Angiotensin-converting enzyme in the human heart. Effect of the deletion/insertion polymorphism

A population study of ethnic variations in the angiotensin-converting enzyme I/D polymorphism: relationships with gender, hypertension and impaired glucose metabolism

BACKGROUND

The presence of the deletion allele of the angiotensin-converting enzyme (ACE) I/D polymorphism is associated with an excess risk of vascular disease and diabetic nephropathy.

OBJECTIVE

To examine the importance of this polymorphism as a determinant of hypertension and impaired glucose metabolism in a population-based study of three ethnic groups and assess the potential modifying effect of gender.

DESIGN

Population-based cross-sectional study in South London. The population-based sample of 1577 men and women, age 40-59 years, was obtained from stratified random sampling of general practice lists where 25% of the residents were born outside the UK. The ACE I/D polymorphism was determined for 1366 individuals (86.6%): 462 whites, 462 of African descent and 442 of South Asian origin.

RESULTS

The genotype frequency within each ethnic group was in Hardy-Weinberg equilibrium. The frequencies were similar in whites and those of African descent (II, ID, DD: 18.4%, 49.6%, 32.0% for whites and 18.4%, 50.5%, 30.9% for those of African descent), but there was a much higher frequency of the II genotype in those of South Asian origin (39.8%, 41.8%, 18.3%; chi2 = 77.6; P < 0.0001). There was no association between the I/D polymorphism and impaired glucose metabolism in any ethnic group. There were also no significant associations between the I/D polymorphism and hypertension in whites and in those of South Asian origin. This contrasts with a highly significant association between the D allele and hypertension in women of African descent (OR = 2.54; 95% CI 1.38-4.65; P = 0.003) but not in men of African descent (0.79; 0.36-1.72) (test for differences between sexes P = 0.023).

CONCLUSIONS

These observations provide estimates of the frequency distribution of the ACE I/D polymorphism in whites, in people of African descent and in people of South Asian origin. Moreover, these results highlight the potential importance of gender-dependent interactions between genetic background and expression of hypertensive phenotype.

Association between angiotensin-converting enzyme gene polymorphisms and regression of left ventricular hypertrophy in patients treated with angiotensin-converting enzyme inhibitors

PURPOSE

An insertion/deletion (ID) polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with left ventricular hypertrophy. The present study examined polymorphisms of the ACE gene in patients with essential hypertension and left ventricular hypertrophy who were participants in a long-term trial of therapy with an ACE inhibitor.

PATIENTS AND METHODS

ACE inhibitor therapy was administered for >2 years to 54 patients with hypertension who had moderate or severe left ventricular hypertrophy. Cardiac dimensions were monitored by echocardiography before the initiation of therapy and after 1 and 2 years of treatment. Serum ACE activity and plasma concentrations of brain natriuretic peptide, a marker for left ventricular hypertrophy, were also monitored.

RESULTS

Eighteen patients had the II genotype for the angiotensin-converting enzyme gene, 19 had the ID genotype, and 17 had the DD genotype. Baseline (mean +/- SD) serum ACE activity was significantly greater (P <0.05) in the DD (18 +/- 7 IU/L) group than in the II (7 +/- 4 IU/L) or ID (12 +/- 6 IU/L) groups. ACE inhibitor therapy was effective in controlling blood pressure, and it reduced posterior and septal wall thickness, left ventricular mass index, and plasma brain natriuretic peptide concentration in all three groups. Despite similar blood pressure reductions, after 2 years, mean (+/- SD) regression in posterior wall thickness was significantly less (P <0.05) in the DD group (-9% +/- 5%) than in the ID (-21% +/- 7%) and II (-21% +/- 9%) groups. Similar results were seen for the reductions in brain natriuretic peptide levels. The magnitudes of regression of septal wall thickness and left ventricular mass index during therapy were less in the DD group than the II group (P <0.05).

CONCLUSION

Hypertensive patients with the DD genotype are less likely to have regression of left ventricular hypertrophy when treated with ACE inhibitors than are patients with other ACE genotypes.

Association of 3 gene polymorphisms with atopic diseases

BACKGROUND

Various peptidases, including angiotensin-converting enzyme (ACE), inactivate some inflammatory peptides that are considered to influence the pathogenesis of atopic diseases. This enzyme is also involved in the conversion or activation of 2 bronchoconstriction mediators: angiotensin II from angiotensinogen and endothelin (ET), respectively.

OBJECTIVE

We tested a hypothesis that asthma or other atopic diseases are associated with insertion/deletion ACE, M235T angiotensinogen, and TaqI ET-1 gene polymorphisms.

METHODS

A case-control approach was used in the study. Healthy subjects (141 persons) were used as control subjects, and 231 patients with histories of atopic asthma, allergic rhinitis, atopic dermatitis, or a combination thereof were studied. ACE genotype was determined by PCR, angiotensinogen M235T and ET-1 by PCR, and restriction analysis by AspI and TaqI, respectively.

RESULTS

We found the significant association of the insertion/deletion polymorphism of the ACE, as well as that of M235T polymorphism of the angiotensinogen genes, with the group of patients with atopic diseases ( P =.0025 and P =.0204, respectively). No difference was proved for the intron 4 (position 8000) polymorphism in the ET-1 gene when comparing the atopic patients with the control group (P =.1774). A significant difference was found between groups of patients with both asthma and rhinitis and patients without both respiratory atopic diseases (P =.0033).

CONCLUSION

It follows that the examined polymorphisms in the genes for ACE, angiotensinogen, and ET-1 could participate in the etiopathogenesis of atopic diseases.

High intensity training and the heart

Absence may make the heart grow fonder, but exercise makes the heart grow stronger. This review discusses the cardiac impact of high intensity training, and discusses the possible mechanisms underlying the risk and benefit of such training.

Abnormal flow-mediated epicardial vasomotion in human coronary arteries is improved by angiotensin-converting enzyme inhibition: a potential role of bradykinin

OBJECTIVES

This study was performed to determine whether angiotensin converting enzyme (ACE) inhibition improves endothelium-dependent flow-mediated vasodilation in patients with atherosclerosis or its risk factors and whether this is mediated by enhanced bradykinin activity.

BACKGROUND

Abnormal coronary vasomotion due to endothelial dysfunction contributes to myocardial ischemia in patients with atherosclerosis, and its reversal may have an antiischemic action. Previous studies have shown that ACE inhibition improves coronary endothelial responses to acetylcholine, but whether this is accompanied by improved responses to shear stress remains unknown.

METHODS

In 19 patients with mild atherosclerosis, metabolic vasodilation was assessed during cardiac pacing. Pacing was repeated during separate intracoronary infusions of low-dose bradykinin (BK) and enalaprilat. Endothelium-dependent and -independent vasodilation was estimated with intracoronary BK and sodium nitroprusside respectively.

RESULTS

Enalaprilat did not alter either resting coronary vascular tone or dilation with sodium nitroprusside, but potentiated BK-mediated dilation. Epicardial segments that constricted abnormally with pacing (-5+/-1%) dilated (3+/-2%) with pacing in the presence of enalaprilat (p = 0.002). Similarly, BK at a concentration (62.5 ng/min) that did not alter resting diameter in the constricting segments also improved the abnormal response to a 6+/-1% dilation (p < 0.001). Cardiac pacing-induced reduction in coronary vascular resistance of 27+/-4% (p < 0.001) remained unchanged after enalaprilat.

CONCLUSIONS

Thus ACE inhibition: A) selectively improved endothelium-dependent but not-independent dilation, and B) abolished abnormal flow-mediated epicardial vasomotion in patients with endothelial dysfunction, in part, by increasing endogenous BK activity.

Insertion/deletion angiotensin converting enzyme gene polymorphism affects the microvascular structure of the kidney in patients with nondiabetic renal disease

OBJECTIVE

It has been reported that the deletion allele of the insertion/deletion polymorphism of the angiotensin I converting enzyme gene is associated with increased cardiovascular risk and progressive renal disease, including immunoglobulin A nephropathy. We therefore investigated the relationship between angiotensin converting enzyme polymorphism and intrarenal microvascular structure in 56 patients with nondiabetic renal disease.

METHODS AND RESULTS

We determined various cardiovascular hormones of the renin-angiotensin system and angiotensin converting enzyme gene polymorphism in 56 patients with nondiabetic renal diseases who underwent a renal biopsy. The patients were divided into three groups by angiotensin converting enzyme genotype (insertion/insertion, n = 21; insertion/deletion, n = 23; deletion/deletion, n = 12) using polymerase chain reaction methods. The angiotensin converting enzyme insertion/ deletion and deletion/deletion genotypes were associated with a significantly higher interlobular artery wall : lumen ratio than the insertion/insertion genotype (insertion/insertion 0.27 +/- 0.01, insertion/deletion 0.32 +/- 0.01, deletion/deletion 0.33 +/- 0.02; P < 0.05). Afferent arteriolar and tubulo-interstitial injury scores were similar among the three genotypes. Although serum angiotensin converting enzyme activity was higher in the deletion/deletion than in the other two genotypes (insertion/insertion 9.7 +/- 0.7, insertion/deletion 10.7 +/- 0.9, deletion/deletion 14.0 +/- 2.4 IU/I; P < 0.05), other factors of the renin-angiotensin system, including blood pressure and serum creatinine levels, were not different among the three groups.

CONCLUSIONS

The angiotensin converting enzyme deletion/deletion genotype may be considered a risk factor for the development of microvascular wall thickening in nondiabetic renal diseases.

Association of left ventricular systolic performance and cavity size with angiotensin-converting enzyme genotype in idiopathic dilated cardiomyopathy

The insertion-deletion (ID) polymorphism of the angiotensin-converting enzyme (ACE) gene is a marker linked to differences in plasma and cardiac ACE activity as well as to an increased mortality in patients with idiopathic heart failure. We examined the possibility that ACE gene ID variants are associated with differences in left ventricular (LV) systolic performance or internal LV dimensions in a high-risk cohort of patients with idiopathic dilated cardiomyopathy (IDC). The ACE genotype was determined in 171 patients selected with IDC in New York Heart Association functional class II to III heart failure and with a LV ejection fraction of < or = 40%. Left ventricular performance and dimensions were assessed using echocardiography (n = 161) and radionuclide ventriculography (n = 169). The frequency of ACE gene ID alleles was not different in the study versus non-age-matched (n = 171; odds ratio 0.94) and age-matched (n = 106, odds ratio 0.88) control groups. Ejection fraction was found to be worse in patients with the DD genotype (echocardiography, DD = 23.5 +/- 0.70, ID + II = 26.8 +/- 0.8, p = 0.009; ventriculography, DD = 21.7 +/- 0.9, ID + II = 25.3 +/- 0.8, p = 0.003). LV end-systolic and end-diastolic diameters were increased in patients with the DD genotype. Multifactor regression analysis showed the ACE genotype to be an independent predictor of both ejection fraction (echocardiography, p <0.02; ventriculography, p <0.03) and end-diastolic diameter (p <0.02). In conclusion, the results of this study indicate that the DD genotype of the ACE gene is independently associated with both a reduced LV systolic performance and an increased LV cavity size in patients with IDC.

Angiotensin-converting-enzyme gene insertion/deletion polymorphism and response to physical training

BACKGROUND

The function of local renin-angiotensin systems in skeletal muscle and adipose tissue remains largely unknown. A polymorphism of the human angiotensin converting enzyme (ACE) gene has been identified in which the insertion (I) rather than deletion (D) allele is associated with lower ACE activity in body tissues and increased response to some aspects of physical training. We studied the association between the ACE gene insertion or deletion polymorphism and changes in body composition related to an intensive exercise programme, to investigate the metabolic effects of local human renin-angiotensin systems.

METHODS

We used three independent methods (bioimpedance, multiple skinfold-thickness assessment of whole-body composition, magnetic resonance imaging of the mid-thigh) to study changes in body composition in young male army recruits over 10 weeks of intensive physical training.

FINDINGS

Participants with the II genotype had a greater anabolic response than those with one or more D alleles for fat mass (0.55 vs -0.20 kg, p=0.04 by bioimpedance) and non-fat mass (1.31 vs -0.15 kg, p=0.01 by bioimpedance). Changes in body morphology with training measured by the other methods were also dependent on genotype.

INTERPRETATION

II genotype, as a marker of low ACE activity in body tissues, may conserve a positive energy balance during rigorous training, which suggests enhanced metabolic efficiency. This finding may explain some of the survival and functional benefits of therapy with ACE inhibitors.

Does angiotensin-converting enzyme polymorphism influence the clinical manifestation and progression of heart failure in patients with dilated cardiomyopathy?

To evaluate the role of angiotensin-converting enzyme (ACE) polymorphism on the development of end-stage dilated cardiomyopathy, the ACE gene polymorphism of 90 patients after heart transplantation because of this disease was compared with the population sample. No difference in gene frequencies was found, but when compared with the population sample there were fewer ID heterozygotes detected; no significant influence of ACE polymorphism on the course of the disease before transplantation was found.

Effect of the insertion/deletion polymorphism of the angiotensin-converting enzyme gene on response to angiotensin-converting enzyme inhibitors in patients with heart failure

There is marked interindividual variation in serum and tissue angiotensin-converting enzyme (ACE) levels for which the insertion (I)/deletion (D) polymorphism in intron 16 of the ACE gene is a marker. ACE inhibitors have important effects on morbidity and mortality in heart failure. The influence of this polymorphism on the response to ACE inhibitors in patients with heart failure is not known. We studied response by ACE genotype of 34 subjects in a randomised, double-blind, crossover study comparing 6 weeks of lisinopril (10 mg, o.d.) or captopril (25 mg, t.d.s.) on 24-h blood pressure (BP) profile and on renal function in patients with symptomatic heart failure [mean left ventricular ejection fraction (LVEF), 24%]. Glomerular filtration rate (GFR), 99mTc diethylenetriaminepentaacetic acid (DTPA), and ambulatory 24-h mean arterial pressure (MAP; Spacelabs 90207) were assessed at the beginning and end of treatment periods. There was a significant relation between ACE genotype and change in MAP with captopril (mm Hg; DD group, -0.5; ID, -4.7; II, -7.4; p = 0.02) but not to lisinopril (mm Hg DD, -6.0; ID, -6.6; II, -7.4; p = 0.89) in these patients. There was no significant relation between genotype and change in GFR with captopril (percentage change from baseline: DD, +7.9; ID, +13.1; II, -0.6; p = 0.45) or lisinopril (percentage change from baseline: DD, -0.1; ID, -3.0; II, -13.3; p = 0.39), but the decline in renal function tended to be greatest in II subjects. Whereas the results are not conclusive, there may be a significant interaction between ACE genotype and response to ACE inhibitors in patients with heart failure.

Angiotensinogen (M235T) and angiotensin-converting enzyme (I/D) polymorphisms in association with plasma renin and prorenin levels

OBJECTIVE

The angiotensinogen T235 allele is associated with elevated plasma angiotensinogen levels whereas the angiotensin-converting enzyme (ACE) deletion (D) allele is associated with elevated ACE activity. It remains unclear, however, whether these genetically mediated elevations of angiotensinogen and ACE levels are functionally relevant Given that the renin-angiotensin system is subject to renin feedback regulation, we specifically investigated the associations between the angiotensinogen T235 allele and the ACE D allele with plasma renin and prorenin levels.

DESIGN AND METHODS

Plasma levels of renin, prorenin, angiotensinogen, ACE and aldosterone, as well as angiotensinogen and ACE genotypes were determined in 228 men and 168 women (age 52-65 years), who had participated in a population survey in southern Germany. Subjects taking antihypertensive drugs or oestrogen replacement therapy were excluded.

RESULTS

We corroborated previous findings demonstrating associations between the T235M polymorphism and plasma angiotensinogen levels (P < 0.05) and between the ACE I/D polymorphism and plasma ACE (P < 0.01). After adjustment for sex, age and blood pressure, the T235 allele of the angiotensinogen gene was also related to lower plasma prorenin (P < 0.03) and renin (P < 0.01) levels, but not to plasma ACE and aldosterone. By contrast, the ACE I/D polymorphism was not related to components of the system other than plasma ACE.

CONCLUSIONS

The angiotensinogen T235 allele is associated with decreased renin levels. This finding may point to a mechanism that counteracts the genetic elevation of angiotensinogen plasma levels and, thus, the plasmatic angiotensin II-generating pathway in subjects carrying the angiotensinogen T235 allele. These results may help to explain discrepant findings regarding associations between this allele and cardiovascular disorders. Furthermore, the presumed feedback downregulation of renin levels supports the importance of angiotensinogen as a determinant of angiotensin II generation. Finally, no evidence was found suggesting that the ACE D allele affects components of the circulating renin-angiotensin system other than plasma ACE.

Decrease with age in frequency of the homozygous deletional angiotensin-converting enzyme genotype in hypertensive patients

1. Angiotensin-converting enzyme (ACE) genotypes in hypertensive patients were studied in order to delineate their cardiovascular risk due to the ACE gene. We hypothesized that the distribution of ACE genotypes may change with age because of the risk of myocardial infarction associated with the homozygous deletional (DD) genotype. 2. A total of 223 subjects were recruited from the Hypertension Outpatient Clinic of the Sai Ying Pun Hospital with consent. They consisted of 75 patients with newly diagnosed or documented hypertension, 46 patients with ischaemic heart disease and 102 normal controls. Genomic DNA was extracted from peripheral leucocytes and amplified by polymerase chain reaction. Insertion (I) or deletion (D) alleles were identified after electrophoresis. The frequencies of ACE genotypes and alleles were measured in three age groups: < 50 years, 50-59 years and > or = 60 years. 3. A significant correlation between ACE genotype and age was found (P = 0.03). The relative frequency of the D allele in those under 50 years of age was similar in controls and hypertensive patients (0.40 vs 0.41; P = 0.94), but was significantly lower in patients > or = 50 years compared with those patients < 50 years of age (0.22 vs 0.41; P = 0.01). 4. The observed decrease in frequency of the DD genotype in older hypertensive patients is consistent with the increase in cardiovascular risk associated with the D allele and raises the possibility that the DD genotype may increase the risk of premature death, at least in the population studied.

Polymorphisms of angiotensin converting enzyme and plasminogen activator inhibitor-1 genes in diabetes and macroangiopathy1

BACKGROUND

An insertion or deletion (I/D) polymorphism in the angiotensin converting enzyme (ACE) gene and a 4/5-guanine tract polymorphism (4G/5G) in the promoter region of the plasminogen activator inhibitor-1 (PAI-1) gene are associated with the plasma activities of these substances and with coronary heart disease. In smooth muscle cells and mesangial cells, the angiotensin II synthesized by ACE increases mRNA expression and the activity of PAI-1, which promotes antifibrinolysis and the accumulation of extracellular matrix. Therefore, ACE and PAI-1 polymorphisms may have a synergistic effect on diabetic nephropathy and macroangiopathy.

METHODS

Using multivariate logistic regression analyses, we investigated the independent or synergistic effects of the ACE I/D and PAI-1 4G/5G polymorphisms on the development of diabetic nephropathy and macroangiopathy in 208 patients with non-insulin dependent diabetes mellitus (NIDDM) over a 15 year period.

RESULTS

Advanced diabetic nephropathy, defined as impaired renal function and diabetic retinopathy, was present in 98 patients. Manifest macrovascular diseases, confirmed by both clinical signs and physical and laboratory examinations, were present in 56 patients. There was no significant difference in the genotype distribution of ACE or PAI-1 polymorphisms between subjects with advanced nephropathy and those with normal renal function. There was no significant difference in the renal survival rate between patients with differing ACE or PAI-1 genotypes. Subjects with macroangiopathy had a higher frequency of the DD genotype than those without macroangiopathy. Subjects with both DD and 4G4G genotypes had a higher incidence of macroangiopathy than those with any other pair of genotypes. Multivariate logistic regression analysis showed that there was no association between ACE or PAI-1 polymorphisms and diabetic nephropathy. The ACE DD genotype and its interaction with the PAI-1 4G4G genotype and the presence of advanced diabetic nephropathy were positively associated with macrovascular disease.

CONCLUSION

These results indicate that the ACE DD genotype and its interaction with the PAI-1 4G4G genotype are independent risk factors for macroangiopathy, but not for the progression of diabetic nephropathy in NIDDM patients, and that the genotyping of PAI-1 and ACE polymorphisms, especially in patients with advanced diabetic nephropathy, may be useful for predicting and preventing macroangiopathy-related events.

Induction of angiotensin I-converting enzyme transcription by a protein kinase C-dependent mechanism in human endothelial cells

Angiotensin I-converting enzyme (ACE) has been implicated in various cardiovascular diseases; however, little is known about the ACE gene regulation in endothelial cells. We have investigated the effect of the protein kinase C activator phorbol 12-myristate 13-acetate (PMA) on ACE activity and gene expression in human umbilical vein endothelial cells (HUVEC). Our results showed a 3- and 5-fold increase in ACE activity in the medium and in the cells, respectively, after 24-h stimulation by PMA. We also observed an increase in the cellular ACE mRNA content starting after 6 h and reaching a 10-fold increase at 24 h in response to 100 ng/ml PMA as measured by ribonuclease protection assay. This effect was mediated by an increased transcription of the ACE gene as demonstrated by nuclear run-on experiments and nearly abolished by the specific PKC inhibitor GF 109203X. Our results indicate that PMA-activated PKC strongly increases ACE mRNA level and ACE gene transcription in HUVEC, an effect associated with an increased ACE secretion. A role for early growth response factor-1 (Egr-1) as a factor regulating ACE gene expression is suggested by both the presence of an Egr-1-responsive element in the proximal portion of the ACE promoter and the kinetics of the Egr-1 mRNA increase in HUVEC treated with PMA.

Left ventricular dilatation after myocardial infarction: ACE inhibitors, beta-blockers, or both?

Left ventricular (LV) dilatation after myocardial infarction (MI) is a major predictor of prognosis and identifies which patients will develop heart failure. Left ventricular dilatation or remodeling starts immediately after MI and progresses in the chronic phase of heart failure. Factors influencing remodeling, such as infarct size and neurohumoral activation, including the sympathetic and renin-angiotensin system, are discussed. Remodeling can be affected by reduction of infarct size and inhibition of neurohumoral activation. The effect of thrombolysis, beta-blockade, and angiotensin-converting enzyme (ACE) inhibition in the acute phase after MI and in the chronic phase of heart failure on remodeling are discussed. On the basis of beneficial effects of ACE inhibition and beta-blockade in acute MI and in chronic heart failure, a treatment strategy is proposed in which both ACE inhibition and beta-blockade are started early after MI. Depending on infarct size and ventricular function, continued treatment in the chronic phase of heart failure must be considered.

Renal angiotensin converting enzyme promotes renal damage during ureteral obstruction

PURPOSE

We and others have shown that angiotensin II has a pivotal role in renal damage in various renal injuries. Although most angiotensin II actions are associated with the angiotensin type 1 receptor, there is increasing evidence that the angiotensin type 2 receptor also transduces some important effects of angiotensin II. In this regard we recently observed that mice with genetically engineered disruption of the angiotensin type 2 receptor, termed Agtr2 mutants, are more susceptible to structural renal damage after ureteral obstruction. Recent evidence suggests that a genetically determined increase in angiotensin converting enzyme activity in humans promotes end organ damage. Therefore, we determined whether renal damage in Agtr2 mutants is associated with heightened angiotensin converting enzyme activity.

MATERIALS AND METHODS

We studied 28 wild type and 19 Agtr2 mutant mice with unilateral ureteral obstruction. Seven days after obstruction was created serum samples were obtained to evaluate angiotensin converting enzyme activity. The obstructed and contralateral kidneys were harvested for histological analysis and determination of renal angiotensin converting enzyme activity by high pressure liquid chromatography.

RESULTS

Renal angiotensin converting enzyme was uniformly higher than serum angiotensin converting enzyme in normal wild type and Agtr2 mutant mice. However, even at baseline Agtr2 mutant mice had strikingly higher renal angiotensin converting enzyme activity than normal wild type mice (mean plus or minus standard error 1,492+/-83 versus 450+/-60 milliunits per gm. tissue weight, p <0.0005). Histological analysis revealed more extensive parenchymal damage in the obstructed kidneys of mutant mice than in identically treated controls. Notably while unilateral ureteral obstruction decreased renal angiotensin converting enzyme activity in each group, activity remained persistently higher in the Agtr2 mutants than in normal mice (mean 742+/-146 versus 310+/-43 milliunits per gm. tissue weight, p <0.005).

CONCLUSIONS

We propose that elevated renal angiotensin converting enzyme activity contributes to more severe renal parenchymal damage in ureteral obstruction by promoting the availability of growth factors, such as angiotensin II, or depleting antiproliferation factors, such as bradykinin or nitric oxide. These findings complement previous observations that angiotensin converting enzyme inhibition preserves the renal parenchyma after injury, including obstruction.

Association between angiotensin I-converting enzyme genotypes, extracranial artery stenosis, and stroke

The insertion(I)/deletion(D) polymorphism of the angiotensin-converting-enzyme (ACE) gene has been associated with an increased risk of myocardial infarction, lacunar stroke, and with an increased intimal-medial thickness in several populations. The aim of this study was to evaluate whether the ACE I/D genotype is associated with stenosis of extracranial arteries and stroke in middle-aged and aged men and women. We studied 388 patients (247 male, 141 female) using Doppler and Duplex ultrasound of the extracranial arteries. Patients' history was obtained by standard questionnaire and by the hospital case records. Genomic DNA was analyzed by polymerase chain reaction (PCR) to identify the I/D polymorphism, with a second insertion specific PCR in samples classified as homozygous DD genotypes to prevent mistyping. The ACE genotype groups (DD 132, ID 164, II 92) were well matched for the basic characteristics. The DD genotype was more common in patients with extracranial artery stenosis > or = 50%, compared with patients without stenosis (59/147 versus 73/241, odds ratio 1.54, 95%-CI 1.01-2.37), but was not associated with a history of stroke (30/91 versus 102/297, odds ratio 0.94, 95%-CI 0.57-1.54). The association of the DD genotype with extracranial artery stenosis was also present in hypertensive subjects (n = 206, odds ratio 1.76, 95%-CI 0.99-3.17). In the whole group multiple logistic regression analysis revealed that the association of the DD genotype with extracranial artery stenosis was independent of age, gender, hypertension, hyperlipidemia, and diabetes. In conclusion, the ACE DD genotype is a weak risk factor for hemodynamically relevant stenosis of extracranial arteries, but not for stroke.

Angiotensin-converting enzyme gene polymorphism and reversibility of uremic left ventricular hypertrophy following long-term antihypertensive therapy

BACKGROUND

Prolonged antihypertensive therapy might be less effective in reversing the left ventricular hypertrophy (LVH) in uremics bearing the deleted (DD) allele of the angiotensin converting enzyme (ACE) gene than in patients with the inserted (II) allele or in those heterozygous (ID) for the gene.

METHODS

Thirteen DD and 17 II + ID hemodialyzed uremics were followed-up with yearly echocardiography and 24-hour blood pressure (BP) monitoring over five years while on an antihypertensive therapy that included ACE inhibitors as first line drugs.

RESULTS

In the II + ID group there were significant decreases of the left ventricular mass index (LVMi) and of both systolic and diastolic BPs. These changes were less pronounced in the DD group, but the difference was not statistically significant given the wide overlap between the two groups. Further analysis of the data revealed that the only factor associated to a decreased LVMi was the decrease of the systolic BP irrespective of the ACE gene genotype of each individual patient.

CONCLUSIONS

The ACE-gene genotype does not necessarily predict the extent to which LVMi will be lowered by ACE-inhibitors therapy. The LVH of hypertensive uremics is amenable by long-term antihypertensive therapy provided that it results in significantly decreased systolic blood pressure.

Relation between severity of coronary artery disease, left ventricular function and myocardial infarction, and influence of the ACE I/D gene polymorphism

Left ventricular (LV) systolic function is partly determined by severity of coronary artery disease and is improved by angiotensin-converting enzyme (ACE) inhibition, at least in post-infarct patients. Because the ACE insertion/deletion (I/D) gene polymorphism is associated with circulating and tissue ACE activity, we sought to evaluate the role of this genetic variant on LV function in patients studied with coronary angiography, taking into account coronary vessel anatomy and history of infarction. Coronary artery disease extent scores, coronary artery patency, and LV ejection fraction were assessed in 400 consecutive Caucasian patients referred for established or suspected ischemic heart disease. A previous infarction had occurred in 141 patients an average of 3.7 years before the study. The ACE DD genotype, compared with the ACE ID/II genotype, was associated with a 2.7% higher ejection fraction in noninfarct patients (p = 0.047) but a 5.0% lower ejection fraction in post-infarct patients (p = 0.047). An interaction effect between the ACE I/D gene polymorphism, the infarction status, and LV ejection fraction was observed in the whole population (p = 0.003), in patients with no disease and 1-, 2-, and 3-vessel diseases (p = 0.03 and p = 0.06, respectively), and in those with chronically occluded coronary vessels (p = 0.02). The influence of the ACE I/D gene polymorphism on LV function is modulated by infarction status and coronary anatomy.

Genetic determination of plasma aldosterone levels in essential hypertension

The renin-angiotensin-aldosterone system plays an important role in large artery structure and blood pressure homeostasis. Among the genes coding for different components of this system, the aldosterone synthase (CYP11B2) gene could play an important role, but has been less investigated. We examined the role of two variations of the aldosterone synthase gene (CYP11B2), one located in the promoter of the gene, T-344C, the other in the 7th exon, the T4986C (Val/Ala), on plasma levels of renin and aldosterone, blood pressure, and arterial stiffness in subjects with essential hypertension. Subjects of European origin (n = 216) were examined during a 1-day hospitalization. Treatment, if any, was interrupted for at least 21 days before. Arterial stiffness was evaluated by measuring pulse wave velocity. Renin and aldosterone levels were evaluated by using a radioimmunoassay. The two polymorphisms were in complete linkage disequilibrium, as suggested by the presence of only three haplotypes in this population (T-344T4986, T-344C4986, and C-344T4986). The mean age and blood pressure values were similar in the different genotypes. Presence of the -344C allele was associated with elevated levels of plasma aldosterone: 90 +/- 8 pg/mL for TT (n = 67), 110 +/- 6 pg/mL for TC (n = 107), and 129 +/- 10 pg/mL for CC (n = 42) (test of codominant effect, P < .002 after adjustment for age and 24-h Na+ urine excretion). Pulse wave velocity was also increased in the -344C allele carriers: 11.3 +/- 0.4 m/sec, 12.7 +/- 0.3 m/sec, 12.0 +/- 0.5 m/sec in the TT, TC, and CC genotypes, respectively. No association was found between the T4986C polymorphism and the studied variables. In patients with essential hypertension, a variant on the promoter region of the aldosterone synthase gene is associated with significant differences in plasma aldosterone levels and arterial stiffness. These differences are not associated with variations in blood pressure levels.

Insertion/deletion polymorphism in the angiotensin-converting enzyme gene is associated with atrial natriuretic peptide activity after exercise

An insertion/deletion polymorphism in the gene coding for the angiotensin-converting enzyme (ACE) is strongly associated with ACE activity. This polymorphism may be a marker for an increased risk for cardiovascular events. Our study examined a possible relationship between the D/I polymorphism and myocardial release of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). Ninety-six individuals with normal or impaired left ventricular function were included in the study. ANP and BNP plasma levels were measured at rest and after exposure to physical stress. At rest no association of ACE genotypes with ANP and BNP was found. After exercise homozygotes with the genotype DD had significantly higher ANP plasma levels than homozygotes with the genotype II. In contrast to ANP, BNP levels were not significantly different between genotype groups after exercise. Differences in site of production and mode of release between ANP and BNP might explain this difference. We hypothesize that our result might represent a variability gene effect of the ACE gene locus on endocrine processes in the heart during exposure to physical stress.

Angiotensin converting enzyme gene I/D polymorphism in essential hypertension and nephroangiosclerosis

An insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene significantly influences circulating ACE levels and plays a role in the development of target organ damage, that is, left ventricular hypertrophy in essential hypertension (EH), and microalbuminuria in diabetes mellitus. We have examined the role of the I/D polymorphism in essential hypertensive patients with renal involvement. The study was divided in two independent protocols. In protocol 1, we retrospectively analyzed the ACE genotypes in 37 essential hypertensive patients with a clinical and histopathological diagnosis of nephroangiosclerosis. In protocol 2, ACE genotypes as well as microalbuminuria and renal hemodynamic parameters were investigated in 75 patients with EH with normal renal function and a strong family history of hypertension. As control group, 75 healthy subjects with BP < 130/85 mm Hg and no family history of cardiovascular diseases were studied. The ACE variants were determined by PCR and the genotypes were classified as DD, DI and II. In protocol 1, patients with nephroangiosclerosis displayed a significant difference in the genotype distribution (57% DD, 27% DI, 16% II) when compared to the control population (25% DD, 64% DI, 11% II; P < 0.001). There was no significant difference in genotype distribution between hypertensive patients with normal renal function (protocol 2; 33% DD, 59% DI, 8% II) and the control group. There were no differences in age, blood pressure, microalbuminuria and duration of the disease among the three genotypes in the EH group from protocol 2. Taken together, these findings suggest that the DD genotype of ACE is associated with histopathologic-proven kidney involvement in patients with EH and that this polymorphism could be a potential genetic marker in hypertensives at risk of renal complications.

Angiotensin-1-converting enzyme (ACE) gene polymorphism, plasma ACE levels, and their association with the metabolic syndrome and electrocardiographic coronary artery disease in Pima Indians

In Caucasian subjects, an insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with coronary artery disease (CAD) and fatal myocardial infarction. The underlying mechanism(s) of this association is not fully understood. Pima Indians have a low incidence of nonfatal and fatal CAD despite a high prevalence of diabetes. In Pima Indians, circulating ACE levels are related to ACE genotype, but the frequency of the D allele is significantly lower than in Caucasians. A lower frequency of the D allele may underlie a low risk of CAD in this population. We examined the relationship of the ACE genotype and plasma ACE level with electrocardiographic evidence of CAD (Tecumseh criteria), hypertension, and metabolic variables associated with insulin resistance in 305 (146 men and 159 women aged 47+/-9.0 years) Pima Indians characterized for the ACE I/D genotype. The distribution of ACE genotypes was unrelated to diabetes and obesity. Fasting plasma insulin, plasminogen activator inhibitor-1 (PAI-1) activity, plasma triglyceride concentrations, and systolic (SBP) and diastolic (DBP) blood pressure were not significantly different between the three ACE genotypes among nondiabetic and diabetic subjects. There was no significant association of ACE genotype with electrocardiographic evidence of CAD or with hypertension. Plasma ACE concentrations were not significantly different between nondiabetic and diabetic subjects (median, 77 [range, 21 to 1691 v 83 [7 to 238] IU/mL, P=NS). In all subjects, plasma ACE levels were associated weakly with plasma triglyceride (partial r=.20, P < .01) and total cholesterol (partial r=.13, P <.03) concentrations, but not with fasting plasma insulin or PAI-1 activity. In diabetic subjects, ACE levels were related to fasting plasma glucose concentrations (partial r=.15, P=.07). These findings would suggest that ACE gene I/D polymorphism is unlikely to be a major determinant of susceptibility to CAD in Pima Indians. Plasma ACE levels, but not ACE genotype, correlated with lipids, plasma glucose, and blood pressure, suggesting that elevated plasma ACE levels may contribute to the link between insulin resistance and CAD disease or may be a consequence of it.

Molecular genetics of congestive heart failure

The manifestation of congestive heart failure occurs secondary to a great variety of cardiac or systemic disorders that share a temporal or permanent loss of cardiac function. In order to enhance our knowledge about the genetics of heart failure it is mandatory to analyse the aetiologic factors of these underlying disorders separately. Monogenic forms of congestive heart failure have initially been described by observant physicians in consecutive generations of affected families. Molecular genetic analyses of these families subsequently allowed us to localise and identify some of the genes that cause hypertrophic, dilative, or restrictive cardiomyopathies, congenital heart disease, as well as a number of inborn errors of metabolism. However, the great majority of patients develops heart failure as a final consequence of multifactorial conditions such as hypertension, cardiac hypertrophy, or coronary artery disease. Each of these conditions may be the product of a complex equation that includes environmental and genetic factors. Indeed, some of these factors may be harmful, others protective and for most it takes decades before a phenotype will be clinically detectable. Given this complex scenario it was not unexpected that early studies on candidate genes came up with partially controversial information. This review aims to summarize and to comment on the principal findings of this work.

Insertion/deletion polymorphism of the angiotensin I-converting enzyme gene is associated with coronary artery plaque calcification as assessed by intravascular ultrasound

OBJECTIVES

We evaluated the influence of the insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme (ACE) gene on coronary plaque morphology and calcification in patients with angiographically documented coronary artery disease (CAD).

BACKGROUND

The ACE I/D polymorphism has been associated with an increased risk of myocardial infarction in patients with the DD genotype but not with the presence of native CAD.

METHODS

We studied 146 patients undergoing percutaneous transluminal coronary angioplasty for stable angina pectoris by means of preinterventional intravascular ultrasound (IVUS). Qualitative and quantitative criteria were used to classify the target lesions as poorly or highly echoreflective or as calcified. Genomic deoxyribonucleic acid was analyzed by polymerase chain reaction (PCR) to identify the I/D polymorphism, with a second insertion-specific PCR in DD genotypes to prevent mistyping.

RESULTS

The ACE genotype groups (DD 46, ID 68, II 32) were well matched for the basic characteristics. Patients with the DD genotype had significantly more calcified lesions (DD 80%, ID 57%, II 66%; unadjusted odds ratio [OR] 2.88, 95% confidence interval [CI] 1.30 to 6.92, p = 0.008) and more calcifications >180 degrees of the vessel circumference (DD 22%, ID 10%, II 6%; OR 2.80, 95% CI 1.05 to 7.63, p = 0.03). The prevalence of myocardial infarction was not significantly associated with coronary calcification (OR 1.44, 95% CI 0.72 to 2.88, p = 0.31).

CONCLUSIONS

Patients with CAD and the ACE DD genotype have a significantly higher incidence and greater extent of coronary lesion calcification, as determined by IVUS. This finding indicates that the ACE I/D gene polymorphism is related to the development or progression of atherosclerotic plaque calcification.

The deletion/insertion polymorphism of the angiotensin converting enzyme gene and cardiovascular-renal risk

OBJECTIVE

This meta-analysis attempted to derive pooled estimates for the associations between various cardiovascular-renal disorders and the deletion/insertion (D/I) polymorphism of the angiotensin converting enzyme (ACE) gene.

METHODS

Case-control studies were combined, using the Mantel-Haenszel approach. Joint P values for continuous variables were calculated by Stouffer's method. Continuous measurements reported in different units were expressed on a percentage scale using the within-study mean of the II genotype as the denominator.

RESULTS

The computerized database used for this analysis included 145 reports with an overall sample size of 49 959 subjects. Overall, possession of the D allele was associated with an increased risk of atherosclerotic and renal microvascular complications. In comparison with the II reference group, the excess risk in DD homozygotes (P < 0.001) was 32% for coronary heart disease (CHD; 30 studies), 45% for myocardial infarction (20 studies), 94% for stroke (five studies) and 56% for diabetic nephropathy (11 studies). The corresponding risk in DI heterozygotes amounted to 11% (P= 0.02), 13% (P= 0.02), 22% (P= 0.10) and 40% (P < 0.001), respectively. Hypertension (23 studies), left ventricular hypertrophy (five studies), hypertrophic or dilated cardiomyopathy (eight studies) and diabetic retinopathy (two studies) were not related to the DI polymorphism. Publication bias was observed for CHD, myocardial infarction and microvascular nephropathy, but not hypertension. In studies with DNA amplification in the presence of insertion-specific primers, the risk associated with the DD genotype increased to 150% [95% confidence interval (CI) 76-256; four studies] for diabetic nephropathy, but decreased to 12% (95% CI -3 to 28; seven studies) for CHD and 14% (95% CI -6 to 37; four studies) for myocardial infarction. On the other hand, the pooled odds ratios did not materially change if the meta-analysis was limited to articles published in journals with an impact factor of at least 4. Furthermore, compared with the II control group, the circulating ACE levels (29 studies) were raised 58 and 31% (P < 0.001) in DD and DI subjects, respectively. In contrast, plasma renin (10 studies), systolic and diastolic blood pressure (46 studies) and body mass index (30 studies) were not associated with the D allele.

CONCLUSION

The D allele is not associated with hypertension, but behaves as a marker of atherosclerotic cardiovascular complications and diabetic nephropathy. These associations do not necessarily imply a causal relationship and may have been inflated by publication bias. Nevertheless, their possible therapeutic implications may be subject to further investigation in prospective (intervention) studies.

Pressure overload per se rather than cardiac angiotensin converting enzyme activity may be important in the development of rat cardiac hypertrophy

OBJECTIVE

To investigate the roles of the renin-angiotensin system and blood pressure in cardiac hypertrophy caused by a pressure overload.

METHODS

Cardiac hypertrophy was induced by constricting the abdominal aorta above the renal arteries. After they had been banded, the rats were treated with the lower (1 mg/kg per day) or the higher (10 mg/kg per day) dose of quinapril [an angiotensin converting enzyme (ACE) inhibitor], or the lower (1 mg/kg per day) or the higher (10 mg/kg per day) dose of TCV-116 [an angiotensin II (AngII) AT1 receptor antagonist], for 4 weeks. Then, we measured the mean blood pressure (MBP), body weight, left ventricular weight (LVW), and serum and cardiac ACE activities.

RESULTS

The higher dose of quinapril and that of TCV-116 prevented left ventricular hypertrophy and MBP elevation. Both the higher and the lower doses of quinapril reduced the serum and cardiac ACE activities significantly, whereas the higher dose of TCV-116 reduced the cardiac ACE activity and increased the serum ACE activity. The lower dose of quinapril, however, exerted no significant effect on MBP and the LVW:body weight ratio, although it reduced the cardiac and serum ACE activities significantly. There was a significant positive correlation between the MBP and the LVW:body weight ratio regardless of the cardiac ACE activity in data from all groups (r = 0.676, P < 0.0001).

CONCLUSIONS

Our data indicate the importance of the blood pressure as a determinant of cardiac hypertrophy because inhibition of cardiac ACE activity alone without lowering of the blood pressure is insufficient to prevent cardiac hypertrophy. Our results suggest the presence of other pathways for AngII production not mediated by ACE, or growth factors other than AngII in pressure-overload cardiac hypertrophy.

Association of angiotensin I-converting enzyme gene polymorphism with myocardial ischemia and patency of infarct-related artery in patients with acute myocardial infarction

OBJECTIVES

We determined the influence of angiotensin I-converting enzyme (ACE) insertion (I)/deletion (D) polymorphism on the extent of myocardial ischemia in patients with acute myocardial infarction.

BACKGROUND

The I/D polymorphism, which in part controls plasma and tissue expression of ACE, has been implicated in predisposition to myocardial infarction and ventricular remodeling.

METHODS

I/D genotyping, predischarge adenosine-thallium-201 perfusion tomography and radionuclide angiography were performed in 113 patients (72 men, 41 women) with a diagnosis of acute myocardial infarction. A subgroup of 96 patients also underwent coronary angiography.

RESULTS

Genotypes DD, ID and II were present in 27, 56 and 30 patients, respectively. There was no significant difference in the baseline characteristics of patients, total creatine kinase, peak MB fraction, Killip class, mean ejection fraction or the number of diseased vessels in patients with the DD, ID or II genotype. However, the size of the total and the reversible perfusion defects was greater in those with DD than in those with ID or II genotype (total defect size [mean +/- SD] 33.7 +/- 22.5%, 29.5 +/- 19.2% and 22.2 +/- 16.0%, respectively [p = 0.022]; reversible defect size 18.0 +/- 16.0%, 12.1 +/- 11.6% and 8.2 +/- 7.8%, respectively [p = 0.006]). Occlusion of the infarct-related artery was also more common in patients with DD genotype (odds ratio 3.9, 95% confidence interval 1.4 to 11.0). Multivariate analysis showed that the I/D genotype was an independent predictor of perfusion defect size and patency of the infarct-related artery (p = 0.001).

CONCLUSIONS

DD genotype was associated with a larger ischemic defect and occlusion of the infarct-related artery. Patients with DD genotype, having a larger ischemic defect, are expected to be at a greater risk for subsequent cardiovascular events.

Genetic factors in lung disease. Part II: Lung cancer and angiotensin converting enzyme gene

The recent progress in molecular biology has led to the elucidation of pathogenesis of lung cancer. The development of a lung cancer requires multiple genetic changes, consisting of the activation of oncogenes, including the K-ras and myc genes, and of inactivation of tumour suppressor genes, including the Rb, p53 and CDKN2 genes. Knowing the specific genes undergoing such changes should be useful as biomarkers for the early detection of cells destined to become malignant. Moreover, such genetic changes could be targets of newly designed drugs and gene-based therapy. Although the angiotensin I-converting enzyme was originally discovered in equine plasma, it has been recognized in various organs and cells other than vascular endothelial cells. This enzyme is also known to have wide substrate specificity to many peptides. The definite roles of angiotensin converting enzyme (ACE) in the respiratory system are largely unknown. Recent progress in molecular biology of the ACE, however, gives us a good chance to look over the significance of ACE in respiratory diseases as well as cardiovascular disorders. In this review, we show the recent advances in the basic studies of the ACE and refer to its clinical application.

Effect of genotype on the angiotensin-converting enzyme mRNA level in human atria

1. To clarify the mechanism of the association between I/D polymorphism of the angiotensin-converting enzyme (ACE) gene and various cardiovascular disease, ACE mRNA levels in human atrial appendages were assessed in relation to the genotype of the ACE gene. 2. Angiotensin-converting enzyme mRNA levels were positively correlated with age and tended to show a positive correlation with mean pulmonary pressure (mPA). Multiple regression analysis indicated that age and mPA, but not the genotype of the ACE gene, were predictors of ACE mRNA levels in human atrial appendages. 3. The present study indicates that I/D polymorphism of the ACE gene is not simply reflected in ACE mRNA levels and that further study is needed to determine the mechanism of the association between this polymorphism and various cardiovascular diseases.

Large artery stiffness in hypertension

EFFECTS OF HYPERTENSION ON LARGE ARTERIES: The mechanical properties of large arteries make a major contribution to cardiovascular haemodynamics through the buffering of stroke volume and by propagation of the pressure pulse. A sustained increase in blood pressure often leads to stiffness of the large arteries, especially when other risk factors are present. The increased stiffness, in turn, aggravates hypertension by increasing systolic blood pressure and can induce cardiac hypertrophy and arterial lesions. Epidemiological studies strongly suggest that subjects with stiffer arteries have a high pulse pressure, and that stiffening of large arteries is associated with excess morbidity and mortality independently of other cardiovascular risk factors. ENVIRONMENTAL AND GENETIC FACTORS: Apart from high blood pressure and ageing, various environmental and genetic factors that influence the composition of the extracellular matrix of the arterial wall can increase arterial stiffness. Clinical studies suggest that the presence of some genotypes may be a particularly important risk marker for arterial stiffness, and may modulate the effects of hypertension, ageing and lipids on large arteries. EFFECTS OF ANTIHYPERTENSIVE DRUGS: The development of accurate, non-invasive methods has now made it possible to detect alterations of the large arteries. Among antihypertensive drugs, angiotensin converting enzyme inhibitors and calcium channel blockers have proved to be highly effective in improving large artery compliance, and have shown no adverse effects on metabolic factors that can alter arterial structure and function such as lipids, plasma glucose and insulin tolerance. Therefore these drugs may be particularly suitable for treating patients with increased arterial stiffness. Finally, a determination of genotypes may be helpful in the future in choosing antihypertensive therapy.

Associations between circulating components of the renin-angiotensin-aldosterone system and left ventricular mass

OBJECTIVE

Cardiac growth may be modulated in part by the trophic effects of neurohormones. The aim of the present study was to investigate the relation between the basal activity of the renin-angiotensin-aldosterone system and left ventricular mass.

DESIGN

A population based sample of 615 middle-age subjects was studied by standardised echocardiography; anthropometric measurements; and biochemical quantification of renin, pro-renin, angiotensinogen, angiotensin converting enzyme (ACE), and aldosterone.

RESULTS

Echocardiographic left ventricular mass index correlated significantly with arterial blood pressure, age, and body mass index. In addition, in men ACE activity was significantly related to left ventricular mass index in univariate (P = 0.0007) and multivariate analyses (P = 0.008). Men with left ventricular hypertrophy presented with significantly higher serum ACE concentrations than those with normal left ventricular mass index (P = 0.002). In both men and women serum aldosterone was strongly related to septal and posterior wall thickness. Furthermore, in women serum aldosterone was positively and independently associated with left ventricular mass index (P = 0.0001). This effect was most prominent in hypertensive women. Finally, women with left ventricular hypertrophy presented with significantly higher serum aldosterone (P = 0.01). No significant associations with left ventricular mass index were observed for angiotensinogen, renin, or pro-renin.

CONCLUSIONS

The data suggest that the variability of serum ACE or aldosterone, as occurred in this large population based sample, may contribute to the modulation of left ventricular mass.

Role of the renin-angiotensin system as a risk factor for control of morbidity and mortality in coronary artery disease

Coronary heart disease is a multifactorial disease, influenced by environmental and genetic factors. Experimental and clinical data show that the renin-angiotensin system has important indications in coronary artery disease by influencing progressive ventricular dilatation, ventricular function, and outcome. Angiotensin II may have direct toxic effects on myocardial cells, induce hypertrophy in noninfarcted areas, activate the sympathetic nervous system, stimulate fibroblast proliferation, vasoconstrict coronary vessels, increase left ventricular afterload, and impair diastolic relaxation. Associations between a polymorphism of the angiotensinogen gene and angiotensin-converting enzyme gene and the occurrence of myocardial infarction have been reported. Patients with the DD genotype (ACE gene) have higher plasma ACE and myocardial ACE activity. Preliminary data suggest that the DD genotype is associated with more progressive ventricular dilatation post myocardial infarction and with a greater response after ACE inhibition. The DD genotype is also associated with a higher incidence of left ventricular hypertrophy, which may have implications for the induction of hypertrophy in noninfarcted areas. Whatever the mechanisms, chronic ACE inhibition, started early after myocardial infarction, improves survival and reduces mortality and morbidity for major cardiovascular events.

Angiotensin-converting enzyme gene polymorphism in hypertensive individuals with parental history of stroke

BACKGROUND AND PURPOSE

It has been suggested that the insertion (I)/deletion (D) polymorphism of the angiotensin-converting enzyme (ACE) gene is an independent risk factor for coronary artery disease, but its relation to stroke has not yet been proven. We investigated an association of ACE gene polymorphism with parental history of stroke (PHS) in patients with hypertension.

METHODS

We studied 70 hypertensive patients (ambulatory blood pressure > 140/90 mm Hg; age, 59 +/- 11 years) with (n = 27) or without (n = 43) PHS, defined as either one or both parents having had a stroke before 60 years of age. The ACE genotype was analyzed by polymerase chain reaction.

RESULTS

Casual blood pressure and mean ambulatory blood pressure levels were not significantly different between patients with and without PHS. The incidence of left ventricular hypertrophy also did not differ significantly between the two groups. However, the frequency of the D allele was significantly higher in patients with PHS (0.72) than in patients without PHS (0.52) (chi 2 = 5.472, P = .019). The frequency of the DD genotype of the ACE gene was also significantly higher in patients with than in those without PHS (DD, 63.0%; ID, 18.5%; II, 18.5% versus DD, 32.6%; ID, 39.5%; II, 27.9%; chi 2 = 6.395, P = .041).

CONCLUSIONS

The DD genotype of the ACE gene is associated with PHS in patients with hypertension, which is independent of blood pressure levels or presence of cardiac hypertrophy.

Deletion polymorphism of the angiotensin-converting enzyme gene is independently associated with left ventricular mass and geometric remodeling in systemic hypertension

An insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with myocardial infarction, cardiomyopathy, and left ventricular (LV) hypertrophy. LV mass and geometry are related to cardiovascular morbidity and mortality. Two-dimensional directed M-mode echocardiograms and 24-hour ambulatory blood pressure monitoring were performed in 67 hypertensive subjects. Echocardiographic measurements were assessed in blinded fashion. LV mass index and relative wall thickness were calculated. ACE genotypes were determined by polymerase chain reaction amplification of deoxyribonucleic acid prepared from leukocytes, using primers that encompass the polymorphic segment. Systolic ambulatory blood pressure was higher in subjects with the II genotype. All other patient characteristics were similar across genotype groups. After adjustment for other covariables, the DD and ID genotypes were associated with significantly higher LV mass index than was the II genotype. Adjusted relative wall thickness was also higher in subjects with the DD genotype than in subjects with the ID and II genotypes. On multiple regression analysis, systolic ambulatory blood pressure, gender, body mass index, and the ACE genotype were each independently related to LV mass index (R2 = 0.53). Systolic ambulatory blood pressure, race, and ACE genotype were each independently related to relative wall thickness (R2 = 0.34). The ACE genotype explained an additional 3% and 4% of the variations of LV mass index and relative wall thickness, respectively. In conclusion, ACE polymorphism accounted for a small but statistically significant proportion of the variation in LV mass and geometry in our hypertensive subjects.

Genetic basis of left ventricular remodeling after myocardial infarction

The purpose of the present study was to assess whether the insertion (I)/deletion (D) polymorphism of the angiotensin converting enzyme (ACE) gene, and the polymorphism of angiotensinogen (AGT) gene with threonine (T) instead of methionine (M) at amino acid 235 in exon 2 (M235T) were associated with left ventricular dilatation after myocardial infarction. In 103 patients with myocardial infarction, the left ventricular (LV) end-diastolic volume index (EDVI) and the end-systolic volume index (ESVI) were assessed by echocardiography at two time points, namely at 7 +/- 4 days and at 3.9 +/- 1.3 months (mean +/- S.D.) after the infarction. The increases in the LVEDVI and LVESVI on the second echocardiogram were significantly higher in subjects with the DD and ID genotypes than in patients with the II genotype (P < 0.05 and P < 0.005, respectively). Multiple regression analysis revealed that the LVESVI at the first echocardiographic examination and the ACE I/D genotype were significant predictors of the LVEDVI and LVESVI at the second echocardiographic examination. However, the AGT M235T genotype was eliminated. In conclusion, the DD and ID genotypes of the ACE gene were significantly associated with the progression of the LVEDVI and LVESVI after myocardial infarction. The presence of the deletion allele of the ACE gene may be a risk factor of congestive heart failure after a myocardial infarction.