Effect of angiotensin-converting enzyme inhibition on restenosis after coronary stenting

Predictors of restenosis following percutaneous coronary stent implantation: The role of trimetazidine therapy

Aims

In-stent restenosis (ISR) is an unresolved problem following percutaneous coronary intervention (PCI), having a negative impact on clinical outcome. The main goal of this study was to find new independent predictors that may influence the development of ISR.

Methods and results

In this retrospective analysis, 653 PCI patients were involved. All patients had coronary stent implantation and a follow-up coronary angiography. Based on the presence of ISR at follow-up, patients were divided into two groups: 221 in the ISR and 432 in the control group. When evaluating the medical therapy of patients, significantly more patients were on trimetazidine (TMZ) in the control compared to the ISR group (p = 0.039). TMZ was found to be an independent predictor of a lower degree of ISR development (p = 0.007). TMZ treatment was especially effective in bare metal stent (BMS)-implanted chronic coronary syndrome (CCS) patients with narrow coronary arteries. The inflammation marker neutrophil to lymphocyte ratio (NLR) was significantly elevated at baseline in the ISR group compared to controls. The reduction of post-PCI NLR was associated with improved efficacy of TMZ to prevent ISR development. Drug eluting stent implantation (p < 0.001) and increased stent diameter (p < 0.001) were the most important independent predictors of a lower degree of ISR development, while the use of longer stents (p = 0.005) was a major independent predictor of an increased ISR risk.

Conclusion

TMZ reduces the occurrence of ISR following PCI, with special effectiveness in BMS-implanted patients having CCS and narrow coronary arteries. TMZ treatment may help to lower ISR formation in countries with high BMS utilization rates.

Effects of Valsartan on Restenosis in Patients with Arteriosclerosis Obliterans of the Lower Extremities Undergoing Interventional Therapy: A Prospective, Randomized, Single-Blind Trial

BACKGROUND The aim of this study was to further clarify the effects of valsartan on restenosis in patients with arteriosclerosis obliterans of the lower extremities. MATERIAL AND METHODS Patients with arteriosclerosis obliterans of the lower extremities undergoing continuous stent implantation in the superficial femoral artery were enrolled and randomly divided into an ARB group and a control group. Patients in the ARB group received valsartan orally in a single-blind manner and were followed up for 6 months. An evaluation was performed based on the criteria for clinical efficacies designed by the Committee of Vascular Disease, Chinese Association of Integrative Medicine. The total clinical effective rate was calculated, and ankle brachial index (ABI) of the patients was assessed. The concentrations of interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hs-CRP) were measured using enzyme-linked immunosorbent assay. The in-stent restenosis of patients was examined by angiography. RESULTS One patient in the control group died due to acute cerebral hemorrhage 4 months after enrollment, and 1 patient was lost to follow-up due to acute myocardial infarction during follow-up 5 months after enrollment. Age, sex, Fontaine stage, and underlying diseases were comparable between the 2 groups. Hs-CRP (3.93±1.43) and IL-6 (11.26±2.29) levels were significant different in the ARB group compared with the control group. The postoperative follow-up showed that ABI was 0.98±0.20 in the ARB group and 0.62±0.48 in the control group. CONCLUSIONS Valsartan inhibited the increase in hs-CRP and IL-6 levels, improved clinical efficacies, increased ABI, and decreased the restenosis rate after the interventional therapy in patients with arteriosclerosis obliterans of the lower extremities.

Renin-angiotensin system blockade reduces cardiovascular events in nonheart failure, stable patients with prior coronary intervention

BACKGROUND

The effects of renin-angiotensin system (RAS) blockade on the clinical outcome in patients with stable coronary artery disease (SCAD) are conflicting. We evaluated the long-term effects of RAS blockers (angiotensin-converting enzyme inhibitor or angiotensin receptor blocker) on the clinical outcomes in patients with SCAD without heart failure (HF) who underwent percutaneous coronary intervention (PCI) with drug-eluting stent using a large-scale, multicenter, prospective cohort registry.

METHODS

A total of 5722 patients with SCAD were enrolled and divided into two groups according to the use of RAS blockers after PCI: RAS blocker group included 4070 patients and no RAS blocker group included 1652 patients. Exclusion criteria were left ventricular ejection fraction less than 50% and the history of HF or myocardial infarction. A major adverse cardiovascular event (MACE) was defined as a composite of cardiovascular death, nonfatal myocardial infarction, and stroke.

RESULTS

During a median follow-up of 29.7 months, RAS blockers were associated with a significant reduction in the risk of MACE [adjusted hazard ratio (HR): 0.781; 95% confidence interval (CI): 0.626-0.975; P=0.015] and all-cause death (adjusted HR: 0.788; 95% CI: 0.627-0.990; P=0.041) but did not affect the risk of coronary revascularization. In the propensity score matched cohort, overall findings were consistent (MACE: adjusted HR: 0.679; 95% CI: 0.514-0.897; P=0.006; all-cause death: adjusted HR: 0.723; 95% CI: 0.548-0.954; P=0.022), and the benefit of RAS blockade was maintained in all predefined subgroups.

CONCLUSION

This study demonstrated that RAS blockers were effective preventive therapies for reducing long-term cardiovascular events in patients with SCAD without HF who underwent PCI.

Identification of Risk Factors Influencing In-Stent Restenosis with Acute Coronary Syndrome Presentation

Although the angiographic rates of in-stent restenosis (ISR) at later months have reduced dramatically with the introduction of drug-eluting stents (DESs), some patients with ISR after implantation of DES present with acute coronary syndrome (ACS). Here, we sought to identify parameters influencing the likelihood of restenosis with ACS presentation after DES implantation. Stented patients (n=3,817) with DESs in the Korea University Anam Hospital percutaneous coronary intervention registry were reviewed retrospectively for inclusion. In this database, 247 age- and sex-matched patients (6.5%) with ISR were allocated to either the Stable ISR group (n=78) or the ACS ISR group (n=73). Predictors of in-stent restenosis were identified with Cox regression analyses. Age (hazard ratio [HR], 1.14; 95% confidence interval [CI], 1.02 to 1.27; p=0.026), diabetes (HR, 8.40; 95% CI, 1.30 to 54.1; p=0.025), use of aspirin (HR, 0.003; 95% CI, 0.0001 to 0.63; p=0.03), clopidogrel (HR, 0.005; 95% CI, 0.001 to 0.121; p=0.001), renin-angiotensin system (RAS) blocker (HR, 0.02; 95% CI, 0.003 to 0.14; p<0.001), use of first -generation DES (HR, 0.07; 95% CI, 0.009 to 0.59; p=0.014), and matrix metalloproteinase 2 (MMP-2) levels (HR, 1.120; 95% CI, 1.001 to 1.190; p=0.004) during follow-up angiograms were significant predictors of ISR with ACS presentation during the 3 year follow-up. Age, diabetes, the use of first generation DES, and increased MMP-2 levels were significant predictors of ISR with ACS presentation; moreover, the use of aspirin, clopidogrel, RAS blocker, and the use of second generation DESs prevented ISR with ACS presentation.

Relationship of the rs1799752 polymorphism of the angiotensin-converting enzyme gene and the rs699 polymorphism of the angiotensinogen gene to the process of in-stent restenosis in a population of Polish patients with stable coronary artery disease

PURPOSE

The renin-angiotensin-aldosterone system may influence in-stent restenosis (ISR) via angiotensin II, which stimulates the production of growth factors for smooth muscle cells. The aim of this work is to assess the influence of the rs1799752 polymorphism of the angiotensin-converting enzyme (ACE) gene and the rs699 polymorphism of the angiotensinogen (AGT) gene on the ISR in Polish patients with stable coronary artery disease (SCAD) who underwent stent implantation.

MATERIAL/METHODS

Two hundred and sixty-five patients with SCAD were included in the study. All patients underwent stent implantation upon admission to the hospital and had subsequent coronary angiography performed. The patients were divided into two groups - those with significant ISR (n=53) and those without ISR (n=212). The ACE polymorphism was assessed using the classical PCR method and the AGT polymorphism was determined using the TaqMan method for SNP genotyping.

RESULTS

No difference in the frequency of angiographically significant ISR occurrence associated with the different ACE and AGT gene polymorphisms was observed. In a multivariable analysis, after correction for clinical variables, the relationship between the ACE and AGT genotypes within the scope of the analyzed polymorphisms and the process of restenosis was not found using a dominant, recessive and log-additive model. Late lumen loss was also independent of the genotypes of the polymorphisms before and after correction with angiographic variables.

CONCLUSIONS

The rs1799752 polymorphism and the rs699 polymorphism had no relationship with the occurrence of angiographically significant ISR and late lumen loss in a group of Polish patients who underwent metal stent implantation.

Morphological predictors for no reflow phenomenon after primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction caused by plaque rupture

AIMS

Myocardial no reflow after percutaneous coronary intervention (PCI) is associated with poor outcome. Patients with ST-segment elevation myocardial infarction (STEMI) caused by plaque rupture are at high risk for no reflow. However, specific morphologic characteristics associated with no reflow are unknown in this population. The aim of this study is to identify the morphological characteristics of culprit plaques associated with no reflow in patients with STEMI caused by plaque rupture using both optical coherence tomography (OCT) and intravascular ultrasound (IVUS).

METHODS AND RESULTS

We enrolled 145 patients with STEMI who underwent both OCT and IVUS within 12 h of symptom onset. Among these patients, we excluded those with plaque erosion and calcified nodule and included 72 patients who had plaque rupture as an underlying mechanism for STEMI. Myocardial no reflow, defined as Thrombolysis in Myocardial Infarction flow grade 0-2 and/or myocardial blush grade 0-1 after PCI, was observed in 28 patients (38.9%). Onset to recanalization time was similar between the groups with and without no reflow. Receiver-operating curve analysis revealed OCT-derived lipid index > 3500 [area under curve (AUC) 0.77, P < 0.001] and IVUS-derived plaque burden > 81.5% (AUC 0.70, P = 0.002) were the best discriminators for myocardial no reflow.

CONCLUSION

No reflow occurred in nearly 40% of patients with STEMI caused by plaque rupture. Large lipid index and plaque burden were critical morphological discriminators between no reflow and normal flow.

Influence of the angiotensin converting enzyme insertion or deletion genetic variant and coronary restenosis risk: evidence based on 11,193 subjects

The insertion/deletion (I/D) polymorphism of the gene encoding angiotensin converting enzyme is a controversial risk factor for restenosis after percutaneous transluminal coronary angioplasties (PTCA) in patients. Genetic association studies can be problematic to reproduce due to insufficient power, phenotypic heterogeneity, population stratification, small effect of the variant and even publication biases. To derive a more precise estimation of the relationship as well as to quantify the between-study heterogeneity and potential bias, a meta-analysis including 11,193 patients from 33 published cohort studies was performed. In a combined analysis, the summary per-allele odds ratio for restenosis was 1.31 (95% CI: 1.08-1.58, P = 0.006), and 1.22 (95% CI: 0.95-1.56, P = 0.12), for PTCA-stent and PTCA-balloon, respectively. In the subgroup analysis by ethnicity, significantly increased restenosis risks after PTCA-stent were found in Asians for the polymorphism; whereas no significant associations were found among Caucasians. As for restenosis risks after PTCA-balloon, no evidence of any gene-disease association was obtained in the stratified analyses according to ethnicity and study size. In conclusion, this meta-analysis demonstrated that the DD homozygous of ACE I/D polymorphism was significantly associated with elevated restenosis susceptibility after PTCA-stent among Asian populations.

Genetic polymorphism of angiotensin converting enzyme and risk of coronary restenosis after percutaneous transluminal coronary angioplasties: evidence from 33 cohort studies

Background

In the past decade, a number of cohort studies studies have been carried out to investigate the relationship between the insertion/deletion polymorphism of the gene encoding angiotensin-converting enzyme and risk of restenosis after percutaneous transluminal coronary angioplasties in patients. However, these studies have yielded contradictory results. Genetic association studies addressing this issue are frequently hampered by insufficient power. We therefore performed a meta-analysis of the published studies to clarify this inconsistency and to establish a comprehensive picture of the relationship between ACE I/D polymorphism and post-PTCA restenosis risk.

Methods

Databases including Pubmed, EMBASE, ISI Web of Science, EBSCO, Cochrane Library databases and CNKI were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. The random-effects model was applied, addressing heterogeneity and publication bias.

Results

A total of 33 cohort studies involving 11,099 subjects were included. In a combined analysis, the OR for post-PTCA restenosis of the ACE DD genotype was 1.61 (95% CI: 1.27–2.04; P<10⁻⁵). In the subgroup analysis by intervention, significantly increased risks were also found in PTCA-stent and PTCA-balloon for the DD genotype of the polymorphism.

Conclusions

Our meta-analysis showed that the DD genotype of ACE I/D polymorphism was significantly associated with increased risk of restenosis, particularly for PTCA-stent.

Neointimal hyperplasia inhibition effect of angiotensin II type 1 receptor blockers in patients after coronary stent implantation: a meta-analysis

BACKGROUND AND OBJECTIVE

It remains unclear whether angiotensin II type 1 receptor antagonists (angiotensin receptor blockers [ARBs]) can inhibit neointimal hyperplasia after stent implantation in patients with coronary artery disease. The aim of this meta-analysis was therefore to evaluate the benefits of ARBs in patients after coronary stent implantation based on the currently available randomized controlled trials.

METHODS

We conducted a pooled analysis of randomized controlled trials to compare outcomes after stent implantation in patients administered ARBs with those not administered ARBs. We searched Ovid/MEDLINE, EMBASE, and the ISI web of knowledge using the terms 'angiotensin receptor blocker,' 'renin angiotensin system inhibitor,' 'angiotensin receptor antagonist,' 'stent,' 'angiograph,' 'percutaneous coronary intervention (PCI),' and 'coronary artery disease.' Published meta-analyses, review articles, and editorials were reviewed for potential studies of interest. The inclusion criteria were randomized controlled trials published in English, with a follow-up period of 6 months, comparing the outcomes after coronary stent implantation with and without the administration of any kind of ARB, reporting at least one outcome of interest (restenosis rate and late lumen loss). Data abstraction included study design, patient characteristics, follow-up period, type of ARB, type of stent, restenosis rate, and late lumen loss. Fixed-effects models were used to calculate the pooled relative risk for the restenosis rate and the standardized mean difference for late lumen loss.

RESULTS

Five studies were included, with a total number of 624 patients. Seventy-five of 314 patients in the ARB group were diagnosed with in-stent restenosis at the 6-month follow-up, compared with 87 of 310 patients in the control group (relative risk 0.85; 95% CI 0.65, 1.11; p = 0.23). Consistent with this, there was no significant difference in late lumen loss between the two groups (0.04 mm; 95% CI -0.15, 0.23; p = 0.66).

CONCLUSION

There is no evident benefit with the use of an ARB in terms of inhibition of neointimal hyperplasia in patients after coronary stent implantation.

ACE (I/D) polymorphism and response to treatment in coronary artery disease: a comprehensive database and meta-analysis involving study quality evaluation

BACKGROUND

The role of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in modifying the response to treatment modalities in coronary artery disease is controversial.

METHODS

PubMed was searched and a database of 58 studies with detailed information regarding ACE I/D polymorphism and response to treatment in coronary artery disease was created. Eligible studies were synthesized using meta-analysis methods, including cumulative meta-analysis. Heterogeneity and study quality issues were explored.

RESULTS

Forty studies involved invasive treatments (coronary angioplasty or coronary artery by-pass grafting) and 18 used conservative treatment options (including anti-hypertensive drugs, lipid lowering therapy and cardiac rehabilitation procedures). Clinical outcomes were investigated by 11 studies, while 47 studies focused on surrogate endpoints. The most studied outcome was the restenosis following coronary angioplasty (34 studies). Heterogeneity among studies (p < 0.01) was revealed and the risk of restenosis following balloon angioplasty was significant under an additive model: the random effects odds ratio was 1.42 (95% confidence interval:1.07-1.91). Cumulative meta-analysis showed a trend of association as information accumulates. The results were affected by population origin and study quality criteria. The meta-analyses for the risk of restenosis following stent angioplasty or after angioplasty and treatment with angiotensin-converting enzyme inhibitors produced non-significant results. The allele contrast random effects odds ratios with the 95% confidence intervals were 1.04(0.92-1.16) and 1.10(0.81-1.48), respectively. Regarding the effect of ACE I/D polymorphism on the response to treatment for the rest outcomes (coronary events, endothelial dysfunction, left ventricular remodeling, progression/regression of atherosclerosis), individual studies showed significance; however, results were discrepant and inconsistent.

CONCLUSION

In view of available evidence, genetic testing of ACE I/D polymorphism prior to clinical decision making is not currently justified. The relation between ACE genetic variation and response to treatment in CAD remains an unresolved issue. The results of long-term and properly designed prospective studies hold the promise for pharmacogenetically tailored therapy in CAD.

Quinaprilat-eluting stents do not attenuate intimal thickening following stenting in porcine coronary arteries

OBJECTIVE

Vascular injury increases angiotensin-converting enzyme (ACE) activity in the vessel wall, and experimental evidence suggests that high-dose oral ACE inhibition reduces intimal hyperplasia following balloon angioplasty. Local drug delivery can achieve high local concentrations which may be especially efficacious in inhibiting tissue growth following stent implantation. The aim of this study was to evaluate the angiographic and histomorphologic effects of quinaprilat-eluting stents in normal porcine coronary arteries.

METHODS

Ten pigs received phosphorylcholine-coated stents in each of the three major coronary arteries: one loaded with 780 microg quinaprilat, one with the solvent and one non-loaded control. Quantitative angiography was performed before and after stenting and at 4 weeks follow-up. At this time point the stented arteries were also analyzed using histology and morphometry.

RESULTS

Repeated measures ANOVA yielded significantly smaller angiographic lumen in both quinaprilat and solvent groups: 2.62+/-0.31 and 2.65+/-0.31 mm, respectively versus control: 2.70+/-0.32 mm at follow-up, p<0.05. Histology confirmed this finding with an increment in intimal area (2.5+/-0.86 mm(2)) and thickness (0.57+/-0.29 mm) in the quinaprilat group; versus solvent (1.98+/-0.57 mm(2) 0.4+/-0.26 mm) and controls (1.92+/-0.50mm(2) and 0.41+/-0.18 mm).

CONCLUSION

Quinaprilat-eluting stents do not attenuate neointimal thickening following implantation in normal porcine coronary arteries, but rather show a tendency towards the opposite.

Angiotensin II-induced growth of vascular smooth muscle cells is associated with modulation of cell surface area and platelet-derived growth factor receptor expression

1. Excessive growth of vascular smooth muscle cells (VSMC) can lead to critical problems in the treatment of some vascular diseases. Recent studies suggest a connection between this abnormal growth of VSMC and the octapeptide hormone angiotensin (Ang) II. However, the growth-promotive potential of AngII on VSMC is unclear. 2. Using the novel AngII inhibitor E4177 and an original animal model, we confirmed that AngII does function in abnormal growth of VSMC induced after transplantation of vein grafts in an animal model. 3. Furthermore, using a primary culture of human aortic smooth muscle cells (HASMC), we found that AngII augmented the growth of HASMC in a serum-dependent manner and induced enlargement of the cell surface area in HASMC, both effects being nullified by E4177. The latter effect of AngII was associated with an increase in the expression level of platelet-derived growth factor (PDGF) receptors. In specimens obtained from the animal model, PDGF receptors were highly expressed. 4. These data obtained in vitro and in vivo imply that AngII has the potential to promote growth of VSMC and suggest that this growth promotion may be mediated by enlargement of the cell surface area.

The relationship between angiotensin converting enzyme gene polymorphism, coronary artery disease, and stent restenosis: the role of angiotensin converting enzyme inhibitors in stent restenosis in patients with diabetes mellitus

Patients with diabetes mellitus (DM) have advanced atherosclerosis compared with nondiabetics. Restenosis after intracoronary stent implantation occurs frequently in diabetic patients. Angiotensin II is an important growth factor for the development of neointimal hyperplasia after vascular injury. The aim of our study was to evaluate the relationships between angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and coronary artery disease (CAD) and stent restonosis in diabetic patients. One hundred and thirty consecutive patients with CAD and 47 consecutive patients (14 males, mean age, 58.0 +/- 10.0) without CAD were enrolled in the study. All patients had type 2 (noninsulin dependent) DM. The patients with CAD underwent percutaneous transluminal coronary angioplasty (PTCA) and stenting. Ninety-four (59 males, mean age, 60.3 +/- 9.8) underwent control coronary angiography at the end of the follow-up period (mean duration, 9.1 +/- 2.9 months). ACE gene I/D genotyping was identified in all patients. No significant difference was found among patients with and without CAD with respect to ACE gene I/D polymorphism (P = 0.460). In the control coronary angiography, stent restenosis and new lesion development were comparable in each genotyping subgroup. However, a significant relationship was observed between restenosis and the use of ACE inhibitors (ACEI) in patients with D allele (ACEI ratio, 43.5% in the restenosis group and 56.5% in non-restenotic group, P < 0.05). We did not find any relationship between ACE gene I/D polymorphism and CAD and stent restenosis and new lesion development in diabetic patients. On the other hand, ACEI treatment may reduce stent restenosis in type 2 diabetic patients with D allele (DD or ID).

Percutaneous coronary interventions for coronary artery disease: the long and short of optimizing medical therapy

Atherosclerosis is a dynamic process and timely introduction of pharmacological treatment can have a significant bearing on the patient's health and outcome. In addition to treating the culprit lesion mechanically, admission for percutaneous coronary interventions (PCI) for coronary artery disease (CAD) gives an opportunity for the interventional cardiologist to optimize medical therapy. The aim of this review is to provide an overview of the current medical literature pertaining to cardiovascular (CV) risk reduction and vascular event prevention in the setting of PCI, with emphasis on antiplatelet therapies, beta-blockers, HMG-Co A reductase inhibitors (statins) and angiotensin-converting enzyme inhibitors, with regard to therapy optimization during PCI and for chronic CAD. We discuss the effects of these oral therapies in reducing ischaemic events, thus augmenting the benefits of PCI, as well as preventing recurrent CV events after the procedure.

Valsartan versus ACE inhibition after bare metal stent implantation—results of the VALVACE trial

The use of ACE inhibitors (ACE-i) represents an Ia recommendation in the treatment of patients with STEMI and NSTEMI. However, results of smaller studies suggest an increase of in-stent-restenosis under ACE-i administration. The effects of ACE-i and valsartan after bare metal stent implantation of the culprit type B2/C lesion should be compared. Seven hundred patients were treated either by ACE-i in cases of LVEF<50% or 80 mg valsartan in cases of LVEF> or =50%. Restenosis rates after 6 months were analysed in 399 patients under valsartan and 224 patients under ACE-i with control angiography and major adverse cardiac events (death, infarction, reintervention) in a follow-up of up to 4 (mean 2.6) years in all patients. In-stent-restenosis was found in 19.5% under valsartan and in 34% under ACE-i (p<0.005). In diabetic patients, restenosis occurred in 24% under valsartan and in 43% under ACE-i (p<0.01). In initial acute coronary syndrome (ACS), restenosis rate was 14% under valsartan and 43% under ACE-i (p<0.0001). In stable angina, restenosis rates were 26.5% and 27.5%, respectively. Total MACE rates revealed significant differences in ACS due to reintervention rates of 22% and 7% under ACE-i and valsartan (p<0.0001). The administration of 80 mg valsartan after bare metal stent implantation leads to a reduction of in-stent-restenosis compared to ACE-i. This effect is mainly due to beneficial effects of valsartan in cases with initial ACS. Major differences between ACE-i and valsartan are discussed including inflammation, activation of neutrophils, mode of bradykinin activation, AT2 receptor stimulation and apoptosis of smooth muscle cells.

Angiotensin Antagonism in Coronary Artery Disease

The renin-angiotensin system (RAS) is an ancient and complex cascade of homeostatic reactions aimed at regulating primordial functions that ensure organ perfusion through the control of blood pressure and the regulation of renal-cardiac activity. However, the over-expression or lack of compensatory mechanisms of any of its components may initiate detrimental effects that potentially lead to disease, a balance that makes the RAS a sequence with a labile physiological equilibrium and with a strong harm potential. These characteristics of the RAS in general, and of the angiotensin converting enzyme (ACE) in particular, make it not only an important complex for the regulation of blood pressure and neuropeptide metabolism, but also a fascinating subject of study from a biochemical, evolutionary and genetic point of view. Pharmacological interventions that influence the RAS by inhibiting the ACE or the angiotensin II type 1 receptor (AT1R) have demonstrated sustained efficacy in reducing the incidence of cardiovascular events and, consequently, vascular mortality in several clinical situations. ACE inhibitors and angiotensin II receptor antagonists (ARAs) reduce blood pressure and have cardio- and vasculoprotective effects. Anti-atherosclerotic effects have also been attributed to these drugs. For these reasons, it has been hypothesised that RAS inhibitors could also reduce the recurrence of ischaemic events after myocardial revascularisation procedures, namely coronary artery by-pass graft surgery (CABG) or percutaneous coronary interventions (PCI). Information available on the effect of ACE inhibitors and ARAs in patients with coronary artery disease (CAD) previously treated with revascularisation techniques indicates a substantial reduction of mortality and infarction in these patients. However, data regarding the progression of CAD, restenosis or reocclusion of vascular conduits of the coronary circulation after myocardial revascularisation are inconsistent. In most studies, the administration of ACE inhibitors neither improved the ischaemic threshold nor reduced the need for new revascularisation procedures. On the contrary, ACE inhibitors have been associated with higher restenosis rates after PCI in some retrospective series. Conversely, a single, exploratory randomised trial demonstrated that the selective AT1R antagonist valsartan significantly reduced stent restenosis after PCI. In patients undergoing CABG, ACE inhibitors did not reduce the risk of graft degeneration or occlusion. Studies that evaluated a possible anti-atherosclerotic effect of ACE inhibitors (including some large randomised trials) have generally been negative.

Renin-Angiotensin System Intervention to Prevent In-Stent Restenosis

The occurrence of in-stent restenosis is a major drawback of percutaneous transluminal coronary angioplasty with stent placement. Target vessel revascularization is necessary in 15% of patients who receive a stent. Recent advances in the development of drug-eluting stents have reduced these numbers tremendously. However refinement of antirestenotic therapies remains obligatory. The emerging interest in more physiological antirestenotic therapies might unchain an interest in the well-known inhibitors of the rennin-angiotensin system (RAS), the angiotensin-converting enzyme inhibitors, and the angiotensin II type I receptor blockers. Contradictory results overshadow the discussion of whether intervention in the RAS could prevent in-stent restenosis. This review discusses the pathophysiology of in-stent restenosis, the role of the RAS in in-stent restenosis, and the possible role of RAS intervention in the prevention of in-stent restenosis.

Intracoronary β-irradiation prevents excessive in-stent neointimal proliferation in de novo lesions of patients with high plasma ACE levels. The BetAce randomized trial

BACKGROUND

This study evaluated vascular brachytherapy (VBT) as a potent antiproliferative treatment to prevent in-stent restenosis (ISR) after coronary angioplasty of de novo lesions in patients carrying the D allele of the I/D polymorphism of the ACE gene and high ACE plasma levels (>34 U/l).

METHODS AND MATERIALS

A prospective randomized trial was designed to detect a 30% improvement in the minimal lumen diameter (MLD) of the stenotic artery, as measured by quantitative coronary analysis (QCA), 6 months following VBT at the time of stented angioplasty. All patients were carriers of the D allele of the ACE gene, with plasma ACE levels >34 U/l.

RESULTS

Thirty-one patients (33 stenoses) were allocated to stent implantation (control group) and 30 patients (31 stenoses) to VBT and stented angioplasty. After angioplasty, in-stent MLD was similar in the two groups. At 6 months in the control group, in-stent MLD had decreased to 1.74+/-0.8 versus 2.25+/-1.05 mm in the VBT group (P=.04). The mean in-stent diameter was 2.3+/-0.8 mm in the control group versus 2.9+/-1.05 mm after VBT (P=.02), and the restenosis rate was 37.5% versus 17.9%, respectively (P=.08). At 6 months, a higher need for target vessel revascularization (TVR) was observed in the control group: 35.5% versus 13.3% (P=.04).

CONCLUSIONS

This randomized study confirms that patients with high plasma ACE concentrations are exposed to an increased risk for ISR after coronary stenting. The preventive use of VBT in these patients reduced neointimal formation by 65% such that the MLD at follow-up was increased by 29% compared with the control group.

Association study of the I/D polymorphism and plasma angiotensin-converting enzyme (ACE) as risk factors for stent restenosis

The ID (insertion/deletion) polymorphism of the ACE (angiotensin-converting enzyme) gene controls plasma ACE levels. Both have been correlated with ISR (in-stent restenosis) in preliminary analyses, but not confirmed in larger studies. In the present study, baseline and 6-month quantitative coronary analysis were performed in 897 patients who had stent implantation and the ID polymorphism genotyped. Plasma ACE levels were measured in 848 patients (95%). Restenosis rates among genotypes were 31.2% DD, 25.5% ID and 28.8% II (not significant). Plasma ACE levels were significantly higher in restenotic patients compared with patients without restenosis (30.7+/-18.6 units/l compared with 22.8+/-12.8 units/l; P=0.0001) and a strong independent predictor of ISR [OR (odds ratio)=3.70; 95% CI (confidence interval), 2.40-5.71; P<0.0001], except in diabetics. In the subgroup of diabetics and patients with AMI (acute myocardial infarction), the DD genotypes actually had a lower risk of ISR than the II genotypes (diabetics, OR=0.16; 95% CI, 0.04-0.69; P=0.014; and patients with AMI, OR=0.21; 95% CI, 0.061-0.749; P=0.016). After exclusion of diabetics and patients with AMI, ISR rates for genotypes in 632 patients were 31.7% DD, 24.3% ID and 17.6% II (P=0.02; DD compared with non-DD OR=1.57; 95% CI, 1.09-2.25). The association between the D allele and ISR observed in selected populations does not hold with a larger sample size. Other than sample size, clinical variables can modulate the association between ID polymorphism and ISR. Plasma ACE level is a risk factor for ISR, independently of the ID genotype.

Effect of amlodipine on vascular responses after coronary stenting compared with an angiotensin-converting enzyme inhibitor

BACKGROUND

Prevention of restenosis after coronary stenting is clinically important. We compared amlodipine and quinapril to determine which is more effective in preventing restenosis after stenting.

METHODS AND RESULTS

Immediately after successful coronary stenting of 101 lesions in 63 consecutive patients, the patients were randomly divided into 2 groups: 32 patients with 48 lesions were administered amlodipine 5 mg/day (group A), and 31 patients with 53 lesions were administered quinapril 10 mg/day (group Q). Lesions were assessed by quantitative coronary angiography (QCA) before and immediately after stenting and in the follow-up phase. Intravascular ultrasound (IVUS) could only be performed on 20 lesions in group A and 16 lesions in group Q throughout the follow-up period. We analyzed each lesion at 5 sites. In the follow-up phase, the minimal lumen diameter in group A was significantly larger than that in group Q (1.88 +/- 0.64 mm vs 1.52 +/- 0.53 mm, p<0.01). In the follow-up phase, the neointimal area (stent area-lumen area) in group A was significantly smaller than that in group Q (1.9 +/- 0.5 mm2 vs 2.7 +/- 0.8 mm2 at the middle portion of stent, p<0.01).

CONCLUSION

These QCA and IVUS findings suggest that amlodipine has beneficial effects in inhibiting neointimal hyperplasia in stented lesions compared with quinapril.

Genetic predictive factors in restenosis

Restenosis is still the main drawback of percutaneous transluminal coronary angioplasty (PTCA). It is thought to be a multifactorial process where recoil of the vessel, neointimal proliferation and thrombus formation are thought to play a role. Until now it has proven difficult to predict restenosis on clinical and procedural grounds, however, genetic epidemiology might provide more insights. In this review several genetic variables, i.e. polymorphisms that were determined in relation to restenosis are described. The single nucleotide polymorphisms (SNPs) described in the literature so far involve; the renin-angiotensin system, platelet aggregation, the inflammatory response, matrix metalloproteinases, smooth muscle cell proliferation, lipids and oxidative stress and nitric oxide. Nowadays DNA-microarrays have been developed which make it possible to test 50 or 60 polymorphisms at once. However, the risk of error due to multiple testing should be kept in mind. The results of the studies described should be interpreted with care. Many of the published studies are of relatively small sample size, which sometimes show more positive outcomes than the larger studies, this is possibly due to publication bias towards more positive results. The small sample size studies also exhibit wide confidence intervals. On the other hand, one must take into account that the process of restenosis is a multifactorial one and it is likely that multiple genes are involved. Thus, relatively small odds ratios relating to single gene contribution to restenosis can be of paramount importance when encompassed in the overall picture. Although still much research has to be done, stratification according to genetic make-up may enable tailoring of the interventional treatment to the individual patient.

Long-term effects of quinapril with high affinity for tissue angiotensin-converting enzyme after coronary intervention in Japanese

BACKGROUND

Angiotensin-converting enzyme inhibitors have been shown experimentally to prevent restenosis after balloon injury. We previously reported that quinapril reduced the 6-month restenosis (percent diameter stenosis >or=50%) rate after percutaneous coronary intervention (PCI). However, it was not established whether this favorable outcome was maintained for longer periods.

METHODS

This study was a prospective, randomized, open, and non-placebo controlled trial. Patients with coronary artery disease were enrolled after successful coronary balloon angioplasty or stenting. Two hundred and fifty-three patients were randomly assigned to the quinapril (10-20 mg per day) or control groups. The major clinical end points included death, myocardial infarction, cerebrovascular accident, or revascularization (either coronary artery bypass grafting or repeat PCI). These were tabulated according to the intention-to-treat principle.

RESULTS

Long-term follow-up was available with a median of 4.8 (interquartile range 4.2-5.1) years after the procedure. The incidence of combined end points of mortality and morbidity (myocardial infarction and cerebrovascular accident) in the quinapril group was lower than that in the control group (6.1% vs 14.8%; relative risk [RR] 0.42, 95% CI 0.18-0.96, P =.033). The overall incidence of end-point events in patients with quinapril also occurred less frequently (29.8% vs 46.7%; RR 0.58, 95% CI 0.38-0.86, P =.007).

CONCLUSIONS

These clinical outcomes show that the benefit of quinapril in patients following PCI is maintained for 4 years.

Inflammation and restenosis: implications for therapy

Restenosis is the process of luminal narrowing in an atherosclerotic artery after an intra-arterial intervention such as balloon angioplasty and stenting. It is believed that this process is mainly characterized by migration and proliferation of smooth muscle cells and extracellular matrix accumulation. However, there is now increasing evidence for a role of inflammation in the development of restenosis. The underlying molecular mechanisms of restenosis are, in fact, most probably regulated by inflammatory mediators, such as cytokines. Understanding the molecular mechanisms in restenosis is crucial for the development of a suitable therapy for this disease. Recently, the use of immunosuppressives in drug-eluting stents has provided very promising results in the treatment of restenosis. In this review, we will describe the molecular mechanisms involved in restenosis with a focus on the role of inflammation and the use of immunosuppressive therapy.