Renin-Angiotensin System Intervention to Prevent In-Stent Restenosis

Vascular smooth muscle cells in intimal hyperplasia, an update

Arterial occlusive disease is the leading cause of death in Western countries. Core contemporary therapies for this disease include angioplasties, stents, endarterectomies and bypass surgery. However, these treatments suffer from high failure rates due to re-occlusive vascular wall adaptations and restenosis. Restenosis following vascular surgery is largely due to intimal hyperplasia. Intimal hyperplasia develops in response to vessel injury, leading to inflammation, vascular smooth muscle cells dedifferentiation, migration, proliferation and secretion of extra-cellular matrix into the vessel's innermost layer or intima. In this review, we describe the current state of knowledge on the origin and mechanisms underlying the dysregulated proliferation of vascular smooth muscle cells in intimal hyperplasia, and we present the new avenues of research targeting VSMC phenotype and proliferation.

AGTR1rs5186 Polymorphism Is Associated with the Risk of Restenosis after Percutaneous Coronary Intervention: A Meta-Analysis

Background: Progress has been made in genetic investigations on restenosis for the past 20 years, many studies regarding AGTR1 rs5186 polymorphism and restenosis after percutaneous coronary intervention (PCI) have been published, but the result remains controversial. The study aimed to explore the relationship between rs5186 polymorphism and the risk of restenosis after PCI. Methods: We performed a systematic search on PubMed, Web of Science, Embase, CNKI, and Wan Fang databases up to December 2021. Two authors individually extracted all useful data of each study involved in this meta-analysis and assessed the study quality using the Newcastle-Ottawa scale. Odds ratios (ORs) and 95% confidence intervals (CIs) were combined in different genetic models for evaluation using a random-effects model or fixed-effect model. Results: There were eventually 8 studies of 1111 cases and 4097 controls eligible for this meta-analysis. Significant associations were found between rs5186 polymorphism and restenosis after PCI.allelic (OR: 1.31, 95% CI: 1.17−1.47, p < 0.001), homozygous (OR: 1.90, 95% CI: 1.50−2.44, p < 0.001), heterozygous (OR: 1.10, 95% CI: 0.93−1.29, p = 0.27), recessive (OR: 1.80, 95% CI: 1.37−2.36, p < 0.001), dominant genetic model (OR: 1.24, 95% CI: 1.06−1.44, p = 0.006). Subgroup analyses indicated a significant association in Asians. Conclusions: The rs5186 polymorphism in the AGTR1 gene increases the risk of restenosis after PCI in Asians significantly.

ACE Inhibitors Versus ARBs in Patients With NSTEMI With Preserved LV Systolic Function Who Underwent PCI With New Generation Drug-Eluting Stents

The relative superiority of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) on long-term clinical outcomes in patients with non-ST-segment elevation myocardial infarction (NSTEMI) with preserved left ventricular systolic function in the era of new generation drug-eluting stents is not well established. A total of 6436 patients with NSTEMI (ACEIs group: n = 3965 vs ARBs group: n = 2471) were enrolled. The major clinical end point was the occurrences of major adverse cardiac events (MACEs), defined as all-cause death, recurrent myocardial infarction (re-MI), and any repeat revascularization. After propensity score matching analysis, the cumulative incidences of MACEs (hazard ratio, 1.334; 95% confidence interval, 1.045-1.703; P = .021), any repeat revascularization, and target vessel revascularization (TVR) in the ARB group were significantly higher than that in the ACEI group. However, the cumulative incidences of all-cause death, cardiac death, re-MI, target lesion revascularization, and non-TVR were similar between the 2 groups. Hence, although the mortality and re-MI reduction benefits were similar between the 2 groups, the ACEIs group showed more prominent ability to decrease the occurrences of MACEs, any repeat revascularization, and TVR compared to the ARBs group in these patients during a 2-year follow-up period.

Renin-angiotensin system inhibitors in patients with coronary artery disease who have undergone percutaneous coronary intervention

The percutaneous coronary intervention (PCI) procedure has become one of the pivotal options in the treatment of coronary artery disease (CAD). Although the PCI procedure has rapidly developed in China, some concerns including in-stent restenosis and dissatisfactory long-term prognosis remain unsolved. Large-scale randomized controlled clinical trials indicate that angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) can reduce all-cause mortality and recurrent cardiac events in patients with CAD. ACEIs/ARBs are recommended as a fundamental treatment in the secondary prevention of CAD and reduce in-stent restenosis after PCI. This review focuses on the role of ACEIs/ARBs in improving long-term prognosis and reducing in-stent restenosis.

The Role of Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers in Postangioplasty Restenosis

Postangioplasty restenosis remains a clinical problem, and various strategies have been used to minimize or eliminate this complication. Stimulation of the renin-angiotensin system has been shown to cause vascular smooth muscle migration, matrix deposition, and endothelial dysfunction, which are possible causes of postangioplasty restenosis, suggesting that the use of angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin receptor blockers might ameliorate or prevent restenosis. However, data obtained to date in both animal and human studies of various designs show conflicting results regarding the benefit or lack of benefit of angiotensin inhibition strategies. It has also been shown that the type of ACE genotype may influence the effects of drugs on restenosis, suggesting that in the future, a pharmacogenetic approach might be of use for augmenting the benefit in patients from inhibitors of the angiotensin system. As of now, there are no supportive data to suggest a benefit of using routine ACE inhibitors or angiotensin receptor blockers to prevent postangioplasty restenosis in the general 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.

Rescue of arterial function by angiotensin-(1-7): towards improvement of endothelial function by drug-eluting stents

PURPOSE

To explore the hypothesis that stent placement decreases dilator function of various arteries outside the stented segment and that angiotensin- (1-7) improves this function, and to assess the contribution of dilator signal compounds. A further objective was to test the hypothesis that on-stent delivery of Ang-(1-7) reduces neointima formation and improves endothelial function.

METHODS

Abdominal aortic stenting or sham operation was performed in the rat four weeks after stenting and treatment with intravenous saline or Ang-(1-7) infusion (24 mug/kg/h); vasomotor function in isolated thoracic aorta and brachial and iliac artery was measured in organ baths. Furthermore, Ang-(1-7)-eluting stents were designed and placed in rat abdominal aorta. Neointima formation and aortic function were tested after four weeks.

RESULTS

Relaxation of the thoracic aorta to metacholine was decreased after stenting compared with shams due to a decrease in nitric oxide-mediated response (67% reduction in maximal NO-dependent response). Ang-(1-7) restored the response mainly through increased prostaglandin- and possibly also endothelial-derived hyperpolarising factor-mediated relaxation. Relaxation in the brachial artery decreased after stenting (maximal response dropped by 50%), whilst contractions to phenylephrine increased. Ang-(1-7) normalised vasomotor function. Iliac artery function remained unaltered after stenting but Ang-(1-7) increased maximal relaxations by 65%. Delivery of Ang-(1-7) by means of a drug-eluting stent improved endothelial function.

CONCLUSION

Stenting differentially affects dilator and contractile function in various arterial beds. Ang-(1-7) both improves dilator function and normalises contractile function. Delivery of protective peptides such as Ang-(1-7) from the stent is a new therapy option that merits further development and exploration. (Neth Heart J 2008;16:293-8.).

Low-dose spironolactone: effects on artery-to-artery vein grafts and percutaneous coronary intervention sites

The efficacy of vein grafts used in coronary and peripheral artery bypass is limited by excessive hyperplasia and fibrosis that occur early after engraftment. In the present study, we sought to determine whether low-dose spironolactone alleviates maladaptive vein graft arterialization and alters intimal reaction to coronary artery stenting. Yorkshire pigs were randomized to treatment with oral spironolactone 25 mg daily or placebo. All animals underwent right carotid artery interposition grafting using a segment of external jugular vein and, 5 days later, underwent angiography of carotid and coronary arteries. At that time, a bare metal stent was placed in the left anterior descending artery and balloon angioplasty was performed on the circumflex coronary artery. Repeat carotid and coronary angiograms were performed before euthanasia and graft excision at 30 days. Angiography revealed that venous grafts of spironolactone-treated animals had lumen diameters twice the size of controls at 5 days, a finding that persisted at 30 days. However, neointima and total vessel wall areas also were 2- to 3-fold greater in spironolactone-treated animals, and there were no differences in vessel wall layer thicknesses or collagen and elastin densities. In the coronary circulation, there were no differences between treatment groups in any vessel wall parameters in either stented or unstented vessels. Taken together, these observations suggest that low-dose spironolactone may exert a novel protective effect on remodeling in venous arterial grafts that does not depend on the reduction of hyperplastic changes but may involve dilatation of the vessel wall.

Anti-ischemic effects of fasudil, a specific Rho-kinase inhibitor, in patients with stable effort angina

Epicardial coronary stenosis causes myocardial ischemia; however, the role of coronary microvessels is poorly understood in the pathogenesis of effort angina. We have previously demonstrated that Rho-kinase pathway is substantially involved in coronary arterial hyperconstriction in patients with vasospastic angina and those with microvascular angina. In the present study, we tested our hypothesis that Rho-kinase is involved in coronary microvascular constriction in patients with effort angina. Intracoronary administration of fasudil (300 microg/min for 15 min), a specific Rho-kinase inhibitor, significantly increased oxygen saturation in coronary sinus vein from 37 +/- 3% to 41 +/- 3% (P < 0.05) but not in six age-matched controls (from 42 +/- 3% to 43 +/- 3%, P = NS). Furthermore, the fasudil treatment significantly ameliorated pacing-induced myocardial ischemia in patients with effort angina (magnitudes of symptom: 1.5 +/- 0.6 to 0.6 +/- 0.4, P < 0.01; ischemic ST-segment depression, 1.8 +/- 0.3 to 1.0 +/- 0.2 mm, P < 0.01; percent lactate production, 50 +/- 17% to 0.4 +/- 7%, P < 0.01) without significant hemodynamic changes. These results provide the first evidence that Rho-kinase is substantially involved in coronary microvascular dysfunction associated with myocardial ischemia in patients with effort angina, suggesting that Rho-kinase can be a novel therapeutic target in ischemic heart disease.

A double-blind, randomized, placebo-controlled multicenter clinical trial to evaluate the effects of the angiotensin II receptor blocker candesartan cilexetil on intimal hyperplasia after coronary stent implantation

BACKGROUND

Preclinical data suggest beneficial effects of angiotensin II receptor blockers (ARBs) on neointima formation after vascular injury. Preliminary clinical data, however, revealed conflicting results. The AACHEN trial was a double-blind, randomized, placebo-controlled clinical multicenter trial to evaluate the effects of candesartan cilexetil on intimal hyperplasia after coronary stent implantation.

METHODS

A total of 120 patients (61 +/- 9 years, 83% male) were randomized to receive either 32 mg candesartan cilexetil (active) or placebo starting 7 to 14 days before elective coronary stent implantation. A follow-up angiography including intravascular ultrasound assessment of the target lesion was performed 24 +/- 2 weeks after stent implantation. The primary end point was defined as the difference in neointimal area between groups as assessed by intravascular ultrasound. Secondary end points included differences in angiographic parameters (ie, restenosis rate) and incidence of major cardiac events.

RESULTS

The mean stent length measured 15.0 +/- 4.9 mm in the active and 14.6 +/- 5.7 mm in the placebo group (P = .81). There was no significant difference in neointimal area between groups (2.1 +/- 1.0 vs 2.1 +/- 1.5 mm2, P = 1.00), nor were there differences in angiographic end point parameters. Major cardiac event rates were not significantly different between treatment groups (8% vs 11%, P = .75).

CONCLUSIONS

High-dose candesartan cilexetil therapy in patients with symptomatic coronary artery disease undergoing coronary stent implantation does not reduce clinical event rates, restenosis rates, or neointimal proliferation after elective stent implantation.

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.