Angiotensin-converting enzyme inhibitors

Effect of different angiotensin-converting-enzyme inhibitors on mortality among elderly patients with congestive heart failure

BACKGROUND

Existing clinical trial data do not address whether all angiotensin-converting-enzyme (ACE) inhibitors are similarly beneficial in improving survival and reducing the rate of readmission among patients with congestive heart failure. We sought to answer this question using administrative databases from Canada's 3 most populous provinces.

METHODS

Using linked hospital discharge and prescription claims databases in Quebec, Ontario and British Columbia, we identified all patients 65 years or older who were admitted to hospital because of congestive heart failure between Jan. 1, 1998, and Mar. 31, 2002, and who had not been admitted for the same reason in the 3 years preceding the study period. We analyzed the association between the type of ACE inhibitor prescribed within 30 days after discharge and subsequent mortality using Cox proportional hazards models. We then adjusted for demographic, clinical, physician and hospital-related variables, with additional time-dependent variables representing current drug use and dosage. We chose ramipril as the reference category for comparison with the other ACE inhibitors because it has increasingly been prescribed to patients with congestive heart failure.

RESULTS

A total of 43 316 patients with congestive heart failure filled prescriptions for ACE inhibitors within 30 days after discharge from hospital. Demographic, clinical and prescription-related characteristics were similar among users of each type of ACE inhibitor. In the time-dependent model, the mortality associated with 5 ACE inhibitors was similar to that with ramipril: adjusted hazard ratios (and 95% confidence intervals [CIs]) were 0.95 (0.89-1.02) for lisinopril, 0.92 (0.85-1.00) for fosinopril, 0.99 (0.88-1.11) for quinapril, 0.90 (0.77-1.06) for perindopril and 1.00 (0.80-1.24) for cilazapril. However, use of enalapril or captopril was associated with higher mortality compared with ramipril: adjusted hazard ratios (and 95% CIs) were 1.10 (1.04-1.16) for enalapril and 1.13 (1.01-1.26) for captopril.

INTERPRETATION

When prescribing ACE inhibitors to patients, physicians should consider a possible 10%-15% increase in mortality with captopril and enalapril compared with ramipril among patients with congestive heart failure.

The antihypertensive effect of peptides: a novel alternative to drugs?

Many types of bioactive peptides that inhibit angiotensin I, angiotensin I converting enzyme (ACE) and Ang II type 1 receptor (AT1) in the cardiovascular system contribute to the prevention and treatment of hypertension. These inhibitory peptides are derived from many food proteins or artificial synthetic products. Further research examining the bioavailability of ACE inhibitory peptides will lead to the development of more effective ACE inhibitory peptides and foods. Our research also demonstrates that ACE inhibitory peptide LAP may lower blood pressure with no adverse effects.

[Ca2+]i and PKC-alpha are involved in the inhibitory effects of Ib, a novel nonpeptide AngiotensinII subtype AT1 receptor antagonist, on AngiotensinII-induced vascular contraction in vitro

The vasoactive peptide AngiotensinII (AngII) is an important factor in the cardiovascular system, exerting most of its effects through AngII receptor type 1 (AT1). Ib, a new nonpeptide AT1 receptor antagonist, has been observed to play a positive role in the treatment of hypertension in preclinical tests. In this study, the inhibitory effects of Ib on AngII-induced vascular contraction in vitro were investigated, and its molecular mechanisms were further explored. In endothelium-denuded aortic rings from rabbits, Ib produced a rightward shift in the concentration-response curve for AngII with a decrease in the maximal contractile response and the pD2' was 7.29. In vascular smooth muscle cells (VSMCs), the specific binding of [125I]AngII to AT1 receptors was inhibited by Ib in a concentration-dependent manner with IC50 value of 0.96nM. Ib could inhibit both AngII-induced Ca2+ mobilization from internal stores and Ca2+ influx. Moreover, the translocation of PKC-alpha stimulated by AngII was inhibited by Ib. Thus, the inhibitory effects of Ib might be related with the depression on AngII-induced increase in [Ca2+]i and translocation of PKC-alpha through blocking AT1 receptors.

Angiotensin-converting enzyme (ACE) inhibitors have different selectivity for bradykinin binding sites of human somatic ACE

The angiotensin-converting enzyme (ACE) has two natural substrates and two catalytic domains: one cleaving angiotensin I and one inactivating bradykinin. The aim of this study was to investigate the comparative binding affinity of ACE inhibitors for the two binding sites of human endothelial ACE. In vitro binding assays were performed to test the ability of bradykinin, angiotensin I, or various ACE inhibitors (enalaprilat, perindoprilat, quinaprilat, ramiprilat, and trandolaprilat) to displace a saturating concentration of [(125)I]351A, a radiolabeled lisinopril analogue, from ACE binding sites. The calculated IC(50) values for the ACE inhibitors were in the nanomolar range, while those for the natural substrates were in the micromolar range. The bradykinin/angiotensin I selectivity ratios calculated from double displacement experiments were: perindoprilat, 1.44; ramiprilat, 1.16; quinaprilat, 1.09; trandolaprilat, 1.08; enalaprilat, 1.00. The ACE inhibitors generally had higher affinity for the bradykinin than the angiotensin I binding sites, supporting the idea that these agents are primarily inhibitors of bradykinin degradation, and secondarily inhibitors of angiotensin II production. Perindoprilat had the highest selectivity for bradykinin versus angiotensin I binding sites, and enalaprilat has the lowest. These results indicate that there are differences in the affinity of ACE inhibitors toward sites for bradykinin degradation, which could lead to differences in efficacy in cardiovascular disease.

Chronic pretreatment of ACEI reduces no-reflow in patients with acute myocardial infarction treated with primary angioplasty

BACKGROUND

In animal models, pretreatment with angiotensin-converting enzyme inhibitor (ACEI) can reduce no-reflow. In the present study, we investigated whether pretreatment with ACEI may prevent no-reflow in patients who underwent primary coronary intervention for AMI.

METHOD AND RESULTS

A total of 259 consecutive patients who underwent primary angioplasty for a first AMI were studied. No-reflow was defined as a TIMI flow grade < 3. The no-reflow phenomenon was found in 33 of 259 patients. There were no significant differences in clinical characteristics between the patients with and without ACEI pretreatment. However, the 47 patients receiving chronic ACEI treatment before admission had lower incidence of the no-reflow than those without it (4.2 and 14.6%, p<0.05). Multivariable logistic regression analysis revealed that absence of ACEI pretreatment was a significant predictor of the no-reflow along with absence of preinfarction angina, complete occlusion of the culprit lesion, high-burden thrombus, ejection fraction on admission, number of Q-waves, absence of statin pretreatment, and anterior AMI.

CONCLUSION

Pretreatment with ACEI could preserve the microvascular integrity after acute myocardial infarction in humans.

Hereditary angioedema presenting in late middle age after angiotensin-converting enzyme inhibitor treatment

BACKGROUND

Angioedema due to Cl esterase inhibitor (CI-INH) deficiency may be hereditary (HAE), commonly first occurring in childhood, or acquired (AAE), with onset usually in middle age. Type I HAE exhibits low levels of functionally normal C1-INH. Dysfunctional Cl-INH typifies type II HAE. Patients with type I AAE have low levels of Cl-INH, Clq complement, and C4 complement. In type II AAE, there is immune blockade of C1-INH.

OBJECTIVE

To describe a man who first presented at the age of 52 years with type I HAE triggered by the administration of an angiotensin-converting enzyme (ACE) inhibitor.

METHODS

The patient had C1-INH levels, a complement profile, and a lack of underlying co-pathology that led to the diagnosis of type I HAE triggered by the administration of an ACE inhibitor.

RESULTS

The patient presented with life-threatening angioedema. His C4 complement and Cl-INH serum levels were below the reference ranges, and his C3 complement, total hemolytic complement assay, and Clq complement levels remained within the reference ranges. During the 10 years between his initial episode of angioedema and the second, he had not developed any secondary medical conditions, and he had been taking the ACE inhibitor lisinopril for 7 years.

CONCLUSION

Physicians must remain aware of the possibility of unmasking HAE in the adult and geriatric population with the common use of ACE inhibitors for the treatment of hypertension, cardiovascular diseases, and metabolic diseases.

ANG II provokes acute trafficking of distal tubule Na+-Cl(-) cotransporter to apical membrane

The distal convoluted tubule (DCT) Na+-Cl(-) cotransporter (NCC), the target of thiazide diuretics, is responsible for the reabsorption of 5-10% of filtered NaCl. The aim of this study was to test the hypothesis that acute infusion of the angiotensin-converting enzyme (ACE) inhibitor captopril (at 12 microg/min) for 20 min provokes trafficking of NCC from apical plasma membranes (APM) to subapical cytoplasmic vesicles (SCV), which is reversed by acute ANG II infusion (ANG II at 20 ng.kg(-1).min(-1) along with 12 microg/min captopril) for 20 min in male Sprague-Dawley rats (250-350 g). By immuno-electron microscopy using an anti-NCC (D. Ellison) 71.5 +/- SD 4.9% of the NCC gold labeling was associated with the APM in control, sham operated, and infused rats, while captopril infusion reduced NCC in APM to 54.9 +/- 6.9% (P < 0.001) and markedly increased immunogold labeling of SCV. Subsequent infusion of ANG II with captopril restored NCC immunogold labeling of APM to 72.4 +/- 4.2%, that is, 20% of the total NCC trafficked between APM and SCV. Likewise, on density gradients of cortex, captopril provoked redistribution of 27.3% of total NCC from low-density APM-enriched membranes to higher-density membranes and ANG II+captopril restored 20.3% of the NCC to APM-enriched fractions. Redistribution occurred independent of a change in NCC total abundance. In conclusion, this study demonstrates that ACE inhibition provokes acute trafficking of NCC out of the plasma membrane, which likely decreases DCT Na+ reabsorption, while ANG II provokes rapid trafficking of NCC from stores in subapical vesicles to the plasma membrane, which likely increases DCT Na+ reabsorption.

Fixed-dose combination lercanidipine/enalapril

Lercanidipine, a dihydropyridine calcium channel blocker, and enalapril, an ACE inhibitor, are established antihypertensive agents. A fixed-dose tablet formulation of lercanidipine/enalapril is approved in Germany for the treatment of hypertension in patients not responding to monotherapy. Lercanidipine/enalapril 10mg/10mg once daily significantly reduced sitting diastolic blood pressure and sitting systolic blood pressure, relative to lercanidipine 10mg once daily, in a 12-week, randomised, double-blind trial in patients with mild to moderate hypertension who had previously not responded to 4 weeks' treatment with lercanidipine. In a similarly designed trial, lercanidipine/enalapril 10mg/20mg once daily was significantly more effective than enalapril 20mg once daily in hypertensive patients who had previously not responded to enalapril monotherapy. Fixed-dose lercanidipine/enalapril was generally well tolerated, with a tolerability profile similar to that of either of the individual drugs alone or placebo. Cough was reported in <or=5.2% and peripheral oedema in <or=1.5% of lercanidipine/enalapril recipients.

Milk peptides and blood pressure

Epidemiological studies suggest that milk consumption and dietary intake of dairy proteins are inversely related to the risk for hypertension. Also, some intervention studies have shown a blood pressure-lowering effect of milk products and dairy proteins. Milk peptides are formed from milk proteins by enzymatic breakdown by digestive enzymes or by the proteinases formed by lactobacilli during the fermentation of milk. Several milk peptides have been shown to have antihypertensive effects in animal and in clinical studies. The most studied mechanism underlying the antihypertensive effects of milk peptides is inhibition of angiotensin-converting enzyme. Milk peptides may also have other additional mechanisms to lower blood pressure such as opioid-like activities and mineral-binding and antithrombotic properties. The future challenge is to identify the antihypertensive components in milk and their mechanisms of action and thus to find more possibilities for using these constituents and products as a dietary treatment of hypertension.

The role of the renin-angiotensin system and oxidative stress in spontaneously hypertensive rat mesenteric collateral growth impairment

Recent clinical and animal studies have shown that collateral artery growth is impaired in the presence of vascular risk factors, including hypertension. Available evidence suggests that angiotensin-converting enzyme inhibitors (ACEI) promote collateral growth in both hypertensive humans and animals; however, the specific mechanisms are not established. This study evaluated the hypothesis that collateral growth impairment in hypertension is mediated by excess superoxide produced by NAD(P)H oxidase in response to stimulation of the ANG II type 1 receptor. After ileal artery ligation, mesenteric collateral growth did not occur in untreated, young, spontaneously hypertensive rats. Significant luminal expansion occurred in collaterals of spontaneously hypertensive rats treated with the superoxide dismutase mimetic tempol, the NAD(P)H oxidase inhibitor apocynin, and the ACEI captopril, but not ANG II type 1 (losartan) or type 2 (PD-123319) receptor blockers. The ACEI enalapril produced equivalent reduction of arterial pressure as captopril but did not promote luminal expansion. This suggests the effects of captopril on collateral growth might result from its antioxidant properties. RT-PCR demonstrated that ANG II type 1 receptor and angiotensinogen expression was reduced in collaterals of untreated rats. This local suppression of the renin angiotensin system provides a potential explanation for the lack of effect of enalapril and losartan on collateral growth. The results demonstrate the capability of antioxidant therapies, including captopril, to reverse impaired collateral artery growth and the novel finding that components of the local renin angiotensin system are naturally suppressed in collaterals.

Effects of prolonged angiotensin-converting enzyme inhibitor treatment on amyloid beta-protein metabolism in mouse models of Alzheimer disease

Genetic and pathologic studies have associated angiotensin-converting enzyme (ACE) with Alzheimer disease. Previously, we and others have reported that ACE degrades in vitro the amyloid beta-protein (Abeta), a putative upstream initiator of Alzheimer disease. These studies support the hypothesis that deficiency in ACE-mediated Abeta proteolysis could increase Alzheimer disease risk and raise the question of whether ACE inhibitors, a commonly prescribed class of anti-hypertensive medications, can elevate Abeta levels in vivo. To test this hypothesis, we administered the ACE inhibitor captopril to two lines of APP transgenic mice harboring either low levels of Abeta or high levels of Abeta with associated plaque deposition. In both models, we show that captopril does not affect cerebral Abeta levels in either soluble or insoluble pools. Furthermore, we find no change in plaque deposition or in peripheral Abeta levels. Data from these Alzheimer models suggest that captopril and similar ACE inhibitors do not cause Abeta accumulation in vivo.

Acidity, lipophilicity, solubility, absorption, and polar surface area of some ACE inhibitors

Computational chemical methods have been used to correlate the molecular properties of the 10 ACE inhibitors (captopril, enalapril, perindopril, lisinopril, ramipril, trandolapril, quinapril, fosinopril, benazepril, and cilazapril) and some of their active metabolites (enalaprilat, perindoprilat, ramiprilat, trandolaprilat, quinaprilat, fosinoprilat, benazeprilat, and cilazaprilat). The computed pK a values correlate well with the available experimental values. In the dicarboxylic ACE inhibitors, the carboxyalkyl carboxylate group of the ACE inhibitors studied is more acidic than the C-terminal carboxylate. However, at physiological pH = 7.4 both carboxyl groups of ACE inhibitors are completely ionized and the dicarboxyl-containing ACE inhibitors behave as strong acids. The available experimental partition coefficients of these ACE inhibitors investigated are well reproduced by the neural network-based ALOGPs and the fragment-based KoWWiN methods. All parent drugs (and prodrugs), with the exception of fosinopril, are compounds with low lipophilicity. Calculated pK a, lipophilicity, solubility, absorption, and polar surface area of the most effective ACE inhibitors for the prevention of myocardial infarction, perindopril and ramipril, were found similar. Therefore, it is probable that the experimentally observed differences in the survival benefits in the first year after acute myocardial infarction in patients 65 years of age or older correlate closely to the physicochemical and pharmacokinetic characteristics of the specific ACE inhibitor that is used.

Antifibrotic effect of captopril and enalapril on paraquat-induced lung fibrosis in rats

Although different treatment modalities have been implemented for pulmonary fibrosis, the results have not been promising and these conditions have been considered untreatable and irreversible. Thus, a plethora of new drugs has been tried for the control of this condition in recent years. This study examined the effects of two angiotensin-converting enzyme inhibitors, captopril and enalapril, on paraquat-induced pulmonary fibrosis in rats, through biochemical and histopathological parameters. Male albino Wistar rats were divided into eight groups (n = 4-5 each), including control, paraquat, captopril alone, captopril treatment and pre-treatment, enalapril alone, enalapril treatment and pre-treatment. After 21 days of treatment, the lungs were removed and the levels of hydroxyproline, glutathione and lipid peroxidation were determined. Angiotensin-converting enzyme inhibitors showed no effect on glutathione and lipid peroxidation. The results also demonstrated that captopril and enalapril improved pulmonary fibrosis as shown by histopathology, as well as a decreased content of hydroxyproline (P < 0.001) in the lung tissue. In conclusion, the present findings suggest that the antifibrotic effect of these drugs may be related to the inhibition of angiotensin-converting enzyme.

Inhibition of angiotensin-converting enzyme activity by a partially purified fraction of Gynura procumbens in spontaneously hypertensive rats

OBJECTIVES

To investigate the hypotensive and angiotensin-converting enzyme (ACE) inhibitory activities of a partially purified fraction (FA-I) of the leaves of Gynura procumbens and to qualitatively analyse the putative compounds present in the fraction.

MATERIALS AND METHODS

The hypotensive effect of FA-I was tested in both spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) by an intravenous administration of 0-10 mg/kg of the FA-I. Administration of captopril (20 microg/kg) served as the control. In vitro 0.0-2.0 mg/ml FA-I was added to a mixture of ACE and hippuryl-L-histidyl-L-leucine and assayed by a modification of the colourimetric method of Hurst and Lovell-Smith. All blood pressure measurements were monitored by the Macintosh MacLab set-up. ACE activity was measured by an in vitro assay in which the enzymatic cleavage of hippuryl-L-histidyl-L-leucine to form histidyl-leucine and hippurate was determined colourimetrically by a cyanuric chloride/dioxane reagent.

RESULTS

The FA-I produced a marked dose-dependent reduction in mean arterial pressure (MAP) in SHR and WKY rats, with an ED(50) of 1.09 and 1.05 mg/kg, respectively (p < 0.01). Furthermore, FA-I at 10 mg/kg strongly inhibited the angiotensin I-induced rise in MAP (p < 0.01). This response was comparable to that of captopril at 20 microg/kg. In the in vitro assay, ACE activity was inhibited with an IC(50) of 0.8 mg/ml. The qualitative phytochemical analysis of FA-I indicated the presence of glycoconjugates and peptides.

CONCLUSION

These results suggest that the hypotensive effect of G. procumbens may be due, in part, to the glycoconjugated or peptidal substances found in FA-I that exhibit an inhibitory effect on ACE.

Optimal medical management of peripheral arterial disease

Patients with peripheral vascular disease are less likely to receive optimal medical management than patients with coronary artery disease. However, early medical treatment is critical because it is profoundly beneficial and the benefits are maximized. Even in patients with advanced disease requiring invasive intervention, medical management has been proven to improve outcome, prolong the success of the intervention, improve functional capacity, and prolong life. The vascular surgeon should be knowledgeable enough to initiate basic medical therapy and to define for their patients the goals that need to be met to optimize their medical management. The vascular surgeon should be instrumental in assuring that the peripheral vascular patient receives medical therapy of the same standard as the patient with coronary disease. The major modifiable risk factors in the vascular patient are: smoking, high blood pressure, hyperlipidemia, physical inactivity, obesity, and diabetes. In addition, the use of beta blockers for patients with coronary disease and antiplatelet therapy as well as angiotensin-converting enzyme (ACE) inhibitors are recommended for all patients with peripheral vascular disease. Statins have favorable effects on multiple interrelated aspects of vascular biology important in atherosclerosis. In particular they have beneficial effects on inflammation, plaque stabilization, endothelial dysfunction, and thrombosis. Statins have also been shown to be beneficial in acute vascular events. Angiotensin-converting enzyme inhibitors have been shown to reduce cardiovascular morbidity and mortality in patients with peripheral arterial disease regardless of the presence or absence of hypertension. A number of the pleiotropic effects of statins are shared by ACE inhibitors. In summary, patients with known vascular disease should be treated aggressively with a combination of a HMG CoA reductase inhibitor, an angiotensin-converting enzyme inhibitor, an antiplatelet agent and a beta blocker if there is a history of coronary disease. They should also receive tight control of their blood pressure and blood sugar. Smokers should be encouraged to stop smoking and should be provided with pharmaceutical and emotional support by their physicians. All of these patients should have their body mass index as close to normal as possible and be on a therapeutic lifestyle diet. Regular aerobic exercise is also indicated. Patients with symptomatic claudication should be considered for cilostazol. Patients with multiple risk factors for vascular disease, but who do not have documented disease should also be on statin therapy. As more studies define the linear relationship between lower LDL-C levels and lowered risk of vascular events, indicating that the lower the LDL-C level, the lower the risk, experts are advocating more aggressive lipid-lowering therapy. In patients with peripheral arterial disease, some experts now advocate lowering the goal of LDL therapy to 70 mg/dL.

Rapid onset of haemodynamic effects after angiotensin converting enzyme-inhibitor overdose: implications for initial patient triage

BACKGROUND

Angiotensin converting enzyme (ACE)-inhibitor overdose may result in severe hypotension. Existing data do not adequately deal with the likely onset of haemodynamic effects, which has implications for the appropriate duration of monitoring in the acute-care setting. Therefore, the relationship between the interval after an ACE-inhibitor overdose and onset of hypotension was examined.

METHODS

A retrospective case review of patients who attended our institution after an ACE-inhibitor overdose between 1 January 2000 and 31 December 2005 was carried out. Data collected were heart rate, blood pressure, electrolytes, electrocardiogram variables, and interval between ingestion and lowest recorded blood pressure.

RESULTS

33 patients (24 men) who presented after an ACE-inhibitor overdose were identified. Median (interquartile range (IQR)) age was 49 (42-56) years, and stated quantity ingested was 20 (7-42) times the defined daily dose. The median (IQR) interval between ACE-inhibitor ingestion and lowest recorded systolic blood pressure was 4.5 (3.8-5.5) h, diastolic blood pressure was 3.8 (3.3-6.5) h and mean blood pressure was 4.2 (3.5-5.5) h. Heart rate did not increase substantially in response.

CONCLUSION

The lowest blood pressure was recorded within a short interval after an ACE-inhibitor overdose, irrespective of therapeutic intervention. Patients in whom hypotension has not occurred within 6 h of ingestion can be considered for discharge.

Redefining the ACE-inhibitor dose-response relationship: substantial blood pressure lowering after massive doses

OBJECTIVES

The blood pressure-lowering dose-response relationship for angiotensin converting enzyme (ACE) inhibitors is assumed to flatten at doses higher than those conventionally used in clinical practice. However, existing clinical trial data do not adequately address the haemodynamic effects of high ACE inhibitor dosages. Therefore, we examined the blood pressure responses in patients presenting to hospital following a deliberate ACE inhibitor overdose.

METHODS

The study design was a retrospective case review, and included all patients who presented to our hospital in the past 5 years after an ACE inhibitor overdose. The data collected were heart rate and systemic blood pressure at various times after ingestion and maximum haemodynamic derangement; these were compared to baseline or recovered values.

RESULTS

Data from 33 patients (24 men) were evaluated. The median (inter-quartile range, IQR) age of the patients was 49 years (IQR: 42-56 years). The median stated dose ingested was 140 mg (IQR: 60-280 mg), which is 20x (IQR: 7-42) the defined daily dose. The maximum fall in systolic blood pressure was 50 mmHg (IQR: 40-64 mmHg), diastolic blood pressure was 35 mmHg (IQR: 26-43 mmHg) and mean blood pressure was 39 mmHg (IQR: 30-47 mmHg).

CONCLUSIONS

The observed reduction in blood pressure following an overdose of an ACE inhibitor was greater than anticipated based on data from therapeutic doses. We conclude that a blood pressure-lowering dose-response relationship extends to higher ACE inhibitor doses than those conventionally used in clinical practice.

Improvements in clinical outcomes with the use of angiotensin-converting enzyme inhibitors: cross-fertilization between clinical and basic investigation

The expanding clinical indications for the use of angiotensin-converting enzyme (ACE) inhibitors during the past three decades to reduce cardiovascular morbidity and mortality across a broad spectrum of cardiovascular diseases have been the consequence of impressively productive interchanges between basic science and clinical medicine. In some areas, the initial discovery from animal investigations produced the hypotheses that were confirmed and expanded in patients with specific disease processes. In the development of ACE inhibitors, there are also important examples where an unexpected discovery from clinical trials spurred a host of laboratory investigations that uncovered novel mechanisms to underpin the clinical observations. Although developed as an antihypertensive agent, these effective interchanges, termed “translational research,” have collectively produced convincing data to demonstrate that ACE inhibitors can and should be used to slow progression of renal disease, prevent and treat heart failure, attenuate adverse left ventricular remodeling after myocardial infarction and improve prognosis, reduce atherosclerotic complications in patients with coronary artery disease, and, even more recently, reduce the incidence of Type II diabetes.

Atorvastatin and quinapril inhibit blood coagulation in patients with coronary artery disease following 28 days of therapy

BACKGROUND

We evaluated the antithrombotic effects of statins and angiotensin-converting enzyme inhibitor (ACEI) drugs in patients with coronary artery disease (CAD).

METHODS AND RESULTS

Blood coagulation at the site of microvascular injury was assessed in 26 males with CAD before and after treatment with quinapril (10 mg day-1; n=13) or atorvastatin (40 mg day-1; n=13) for 4 weeks and an additional 4 weeks of combined therapy (quinapril+atorvastatin). Rates of prothrombin and factor V activation (FVa), fibrinogen (Fbg) cleavage and FVa inactivation showed that both quinapril and atorvastatin decreased the rates of: formation of thrombin B-chain (by 30.6%, P=0.007; and by 34.3%, P=0.003), formation of thrombin-antithrombin complexes (by 30.4%, P=0.0002; and by 40%, P=0.001), FV activation (by 19.1%, P=0.03; and by 21.8%, P=0.005) and Fbg depletion (by 29.2%, P=0.004; and by 32.7%, P=0.001). Atorvastatin alone accelerated FVa inactivation (P=0.005). A further 4 weeks of combined therapy enhanced most anticoagulant effects only when atorvastatin was added to quinapril.

CONCLUSIONS

In CAD patients, atorvastatin and quinapril slowed blood clotting at the site of microvascular injury after 28 days of therapy. Addition of atorvastatin to quinapril, but not quinapril to the statin, enhanced the anticoagulant effects. Our findings might help explain the reduced risk of myocardial infarction or stroke in patients treated with statins and/or ACEIs and the lack of clinical benefits from ACEI added to prior statin therapy in patients at cardiovascular risk.

Kinin-dependent hypersensitivity reactions in hemodialysis: metabolic and genetic factors

Although the association of angiotensin I-converting enzyme inhibitors (ACEis) with a negatively charged membrane is thought to be responsible for hypersensitivity reactions (HSRs) during hemodialysis, we hypothesize that these complications are due to changes in plasma aminopeptidase P (APP) activity and genotype. To test this hypothesis, we measured plasma APP activity in 14 patients who suffered HSR (HSR+) while dialyzed with an AN69 membrane and simultaneously treated with an ACEi. APP activity was also studied in a control group (n=39) dialyzed under the same conditions, but who did not suffer any side effect (HSR-). We found significantly decreased plasma APP activity (P=0.013) in HSR+ subjects as well as altered degradation of endogenous des-Arginine(9)-bradykinin, with a significantly lower beta value (P<0.001). The same analytical approach was taken in 171 relatives of HSR+ patients. Variance component analysis suggested that genetic differences may explain 61% of the phenotypic variability of plasma APP activity (P<0.001) and the kinetic parameters that characterized kinin degradation. We also showed that the C-2399A single-nucleotide polymorphism at the XPNPEP2 locus was a significant predictor of APP activity in the 39 HSR- controls (P=0.029). Furthermore, a recessive genetic model for the A allele disclosed a significant difference in mean APP activity by genotype (P<0.001). Finally, our study defined the nonspecific inhibition of recombinant APP by some ACEis. In conclusion, this paper highlights the complexity of HSR in hemodialysis, suggesting, as with angioedema, that these rare, but life-threatening adverse events are governed by several metabolic and genetic factors.

Identification and Characterization of Novel Angiotensin-Converting Enzyme Inhibitors Obtained from Goat Milk

The aim of the present study was to identify and characterize new inhibitory peptides of angiotensin I-converting enzyme (ACE) from goat milk and to analyze the effect of long-term intake of a goat milk hydrolysate-supplemented (GP-hyd) diet on the development of hypertension in spontaneously hypertensive rats (SHR). Three new inhibitory peptides for ACE (TGPIPN, SLPQ, and SQPK) were isolated. The inhibitory concentration 50% (IC50) values of individual peptides were 316, 330, and 354 micromol/L, respectively. Only TGPIPN was found to pass intact a monolayer of Caco-2 cells in small amounts. The SHR fed for 12 wk a diet (GP-hyd) enriched in a hydrolysate containing these peptides (estimated intake of TGPIPN was 230 mg/kg per d) showed lower (approximately 15 mmHg) systolic blood pressure than animals fed a control diet. The ACE activities in the aorta, left ventricle, and kidney were significantly decreased in the GP-hyd group compared with those of the control group and were similar to those found in SHR fed captopril (130 mg/kg per d). Impaired endothelium-dependent relaxation to acetylcholine by aortic rings from SHR was improved in those fed the GP-hyd diet. The left ventricle weight and kidney weight index were significantly reduced in the GP-hyd group and captopril groups. Moreover, long-term treatment of SHR with a diet enriched in goat milk hydrolysate, or captopril, attenuated the development of hypertension, cardiac and renal hypertrophy, and endothelial dysfunction. These effects might be related to the in vivo inhibitory effects of the hydrolysate on tissue ACE activity.

Cardiac Medical Therapy among Patients Undergoing Abdominal Aortic Aneurysm Repair

Open abdominal aortic aneurysm (AAA) repair is a common surgical procedure associated with high mortality rates. Our objective was to describe the use of in-hospital cardiac medical therapy among patients undergoing open AAA repair and to examine the effect of perioperative cardiac medical therapy on in-hospital mortality. We examined clinical data and in-hospital medication use among 223 patients who underwent open AAA repair at three North American hospitals, all of which used the Transition resource and cost accounting system. Medication use was described [angiotensin converting enzyme (ACE) inhibitors, aspirin, ss-blockers, and statins] within the cohort at five specific periods of time: presurgery, day of surgery, 1 day after surgery, postsurgery, and discharge. We then performed a matched case-control study where cases were defined as patients who died in-hospital. We compared medication use between cases and controls to assess its impact on in-hospital mortality. Most patients were elderly (mean age 72.5 +/- 9.8 years), 70.4% were male, and in-hospital mortality within the cohort was 10.8%. Medication use in all periods of administration was low. ss-Blocker use was highest among all classes on the day of surgery, with 20.6% of patients undergoing AAA repair receiving the medication. Less than 50% of patients received any of the medications at discharge. After adjusting for baseline differences, perioperative ACE inhibitor use showed a trend toward a protective effect [odds ratio (OR) = 0.09, 95% confidence interval (CI) 0.01-1.31, p = 0.08], and perioperative ss-blocker use was significantly associated with a decrease in mortality (OR = 0.07, 95% CI 0.01-0.87, p = 0.04). Cardiac medical therapy among patients undergoing AAA repair is low throughout all periods of hospitalization. ACE inhibitor and ss-blocker use may be associated with decreased in-hospital mortality.

Angiotensin-converting enzyme inhibitor-related angioedema: how to deal with it

Angiotensin-converting enzyme inhibitor-related angioedema is a well documented condition, which seems to occur in up to 1% of treated patients. It represents a problem for both the clinician and the patient: for the clinician, the diagnosis may be difficult due to its peculiar clinical characteristics, whereas for the misdiagnosed patient the delay prolongs a potentially dangerous situation. If the drug is not discontinued, the attacks tend to become worse and even life-threatening. There are now evidences that increased levels of bradykinin have an important role in the pathophysiology of attacks and, moreover, there are genetic factors that render certain individuals susceptible to angiotensin-converting enzyme inhibitor-related angioedema. In this review, the authors analyse the pathogenetic mechanism, the clinical presentation, the management and future perspectives of research on this condition.

Postexercise hypotension induced by low-intensity resistance exercise in hypertensive women receiving captopril

OBJECTIVE

The present study investigated the effect of a single bout of low-intensity resistance exercise on recovery blood pressure in hypertensive women receiving captopril.

METHODS

Twelve essential hypertensive women, who were receiving captopril, underwent two experimental sessions: control (C - 40 min of seated rest) and low-intensity resistance exercise (E - six resistance exercises, three sets, 20 repetitions, 40% of one repetition maximum). Clinic blood pressure was measured in the laboratory, before and for 120 min after exercise or rest. Moreover, ambulatory blood pressure was also measured for 21 h after exercise or rest.

RESULTS

Clinic blood pressures decreased significantly after exercise (systolic blood pressure =-12+ or -3 mmHg and diastolic blood pressure =-6+ or -2 mmHg, P<0.05), but not after rest. Mean awake blood pressures (systolic: C=132+ or -5 mmHg vs. E=125+ or -4 mmHg and diastolic: C=83+ or -3 mmHg vs. E=78+ or -2 mmHg, P<0.05) were significantly lower in the E than in the C session, while 21-h (systolic blood pressures: C=128+ or -5 mmHg vs. E=123+ or -4 mmHg; and diastolic blood pressures: C=80+ or -3 mmHg vs. E=76+ or -2 mmHg) and asleep (systolic blood pressures: C=120+ or -7 mmHg vs. E=118+ or -5 mmHg; and diastolic blood pressures: C=73+ or -4 mmHg vs. E=71+ or -3 mmHg) blood pressures did not differ between the experimental sessions. Moreover, there was a positive correlation between blood pressure measured in the C session and blood pressure reduction observed in the E session, showing that blood pressure decrease was greater when blood pressure level was higher.

CONCLUSION

In hypertensive women receiving captopril, a single bout of low-intensity resistance exercise reduces blood pressure. This reduction persists for 10 h, during the awake period, while patients were engaged in their daily living activities. It was greater in patients with higher ambulatory blood pressure.

Management of Perioperative Myocardial Infarction in Noncardiac Surgical Patients

Perioperative myocardial infarction (PMI) is a major cause of morbidity and mortality in patients undergoing noncardiac surgery. The incidence of PMI varies depending on the method used for diagnosis and is likely to increase as the population ages. Studies have examined different methods for prevention of myocardial infarction (MI), including the use of perioperative beta-blockers, alpha(2)-agonists, and statin therapy. However, few studies have focused on the treatment of PMI. Current therapy for acute MI generally involves anticoagulation and antiplatelet therapy, raising the potential for surgical site hemorrhage in this population. This article reviews the possible mechanisms, diagnosis, and treatment options for MI in the surgical setting. We also suggest algorithms for treatment.

Angiotensin type 1 and type 2 receptor blockade in chronic allograft nephropathy

Angiotensin-II (Ang-II) type 1 (AT(1)) receptor blockers may delay the progression of chronic allograft nephropathy (CAN). However, neither the optimal time for initiating AT(1) receptor blockade in order to delay CAN potentially nor the role of Ang-II type 2 (AT(2)) receptors under AT(1) receptor blockade is known. Both AT receptors can regulate p53 expression and apoptosis. We investigated what time of initiation with AT(1) blockers most effectively delayed CAN as well as the role of the AT(2) receptor, and how angiotensin receptor blockade affected apoptosis and its regulating factors in this context in a rat model. Kidneys of Fisher (F344) rats were transplanted into Lewis rats. Animals were treated with AT(1) (candesartan) and/or AT(2) (PD123319) receptor antagonists, a calcium channel blocker, or vehicle (treatment periods: day -7 before to week 24 after transplantation (long term), week 12 to week 24 (late), day -7 to day +5 (early)) and observed the animals for 24 weeks. Reduction of proteinuria, grade of CAN, and number of apoptotic cells was most pronounced in animals receiving long-term AT(1) receptor blockade. A combined AT(1)/AT(2) blocker treatment reduced CAN similarly to AT(1) blocker treatment alone. The number of apoptotic cells and the level of p53 mRNA were significantly lower in long-term AT(1) blocker-treated animals. In summary, AT(1) receptor blockade delayed the progression of CAN, particularly in animals treated long term. Reduction of apoptosis could be related to these beneficial effects. The AT(2) receptor does not appear to play an important role in CAN.

Pharmacological targets in the treatment of abdominal aortic aneurysms

The natural history of an abdominal aortic aneurysm (AAA) is of progressive aortic wall degeneration occurring over the course of many years, ultimately, culminating in loss of structural integrity and fatal aortic rupture. Although surgical exclusion of an aneurysm can effectively prevent aortic rupture in large aneurysms, small aneurysms are generally completely asymptomatic and are very unlikely to rupture. Further, AAA can be easily diagnosed with noninvasive testing; thus, small aneurysms present an excellent opportunity for disease-modifying pharmacological intervention. Research over the past two decades has defined many of the mechanisms which result in aortic matrix degeneration in both human tissue and particularly within animal models. This has resulted in the identification of several potential targets for pharmacological intervention. Drugs directed at inhibition of the inflammatory process and matrix degrading enzymes have been successful in multiple animal models, and early evidence now suggests that disease modification with some of these agents may be successful in slowing AAA growth in humans as well. The future of AAA therapy, however, may belong to agents which can induce aneurysm regression and to delivery methods which specifically target affected arterial tissue.

Synthesis and molecular modeling of a lisinopril-tryptophan analogue inhibitor of angiotensin I-converting enzyme

With a view to developing a more C-domain-selective angiotensin I-converting enzyme (ACE)-inhibitor, a novel analogue of lisinopril has been synthesized which incorporates a bulky P(2)(') tryptophan functionality. This inhibitor demonstrated a significantly increased specificity for the C-domain as compared with lisinopril. Molecular docking revealed hydrophobic and hydrogen-bonding interactions with residues of the C-domain S(2)(') subsite.

Development and validation of a liquid chromatographic/electrospray ionization mass spectrometric method for the determination of benazepril, benazeprilat and hydrochlorothiazide in human plasma

A new method was developed and fully validated for the quantitation of benazepril, benazeprilat and hydrochlorothiazide in human plasma. Sample pretreatment was achieved by solid-phase extraction (SPE) using Oasis HLB cartridges. The extracts were analysed by high-performance liquid chromatography (HPLC) coupled to a single-quadrupole mass spectrometer (MS) with an electrospray ionization interface. The MS system was operated in selected ion monitoring (SIM) modes. HPLC was performed isocratically on a reversed-phase porous graphitized carbon (PGC) analytical column (2.1 x 125.0 mm i.d., particle size 5 microm). The mobile phase consisted of 55% acetonitrile in water containing 0.3% v/v formic acid and pumped at a flow rate of 0.15 ml min(-1). Chlorthalidone was used as the internal standard (IS) for quantitation. The assay was linear over a concentration range of 5.0-500 ng ml(-1) for all the compounds analysed, with a limit of quantitation of 5 ng ml(-1) for all the compounds. Quality control (QC) samples (5, 10, 100 and 500 ng ml(-1)) in five replicates from three different runs of analyses demonstrated intra-assay precision (coefficient of variation (CV) < or =14.6%), inter-assay precision (CV < or = 5.6%) and overall accuracy (relative error less than -8.0%). The method can be used to quantify benazepril, benazeprilat and hydrochlorothiazide in human plasma, covering a variety of pharmacokinetic or bioequivalence studies.

Effects of ACE inhibition on proximal tubule sodium transport

Angiotensin-converting enzyme (ACE) inhibitors such as captopril, which block ANG II formation, are commonly used for treatment of hypertension. There is substantial evidence that the proximal tubule (PT) is a primary target site for captopril but the molecular mechanisms for its action in PT are not well defined. The aim of this study was to determine the physiological and molecular changes in PT provoked by acute captopril treatment in the absence of changes in blood pressure or glomerular filtration rate (GFR). Captopril (infused at 12 μg/min for 20 min) did not change blood pressure or GFR but induced an immediate (<10 min) increase in PT flow measured with a nonobstructive optical method (to 117 ± 14% of baseline) along with a rapid diuresis from 2.1 ± 0.6 mg/min (baseline) to 3.7 ± 0.9 mg/min (captopril). Captopril also provoked a significant retraction of PT Na+/H+exchanger isoform 3 (NHE3), NHE regulatory factor (NHERF)-1, myosin-VI, and Na+-Picotransporter type 2 (NaPi2), but not ACE, out of apical microvillus-enriched membranes. Proteomic analysis with MALDI-TOF MS revealed an additional eight abundant membrane-associated proteins that redistributed out of the microvillus-enriched membrane during captopril treatment: megalin, myosin II-A, clathrin, aminopeptidase N, DPPIV, ezrin, moesin, and vacuolar H+-ATPase subunit β2. In summary, captopril can rapidly depress PT reabsorption in the absence of a change in GFR or BP and provokes the redistribution of a set of transporters and transporter-associated proteins that likely participate in the decrease in PT reabsorption and may also contribute to the blood pressure-lowering effect of ACE inhibitors.

Exploring an Optimum Intra/Postoperative Management Strategy for Acute Hypertension in the Cardiac Surgery Patient

An estimated 50% of patients undergoing routine cardiac surgery require intravenous antihypertensive therapy to manage life-threatening arterial bleeding, myocardial ischemia, or cardiac failure in the perioperative period. Managing hypertension in this setting can be challenging because of the need to reduce blood pressure while maintaining adequate end organ perfusion. Hypotensive episodes can increase the risk of cardiac complications and end organ hypoperfusion, particularly in patients whose underlying cardiovascular disease has altered autoregulation of blood flow. To decrease the risk of hypertensive or hypotensive episodes, blood pressure is monitored continuously, and short-acting intravenous antihypertensive agents are administered in an effort to target a mean arterial pressure generally within 20% of the patient's baseline value. Efforts to optimize end organ perfusion and avoid recognized adverse drug effects may influence the choice of antihypertensive agents. The ideal agent for postoperative hypertension should have a rapid onset of action, be highly vascular selective, and be rapidly reversible. In addition, it should be safe, with little risk of overshoot hypotension or adverse drug reaction. Precise management of arterial pressure in the perioperative period has the potential to improve clinical outcome by avoiding hypotensive episodes, ensuring adequate end organ perfusion, decreasing the risk of adverse drug effects, and serving as a bridge to definitive long-term therapy for essential hypertension.

ACE inhibition in secondary prevention: are the results controversial?

Results from the HOPE and EUROPA trials showed that ACE inhibitors lower cardiovascular mortality of patients with atherosclerosis and preserved left ventricular function. However, despite apparently adequate study design, the recently conducted PEACE trial detected no benefit of an additional ACE inhibitor treatment in patients with coronary artery disease and no heart failure with respect to cardiovascular risk reduction. One of the main reasons for this discrepancy might be the lower cardiovascular baseline risk of the PEACE study population, which was more intensively treated with lipid lowering drugs and myocardial revascularization prior to enrollment than patients in HOPE or EUROPA. Another reason for the negative results of PEACE might be substance-specific differences between individual ACE inhibitors (trandolapril in PEACE, ramipril in HOPE, and perindopril in EUROPA) in their clinical efficacy to reduce cardiovascular end-points. The PEACE trial did not achieve the originally projected sample size and the addition of a soft end-point of revascularization has not been helpful. While the results from the PEACE trial suggest that low-risk patients with coronary artery disease and with preserved left ventricular function who receive intensive standard therapy including lipid lowering and coronary revascularization may not benefit from additional ACE inhibition therapy, this conclusion should be made with caution. A number of reasons, other than drug treatment efficacy, may explain the neutral results in the PEACE trial. Further studies are needed to try to resolve this issue. In the meantime, the overwhelming data still support the use of ACE inhibitors in patients with coronary artery disease with preserved left ventricular function.

Interplay between parasite cysteine proteases and the host kinin system modulates microvascular leakage and macrophage infection by promastigotes of the Leishmania donovani complex

Kinins, the vasoactive peptides proteolytically liberated from kininogens, were recently recognized as signals alerting the innate immune system. Here we demonstrate that Leishmania donovani and Leishmania chagasi, two etiological agents of visceral leishmaniasis (VL), activate the kinin system. Intravital microscopy in the hamster cheek pouch showed that topically applied promastigotes induced macromolecular leakage (FITC-dextran) through postcapillary venules. Peaking at 15 min, the parasite-induced leakage was drastically enhanced by captopril (Cap), an inhibitor of angiotensin-converting enzyme (ACE), a kinin-degrading metallopeptidase. The enhanced microvascular responses were cancelled by HOE-140, an antagonist of the B2 bradykinin receptor (B2R), or by pre-treatment of promastigotes with the irreversible cysteine proteinase inhibitor N-methylpiperazine-urea-Phe-homoPhe-vinylsulfone-benzene (N-Pip-hF-VSPh). In agreement with the above-mentioned data, the promastigotes vigorously induced edema in the paw of Cap-treated J129 mice, but not Cap-B2R-/- mice. Analysis of parasite-induced breakdown of high molecular weight kininogens (HK), combined with active site-affinity-labeling with biotin-N-Pip-hF-VSPh, identified 35-40 kDa proteins as kinin-releasing cysteine peptidases. We then checked if macrophage infectivity was influenced by interplay between these kinin-releasing parasite proteases, kininogens, and kinin-degrading peptidases (i.e. ACE). Our studies revealed that full-fledged B2R engagement resulted in vigorous increase of L. chagasi uptake by resident macrophages. Evidence that inflammatory macrophages treated with HOE-140 became highly susceptible to amastigote outgrowth, assessed 72 h after initial macrophage interaction, further suggests that the kinin/B2R activation pathway may critically modulate inflammation and innate immunity in visceral leishmaniasis.

The relationship between ACE insertion/deletion polymorphism and coronary artery disease with or without myocardial infarction

OBJECTIVES

Presence of the D allele or homozygosity for the deletion (D) allele of the angiotensicen-converting enzyme (ACE) insertion/deletion (I/D) polymorphism has been discussed as potent risk factor for coronary artery disease (CAD) and myocardial infarction (MI). The D allele is associated with higher levels of circulating ACE and therefore may predispose one to cardiovascular damage.

DESIGN AND METHODS

The study presented here was performed to investigate the association between the ACE genotype and ACE levels. The study group was comprised of 118 angiographically verified CAD patients. 65 patients were MI (+) and 53 patients were MI (-) in this group. A total of 70 healthy individuals were taken as controls. Genomic DNA of 188 subjects was extracted from whole blood. The polymerase chain reaction was used for ACE genotyping, and ACE levels were measured by ELISA.

RESULTS

The D allele was found to be significantly more frequent in patients with MI (+) compared with controls (P = 0.024). ACE levels were significantly higher in both MI (-) and MI (+) groups with CAD patients than in controls (P < 0.005). Plasma ACE level was higher in all three groups in the DD genotype compared to II genotype. In groups I and III, this was statistically significant (P < 0.0001, P < 0.01).

CONCLUSIONS

It was shown that the I/D polymorphism in the gene for ACE is a genetic risk factor for CAD patients who have a history of MI. ACE insertion/deletion gene polymorphism is also associated with plasma ACE levels in CAD patients with a history of MI.

Novel ketomethylene inhibitors of angiotensin I-converting enzyme (ACE): inhibition and molecular modelling

Inhibition of angiotensin I-converting enzyme (ACE) has become an effective strategy in the treatment of hypertension and cardiovascular disease. Keto-ACE, a previously described C-domain selective ACE inhibitor, was used as the basis for the design, synthesis and molecular modelling of a series of novel ketomethylene derivatives for which ACE inhibition profiles and structural characterisation are reported. Ki determinations indicated that the introduction of a bulky aromatic tryptophan at the P2' position of keto-ACE significantly increased selectivity for the C-domain, while an aliphatic P2 Boc group conferred N-domain selectivity. These data were supported by the potential energies of the compounds docked with the C- and N-domains of ACE.

Effects of angiotensin-converting enzyme inhibition on mitral regurgitation severity, left ventricular size, and functional capacity

BACKGROUND

Mitral regurgitation (MR) is a progressive disorder that leads to left ventricular (LV) dilatation and dysfunction. Previous small studies have shown conflicting results regarding the benefits of afterload reduction for MR.

METHODS

We assessed by serial echocardiography the effects of ramipril on MR severity and LV size by a number of quantitative methods in 26 asymptomatic patients with moderate to severe MR at baseline and again after 6 months of ramipril treatment. We also evaluated exercise capacity, neurohormonal levels, and the Minnesota Living With Heart Failure score.

RESULTS

Despite a significant reduction in blood pressure with ramipril, there was no change in MR severity. MR severity, as assessed by effective regurgitant orifice area, was reduced in individuals with baseline systolic blood pressure (SBP) > or = 140 mm Hg (55.1 +/- 26 vs 37.4 +/- 35.4 mm2, P = .03), but not in individuals with SBP < 140 mm Hg (39.7 +/- 37.7 vs 46.1 +/- 34.1 mm2, P = not significant). Neither LV cavity size, exercise capacity, nor the Minnesota Living With Heart Failure score exhibited a significant change.

CONCLUSIONS

Patients with MR do not experience significant changes in MR severity, LV size, or functional status after 6 months of treatment with angiotensin-converting enzyme inhibition. However, patients with SBP > or = 140 mm Hg represent a subgroup that shows reduction in MR. These data are consistent with current American College of Cardiology/American Heart Association guidelines, which reserve the use of afterload reduction for MR patients with systemic hypertension or LV dysfunction.

A variant in XPNPEP2 is associated with angioedema induced by angiotensin I-converting enzyme inhibitors

Angiotensin I-converting enzyme inhibitors (ACEi), which are used to treat common cardiovascular diseases, are associated with a potentially life-threatening adverse reaction known as angioedema (AE-ACEi). We have previously documented a significant association between AE-ACEi and low plasma aminopeptidase P (APP) activity. With eight large pedigrees, we hereby demonstrate that this quantitative trait is partially regulated by genetic factors. We tested APP activity using a variance-component QTL analysis of a 10-cM genomewide microsatellite scan enriched with seven markers over two candidate regions. We found significant linkage (LOD = 3.75) to a locus that includes the XPNPEP2 candidate gene encoding membrane-bound APP. Mutation screening of this QTL identified a large coding deletion segregating in one pedigree and an upstream single-nucleotide polymorphism (C-2399A SNP), which segregates in the remaining seven pedigrees. Measured genotype analysis strongly suggests that the linkage signal for APP activity at this locus is accounted for predominantly by the SNP association. In a separate case-control study (20 cases and 60 controls), we found significant association of this SNP to ACEi-induced AE (P=.0364). In conclusion, our findings provide supporting evidence that the C-2399A variant in XPNPEP2 is associated with reduced APP activity and a higher incidence of AE-ACEi.

Cardiac resynchronization--a heart failure perspective

Over the past 15-20 years the development of new heart failure pharmacologic therapy has lowered mortality by 30-40% for this serious and prevalent clinical syndrome, within clinical trials conducted in patients with a dilated cardiomyopathy phenotype. However, over the past 5 years progress in the development of additional effective drugs has slowed, in part due to the success of neurohormonal inhibitors, on which background new therapies must be developed. That there is not an absolute ceiling on the development of new heart failure therapies has been convincingly recently demonstrated in electrophysiologic device trials, conducted on the background of maximal neurohormonal inhibition. Two trials, COMPANION and CARE-HF, have demonstrated unambiguously that in advanced heart failure patients with a marker of mechanical intraventricular dyssynchrony, increased QRS duration, cardiac resynchronization therapy in the form of biventricular pacing can improve major clinical outcomes including mortality. In addition, COMPANION also demonstrated that the addition of an ICD further improved mortality reduction, by lowering the incidence of sudden death. These trials indicate that device/drug therapy is at least additive in the treatment of heart failure, and they herald a new era in the multi-modality approach to therapeutics.

Addition of an angiotensin receptor blocker to full-dose ACE-inhibition: controversial or common sense?

Both angiotensin-converting enzyme (ACE)-inhibitors and angiotensin receptor blockers (ARBs) interfere with the activity of the renin-angiotensin system (RAS) in a different way. Theoretically, one might expect beneficial effects when they are used in combination, as a more complete suppression of the RAS can be achieved. But can this additional effect still be seen in patients on full-dose ACE-inhibition? Several controlled trials demonstrated that combination therapy can have additional benefits in hypertensive patients, in chronic heart failure patients, and in both diabetic and non-diabetic nephropathy patients. However, the clinical benefit was not always as pronounced as expected and not every patient will benefit from dual blockade of the RAS. There is some evidence of a less pronounced effect of combination therapy when a full dose of the ACE-inhibitor is given. However, it is well known that ACE-inhibitors cannot completely suppress the formation of angiotensin II, in particular, when the RAS is activated. Indeed, clinical trials indicated that add-on therapy with an ARB was especially of use when the RAS remained activated despite full-dose ACE-inhibitor treatment. In summary, combination of a full-dose ACE-inhibitor and an ARB can be a rational choice in selected patients.