, P < 0.05), thin-cap fibroatheroma prevalence (11 vs. 22%, P < 0.05) and percentage of necrotic core area (16 ± 8 vs. 31 ± 7%, P < 0.05). Compared with the control group, serum high-sensitivity C-reactive protein and plasma endothelin-1 levels were significantly lower and adiponectin level significantly higher in patients in the pioglitazone group. Serum adiponectin level was negatively correlated with plasma endothelin-1 level and coronary plaque area (r = 0.739 and -0.431, respectively, both P < 0.05).

CONCLUSIONS

Pioglitazone may induce regression and stabilization of coronary atherosclerotic plaques. The mechanisms might involve inhibition of inflammation, increase in adiponectin level and improvement in endothelial function.

The angiographic and clinical outcomes after coronary stenting in patients with metabolic syndrome

BACKGROUND

Metabolic syndrome (MetS) is regarded as a risk factor for coronary artery disease (CAD). But the influence of MetS on morbidity and mortality after stent implantation in CAD patients remains unknown.

METHODS

This article presents a meta-analysis of available data on the association between the MetS and the risk of angiographic and clinical outcomes following stent implantation.

RESULTS

MetS was associated with a significant increased risk of post-stent all-cause mortality (odd ratio (OR), 2.17, 95% CI, 1.56-3.01), in-lesion restenosis (OR, 1.35, 95% CI, 1.00-1.84) and major adverse cardiac events (MACE) (OR 1.35, 95% CI 1.13-1.61) in CAD patients. Even with drug-eluting stent (DES) implantation, significant increased risk in all-cause mortality (OR, 2.25, 95% CI, 1.61-3.15) and MACE (OR 1.42, 95% CI 1.14-1.76) were remain in patients with MetS. However, the OR of cardiovascular (CV) mortality (1.25, 95% CI 0.71-2.22), MI (1.27, 95% CI 0.87-1.85) and TLR (OR 1.21, 95% CI 0.96-1.53) was not statistically different between the patients with and without metabolic syndrome.

CONCLUSIONS

Metabolic syndrome is an important risk factor in patients with CAD following stent implantation. Although DES implantation decreased the incidence of angiographic events, further progress in adequate treatment of MetS is still required to improve the clinical outcome.

Evaluation of in-stent restenosis in the APPROACH trial (Assessment on the Prevention of Progression by Rosiglitazone On Atherosclerosis in diabetes patients with Cardiovascular History)

To determine (1) the medium-term effect of rosiglitazone and glipizide on intra-stent neointima hyperplasia, (2) restenosis pattern as assessed by intra-vascular ultrasound (IVUS) and quantitative coronary angiography (QCA) in patients with T2DM and coronary artery disease. A total of 462 patients with T2DM were randomized to rosiglitazone or glipizide for up to 18 months in the APPROACH trial, and had evaluable baseline and follow-up IVUS examinations. There was no significant difference in the size of plaque behind stent between the rosiglitazone and glipizide groups at 18 months among those treated with a bare metal stent (−5.6 mm³ vs. 1.9 mm³; P = 0.61) or with a drug-eluting stent (12.1 mm³ vs. 5.5 mm³; P = 0.09). Similarly, there was no significant difference in percentage intimal hyperplasia volume between the rosiglitazone and glipizide groups at 18 months among those treated with a bare metal stent (24.1% vs. 19.8%; P = 0.38) or with a drug-eluting stent (9.8% vs. 8.3%; P = 0.57). QCA data (intra-stent late loss, intra-stent diameter stenosis or binary restenosis) were not different between the rosiglitazone and glipizide groups. This study suggests that both rosiglitazone and glipizide have a similar effect on neointimal growth at medium term follow-up, a finding that warrants investigation in dedicated randomized trials.

[The degree of coronary atherosclerosis as a marker of insulin resistance in non-diabetics]

INTRODUCTION

The metabolic syndrome and its influence on coronary artery disease development and progression remains in focus of international research debates, while insulin resistance, which represents its core, is the key component of hypertension, dyslipidaemias, glucose intolerance and obesity.

OBJECTIVE

The aim of this study was to establish relationship between basal glucose and insulin levels, insulin sensitivity and lipid panel and the degree of coronary atherosclerosis in nondiabetic patients.

METHODS

The coronary angiograms were evaluated for the presence of significant stenosis, insulin sensitivity was assessed using the intravenous glucose tolerance test with a minimal model according to Bergman, while baseline glucose (GO), insulin (10) and lipid panel measurements (TC, HDL, LDL, TG) were taken after a 12-hour fasting.

RESULTS

The protocol encompassed 40 patients (19 men and 21 women) treated at the Institute for Cardiovascular Diseases of the Clinical Centre of Serbia, Belgrade. All were non-diabetics who were divided into 3 groups based on their angios: Group A (6 patients, 15%, with no significant stenosis), Group B (18 patients, 45%, with a single-vessel disease) and Group C (16 patients, 40%, with multi-vessel disease). Presence of lower insulin sensitivity, higher 10 and TC in the group of patients with a more severe degree of coronary atherosclerosis (insulin sensitivity: F = 4.279, p = 0.023, A vs. C p = 0.012, B vs. C p = 0.038; 10: F = 3.461 p = 0.042, A vs. B p = 0.045, A vs. C p = 0.013; TC: F = 2.572, p = 0.09), while no significant difference was found for GO, LDL, HDL and TG.

CONCLUSION

Baseline insulinaemia, more precisely, fasting hyperinsulinaemia could be a good predictor of significant coronary atherosclerosis in non-diabetic patients, which enables a more elegant cardiometabolic risk assessment in the setting of everyday clinical practice.

Predictors of restenosis after percutaneous coronary intervention using bare-metal stents: a comparison between patients with and without dysglycemia

The objective of this study was to identify intravascular ultrasound (IVUS), angiographic and metabolic parameters related to restenosis in patients with dysglycemia. Seventy consecutive patients (77 lesions) selected according to inclusion and exclusion criteria were evaluated by the oral glucose tolerance test and the determination of insulinemia after a successful percutaneous coronary intervention (PCI) with a bare-metal stent. The degree of insulin resistance was calculated by the homeostasis model assessment of insulin resistance (HOMA-IR). Six-month IVUS and angiogram follow-up were performed. Thirty-nine patients (55.7%) had dysglycemia. The restenosis rate in the dysglycemic group was 37.2 vs 23.5% in the euglycemic group (P = 0.299). The predictors of restenosis using bivariate analysis were reference vessel diameter (RVD): pound2.93 mm (RR = 0.54; 95%CI = 0.05-0.78; P = 0.048), stent area (SA): <8.91 mm(2) (RR = 0.66; 95%CI = 0.24-0.85; P = 0.006), stent volume (SV): <119.75 mm(3) (RR = 0.74; 95%CI = 0.38-0.89; P = 0.0005), HOMA-IR: >2.063 (RR = 0.44; 95%CI = 0.14-0.64; P = 0.027), and fasting plasma glucose (FPG): < or =108.8 mg/dL (RR = 0.53; 95%CI = 0.13-0.75; P = 0.046). SV was an independent predictor of restenosis by multivariable analysis. Dysglycemia is a common clinical condition in patients submitted to PCI. The degree of insulin resistance, FPG, RVD, SA, and SV were correlated with restenosis. SV was inversely correlated with an independent predictor of restenosis in patients treated with a bare-metal stent.

Chronic insulin treatment suppresses PTP1B function, induces increased PDGF signaling, and amplifies neointima formation in the balloon-injured rat artery

We tested the hypothesis that hyperinsulinemia induces the suppression of protein tyrosine phosphatase 1B (PTP1B) function, leading to enhanced PDGF receptor (PDGFR) signaling and neointimal hyperplasia. Rats were implanted with insulin-releasing pellets or sham pellets. Blood glucose levels, insulin levels, food and water intake, body weights, and blood pressures were measured. Neointimal hyperplasia was assessed by computerized morphometry 14 days after carotid balloon injury. PTP1B protein expression in injured arteries was determined via Western blot analysis, whereas PTP1B activity was determined via an immunophosphatase assay. Serum insulin levels were two- to threefold greater in hyperinsulinemic rats, whereas systolic blood pressures, food and water intake, serum triglyceride levels, plasma cortisol levels, and urinary catecholamine levels were not affected. Fourteen days after injury, neointima-to-media area ratios were 0.89 +/- 0.23 and 1.35 +/- 0.22 in control and hyperinsulinemic rats, respectively (P < 0.01). PTP1B protein levels and total PTP1B activity in injured carotid arteries from the insulin-treated group were significantly decreased 7 or 14 days after injury, whereas PTP1B specific activity was decreased only 14 days after injury. These findings were associated with decreased PTP1B mRNA levels and increased PDGFR tyrosyl phosphorylation in insulin-treated rats. These observations support the hypothesis that hyperinsulinemia induces the suppression of PTP1B function, leading to enhanced PDGFR signaling and neointimal hyperplasia.

Pioglitazone induces regression of coronary atherosclerotic plaques in patients with type 2 diabetes mellitus or impaired glucose tolerance: a randomized prospective study using intravascular ultrasound

BACKGROUND

A large clinical trial clarified that pioglitazone reduces cardiovascular events in diabetic patients. However, effects of pioglitazone on structure of coronary atherosclerotic plaques have not been demonstrated. We examined whether pioglitazone reduces volumes of coronary atherosclerotic plaques using intravascular ultrasound (IVUS).

METHODS

Twenty-six consecutive patients with type 2 diabetes mellitus (DM) or impaired glucose tolerance (IGT) undergoing percutaneous coronary intervention (PCI) were enrolled. Echolucent plaques without significant stenosis were selected in IVUS video images at non-PCI-influenced coronary segments and volumetric analysis of the targeted plaques was performed. The patients were randomly assigned into 2 groups: pioglitazone group consisted of 13 patients taking pioglitazone 15 mg/day for initial 14 days after PCI and subsequent 30 mg/day during 6-month follow-up, and control group with 13 patients as control. The plaque volumes and some parameters such as plasma lipid profiles and high-sensitive C-reacting protein (hs-CRP) levels were compared between baseline and the follow-up in those groups.

RESULTS

In the pioglitazone group after 6 months, the plaque volume was significantly reduced (101.3+/-32.1 to 94.6+/-33.6 mm(3), -7.2%; p=0.0023), plasma triglyceride was significantly decreased (- 14.9%) and high density lipoprotein cholesterol was substantially increased (+20.0%) without any significant change in low density lipoprotein cholesterol (LDL-C). Also, hs-CRP level tended to be decreased. However, no significant change in plaque volumes and those parameters was observed in the control group.

CONCLUSIONS

Pioglitazone may induce regression of coronary atherosclerotic plaques without LDL-C reduction in patients with DM and IGT.

[Adjuvant drug treatment in diabetic patients undergoing percutaneous coronary intervention]

The authors describe the adjuvant drug treatment during and after percutaneous coronary intervention in order to obtain the reduction of major cardiovascular events, focusing in diabetic patients. In the clinical follow-up of diabetic patients after PCI, special attention to the control measures of cardiovascular risk factors should be observed. Among those measures, a normal glycemic level is fundamental, which can be achieved with usual clinical care. Antiplatelet therapy is a controversy issue until know. Although combined antiplatelet therapy with aspirin and a thienopyridynic is well supported by a number of clinical trials, adding GPIIb/IIIa agents as adjuvants in diabetic patients should not be irrestrictive as suggested by some authors; they should be restricted to patients with a significative thrombotic burden.

Chronic insulin treatment amplifies PDGF-induced motility in differentiated aortic smooth muscle cells by suppressing the expression and function of PTP1B

Hyperinsulinemia plays a major role in the pathogenesis of vascular disease. Restenosis occurs at an accelerated rate in hyperinsulinemia and is dependent on increased vascular smooth muscle cell movement from media to neointima. PDGF plays a critical role in mediating neointima formation in models of vascular injury. We have reported that PDGF increases the levels of protein tyrosine phosphatase PTP1B and that PTP1B suppresses PDGF-induced motility in cultured cells and that it attenuates neointima formation in injured carotid arteries. Others have reported that insulin enhances the mitogenic and motogenic effects of PDGF in cultured smooth muscle cells and that hyperinsulinemia promotes vascular remodeling. In the present study, we tested the hypothesis that insulin amplifies PDGF-induced cell motility by suppressing the expression and function of PTP1B. We found that chronic but not acute treatment of cells with insulin enhances PDGF-induced motility in differentiated cultured primary rat aortic smooth muscle cells and that it suppresses PDGF-induced upregulation of PTP1B protein. Moreover, insulin suppresses PDGF-induced upregulation of PTP1B mRNA levels, PTP1B enzyme activity, and binding of PTP1B to the PDGF receptor-beta, and it enhances PDGF-induced PDGF receptor phosphotyrosylation. Treatment with insulin induces time-dependent upregulation of phosphatidylinositol 3-kinase (PI3-kinase)-delta and activation of Akt, an enzyme downstream of PI3-kinase. Finally, inhibition of PI3-kinase activity, or its function, by pharmacological or genetic means rescues PTP1B activity in insulin-treated cells. These observations uncover novel mechanisms that explain how insulin amplifies the motogenic capacity of the pivotal growth factor PDGF.

Hyperinsulinemia and impaired leptin-adiponectin ratio associate with endothelial nitric oxide synthase polymorphisms in subjects with in-stent restenosis

Little is known about the association of endothelial nitric oxide synthase (NOS3) gene polymorphisms and the presence of insulin resistance and the early evolution of atherosclerosis in nondiabetic subjects with cardiovascular disease (CAD) and stent implantation. The present study was performed in an attempt to better understand whether metabolic, endothelial, and angiographic findings characteristic of subjects with cardiovascular disease and in-stent restenosis are related to NOS3 variants. This is a case-control study performed from 2002 to 2006. All subjects admitted to the study were recruited in the Nord-Centre of Italy, most from Milan and its surrounding towns. Measures of glucose tolerance, insulin sensitivity, markers of endothelial dysfunction, forearm vasodilation, and adipokine levels were determined and associated to the frequency of two single-nucleotide polymorphisms of NOS3, i.e., Glu298Asp (rs1799983, G/T) and rs753482 (intron 18 A/C). A total of 747 subjects, not known to have diabetes, were evaluated: 333 subjects had asymptomatic CAD, 106 subjects had unstable angina and were evaluated for in-stent restenosis 6 mo after stent placement, and 308 were control subjects. The presence of TT and CC minor alleles was significantly greater in case groups compared with control subjects. At phenotypic level, subjects with the polymorphisms were characterized by hyperinsulinemia and reduced reactive hyperemia, whereas increased leptin and decreased adiponectin levels were present in subjects with restenosis in the presence of reduced minimal lumen diameter and length of stenosis almost doubled. Hyperinsulinemia, endothelial dysfunction, and a more atherogenic profile seem to be peculiar features of subjects with asymptomatic CAD and restenosis carrying NOS3 gene variants.

Metabolic syndrome does not increase angiographic restenosis rates after drug-eluting stent implantation

Metabolic syndrome (MS) is associated with an increased risk of coronary heart disease, stroke, and cardiovascular mortality; but its effect on patients undergoing cardiac revascularization is still unclear. Robust evidence demonstrates that diabetes mellitus and insulin resistance are among the main risk factors for restenosis in patients requiring percutaneous myocardial revascularization. The recent advent of drug-eluting stents (DESs) has significantly reduced the incidence of restenosis compared with bare-metal stents, both in nondiabetic and in diabetic patients. The aim of the study was to evaluate the effect of MS on the risk of binary restenosis in DES implant recipients. One hundred eighty-nine recipients of successful DES implants performed between January and March 2005 for stable coronary artery disease underwent 1-year clinical and angiographic follow-up. Body mass index (BMI), blood pressure, fasting blood glucose, and lipid profile were determined. Metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel III criteria, with the waist criterion being substituted by a BMI>or=28.8 kg/m2. Metabolic and anthropometric information for MS diagnosis was available for 148 of 189 patients; 87 of 148 patients (58%) had MS. Patients with MS had higher BMI (28.4+/-3.8 vs 26+/-2.7 kg/m2, P<.0001), systolic blood pressure (133+/-14 vs 124+/-14 mm Hg, P=.0004), and fasting glucose (113+/-37 vs 92+/-17 mg/dL, P<.0001). They also had higher serum triglycerides (154+/-94 vs 113+/-43, P=.0018) and lower high-density lipoprotein cholesterol levels (39+/-9 vs 46+/-10, P<.0001). Rates of restenosis (10.5% vs 8.1%, P=not significant [NS]), target vessel revascularization (10.5% vs 11.3%, P=NS), and major adverse cardiac events (11.6% vs 14.5%, P=NS) were not significantly different in patients with MS compared with those without MS, nor was any association found between increased end point risk and presence of MS. When patients were subdivided into 6 subgroups by the presence of 0, 1, 2, 3, 4, or 5 of the MS components, restenosis rates were not significantly different among subgroups. In conclusion, MS is not associated with higher rates of restenosis, target vessel revascularization, or major adverse cardiac events; and no additional MS feature was associated with an increased risk.

Impact of the metabolic syndrome on angiographic and clinical events after coronary intervention using bare-metal or sirolimus-eluting stents

Patients with metabolic syndrome (MS) are at increased risk for cardiovascular events. Although the number of patients with MS requiring coronary revascularization is increasing rapidly, the impact of MS on clinical events and restenosis in patients who undergo stent placement is not well defined. Seven hundred thirty-four consecutive patients with 734 de novo coronary lesions (<50 mm lesion length, reference vessel diameter <3.5 mm) were enrolled in this study. Four hundred thirty-seven patients were treated with bare-metal stents, and 297 patients were treated with sirolimus-eluting stents. Patients with bifurcation lesions, left main lesions, and ST-segment-elevation myocardial infarctions were excluded from the study. Patients were categorized into 3 groups: those with (1) diabetes mellitus (DM), (2) MS without DM, and (3) no MS and no DM. MS was defined according to American Heart Association and National Heart, Lung, and Blood Institute criteria (the presence of > or =3 of the following criteria: obesity, hypertension, hypertriglyceridemia, low high-density lipoprotein cholesterol, and increased fasting glucose). Clinical follow-up was performed for > or =1 year (mean 27.5 +/- 18.1 months). One hundred sixty-four patients (22%) had DM, 180 patients (25%) had MS without DM, and 390 patients (53%) had no MS and no DM. Baseline clinical and angiographic parameters were comparable among the 3 groups, including lesion length and reference vessel diameter. In patients treated with bare-metal stents, the rates of major adverse cardiac events (MACEs) at 12 months were 14% in patients without DM or MS, 18% in those with MS but no DM, and 33% in those with DM (p = 0.046). In patients treated with sirolimus-eluting stents, the MACE rates were 3% in patients without DM or MS, 4% in those with MS, and 13% in those with DM (p = 0.034). DM (odds ratio 2.14, 95% confidence interval 1.48 to 3.07, p <0.001) and bare-metal stent (odds ratio 2.51, 95% confidence interval 1.49 to 4.22, p <0.001) implantation were independent predictors of MACEs during follow-up, whereas MS was not predictive. Similarly, MS was not a predictor of target lesion revascularization. In conclusion, patients with MS did not have an increased risk for target lesion revascularization or a greater MACE rate compared with control patients during a 12 month follow-up period after bare-metal or drug-eluting stent placement. In contrast, DM is associated with significantly increased event rates.

Analysis of Clinical Factors that Influence Re-stenosis after Percutaneous Coronary Stenting

Evidence has recently been accumulating that a sirolimus-eluting stent (DES) is superior to a bare-metal stent (BMS) in preventing restenosis after percutaneous coronary intervention (PCI), and an increasing number of Japanese hospitals have been adopting DES. We conducted a retrospective study to identify clinical factors that influence the risk of restenosis after PCI, including stent types, by analyzing the data of 49 continuous patients who received PCI and follow-up coronary angiography in Hiratsuka City Hospital between March, 2004 and March, 2005. Age, sex, body mass index, smoking, complications, clinical diagnosis before PCI, the site and number of stenoses, implanted stent type (BMS or DES), the number of stents used, maximum inflating pressure and withdrawal of ticlopidine due to its adverse drug reactions were chosen as potential factors that may influence the risk of restenosis, and the correlation between these factors and restenosis was tested by Student's t-test or chi-square test. Coronary restenosis developed in 10 out of 49 patients, and factors having significant correlation with restenosis were age (73+/-7 in the restenosis group (R) and 64+/-12 in the non-restenosis group (N) (p<0.05)) and the type of stent (DES used in only one of 10 cases in R whereas in 24 of 39 in N (p<0.001)). Multivariate analysis showed older age (odds ratio (OR): 1.200 (95% CI: 1.038-2.823)) and the use of DES are independent predictors for restenosis (OR: 0.015 (95%CI: 0.001-0.249)). Our study further supports the efficacy of DES in PCI, but its long-term outcome is yet to be confirmed.

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.

Long-term effects of a PPAR-gamma agonist, pioglitazone, on neointimal hyperplasia and endothelial regrowth in insulin resistant rats

OBJECTIVE

Insulin resistance is an independent risk factor for cardiovascular disease. PPAR-gamma agonists like pioglitazone decrease insulin resistance and have been shown to reduce neointimal hyperplasia in the short-term. However long-term studies on endothelial regrowth and neointimal hyperplasia have not been done.

METHODS AND RESULTS

We used hyperinsulinemic, normoglycemic Zucker fatty rats. Rats were treated with either 10 mg/kg body wt. pioglitazone or placebo till the end of the experiment. Rats underwent carotid angioplasty at age 12-14 weeks, 1 week after treatment was begun. In one set of experiments rats were sacrificed at 6 months and neointimal hyperplasia and VEGF expression was assessed. In another set of experiments rats were sacrificed at 3 and 6 months. Endothelial regrowth was determined. The rats were all normoglycemic and hyperinsulinemic. Pioglitazone treated rats had a significantly lesser degree of neointimal hyperplasia than control rats. Treated rats also had decreased VEGF expression. Endothelial regrowth was decreased in the treated rats at 6 months.

CONCLUSION

We conclude that although pioglitazone decreases neointimal hyperplasia even at 6 months, it retards endothelial regrowth, which could predispose the denuded vessel to thrombotic events. This may be modulated by a suppression of VEGF expression.

Percutaneous coronary revascularization in diabetics: from balloon angioplasty to drug-eluting stents

Diabetic patients may have aggressive coronary disease with an excessive rate of restenosis and accelerated atherosclerotic progression. This article reviews the different modalities of percutaneous treatment and their results in the diabetic population, from the early days of balloon angioplasty to the current implementation of drug-eluting stents. As restenosis may be virtually eradicated in the near future, plaque progression remains the cornerstone for interventional cardiologists and the medical community. In this regard, attempts to modify life habits, and a more accurate control of the components of the metabolic syndrome should be the main therapeutic objective.

gamma-tocopherol, but not alpha-tocopherol, potently inhibits neointimal formation induced by vascular injury in insulin resistant rats

Insulin resistance may enhance the neointima formation via increased oxidative stress. However, clinical trials investigating the benefit of antioxidant therapy with alpha-tocopherol showed negative results. Recent studies showed that chemical characteristics of gamma-tocopherol are distinct from those of alpha-tocopherol. We hypothesized that gamma-tocopherol is superior to alpha-tocopherol in preventing the neointima growth after arterial injury in insulin resistance. Male rats were fed with standard chow or a high fructose diet for induction of insulin resistance. Thereafter, the left carotid artery was injured with a balloon catheter. After 2 weeks, the carotid arteries were harvested and histomorphometrically analyzed. The neointima-media ratio of the injured artery was significantly greater in insulin resistance group (n=8, 1.33+/-0.12) than in normal group (n=10, 0.76+/-0.11, p<0.01). gamma-Tocopherol (100 mg/kg/day) reduced the ratio (n=5, 0.55+/-0.21, p<0.01 vs. insulin resistance group), while alpha-tocopherol was without effect (n=7, 1.08+/-0.14). The quantification of plasma phosphatidylcholine hydroperoxide, an indicator of systemic oxidative stress, and dihydroethidium fluorescence staining of the carotid artery, an indicator of the local superoxide production, showed that oxidative stress in the systemic circulation and local arterial tissue was increased in insulin resistance. Both tocopherols decreased plasma phosphatidylcholine hydroperoxide, but failed to suppress the superoxide production in the carotid arteries. Increased 3-nitrotyrosine in neointima by insulin resistance was greatly reduced only by gamma-tocopherol. In conclusion, gamma-tocopherol, but not alpha-tocopherol, reduces the neointima proliferation in insulin resistance, independently of its effects on superoxide production. The beneficial effect may be related with its inhibitory effects on nitrosative stress.

The relationship of obesity to ischemic outcomes following coronary stent placement in contemporary practice

OBJECTIVES

We analyzed the relationship of obesity, determined by body mass index (BMI), to short- and long-term outcomes in the TARGET trial.

BACKGROUND

: Previous studies have conflicting findings regarding the relationship of BMI to outcomes following percutaneous coronary intervention (PCI).

METHODS

The TARGET trial studied the use of glycoprotein (GP) IIb/IIIa inhibition in patients undergoing planned coronary stent placement.

RESULTS

Eighty-one percent of all patients were overweight (BMI > 25), 36% were obese (BMI > 30), and United States patients were more frequently obese (38.7% vs. 25.8%, P < 0.001). Obese patients had a similar 30-day ischemic event rate compared with nonobese patients, but less major bleeding (0.4% vs. 1.1%, P = 0.013). Six-month death and myocardial infarction rates were similar in obese and nonobese patients. There was a J-shaped relationship between 6-month target vessel revascularization (TVR) and BMI with the lowest incidence of TVR at BMI 27.5. Six-month TVR was higher in the morbidly (BMI > 35) obese (12.4% vs 8.7%, P < 0.05). In extremely (BMI > 32) obese patients, this relationship was more significant (TVR 11.3% vs. 8.5%, P = 0.007), particularly in patients <65 years of age (TVR 12.3% vs. 8.4%, P = 0.003).

CONCLUSION

The majority of patients undergoing PCI are overweight, especially in the United States. Extreme obesity is associated with a significant increase in TVR following intent-to-stent PCI, especially in patients <65 years of age. With routine use of GP IIb/IIIa inhibitors, other long- and short-term ischemic events are similar in obese and nonobese patients. However, obese patients have significantly less major bleeding.

Anti-Atherogenic Effect of Insulin in vivo

Metabolic syndrome is a risk factor for atherosclerosis and restenosis. In metabolic syndrome, insulin resistance coexists with hyperinsulinemia and hyperlipidemia. Hyperlipidemia has growth-promoting effects, whereas insulin has both growth-promoting and growth-inhibitory effects on vascular smooth muscle cells in vitro. The objective of this study was to investigate the effects of hyperlipidemia and hyperinsulinemia on vascular cell growth in vivo after arterial injury. Rats fed a low-fat diet were treated with either subcutaneous blank (LFC) or insulin (LFI) implants. Rats fed a high-fat diet also received blank (HFC) or insulin (HFI) implants. After 3 days, rats received balloon carotid injury, and 14 days later they were sacrificed to measure neointimal area and proliferation. Hyperinsulinemia was present in LFI and HFI and hyperlipidemia was present in HFC and HFI. Neointimal area was higher in HFC (0.153 +/- 0.009 mm(2), p < 0.05) but lower in LFI (0.098 +/- 0.005, p < 0.01) than LFC (0.127 +/- 0.005). In HFI (0.142 +/- 0.008, p < 0.05) neointimal area was not different from HFC or LFC. In conclusion, insulin reduced neointimal growth, but the effect of insulin was diminished by the high-fat diet. Thus, our results demonstrate an anti-atherogenic effect of insulin in vivo and suggest that in metabolic syndrome insulin resistance rather than hyperinsulinemia is the atherogenic risk factor.

Insulin resistance as a predictor for restenosis after coronary stenting

PURPOSE

The rationale of this study was to determine whether insulin resistance is an independent risk factor for restenosis after coronary stenting.

BACKGROUND

Previous studies suggested that hyperinsulinemia may be an important risk factor for ischemic heart disease. Restenosis after coronary stenting is neointimal tissue proliferation and de-novo stenosis is atherosclerosis from the point of view of histology. However, it has not been determined whether insulin resistance is independently related to restenosis after coronary stenting.

METHODS

Clinical variables of unselected population of 110 patients were analyzed in multivariate logistic regression analyses for both restenosis and de-novo stenosis. Clinical, lesion-related, and procedural variables were analyzed by chi-square analysis, and relative risk.

RESULTS

Multivariate logistic regression analysis showed that homeostasis model assessment insulin resistance (HOMA-IR) and HbA1c were associated with restenosis after coronary stenting (HOMA-IR; P=0.0447, HbA1c; P=0.0462), and HbA1c and low-density lipoprotein cholesterol (LDL-C) were associated with de-novo stenosis (HbA1c; P=0.0201, LDL-C; P=0.0204). Restenosis was influenced by insulin resistance [Relative Risk (RR) 2.06; 95 percent confidence interval (95%CI) 1.20 to 3.56], diabetes mellitus (DM: RR 1.92; 95%CI 1.25 to 2.95), and final minimal lumen diameter (RR 2.83; 95%CI 1.32 to 6.06).

CONCLUSIONS

HOMA-IR and DM are the predictors of restenosis after coronary stenting, and HbA1c and LDL-C are the predictors of de-novo stenosis. These results may be reflected in histological differences between neointimal tissue proliferation as restenosis and atherosclerosis as de-novo stenosis.

Neointimal hyperplasia and vascular endothelial growth factor expression are increased in normoglycemic, insulin resistant, obese fatty rats

OBJECTIVE

Insulin resistance is associated with a constellation of factors that enhance the artherosclerotic process. Vessel injury results in the formation of a markedly increased neointima in type 2 diabetes. Increased neointimal hyperplasia (NH) and vascular endothelial growth factor (VEGF) expression may lead to restenosis post angioplasty. We studied NH and VEGF expression in an obese, insulin resistant, but normoglycemic rat model, after carotid balloon injury.

METHODS AND RESULTS

Diabetic rats (ZDF, n=10), normoglycemic, insulin-resistant rats (ZDF-normoglycemic, n=6) as well as Zucker fatty rats (FZ, n=6), and lean Zucker rats (LZ, n=6), all 13-16 weeks old, were subjected to right carotid injury by an angioplasty catheter introduced via the femoral artery. Three weeks later the rats were sacrificed and serum and carotids obtained. The intima-media ratio (I/M) was then calculated. ZDF-normoglycemic, FZ and ZDF-diabetic rats were all hyperinsulinemic and hypertriglyceridemic when compared to LZ rats. ZDF diabetic rats were hyperglycemic while FZ, ZDF-normoglycemic and LZ rats were normoglycemic. The I/M ratio for ZDF and FZ rats were significantly greater than for LZ rats. The VEGF expression was significantly greater in ZDF and FZ rats than LZ rats.

CONCLUSIONS

In conclusion, insulin resistance increases neointimal hyperplasia and VEGF expression even with normoglycemia, after carotid angioplasty in rats.

Sophisticated tests for susceptibility to atherosclerosis: an added value for heart hospitals

Coronary atherosclerosis is the result of multiple complex metabolic disorders acting alone or in combination. Metabolic cardiology has advanced considerably in the past decade and now offers cardiologists a sophisticated approach to treating the underlying cause(s) of coronary artery disease in patients seen in invasive cardiology practices. Disorders which have now been powerfully linked to coronary artery disease include the small low-density lipoprotein trait, impaired reverse cholesterol transport, homocysteinemia, insulin resistance, aspects of inflammation, and infectious burden. These disorders are common and alone, or in combination, are found in over 90% of patients with coronary artery disease. Treatments for these disorders are well elucidated and have been associated with cardiovascular benefit. Incorporation of a sophisticated metabolic atherosclerosis management unit into existing invasive cardiology practices offers the cardiologist and patient many benefits. The cardiologist obtains a powerful tool that complements invasive cardiology, provides patients with access to cutting-edge diagnosis and treatment, and provides a forum that allows incorporation of clinically valid advances in metabolic cardiovascular care in a time frame far shorter than the traditional consensus recommendation approach. Incorporation of such a clinical service is consistent with the recent American College of Cardiology focus on the "CardioTeam."

Impact of obesity on revascularization and restenosis rates after bare-metal and drug-eluting stent implantation (from the TAXUS-IV trial)

The effect of obesity on repeat coronary revascularization and restenosis in patients who undergo stent implantation has not been reported. We therefore examined the database from the multicenter randomized TAXUS-IV trial to determine the effect of body mass index (BMI) on outcomes after bare-metal and drug-eluting stent implantation. In TAXUS-IV, patients were randomized to receive a slow-release, polymer-based, paclitaxel-eluting stent or a bare-metal stent. Outcomes were stratified by baseline BMI. Of the 1,307 randomized patients who had documented BMI, 233 (17.8%) had normal weight (BMI <25 kg/m2), 531 (40.6%) were overweight (BMI < or =25 to 30 kg/m2), and 543 (41.5%) were obese (BMI > or =30 kg/m2). Patients who had been assigned to receive bare-metal stents and were overweight and obese compared with those who had normal weight had higher rates of 9-month binary restenosis (29.2% and 30.5% vs 9.3%, respectively; p = 0.01) and 1-year major adverse cardiac events (20.8% and 23.2% vs 11.1%, respectively; p = 0.02), whereas rates of these events did not differ significantly among those who received a paclitaxel-eluting stent (7.6% and 9.3% vs 4.9%, respectively for binary restenosis; p = 0.65; 11.3% and 10.4% vs 10.1%, respectively; p = 0.82 for major adverse cardiac events). By multivariate analysis, BMI > or =30.0 kg/m2 independently predicted binary restenosis (hazard ratio 4.26, p = 0.005), 1-year target vessel revascularization (hazard ratio 1.95, p = 0.04), and major adverse cardiac events (hazard ratio 1.95, p = 0.004) in patients who received bare-metal stents but not paclitaxel-eluting stents. In conclusion, obesity is an important risk factor for clinical and angiographic restenosis and for composite major adverse cardiac events in patients who receive bare-metal stents. Paclitaxel-eluting stents attenuate the increased risk associated with obesity, such that the intermediate-term prognosis after percutaneous coronary intervention is independent of weight.

Relation of fasting insulin plasma levels to restenosis after elective coronary stent implantation in patients without diabetes mellitus

The results of this study in 172 patients without diabetes who underwent elective stent implantation showed a significant correlation between preprocedural fasting insulin serum levels and angiographic late lumen loss (correlation coefficient 0.49, p <0.0001). Furthermore, the waist-to-hip ratio and C-peptide and hemoglobin A1c serum levels were associated with the occurrence of binary angiographic restenosis.

Association of insulin resistance, hyperleptinemia, and impaired nitric oxide release with in-stent restenosis in patients undergoing coronary stenting

BACKGROUND

Previously undiagnosed diabetes, impaired glucose tolerance, and insulin resistance are common in patients with acute myocardial infarction and coronary heart disease (CHD) and might be involved in early restenosis after stent implantation. To evaluate whether markers of insulin resistance syndrome, including leptin, and endothelial dysfunction are related to increased rate of early restenosis, we studied nondiabetic patients with CHD after successful coronary stenting.

METHODS AND RESULTS

Both patients with CHD undergoing coronary stenting (120 patients) and control subjects (58 patients) were submitted to an oral glucose tolerance test (OGTT). Fasting leptin levels and fasting and postglucose load insulin sensitivity were assessed. Endothelial function was measured by nitrite and nitrate release (NOx) during OGTT. More than 50% of patients treated with stent implantation presented impaired glucose tolerance or type 2 diabetes, which was previously undiagnosed. These patients also had higher glucose, insulin, and leptin levels than control subjects. Among the stented patients, insulin and leptin levels were higher in patients with restenosis than in patients without restenosis. A significant increase in NOx levels was found during OGTT both in patients without restenosis and in control subjects. On the contrary, NOx profiles were blunted in patients with restenosis. At multiple regression analysis, only DeltaAUC-NOx areas and insulin sensitivity index showed an independent correlation with the minimal lumen diameter at follow-up.

CONCLUSIONS

We demonstrated that insulin resistance and endothelial dysfunction are independent predictors of early restenosis after coronary stenting.

Pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus: an intravascular ultrasound scanning study

BACKGROUND

It has been reported that pioglitazone reduces neointimal hyperplasia after balloon-induced vascular injury in an experimental model.

METHODS

To determine whether pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus, we studied 44 stented lesions in 44 patients with diabetes mellitus who underwent successful coronary stent implantation. Study patients were randomized into 2 groups: the pioglitazone group (23 patients with 23 lesions) and the control group (21 patients with 21 lesions). All patients underwent serial quantitative coronary angiography and serial intravascular ultrasound scanning studies. With a motorized pullback system, multiple image slices within the stent were obtained at every 1 mm. The stent area and lumen area were measured, and the neointimal area was calculated. Measurements were averaged over the number of selected image slices. The neointimal index was calculated as the averaged neointimal area divided by the averaged stent area multiplied by 100 (%).

RESULTS

After 6 months of treatment, angiographic in-stent restenosis (17% vs 43%, respectively, P =.0994) and target lesion revascularization (13% vs 38%, respectively, P =.0835) were less frequent in the pioglitazone group than the control group; however, these differences did not reach significance. The intravascular ultrasound scanning study demonstrated that the neointimal index in the pioglitazone group was significantly smaller than that in the control group (28% +/- 9% vs 48% +/- 15%, respectively, P <.0001).

CONCLUSION

A serial intravascular ultrasound scanning assessment demonstrated that pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus.

Predictors of angiographic restenosis after coronary intervention in patients with diabetes mellitus

BACKGROUND

Patients with diabetes mellitus are particularly prone to restenosis after percutaneous coronary intervention. An exploratory, nested, case-control study was undertaken to identify clinical, lesional, and procedural predictors of angiographic restenosis in these patients.

METHODS

Seventy-five patients with diabetes mellitus with 86 coronary lesions were selected from a larger population of 217 patients who had undergone 6-month angiographic follow-up after a first, successful balloon angioplasty (PTCA) or stent implantation procedure. Data collection was by patient interview and review of hospital database and other medical records. All angiograms were analyzed with quantitative coronary angiography, and restenosis was defined as a >or=50% diameter reduction at the treated site. A multivariate analysis of 10 prespecified explanatory variables, derived from a literature review, was performed on a per-lesion basis.

RESULTS

There were 45 patients (53 lesions) with restenosis and 30 patients (33 lesions) without restenosis. Univariate predictors of binary restenosis were periprocedural glycosylated hemoglobin level, vessel reference diameter, PTCA, and larger final balloon size to reference artery diameter ratio. Multiple logistic regression identified poor glycemic control (odds ratio [OR] 3.03, 95% CI 1.06-8.65, P =.038), small vessel reference diameter (OR 3.41, 95% CI 1.17-9.95, P =.025), and mode of intervention (OR 3.12, 95% CI 1.08-9.00, P =.036) as independent risk factors. Vessel reference diameter appeared to be an important effect modifier of the association between type of intervention and angiographic outcome, with stenting no longer superior to PTCA in patients with diabetes mellitus who had vessels <2.87 mm in diameter (P =.054).

CONCLUSION

Poor glycemic control, vessel size, and PTCA were independent predictors of restenosis in patients with diabetes mellitus. It is possible that improved periprocedural glycemic control, in addition to stenting, may reduce the restenosis rate in these patients.

Increased secretion of insulin during oral glucose tolerance test can be a predictor of stent restenosis in nondiabetic patients

Insulin is known to stimulate proliferation and migration of vascular smooth muscle cells. As the predominant mechanism of restenosis after stent implantation is neointimal tissue proliferation, one can expect a relationship between hyperinsulinemia and restenosis in these patients. The aim of this study was to determine whether hyperinsulinemia during oral glucose tolerance test is a predictor of the development of restenosis after stent implantation in nondiabetic patients. We prospectively studied 52 nondiabetic patients with effort angina who underwent elective stent implantation for single-vessel coronary artery disease. In order to increase the statistical power of the study, numerous exclusion criteria were applied. All patients were subjected to a 75 g oral glucose tolerance test a day before the stent implantation and underwent follow-up angiography 6 months later. Plasma insulin levels in fasting (6.77 +/- 1.57 vs. 5.36 +/- 1.35 micro U/ml; P = 0.005), at 30 min (102.48 +/- 10.6 vs. 47.74 +/- 12.75 micro U/ml; P = 0.001), 1 hr after (120.23 +/- 14.1 vs. 63.08 +/- 12.62 micro /ml; P = 0.001), 2 hr after (63.58 +/- 8.64 vs. 34.88 +/- 6.82 micro /ml; P = 0.001), and 3 hr after (25.71 +/- 5.65 vs. 23.02 +/- 4.61 micro /ml; P = 0.04) loading were significantly higher in patients with stent restenosis than in patients without stent restenosis. Insulin area and insulin area/glucose area were also significantly higher in patients with stent restenosis than in patients without (219.5 +/- 23.8 vs. 118.9 +/- 21.8, P = 0.001, and 0.62 +/- 0.09 vs. 0.33 +/- 0.06, P = 0.001, respectively). By multiple logistic regression analysis, insulin area during oral glucose tolerance test was found to be an independent predictor of stent restenosis (OR = 1.12; 95% CI = 1.01-1.25; P = 0.031). In conclusion, nondiabetic patients with hyperinsulinemia during oral glucose tolerance test have a high risk for restenosis after stent implantation, and performing this simple test before intervention may be useful for the prediction of stent restenosis.

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.

[Coronary angioplasty in diabetic patients. Current and future perspectives]

It has been estimated that 15-25% of patients who undergo percutaneous or surgical coronary angioplasty are diabetics. The indications for coronary revascularization and initial results of the procedure do not differ substantially between patients with diabetes mellitus and non-diabetics. However, the long-term results of both percutaneous and surgical coronary angioplasty are less favorable in diabetics in terms of mortality and the need for new revascularization procedures. The development and widespread use of stents and glycoprotein IIb/IIIa receptor inhibiting drugs have improved the clinical evolution of diabetics treated with angioplasty. Currently available data show that the administration of glycoprotein IIb/IIIa inhibitors to patients undergoing coronary angioplasty is especially useful in diabetics and improves short-term and long-term results, decreasing one-year mortality by 45%. There seem to be indications for the routine use of glycoprotein IIb/IIIa inhibitors in diabetics treated with angioplasty. While the use of stents has improved long-term and short-term results in diabetics, the success rates of angioplasty in diabetics are still lower than in non-diabetics. Diabetes is still an independent predictor of restenosis and long-term events after stenting interventions. Analysis of the studies comparing percutaneous and surgical revascularization in diabetic patients with multivessel disease shows that surgery is superior in terms of long-term mortality and need for new revascularization procedures. Stenting has improved, but not substantially, the results of multivessel angioplasty in diabetics. Therefore, the indications for angioplasty in multivessel diabetics should be evaluated individually. Factors that contribute to the less favorable post-angioplasty evolution of diabetic patients are more rapid progression of atherosclerosis and, especially, a higher rate of restenosis. New angioplasty techniques, such as brachytherapy and drug-eluting stents, are likely to significantly improve the results of percutaneous interventions in diabetics, thus allowing the indications for angioplasty in diabetics to be extended even further in the near future.

Impact of insulin resistance on neointimal tissue proliferation after coronary stent implantation. Intravascular ultrasound studies

Serial intravascular ultrasound (IVUS) studies in 55 nondiabetic patients showed that neointimal tissue proliferation after stent implantation in patients with impaired glucose tolerance (IGT) was greater than that in patients with normal glucose tolerance at follow-up. Multiple regression analysis showed that the sum of insulin levels was the best predictor of the greater neointimal index at follow-up. Another group of serial IVUS studies were performed in 62 stented lesions in 52 patients with Type 2 diabetes mellitus (DM). The study patients were randomized into a troglitazone group and a control group. The neointimal tissue proliferation at follow-up in the troglitazone group was significantly smaller than that in the control group.

Impact of peri-stent remodeling on restenosis: a volumetric intravascular ultrasound study

BACKGROUND

Vessel remodeling is an important mechanism of late lumen loss after nonstent coronary interventions. However, its impact on in-stent restenosis has not been systematically investigated.

METHODS AND RESULTS

Serial volumetric intravascular ultrasound analyses (poststent and follow-up) were performed in 55 lesions treated with a balloon-expandable stent (ACS MultiLink) using standard stent deployment techniques. The vessel volume (VV), lumen volume (LV), and volume bordered by the stent (SV) were measured using Simpson's method. The volume of plaque and neointima outside the stent (peri-stent volume, PSV) and volume of neointima within the stent (intrastent volume) were also measured. The change of each parameter during the follow-up period (follow-up minus poststent) was calculated and then divided by SV to normalize these values (designated as percent change [%]). As expected, %PSV directly correlated with %VV (P<0.0001, r=0.935), with no significant SV. A highly significant inverse correlation was seen between %PSV and the percent change of intrastent volume (P<0.0001, r=0.517). Consequently, %LV significantly correlated with peri-stent remodeling, as measured by %VV (P<0.0001, r=0.602).

CONCLUSION

Positive remodeling of the vessel exterior to a coronary stent occurs to a variable degree after stent implantation. There is a distinct trade-off between positive remodeling and in-stent hyperplasia: in segments in which the degree of peri-stent remodeling is less, intrastent neointimal proliferation is greater and accompanied by more significant late lumen loss.