Effect of Quinapril on In-Stent Restenosis and Relation to Plasma Apoptosis Signaling Molecules
Article Outline
Angiotensin-converting enzyme inhibitors have been reported to inhibit in-stent restenosis. To assess the effect of angiotensin-converting enzyme inhibition on in-stent restenosis and its relation to apoptosis, 86 patients with chronic coronary artery disease who required stent implantation in the left anterior descending coronary artery or a major diagonal branch were studied. Patients were randomized to receive quinapril 40 mg/day orally (n = 43) or a placebo (n = 43). Drug therapy was initiated 1 week before initial stenting and continued for 6 months. Plasma levels of the apoptotic signaling molecules soluble Fas and soluble Fas ligand obtained from blood drawn from the left anterior descending coronary artery were measured just before initial stenting and 6 months later, at the time of repeat coronary angiography. In-stent restenosis was present in 9.3% of patients in the quinapril group and 25.6% of patients in the placebo group (p = 0.047). Mean late luminal loss was 0.56 ± 0.51 mm in the quinapril group and 0.95 ± 0.95 mm in the placebo group (p = 0.003). There were no significant differences in plasma soluble Fas or soluble Fas ligand levels at baseline. At 6 months, the change in plasma soluble Fas level was significantly higher in the quinapril group (0.72 ± 1.24 ng/ml) than in the placebo group (0.28 ± 0.72 ng/ml) (p = 0.024). The change in plasma soluble Fas ligand levels at 6 months was significantly higher in the quinapril group (7.43 ± 12.2 pg/ml) than in the placebo group (0.06 ± 6.8 pg/ml) (p = 0.002). In conclusion, the angiotensin-converting enzyme inhibitor quinapril inhibits in-stent restenosis by stimulating apoptosis after percutaneous intervention.
Neointimal proliferation plays a key role in the pathogenesis of in-stent restenosis.1 A delicate balance exists in vascular smooth muscle between cell proliferation and apoptosis. The apoptosis signaling molecules soluble Fas (sFas) and soluble Fas ligand (sFasL) have been implicated in the regulation of vascular smooth muscle cell proliferation and thus are linked to atherogenesis.2 Alterations in the balance between cell proliferation and apoptosis may contribute to the transformation of vascular smooth muscle cells in response to arterial injury, a major feature of neointimal proliferation after percutaneous coronary intervention (PCI).3 The membrane-bound and soluble forms of Fas and Fas ligand have been shown inhibit smooth muscle cell proliferation, thereby showing a potential for reducing in-stent restenosis and late luminal loss.2, 3 Angiotensin-converting enzyme (ACE) inhibition has been shown to inhibit neointimal proliferation by promoting apoptosis.4 In this study, we assessed the relation between the effect of ACE inhibitor therapy on in-stent late luminal loss after PCI and apoptotic activity in patients with chronic coronary artery disease.
Methods
Patients aged 35 to 75 years with chronic stable angina pectoris and/or positive stress test results were selected for coronary angiography. Those with ≥70% stenosis of the left anterior descending coronary artery or a major diagonal branch (diameter ≥2 mm) were entered into the study and underwent stent placement. Patients with stenoses at bifurcations or trifurcations, known hypersensitivity to ACE inhibitors, serum creatinine levels ≥3.0 ng/dl, or unstable angina pectoris or acute myocardial infarctions were excluded from the study.
Patients were randomly assigned in a l:l fashion to receive quinapril 40 mg/day orally or a placebo. Drug therapy was initiated 1 week before PCI and continued 6 months after PCI. Plasma quinapril levels were not measured. All patients received oral aspirin 100 mg/day and oral clopidogrel 75 mg/day for the duration of the study. Antihypertensive therapy with drugs other than ACE inhibitors or angiotensin receptor blockers was permitted at the discretion of the attending cardiologist. The protocol was approved by the research committees of participating hospitals. Informed consent was obtained in accordance with the principles of the Declaration of Helsinki.
All patients entered into the study underwent left-sided cardiac catheterization with coronary angiography and stent placement. Follow-up coronary angiography was performed 6 months after the initial catheterization. Left-sided cardiac catheterization was performed using the Judkins technique. Left ventriculography was performed in the 30° right interior oblique and 60° left interior oblique views. Coronary stenoses were evaluated in ≥2 orthogonal views. Normal arterial segments were identified immediately proximal and distal to the index lesion. Electronic calipers were used to assess normal and stenosed segments. Minimum luminal diameter was measured, and the severity of stenosis was expressed as a percentage of normal luminal diameter. Significant coronary stenosis was defined as a ≥70% decrease in luminal diameter in the left anterior descending coronary artery or a diagonal branch with a luminal diameter ≥2 mm. Coronary stenting was preceded by predilation using angioplasty balloon catheters. Balloons were inflated to their nominal pressures corresponding to the diameter of the vessel. Additional inflations were used if necessary. Stents were then deployed using standard techniques and protocols. The choice of guidewires, balloon catheters, and stents was left to the discretion of the interventional cardiologist. Restenosis at 6 months was defined as in-stent narrowing ≥50% of normal luminal diameter. Late loss was defined as the difference between minimum luminal diameter immediately after the initial PCI and the minimum luminal diameter at 6 months. Lesion length was defined as the axial extent of the lesion that contained luminal reduction of ≥20%.
Plasma levels of sFas and sFasL were measured in blood samples drawn from the left anterior descending coronary artery immediately before baseline angiography and immediately before angiography 6 months later. The left anterior coronary artery was chosen rather than the peripheral venous system to reduce the likelihood of contamination related expression of sFas and sFasL from cell populations other than endothelium. Blood samples were transferred to pyrogen-free collection tubes using ethylenediaminetetraacetic acid as the anticoagulant. Samples were centrifuged within 15 minutes of collection using a centrifuge with an integrated refrigerator system (at 4°C and 2,000g for 20 minutes). Samples were then maintained at 8°C in multiple aliquots until analysis. Each plasma aliquot was thawed and analyzed once. No aliquots were refrozen. Plasma sFas and sFasL were measured using commercially available enzyme-linked immunosorbent assay kits (R&D Systems, Minneapolis, Minnesota) in accordance with the manufacturer's instructions. The minimum detectable plasma levels of sFas and sFasL were 20 ng/ml and 2.5 pg/ml, respectively.
Only soluble forms of Fas and Fas ligand were measured. Genetic testing for ACE genotypes was not performed, a potential limitation.
Continuous variables are expressed as mean ± SD. Categorical variables are expressed as numbers of patients and percentages of the group as a whole or subgroups. Comparisons of mean values for continuous variables were accomplished using Student's t test for paired data. Proportions of categorical variables were compared using the chi-square test or Fisher's exact test. Stepwise multivariate linear regression analysis was applied to assess the associations of various clinical and angiographic parameters with late luminal loss, which served as the dependent variable. A p value <0.05 was required for statistical significance. All statistical analyses were performed using SPSS (SPSS, Inc., Chicago, Illinois).
Results
A total of 86 consecutive eligible patients were enrolled in the study. Patients were randomized in a l:l fashion to receive oral quinapril or placebo. Each group consisted of 43 patients. Baseline clinical, demographic, and angiographic characteristics are listed in Table 1. All patients were Greek.
Table 1. Baseline patient characteristics
| Variable | Quinapril | Placebo | |
|---|---|---|---|
| Total (n = 86) | Group (n = 43) | Group (n = 43) | |
| Men | 57 (66%) | 29(67%) | 28(65%) |
| Age (years) | 61.95±10.8 | 63.98±10.4 | 59.93±10.9 |
| Diabetes mellitus | 31(36%) | 14(33%) | 17(40%) |
| Hypertension⁎ | 51(59%) | 26(61%) | 25(58%) |
| Smokers | 49(57%) | 26(61%) | 23(54%) |
| Dyslipidemia† | 55(64%) | 27(63%) | 28(65%) |
| Serum creatinine (mg/dl) | 1.00±0.20 | 1.00±0.21 | 0.98±0.19 |
| Drug therapy | |||
| β blocker | 85(99%) | 42(98%) | 43(100%) |
| Calcium channel blocker | 45(52%) | 24(56%) | 21(49%) |
| Warfarin | 5(5.8%) | 2(4.7%) | 3(6.9%) |
| Statin | 83(97%) | 42(98%) | 41(95%) |
| Left ventricular ejection fraction (%) | 58±7 | 59±6 | 57±8 |
| Coronary artery stented‡ | |||
| Left anterior descending | 86(100%) | 43(100%) | 43(100%) |
| Circumflex | 3(3.4%) | 1(2.3%) | 2(4.7%) |
| Right | 3(3.4%) | 2(4.7%) | 1(2.3%) |
| Drug-eluting stent§ | 25(29%) | 12(28%) | 13(30%) |
| Stent length (mm)§ | 25.1±7.1 | 24.3±7.2 | 26.0±7.0 |
| Luminal stenosis (%)§ | 86.9±9.6 | 87.6±10.0 | 86.2±9.3 |
| Minimum luminal diameter after stent implantation (mm)§ | 2.95±12 | 2.92±11 | 2.98±13 |
⁎Systolic blood pressure >140 mm Hg and/or diastolic blood pressure >90 mm Hg or receiving antihypertensive medication. |
†Low-density lipoprotein cholesterol >100 mm/dl and/or high-density lipoprotein cholesterol <40 mg/dl in men or <50 mg/dl in women or receiving lipid-modifying medication. |
‡Coronary artery or a major branch (≥2 mm). |
§Left anterior descending coronary artery. |
There were no complications during initial PCI. By 6 months after initial angiography, 2 patients in the placebo group and no patients in the quinapril group had developed unstable angina pectoris or myocardial infarction. A single patient in the quinapril group had a nonfatal stroke. There were no deaths in either group. There were no significant differences in mean systolic or diastolic blood pressure values between baseline and 6 months in either the quinapril or the placebo group.
In-stent restenosis was present at 6 months in 17.4% of the 86 patients studied. The restenosis rates were 9.3% in the quinapril group and 25.6% in the placebo group (p = 0.047, univariate odds ratio 2.06, 95% confidence interval 1.09 to 4.89). Late luminal loss was 0.56 ± 0.51 mm in the quinapril group and 0.95 ± 0.95 mm in the placebo group (p = 0.003). In-stent restenosis at 6 months occurred in the circumflex coronary artery in 1 patient in the quinapril group and in the right coronary artery in 1 patient in the placebo group.
Table 2 lists mean plasma sFas and sFasL values at baseline and 6 months. There were no significant differences between groups in baseline plasma levels of either sFas or sFasL. Mean changes in plasma sFas levels were significantly greater in the quinapril than in the placebo group (p = 0.024). Similarly, mean changes in plasma sFasL levels were significantly greater in the quinapril group than in the placebo group (p = 0.002). There were no significant differences in plasma sFas or sFasL levels between the bare-metal stent and drug-eluting stent groups in either the quinapril or placebo groups.
Table 2. Plasma apoptotic signaling molecules before and 6 months after stent implantation
| Plasma Apoptotic Marker | All Patients | Quinapril Group | Placebo Group | p Value |
|---|---|---|---|---|
| (n = 86) | (n = 43) | (n = 43) | ||
| sFas (ng/mL) | ||||
| Baseline | 2.79±0.61 | 2.76±0.72 | 2.82±0.48 | NS |
| 6 months | 3.27±1.08 | 3.48±1.20 | 3.07±0.87 | 0.075 |
| Change in sFas | 0.48±0.98 | 0.72±1.74 | 0.25±0.72 | 0.024 |
| p | <0.001 | <0.001 | 0.029 | |
| sFasL (pg/ml) | ||||
| Baseline | 30.43±7.25 | 29.86±8.84 | 30.99±5.24 | NS |
| 6 months | 34.44±11.64 | 37.29±13.70 | 31.59±8.40 | 0.023 |
| Change in sFas ligand | 4.02±10.4 | 7.43±12.2 | 0.60±6.8 | 0.002 |
| p | <0.001 | <0.001 | NS |
Figure 1 shows scatterplot distributions of the changes in individual plasma sFas and sFasL levels from baseline to 6 months in the quinapril and placebo groups.
Figure 1.
Scatterplots of the differences between baseline and follow-up values of sFas and sFasL plasma levels in the quinapril and the control groups. Positive values denote increases in plasma apoptotic signaling molecule levels. Note that substantially more patients in the quinapril group experienced increases in plasma sFas and sFasL levels 6 months after stenting than in the placebo group.
There was a weak but significant negative univariate correlation between change in sFas and late luminal loss in the left anterior descending coronary artery in the quinapril group (r = −0.14, p = 0.015; Figure 2). There was no correlation between plasma sFasL and late luminal loss in the placebo group.
Figure 2.
Relation of change in plasma sFas levels to late luminal loss in the quinapril and placebo groups. In quinapril-treated patients, there was a significant negative correlation between the change in plasma sFas levels obtained from the left anterior descending coronary artery and late luminal loss (r = −0.14, p = 0.015). No such correlation was observed in the placebo group.
Stepwise multivariate linear regression analysis was applied to test the independence of univariate correlations of potentially confounding variables (age, gender, diabetes mellitus, dyslipidemia, smoking, quinapril treatment, stent type, length of lesion or stent, severity of stenosis, and post-PCI minimum luminal diameter) using late luminal loss as the dependent variable. After correcting for the aforementioned confounding variables, quinapril treatment was significantly and independently predictive of late luminal loss (β = −0.341, p = 0.008), as was stent length (β = 0.225, p = 0.017). None of the other variables studied were independently predictive of late luminal loss.
Discussion
In this study, long-term treatment with the ACE inhibitor quinapril was associated with a significant decrease in in-stent late luminal loss in the index segment of the left anterior descending coronary artery and significant long-term increases in the plasma levels of the apoptotic signaling molecules sFas and sFasL. These observations suggest that the ability of ACE inhibitors to inhibit in-stent restenosis may be mediated by increased apoptosis in modified vascular smooth muscle cells stimulated by local arterial endothelial injury.
Fas (APO-1 or CD-95) is a cell surface receptor that transduces apoptotic signals from Fas ligand.5 It is a member of the tumor necrosis factor superfamily and shares a cytoplasmic motif with tumor necrosis factor R1, referred to as the “death domain.” The stimulation of these receptors results in binding of cytoplasmic signaling molecules, which trigger a cytoplasmic apoptotic signal.5, 6 FasL, the physiologic agonist for Fas, is also a transmembrane protein5, 6 with homology to the tumor necrosis factor family in its extracellular domain.
There is experimental evidence to suggest a relation between these apoptotic signal molecules and cardiovascular disease. Okura et al7 demonstrated that the plasma sFasL concentration was associated with atherosclerosis and inflammation in patients with hypertension. Adamopoulos et al8 noted that the sFas-sFasL system is upregulated in patients with myocardial dysfunction in proportion to the severity of heart failure. These molecules have also been implicated in the regulation of vascular cell proliferation and thus in the processes that lead to the development of atherosclerotic plaque.2 It has been hypothesized that sFas and sFasL help modulate the balance between cell proliferation and apoptosis. An imbalance in this system favoring cell proliferation may lead to neointimal hyperplasma and has in fact been implicated as an important factor promoting in-stent restenosis after PCI.9
ACE inhibition has been shown to prevent myointimal proliferation after vascular injury.10 Ellis et al11 reported a decrease in the need for late revascularization in patients receiving ACE inhibitors after PCI, possibly due to reduced restenosis after coronary stenting. Reductions in the incidence and degree of in-stent restenosis in patients treated with quinapril were reported in 2 studies.12, 13 However, other studies have reported no effect14 or an increase15 in in-stent restenosis after PCI in patients treated with ACE inhibitors. Thus, controversy exists concerning the role of ACE inhibitors after PCI. Adverse effects of ACE inhibitors in such patients may be confined to a select subpopulation of patients bearing the DD polymorphism of the ACE gene.14, 15 The Quinapril Ischemic Event Trial (QUIET) failed to identify an adverse effect of ACE inhibitors on in-stent restenosis in a genetically heterogenous population.16 Reduction of in-stent restenosis may not be confined to ACE inhibition. Peters et al17 reported reduced in-stent restenosis in the Valsartan for Prevention of Restenosis After Stenting of Type B2/C Lesions (VAL-PREST) trial using the angiotensin receptor blocker valsartan.
Holm et al4 reported that enalapril induced apoptosis in an animal model with carotid artery injury, supporting the findings of a previous study by deBois et al18 on the promotion of apoptosis by captapril in hypertensive rats. Our results suggest that the antiproliferative effect of the ACE inhibitor quinapril after PCI may be mediated by induction of apoptosis, possibly leading to the inhibition or retardation of neointimal hyperplasia.
The present study was not powered to study clinical end points such as cardiovascular events or death. Thus, no conclusion should be drawn concerning the clinical outcomes in this study. Our results should be considered as proof of concept and may be used to stimulate further research concerning the relation of apoptosis to neointimal proliferation after PCI. Although the results suggest a relation between quinapril and inhibition of in-stent restenosis and late luminal loss mediated by apoptosis, we cannot completely exclude the possibility that sFas and sFasL represent an epiphenomenon. Because this study was not powered to detect clinical end points, a clear-cut cause-and-effect relation between quinapril-induced apoptosis and in-stent restenosis cannot be firmly established.
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PII: S0002-9149(09)02213-9
doi:10.1016/j.amjcard.2009.08.648
© 2010 Elsevier Inc. All rights reserved.
