Does the new angiotensin converting enzyme inhibitor cilazapril prevent restenosis after percutaneous transluminal coronary angioplasty? Results of the MERCATOR study: a multicenter, randomized, double-blind placebo-controlled trial. Multicenter European Research Trial with Cilazapril after Angioplasty to Prevent Transluminal Coronary Obstruction and Restenosis (MERCATOR) Study Group

Hydrogen Sulphide Release via the Angiotensin Converting Enzyme Inhibitor Zofenopril Prevents Intimal Hyperplasia in Human Vein Segments and in a Mouse Model of Carotid Artery Stenosis

OBJECTIVE

Hypertension is a major risk factor for intimal hyperplasia (IH) and re-stenosis following vascular and endovascular interventions. Preclinical studies suggest that hydrogen sulphide (H₂S), an endogenous gasotransmitter, limits re-stenosis. While there is no clinically available pure H₂S releasing compound, the sulfhydryl containing angiotensin converting enzyme inhibitor zofenopril is a source of H₂S. Here, it was hypothesised that zofenopril, due to H₂S release, would be superior to other non-sulfhydryl containing angiotensin converting enzyme inhibitors (ACEi) in reducing intimal hyperplasia.

METHODS

Spontaneously hypertensive male Cx40 deleted mice (Cx40^-/-) or wild type (WT) littermates were randomly treated with enalapril 20 mg or zofenopril 30 mg. Discarded human vein segments and primary human smooth muscle cells (SMCs) were treated with the active compound enalaprilat or zofenoprilat. IH was evaluated in mice 28 days after focal carotid artery stenosis surgery and in human vein segments cultured for seven days ex vivo. Human primary smooth muscle cell (SMC) proliferation and migration were studied in vitro.

RESULTS

Compared with control animals (intima/media thickness 2.3 ± 0.33 μm), enalapril reduced IH in Cx40^-/- hypertensive mice by 30% (1.7 ± 0.35 μm; p = .037), while zofenopril abrogated IH (0.4 ± 0.16 μm; p < .002 vs. control and p > .99 vs. sham operated Cx40^-/- mice). In WT normotensive mice, enalapril had no effect (0.9665 ± 0.2 μm in control vs. 1.140 ± 0.27 μm; p > .99), while zofenopril also abrogated IH (0.1623 ± 0.07 μm; p < .008 vs. control and p > .99 vs. sham operated WT mice). Zofenoprilat, but not enalaprilat, also prevented IH in human vein segments ex vivo. The effect of zofenopril on carotid and SMCs correlated with reduced SMC proliferation and migration. Zofenoprilat inhibited the mitogen activated protein kinase and mammalian target of rapamycin pathways in SMCs and human vein segments.

CONCLUSION

Zofenopril provides extra beneficial effects compared with non-sulfhydryl ACEi in reducing SMC proliferation and re-stenosis, even in normotensive animals. These findings may hold broad clinical implications for patients suffering from vascular occlusive diseases and hypertension.

Impact of renin-angiotensin system inhibitors after revascularization of patients with left main coronary artery disease

BACKGROUND

There is a paucity of data regarding the effect of inhibition of the renin-angiotensin system on outcomes after percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). We sought to examine long-term outcomes of patients with left main coronary disease (LMCAD) randomized to PCI with fluoropolymer-based cobalt-chromium everolimus-eluting stents or CABG according to treatment at discharge with angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) in the large-scale, multicenter, randomized EXCEL trial.

METHODS

EXCEL randomized 1905 patients with LMCAD of low and intermediate anatomical complexity (visually-assessed SYNTAX score ≤32) to PCI (n = 948) versus CABG (n = 957). Patients were categorized according to whether they were treated with ACEI/ARB at discharge; their outcomes from discharge to 5 years were examined using multivariable logistic regression with an offset for follow-up time.

RESULTS

Among 1775 patients discharged alive with known ACEI/ARB treatment status, 896 (50.5%) were treated with one of these agents. Among those treated with ACEI/ARB, the 5-year rate of all-cause death was similar after PCI or CABG (10.7% versus 9.8% respectively, adjOR, 0.94; 95% CI, 0.56-1.57) in contrast to patients not treated with ACEI/ARB (15.0% versus 7.8%, respectively, adjOR, 2.20; 95% CI, 1.32-3.67) (Pinteraction = 0.02). Significant interactions between treatment arm (PCI versus CABG) and ACEI/ARB treatment status were also found for cardiovascular death (Pinteraction = 0.03), ischemia-driven revascularization (Pinteraction = 0.03), target vessel revascularization (Pinteraction = 0.007) and target vessel failure (Pinteraction = 0.0009).

CONCLUSION

In the EXCEL trial, the postdischarge rates of death and revascularization after 5 years were similar after PCI and CABG in patients with LMCAD treated with ACEI/ARB at discharge. In contrast, event rates were higher after PCI versus CABG in those not so treated.

Angiotensin Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers (ACEI/ARB) are Associated with Improved Limb Salvage after Infrapopliteal Interventions for Critical Limb Ischemia

BACKGROUND

Angiotensin-converting enzyme Inhibitors and Angiotensin II Receptor Blockers (ACEI/ARB) reduce the risk of cardiovascular events and mortality in patients with peripheral arterial disease (PAD). However, their effect on limb-specific outcomes is unclear. The objective of this study is to assess the effect of ACEI/ARB on patency and limb salvage in patients undergoing interventions for critical limb ischemia (CLI).

METHODS

Patients undergoing infrainguinal revascularization for CLI (Rutherford 4-6) between 06/2001 and 12/2014 were retrospectively identified. Primary Patency (PP), Secondary Patency (SP), Limb Salvage (LS), major adverse cardiac events (MACE), and survival rates were calculated using Kaplan-Meier. Multivariate analysis was performed using Cox regression.

RESULTS

A total of 755 limbs in 611 patients (311 ACEI/ARB, 300 No ACEI/ARB) were identified. Hypertension (86% vs. 70%, P < 0.001), diabetes (68% vs. 55%, P = 0.001) and statin use (61% vs. 45%, P < 0.001) were significantly greater in the ACEI/ARB group. Interventions were performed mostly for tissue loss (83% ACEI/ARB vs. 84% No ACEI/ARB, P = 0.73). Comparing ACEI/ARB versus No ACEI/ARB, in femoropopliteal interventions, 60-month PP (54% vs. 55%, P = 0.47), SP (76% vs. 75%, P = 0.83) and LS (84% vs. 87%, P = 0.36) were not significantly different. In infrapopliteal interventions, 60-month PP (45% vs. 46%, P = 0.66) and SP (62% vs. 75%, P = 0.96) were not significantly different. LS was significantly greater in ACEI/ARB (75%), as compared to No ACEI/ARB (61%) (P = 0.005). Cox regression identified diabetes (HR 2.4 (1.4-4.1), P = 0.002), ESRD (HR 3.5 (2.1-5.7), P < 0.001), hypertension (HR 0.4 (0.2-0.6), P < 0.001), and ACEI/ARB (HR 0.6 (0.4-0.9), P = 0.03), as factors independently associated with LS after infrapopliteal interventions. Freedom from MACE (ACEI/ARB 37% vs. 32%, P = 0.82) and overall survival (ACEI/ARB 42% vs. 35% No ACEI/ARB, P = 0.84) were not significantly different.

CONCLUSIONS

ACEI/ARB is associated with improved limb salvage in CLI patients undergoing infrapopliteal interventions, but not after femoropopliteal interventions. ACEI/ARB had no impact on patency rates. They were also associated with a trend toward improved survival and freedom from MACE. Our findings suggest that the use of ACEI/ARB may improve outcomes in the high-risk CLI patient population.

Positive Vessel Remodelling

Since its introduction, the success of percutaneous transluminal coronary angioplasty (PTCA) has been jeopardised by recoil, neointima proliferation, and luminal renarrowing; however, the benefit of positive remodelling has not gained widespread attention. While vessels will remodel positively up to a certain stage in the development of atherosclerosis, the therapeutic application of this process remains low. The prevention of vessel shrinkage during the healing process, which represents the predominant mechanism of restenosis after PTCA, is a prerequisite of long-term success in PTCA. The antiproliferative drugs that are currently used mainly on stents are known to be capable of this. Primary clinical studies have reported that positive remodelling leads to beneficial effects in coronary and peripheral angioplasty if no foreign body is inserted, and a paradigm change in percutaneous coronary intervention towards far fewer implants is within reach.

Transfer and Expression of the Interferon Gamma Gene in Human Endothelial Cells Inhibits Vascular Smooth Muscle Cell Growth in Vitro

Intimal hyperplasia in blood vessels is primarily caused by the migration and proliferation of vascular smooth muscle cells. Excessive intimal thickening characterizes atherosclerosis as well as bypass graft and angioplasty failures. Endothelial cell-smooth muscle cell interactions and local cytokine production are important regulators of smooth muscle cell growth. Interferon gamma (γ-IFN), a product of T lymphocytes found in atherosclerotic lesions, inhibits smooth muscle cell proliferation in vitro. To determine if local delivery of γ-IFN may be useful in the treatment or prevention of vascular proliferative diseases, we transferred the human γ-IFN gene into endothelial cells isolated from human arteries and microvessels using a retroviral vector. Biologically active γ-IFN was produced and secreted by γ-IFN transduced endothelial cells, but not by control, nontransduced cells, or cells identically transduced with E. coli beta galactosidase (β-gal). To more closely approximate the microenvironment of blood vessels, subconfluent smooth muscle cells were plated in coculture with control, nontransduced endothelial cells, γ-IFN transduced endothelial cells, or β-gal transduced endothelial cells. Smooth muscle cell growth was inhibited 30-70% by coculture with γ-IFN transduced endothelial cells compared to coculture with β-gal transduced or control endothelial cells (p < 0.05). Our results suggest endothelial cells modified to produce γ-IFN may be a useful therapy in proliferative vascular diseases. Copyright © 1997 Elsevier Science Inc.

Atherosclerosis Induced by a High-Cholesterol and High-Fat Diet in the Inbred Strain of the Wuzhishan Miniature Pig

Coronary artery disease has a significant genetic predisposition, which mainly results from atherosclerosis. Miniature pig is an excellent model to investigate atherosclerosis. This study investigated whether the occurrence and development of atherosclerosis in the Wuzhishan miniature pigs (WZSPs) that were closely bred 12 generations had better consistency. The WZSPs (n = 9) were fed a high-cholesterol and high-fat diet (HCFD). After continuous feeding, 3 WZSPs each were sacrificed at 6, 8, and 12 months, respectively, and the general clinical manifestations and serological indexes were detected. The pathological changes of the major arteries and main organs were recorded. The results showed WZSPs were quite susceptible to the HCFD. At 6 months, plaque lesions appeared in the abdominal aorta and iliac artery, while at 8 months, they appeared in the coronary artery. At 12 months, atherosclerotic lesions could be found in all major arteries, while lipid core, cholesterol precipitation, and calcium deposition appeared in the most serious sites. The progression of arterial lesions and distribution of the lesions were highly consistent in the pigs. However, apparent variations in serum markers were observed. In conclusion, inbred WZSP is a good model to investigate atherosclerosis and has good predictability for the occurrence and development of the disease.

Vascular balloon injury and intraluminal administration in rat carotid artery

The carotid artery balloon injury model in rats has been well established for over two decades. It remains an important method to study the molecular and cellular mechanisms involved in vascular smooth muscle dedifferentiation, neointima formation and vascular remodeling. Male Sprague-Dawley rats are the most frequently employed animals for this model. Female rats are not preferred as female hormones are protective against vascular diseases and thus introduce a variation into this procedure. The left carotid is typically injured with the right carotid serving as a negative control. Left carotid injury is caused by the inflated balloon that denudes the endothelium and distends the vessel wall. Following injury, potential therapeutic strategies such as the use of pharmacological compounds and either gene or shRNA transfer can be evaluated. Typically for gene or shRNA transfer, the injured section of the vessel lumen is locally transduced for 30 min with viral particles encoding either a protein or shRNA for delivery and expression in the injured vessel wall. Neointimal thickening representing proliferative vascular smooth muscle cells usually peaks at 2 weeks after injury. Vessels are mostly harvested at this time point for cellular and molecular analysis of cell signaling pathways as well as gene and protein expression. Vessels can also be harvested at earlier time points to determine the onset of expression and/or activation of a specific protein or pathway, depending on the experimental aims intended. Vessels can be characterized and evaluated using histological staining, immunohistochemistry, protein/mRNA assays, and activity assays. The intact right carotid artery from the same animal is an ideal internal control. Injury-induced changes in molecular and cellular parameters can be evaluated by comparing the injured artery to the internal right control artery. Likewise, therapeutic modalities can be evaluated by comparing the injured and treated artery to the control injured only artery.

Renin-angiotensin system gene polymorphisms among Saudi patients with coronary artery disease

BACKGROUND

The polymorphisms in the components of the renin-angiotensin system (RAS) are important in the development and progression of coronary artery disease (CAD) in some individuals. Our objectives in the present investigation were to determine whether three RAS polymorphisms, angiotensin-converting enzyme insertion/deletion (ACE I/D), angiotensin receptor II (Ang II AT2 - C3123A) and angiotensinogen (AGT-M235T), are associated with CAD in the Saudi population. We recruited 225 subjects with angiographically confirmed CAD who had identical ethnic backgrounds and 110 control subjects. The polymerase chain reaction-restriction fragment length polymorphisms (RFLP) technique was used to detect polymorphisms in the RAS gene.

RESULTS

Within the CAD group, for the ACE I/D genotype, DD was found in 64.4%, 26.3% carried the ID genotype, and 9.3% carried the II genotype. Within the control group, the DD genotype was found in 56.4%, 23.6% carried the ID genotype, and 20% carried the II genotype. The odds ratio (OR) of the ACE DD vs II genotype with a 95% confidence interval (CI) was 2.45 (1.26-4.78), with p = 0.008. For the Ang II AT2 receptor C3123A genotype, within the CAD group, CC was found in 39.6%, 17.8% carried the CA genotype, and 42.6% carried the AA genotype. Within the control group, CC was found in 39.1%, 60.9% carried the CA genotype, and there was an absence of the AA genotype. The OR of the Ang II AT2 receptor C3123A CC vs AA genotypes (95% CI) was 0.01, with p = 0.0001. A significant association with CAD was shown. For the AGT-M235T genotype, within the CAD group, MM was found in 24.0%, 43.6% carried the MT genotype and 32.4% carried the TT genotype. Within the control group, MM was found in 26.4%, 45.5% carried the TT genotype and 28.2% carried the MT genotype. The OR of MM vs TT (95% CI) was 0.79 (0.43 to 1.46), which was insignificant.

CONCLUSIONS

There is an association between the ACE I/D and Ang II AT2 receptor C3123A polymorphisms and CAD, however, no association was detected between the AGT M235T polymorphism and CAD in the Saudi population.

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.

Innovations in studying in vivo cell behavior and pharmacology in complex tissues--microvascular endothelial cells in the spotlight

Many studies on the molecular control underlying normal cell behavior and cellular responses to disease stimuli and pharmacological intervention are conducted in single-cell culture systems, while the read-out of cellular engagement in disease and responsiveness to drugs in vivo is often based on overall tissue responses. As the majority of drugs under development aim to specifically interact with molecular targets in subsets of cells in complex tissues, this approach poses a major experimental discrepancy that prevents successful development of new therapeutics. In this review, we address the shortcomings of the use of artificial (single) cell systems and of whole tissue analyses in creating a better understanding of cell engagement in disease and of the true effects of drugs. We focus on microvascular endothelial cells that actively engage in a wide range of physiological and pathological processes. We propose a new strategy in which in vivo molecular control of cells is studied directly in the diseased endothelium instead of at a (far) distance from the site where drugs have to act, thereby accounting for tissue-controlled cell responses. The strategy uses laser microdissection-based enrichment of microvascular endothelium which, when combined with transcriptome and (phospho)proteome analyses, provides a factual view on their status in their complex microenvironment. Combining this with miniaturized sample handling using microfluidic devices enables handling the minute sample input that results from this strategy. The multidisciplinary approach proposed will enable compartmentalized analysis of cell behavior and drug effects in complex tissue to become widely implemented in daily biomedical research and drug development practice.

Animal models of restenosis

Percutaneous transluminal coronary angioplasty is a widely used technique for recanalizing arteries that are occluded by atherosclerotic plaque, but its usefulness is limited by the occurrence ofrestenosis in a high proportion of patients. The development of new therapies for this currently intractable problem will be facilitated by the use of animal models of restenosis that are predictive of drug efficacy in humans. Two approaches for improving predictivity can be identified. In the first of these, the goal is to maximize the anatomical and procedural resemblance of the model to humans. The second approach seeks to maximize the pathophysiological and molecular biological resemblance of the model to humans. Tangible progress is being made toward the first goal, but lack of understanding of the basic biology of human restenosis is hampering progress toward the second.

Tissue-engineered vascular grafts for use in the treatment of congenital heart disease: from the bench to the clinic and back again

Since the first tissue-engineered vascular graft (TEVG) was implanted in a child over a decade ago, growth in the field of vascular tissue engineering has been driven by clinical demand for improved vascular prostheses with performance and durability similar to an autologous blood vessel. Great strides were made in pediatric congenital heart surgery using the classical tissue engineering paradigm, and cell seeding of scaffolds in vitro remained the cornerstone of neotissue formation. Our second-generation bone marrow cell-seeded TEVG diverged from tissue engineering dogma with a design that induces the recipient to regenerate vascular tissue in situ. New insights suggest that neovessel development is guided by cell signals derived from both seeded cells and host inflammatory cells that infiltrate the graft. The identification of these signals and the regulatory interactions that influence cell migration, phenotype and extracellular matrix deposition during TEVG remodeling are yielding a next-generation TEVG engineered to guide neotissue regeneration without the use of seeded cells. These developments represent steady progress towards our goal of an off-the-shelf tissue-engineered vascular conduit for pediatric congenital heart surgery.

Role of the renin-angiotensin system in the pathogenesis of intimal hyperplasia: therapeutic potential for prevention of vein graft failure?

The saphenous vein remains the most widely used conduit for peripheral and coronary revascularization despite a high rate of vein graft failure. The most common cause of vein graft failure is intimal hyperplasia. No agents have been proven to be successful for the prevention of intimal hyperplasia in human subjects. The renin-angiotensin system is essential in the regulation of vascular tone and blood pressure in physiologic conditions. However, this system mediates cardiovascular remodeling in pathophysiologic states. Angiotensin II is becoming increasingly recognized as a potential mediator of intimal hyperplasia. Drugs modulating the renin-angiotensin system include angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. These drugs are powerful inhibitors of atherosclerosis and cardiovascular remodeling, and they are first-line agents for management of several medical conditions based on class I evidence that they delay progression of cardiovascular disease and improve survival. Several experimental models have demonstrated that these agents are capable of inhibiting intimal hyperplasia. However, there are no data supporting their role in prevention of intimal hyperplasia in patients with vein grafts. This review summarizes the physiology of the renin-angiotensin system, the role of angiotensin II in the pathogenesis of cardiovascular remodeling, the medical indications for these agents, and the experimental data supporting an important role of the renin-angiotensin system in the pathogenesis of intimal hyperplasia.

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.

Experimentally modified Fontan circulation in an adolescent pig model without the use of cardiopulmonary bypass

Background

The feasibility and the hemodynamic outcome of Fontan circulation, without the use of cardiopulmonary bypass, were studied on a beating heart of an adolescent pig model, using a modified total cavopulmonary connection.

Material/Methods

Eight open-chest anesthetized pigs underwent a successful total cavopulmonary connection with the use of an appropriate Y-shaped Dacron-type conduit. Through a median sternotomy, the distal part of the superior vena cava was anastomosed end-to-end to one side of the conduit. The other side of the graft was anastomosed end-to-side to the main pulmonary artery. The conduit was tailored to an appropriate length and anastomosed end-to-end to the inferior vena cava. The hemodynamic status of the animals was recorded before and after the establishment of the total cavopulmonary connection.

Results

Forty-five minutes after completion of total cavopulmonary connection, and for a total of 1 hour, hemodynamic measurements showed a decrease in mean arterial and mean pulmonary artery pressures, heart rate and cardiac output. The inferior vena caval pressure and total pulmonary vascular resistance were increased.

Conclusions

A total cavopulmonary connection, performed on a beating heart, without extracorporeal circulation or other means of temporary bypass, although it is technically demanding, is feasible.

Targets of chymase inhibitors

INTRODUCTION

Chymase converts angiotensin I to angiotensin II and it can also convert precursors of TGF-β and MMP-9 to their active forms. Therefore, diseases related to angiotensin II TGF-β, and MMP-9 could potentially be treated with chymase inhibitors.

AREAS COVERED

This review discusses the appropriate targets and safety of chymase inhibitors. Six diseases with notable mortality or morbidity as targets of chymase inhibitors are focused on; abdominal aortic aneurysms (AAAs), nephropathy and retinopathy, cardiomyopathy, nonalcoholic steatohepatitis (NASH), organ fibrosis and intestinal diseases.

EXPERT OPINION

If chymase inhibition proves to be a useful strategy for the attenuation of angiotensin II, TGF-β and MMP-9 in vivo, the application of chymase inhibitors is likely to become widespread in various diseases in the clinical setting. Chymase inhibitors are anticipated not to interfere with the homeostasis of resting tissues, that is, those not affected by injury or inflammation.

Angiotensin-converting enzyme inhibitor associated cough: deceptive information from the Physicians' Desk Reference

BACKGROUND

Dry cough is a common, annoying adverse effect of all angiotensin-converting enzyme (ACE) inhibitors. The present study was designed to compare the rate of coughs reported in the literature with reported rates in the Physicians' Desk Reference (PDR)/drug label.

METHODS

We searched MEDLINE/EMBASE/CENTRAL for articles published from 1990 to the present about randomized clinical trials (RCTs) of ACE inhibitors with a sample size of at least 100 patients in the ACE inhibitors arm with follow-up for at least 3 months and reporting the incidence or withdrawal rates due to cough. Baseline characteristics, cohort enrolled, metrics used to assess cough, incidence, and withdrawal rates due to cough were abstracted.

RESULTS

One hundred twenty-five studies that satisfied our inclusion criteria enrolled 198,130 patients. The pooled weighted incidence of cough for enalapril was 11.48% (95% confidence interval [CI], 9.54% to 13.41%), which was ninefold greater compared to the reported rate in the PDR/drug label (1.3%). The pooled weighted withdrawal rate due to cough for enalapril was 2.57% (95% CI, 2.40-2.74), which was 31-fold greater compared to the reported rate in the PDR/drug label (0.1%). The incidence of cough has increased progressively over the last 2 decades with accumulating data, but it has been reported consistently several-fold less in the PDR compared to the RCTs. The results were similar for most other ACE inhibitors.

CONCLUSION

The incidence of ACE inhibitor-associated cough and the withdrawal rate (the more objective metric) due to cough is significantly greater in the literature than reported in the PDR/drug label and is likely to be even greater in the real world when compared with the data from RCTs. There exists a gap between the data available from the literature and that which is presented to the consumers (prescribing physicians and patients).

New approaches to blockade of the renin-angiotensin-aldosterone system: chymase as an important target to prevent organ damage

Chymase plays a crucial role in angiotensin II formation in various tissues. Angiotensin II induces gene expression of transforming growth factor (TGF)-beta and matrix metalloproteinase (MMP)-9 precursors, and chymase can convert precursors of TGF-beta and MMP-9 to their active forms. In cultured fibroblasts, significant increases in cell growth and TGF-beta levels were observed after chymase injection; these increases were inhibited by a chymase inhibitor, but not by an angiotensin II-receptor blocker. In apolipoprotein E-deficient mice, abdominal aortic aneurysm (AAA) development depends on an increase in MMP-9 activities induced by angiotensin II infusion, but the inhibition of MMP-9 activation by a chymase inhibitor resulted in attenuation of the angiotensin II-induced AAA development. The upregulation of MMP-9 and TGF-beta levels is involved in damage to various organs, but these gene expressions are not completely induced by angiotensin II alone. Therefore, chymase inhibition may be useful for attenuating MMP-9 and TGF-beta levels, in addition to reducing angiotensin II formation, and this function may provide powerful organ protection. In this review, we propose the possible use of chymase inhibitors as agents to prevent organ damage.

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.

Increased expression of angiotensin converting enzyme 2 in conjunction with reduction of neointima by angiotensin II type 1 receptor blockade

Angiotensin converting enzyme 2 (ACE2), a newly recognized homolog of ACE that converts angiotensin II (Ang II) to angiotensin-1-7 (Ang-(1-7)), is found in vascular smooth muscle cells. Expression of ACE2 may be a local determinant of vascular Ang-(1-7) production and, when increased, may augment the increasingly recognized protective effects of this peptide within injured tissues. We previously showed that treatment with the angiotensin II type 1 (AT1) receptor blocker (ARB) olmesartan increased aortic ACE2 and Ang-(1-7) in conjunction with improved vascular remodeling in spontaneously hypertensive rats (SHR). In the present study, we investigated balloon injury-related ACE2 in the vasculature by determining the effect of sustained AT1 blockade on ACE2 protein expression in the carotid arteries of 12-week-old male SHR treated with either vehicle (n=5) or 10 mg/kg olmesartan (n=5) in drinking water for 14 days. Olmesartan treatment caused a 61% reduction in the cross-sectional area of the neointima, from 0.27+/-0.01 mm2 in vehicle-treated rats to 0.11+/-0.01 mm2 in olmesartan-treated rats. In contrast, olmesartan treatment had no effect on the medial area of injured or uninjured carotid arteries compared to that in vehicle-treated rats. Quantitative analysis of ACE2 immunostaining intensity in the carotid artery of SHR was significantly greater (p<0.05) in the neointima of olmesartan-treated SHR compared to that in vehicle-treated animals. In contrast, ACE2 immunostaining intensity was not quantitatively different in uninjured carotid arteries of olmesartan and vehicle-treated animals. These studies suggest that changes in ACE2 within the vascular system of SHR are regulated by a factor other than arterial pressure.

Synthesis and anti-platelet activity of novel arylsulfonate–acylhydrazone derivatives, designed as antithrombotic candidates

In this work, we describe a new class of promising anti-platelet drug candidates with significant antithrombotic activity in vivo. This new series of compounds was structurally planned by modification of known thrombin inhibitors based on the use of acylhydrazone subunit, as a nonpeptide scaffold, and variations at P1 moiety. Three different families of arylsulfonate-acylhydrazone derivatives were designed. The bioassays indicated the first class of derivatives represented by 4f (LASSBio-693) and 4j (LASSBio-743), which were active in inhibiting the platelet aggregation induced by thrombin. The second class represented by compounds 4e (LASSBio-774) and 4h (LASSBio-480) that selectively inhibit the platelet aggregation involving TXA(2) formation. Finally, the third class of derivatives was identified acting as a novel symbiotic agent able to inhibit the platelet aggregation induced by collagen or AA and by thrombin, represented by compounds 4b (LASSBio-694) and 4g (LASSBio-770).

Missed opportunities for the secondary prevention of cardiovascular disease in Canada

BACKGROUND

Strong evidence supports the use of antithrombotic agents (antiplatelets or oral anticoagulants), statins and angiotensin-converting enzyme inhibitors in patients with atherosclerotic cardiovascular disease; beta-blockers are additionally indicated in patients with coronary artery disease.

OBJECTIVES

The investigators sought to determine the extent to which guideline-recommended treatments and target goals are adopted in ambulatory patients with cardiovascular disease in Canada.

METHODS

Two large, prospective, community-based registries (the Vascular Protection Registry and the Guideline Oriented Approach to Lipid Lowering Registry) enrolled 9809 outpatients with coronary artery disease, cerebrovascular disease, peripheral vascular disease or multiple cardiovascular risk factors from primary care settings in nine provinces across Canada between 2001 and 2004. This analysis focused primarily on patients with cardiovascular disease (n=6296).

RESULTS

At baseline, antithrombotics, statins and angiotensin-converting enzyme inhibitors were used in 92%, 80% and 57% of patients, respectively; beta-blockers were used in 59% of patients with coronary artery disease. The dosing of most drug therapies was suboptimal compared with guideline-recommended dosing derived from clinical trials. Treatment goals for cardiovascular risk factors were suboptimally attained: low-density lipoprotein cholesterol in 50% of patients, total to high-density lipoprotein cholesterol ratio in 51% of patients, systolic and diastolic blood pressure in 58% and 78% of patients, respectively, and waist circumference and body mass index in 45% and 19%, respectively.

CONCLUSIONS

These data suggest specific opportunities for improving the care of patients with cardiovascular disease in Canada. The focus must now shift from awareness of treatment gaps to implementation of effective solutions.

Comparison of Selective AT1-Receptor Blockade Versus ACE Inhibition for Restenosis Prophylaxis in Patients With Peripheral Occlusive Arterial Disease After Stent Angioplasty: A Randomized, Controlled, Proof-of-Concept Study

Different components of the renin-angiotensin system (RAS) have been demonstrated in atherosclerotic plaques. However, the involvement of the RAS in the complex process of in-stent restenosis is not yet clear. In this prospective, randomized, double-blind, controlled proof-of-concept study, we compared the 2 different pharmacological approaches, selective AT1-receptor-blockade with candesartan vs ACE inhibition with quinapril to reduce in-stent restenosis after stent angioplasty of the superficial femoral artery. Twenty-two hypertensive patients with stage IIb peripheral occlusive arterial disease and severe claudication who had been successfully treated with percutaneous transluminal angioplasty (PTA) and stent implantation were randomly assigned to receive daily doses of either candesartan (32 mg) or quinapril (20 mg). Primary end point was restenosis 6 months after intervention, assessed by angiography. Secondary end points were pain-free walking distance, determined by treadmill ergometry; determination of crurobrachial indices; and intima-media thickness (IMT). At 6 months, the rate of restenosis on angiography was 34% in the candesartan group and 71% in the quinapril group (P = .043). Relevant restenosis was found in 3 patients (27%) in the candesartan group and in 7 patients (64%) in the quinapril group. Patients in the candesartan group were able to walk farther on a treadmill (increase: 135 m ± 20 m) compared with patients in the quinapril group (increase: 83 m ± 21 m). The IMT at the stent edge was not significantly different in the 2 groups (candesartan: 1.9 mm ± 0.5 mm; quinapril: 2.0 mm ± 0.3 mm). This study revealed significant benefit of a pharmacological restenosis regimen using the AT1-receptor antagonist candesartan in patients with severe atherosclerosis after superficial femoral artery stenting compared with treatment with the ACE inhibitor quinapril. Further prospective studies in patients are required to confirm these results.

The effects of chymase on matrix metalloproteinase-2 activation in neointimal hyperplasia after balloon injury in dogs

Chymase is known to generate angiotensin II in the vascular wall. In this study we investigated a novel role for chymase other than angiotensin II production in vascular proliferation after balloon injury. Chymase promoted the migration of vascular smooth muscle cells in the matrix-coated invasion chambers and activated promatrix metalloproteinase-2 obtained from the culture medium of vascular smooth muscle cells. Two weeks after balloon injury, significant neointimal formation was found in dog carotid arteries. After injury, active matrix metalloproteinase-2 was increased in parallel with the augmentation of chymase activity that was seen in the proliferating region of the vascular wall. The oral administration of NK3201 (1 mg/kg per day), a chymase inhibitor, prevented neointimal formation and significantly suppressed both active matrix metalloproteinase-2 and chymase activities 2 weeks after injury. These results suggest that chymase inhibitors can prevent the development of intimal hyperplasia via the inhibition of matrix metalloproteinase-2 activation in balloon-injured arteries.

Pharmacogenomics of Renin Angiotensin System Inhibitors in Coronary Artery Disease

Renin Angiotensin System (RAS) inhibitors comprise some of the most commonly used medications in coronary artery disease (CAD) and its related syndromes. Unfortunately, significant inter-patient variability seems likely in response to these agents; of which, the influence of genetic determinants is of interest. This review summarizes the available RAS inhibitor pharmacogenomic studies which have evaluated RAS polymorphisms that either elucidate mechanism via surrogate endpoint measurements, or predict efficacy via clinical outcomes in CAD related syndromes.Regardless of the endpoint, none of the RAS genotypes conclusively predicts efficacy of RAS inhibitors. In fact, the results of the pharmacogenomic studies were often in direct conflict with one another. Varied results appear due to methodological limitations (e.g., inadequate study power, genotyping error, methods of endpoint measurement), study conceptualization (e.g., overestimating the contribution of polymorphism to disease, lack of haplotype approach), and differences between studies (e.g., genotype frequency, study subject characteristics, the specific medication and dose used). Thus investigators should consider the various methodological limitations to improve upon the current approach to RAS inhibitor pharmacogenomic research in the vast CAD population.

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.

Univentricular Heart

As early as 1699, Chemineau described a heart composed of 2 auricles but only 1 ventricle. 1 The univentricular heart has since fascinated the medical community. Unique in its complexity and scope, the univentricular heart has sparked intense debates about embryology and nomenclature, challenged our understanding of cardiovascular physiology and hemodynamics, and inspired some of the most creative surgical and interventional approaches in human history. The present report provides an overview of the nomenclature and classification of the univentricular heart, epidemiology and pathological subtypes, genetic factors, physiology, clinical features, diagnostic assessment, therapy, and postoperative sequelae. Although the present report touches on issues applicable to neonates and children with univentricular hearts, the focus is on information of interest and relevance to the adult cardiologist.

Upregulation of proteinase-activated receptors and hypercontractile responses precede development of arterial lesions after balloon injury

Thrombin and other proteinases exert vascular effects by activating the proteinase-activated receptors (PARs). The expression of PARs has been shown to be upregulated after balloon injury and in human arteriosclerosis. However, the relationship between the receptor upregulation and the alteration of vasomotor function remains to be elucidated. We herein demonstrated that the contractile responses to the PAR-1 and PAR-2 agonist were markedly enhanced in the rabbit femoral arteries after balloon injury. Neointimal thickening was established 4 wk after the injury. No histological change was observed in the sham operation, where the saphenous artery was ligated without any balloon injury. The contractile response to K+depolarization was significantly attenuated 1 wk after the injury and then partly recovered after 4 wk. Thrombin, PAR-1-activating peptide, trypsin, and PAR-2-activating peptide induced no significant contraction in the control. All these stimulants induced enhanced responses 1 wk after balloon injury. Such enhanced responses were seen 4 wk after the injury, except for thrombin. There was no change in the Ca2+sensitivity of the contractile apparatus as evaluated in the permeabilized preparations. PAR-1-activating peptide (100 μmol/l), but no other stimulants, induced an enhanced contraction in the sham operation. The expression of PAR-1 and PAR-2 slightly increased after the sham operation, whereas it markedly and significantly increased after balloon injury. Our observations suggest that balloon injury induced the receptor upregulation, thereby enhancing the contractile response before the establishment of vascular lesions. The local inflammation associated with the sham operation may also contribute to the receptor upregulation.

Drug-eluting stents for infrainguinal occlusive disease: progress and challenges

High restenosis rate is still the major limitation of peripheral arterial interventions. Within the last years, drug-eluting stents have gained wide acceptance in the coronary arteries, however, these devices are not currently available for arteries outside the coronary vasculature. This article summarizes the special role of the superficial femoral artery in restenosis, with efforts being made to reduce the restenosis rate in this artery, focusing on stents and drug-eluting stents.

Effects of angiotensin-converting enzyme inhibitors or an angiotensin receptor blocker in combination with aspirin and cilostazol on in-stent restenosis

It remains to be determined whether adding an angiotensin-converting enzyme inhibitor (ACEI) or an angiotensin II receptor blocker (ARB) to antiplatelet therapy has a therapeutic benefit on in-stent restenosis. After successful coronary stenting, 165 patients (167 lesions) were randomly assigned to a basal (aspirin 162 mg + cilostazol 200 mg/day), ACEI (basal treatment + quinapril 10 mg or perindopril 4 mg/day), or ARB (basal treatment + losartan 50 mg/day) treatment group. Quantitative coronary angiography was performed before, immediately following, and 6 months after stenting. Follow-up coronary angiography was completed in 126 patients (128 lesions). Restenosis rates tended to be higher (12, 26, and 12% for the basal, ACEI, and ARB groups, respectively), and target lesion revascularization rates were higher in the ACEI group than in the other groups (9, 23,* and 5%, respectively, *P < 0.05 versus basal group). Moreover, late lumen loss was higher in the ACEI group than in the basal group (0.60 +/- 0.55, 0.98 +/- 0.61* and 0.73 +/- 0.64 mm in the basal, ACEI, and ARB groups, respectively). The combinations of an ACEI or ARB with aspirin and cilostazol are ineffective for the prevention of in-stent restenosis, and an ACEI may even promote intimal proliferation after stent implantation.

Tissue angiotensin II generating system by angiotensin-converting enzyme and chymase

It had been believed that angiotensin II (Ang II) was produced by the renin-angiotensin system (RAS), which was established in the 1950's. After a while, people realized that the multiple functions of Ang II could not be explained by the conventional RAS. We have tried to determine the existence of the tissue Ang II generating system. At first, we found that vascular angiotensin-converting enzyme (ACE) was increased to generate local Ang II in the vessels of hypertension and was enhanced in lipid-loaded atherosclerosis, to respond to ACE inhibitor or Ang II antagonist (ARB). In both cases, Ang II production in vessels was independent from the systemic RAS that was estimated by the plasma renin activity. On the way to clarifying the roles of the vascular ACE, we noticed that vascular Ang II production was not completely suppressed by ACE inhibitor alone. This evidence led us to discover different types of chymase as a new Ang II producing enzyme. Now, we have obtained a strategy to distinguish the Ang II one by one, that is, circulating RAS derived, tissue ACE derived, and chymase derived. It is essential to understand not only the intracellular mechanisms of Ang II but also the process of Ang II productions in each disease to show accurate indications of the effectiveness of ACE inhibitor, ARB, and chymase inhibitor.

Restenosis after percutaneous coronary intervention is associated with the angiotensin-II type-1 receptor 1166A/C polymorphism but not with polymorphisms of angiotensin-converting enzyme, angiotensin-II receptor, angiotensinogen or heme oxygenase-1

OBJECTIVES

The renin-angiotensin system (RAS) is thought to play a major role in the pathophysiology of de-novo restenotic lesions and in-stent restenosis after percutaneous coronary intervention (PCI). Heme oxygenase-1 (HO-1), is thought to beneficially influence these processes. We examined the effect of pharmacologic as well as genetic RAS interactions on restenosis in a large population of consecutive patients undergoing PCI, and evaluated possible gene-gene interactions in both systems.

METHODS

The GENDER project is a multicenter prospective follow-up study, including 3146 patients after successful PCI. Genotyping in these patients was performed for the ACE gene insertion/deletion, the angiotensinogen 235Met/Thr, T174M and A(-6)G, the angiotensin-II type 1 receptor (AT1R) 1166A/C and T810A, the angiotensin-II type 2 receptor (AT2R) 1675G/A and 3123A polymorphisms and the length polymorphism in the HO-1 promoter region.

RESULTS

A total of 3104 patients were followed for 10 months. In 2975 patients at least one of the nine genotypes could be determined. The AT1R 1166 CC genotype showed a significant association with TVR; the other polymorphisms did not. RAS-inhibitory drugs were not associated with the incidence of TVR, nor did they interact with any of the investigated polymorphisms. Patients with the ACE I/I polymorphism showed a trend towards a better outcome if they had a short number of repeats in the HO-1 promoter. This relationship was inversely present in carriers of the ACE D/D polymorphism.

CONCLUSION

We could only establish a role for the AT1R 1166A/C polymorphism in restenosis after PCI. However, significant gene-gene interaction was suggested for the ACE gene and the HO-1 promotor. The RAS and HO-1 relation in restenosis merits further investigation.

Glyceryl trinitrate-induced angiotensin-converting enzyme (ACE) inhibition in healthy volunteers is dependent on ACE genotype

Evidence concerning the importance of angiotensin-converting enzyme (ACE) genotype in cardiovascular diseases is accumulating. The aim of this study was to investigate if nitric oxide (NO), generated from glyceryl trinitrate (GTN), affects human serum ACE activity in vivo, and if so, whether this effect was dependent on ACE genotype and (or) reflected in blood pressure reduction. A tablet containing 5 mg GTN was bucally administered for 5 minutes to 17 healthy volunteers. Blood pressure (BP) was recorded, and serum ACE activity, ACE genotype, and plasma cGMP was analyzed. GTN administration significantly reduced BP only in individuals with the deletion/deletion (DD) genotype. Sixty minutes after GTN administration, serum ACE activity was reduced in individuals with the insertion/insertion (II) and insertion/deletion (ID) genotypes, but not the DD genotype. Comparing the change in ACE activity over time between the genotypes resulted in the following: II vs. DD, p < 0.01; II vs. ID, p < 0.05; and ID vs. DD, p < 0.05. There was no significant difference in plasma cGMP content neither between the ACE genotypes nor before and after GTN administration. In conclusion, GTN inhibits serum ACE in vivo in individuals with the II and ID, but not the DD genotype.

Present status of outcome prediction of invasive coronary treatment by using genetic markers

A growing number of studies suggest that the outcome after invasive coronary treatment may be in part genetically determined. Here, we review the present status of outcome prediction of invasive coronary treatments by using genetic markers. Although some studies found an association between one or another genetic marker with one or another clinical endpoint, many other studies found no such relations; to date, none of the genetic markers that have been investigated in association studies are used in routine clinical practice to prospectively assess the prognosis following invasive coronary treatment or to decide upon therapeutic strategies. Many associations between genetic markers and certain clinical endpoints were initially reported in small studies but could not be confirmed in larger ones. Some of these discrepancies may be explained by publication bias. Some genetic variants may have true effects on clinical endpoints, which, albeit biologically interesting, do not bear much clinical relevance. On the other hand, many-if not most-studies that have been published to date are more or less grossly underpowered and very rarely report on the results of an a priori power analysis. Thus, there is still a need for further high-quality studies designed to investigate the specific contribution of genetic factors to the outcome after invasive coronary interventions.

Inhibition of intimal/medial hyperplasia by perindopril in canine vein grafts

We used a canine model to assess the efficacy of an angiotensin-converting enzyme inhibitor (perindopril) at modulating intimal/medial hyperplasia in vein bypass grafts. Fourteen beagle dogs were divided into medicated and control groups and underwent bilateral grafting of external jugular veins into the common carotid artery. Samples of normal veins were obtained from the control group during vein grafting. Vein grafts were harvested 1 week and 4 weeks after surgery in both groups. Subsequently, intimal/medial thickness was measured by staining with hematoxylin and eosin; antibodies for proliferating cell nuclear antigen were employed to determine the degree of cellular proliferation; apoptotic cells were detected using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling method. In the medicated group, the intimal/medial cross-sectional area was significantly smaller and increased 8- to 9-fold in comparison to the control group, which increased 12- to 20-fold. There was a significantly higher rate of cell proliferation in the control group, whereas the medicated group showed a significantly higher rate of apoptotic cells. These data support the efficacy of perindopril at reducing intimal/medial hyperplasia in arterialized vein grafts during a short postoperative period.